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# Designing Multispecies Worlds for Robots, Cats, and Humans

Eike Schneiders  University of NottinghamNottinghamUnited Kingdom
<EMAIL_ADDRESS>,  Steve Benford  University of
NottinghamNottinghamUnited Kingdom<EMAIL_ADDRESS>,  Alan
Chamberlain  University of NottinghamNottinghamUnited Kingdom
<EMAIL_ADDRESS>,  Clara Mancini  The Open UniversityMilton
KeynesUnited Kingdom<EMAIL_ADDRESS>,  Simon Castle-Green
University of NottinghamNottinghamUnited Kingdom simon.castle-
<EMAIL_ADDRESS>,  Victor Ngo  University of NottinghamNottinghamUnited
Kingdom<EMAIL_ADDRESS>,  Ju Row Farr  ,  Matt Adams  ,  Nick
Tandavanitj  Blast TheoryBrightonUnited Kingdom<EMAIL_ADDRESS>and  Joel Fischer  University of NottinghamNottinghamUnited Kingdom
<EMAIL_ADDRESS>
(2024)

###### Abstract.

We reflect on the design of a multispecies world centred around a bespoke
enclosure in which three cats and a robot arm coexist for six hours a day
during a twelve-day installation as part of an artist-led project. In this
paper, we present the project’s design process, encompassing various
interconnected components, including the cats, the robot and its autonomous
systems, the custom end-effectors and robot attachments, the diverse roles of
the humans-in-the-loop, and the custom-designed enclosure. Subsequently, we
provide a detailed account of key moments during the deployment and discuss
the design implications for future multispecies systems. Specifically, we
argue that designing the technology and its interactions is not sufficient,
but that it is equally important to consider the design of the ‘world’ in
which the technology operates. Finally, we highlight the necessity of human
involvement in areas such as breakdown recovery, animal welfare, and their
role as audience.

artist-led research, performance-led research, animal-computer interaction

††journalyear: 2024††copyright: rightsretained††conference: Proceedings of the
CHI Conference on Human Factors in Computing Systems; May 11–16, 2024;
Honolulu, HI, USA††booktitle: Proceedings of the CHI Conference on Human
Factors in Computing Systems (CHI ’24), May 11–16, 2024, Honolulu, HI,
USA††doi: 10.1145/3613904.3642115††isbn: 979-8-4007-0330-0/24/05††ccs: Human-
centered computing Human computer interaction (HCI)††ccs: General and
reference Design††ccs: Computer systems organization Robotic autonomy††ccs:
Applied computing Media arts

##  1\. Introduction

From cleaning our homes (Schneiders et al., 2021), to mowing our lawns (Verne,
2020), to delivering shopping (Valdez et al., 2021) and couriering items
around hospitals, (Tornbjerg et al., 2021), robots are finding their place in
daily life. As they do so, they will inevitably interact with and be
encountered by animals. These might be companion animals, the pets who share
our homes or the guide dogs who help us navigate public places, but they might
also be wildlife. Often these encounters will be unplanned and secondary to
the robot’s intended task, for example cats riding
Roombas111https://youtu.be/uGI8Od22WM4, guide dogs being confused by delivery
robots (Bhat and Zhao, 2022), or hedgehogs having to navigate in a world
inhabited by lawn mowing robots (Rasmussen et al., 2021). However, they could
also be intentional. We could design robots to serve animals too. Despite the
inevitability of such encounters, planned or otherwise, little is known about
how to design robots for animals. Can we even trust them with each other?

We present Cat Royale (Theory, 2022; Schneiders et al., 2024b, 2023; Benford
et al., 2024; Schneiders et al., 2024a), a creative exploration of designing a
domestic robot to enrich the lives of cats through play. A robot, in contrast
to non-embodied technology, offers the advantage of physical manipulation of
objects in the enclosure. Therefore, it lends itself well to the context of
cat play as it is able to, e.g., wave feathers, provide treats, or drag
strings around the enclosure for the enrichment of the cats. Cat Royale was an
artist-led project (Benford et al., 2013) that set out to tackle the wider
question of trust in autonomous systems. The idea of creating a playful robot
for cats emerged as a means to achieve this goal, while also providing
benefits for the cats. Over the course of eighteen months, the artists, in
partnership with a team of HCI/HRI researchers, and supported by experts in
cat play and welfare, and animal-computer interaction created a bespoke
enclosure, a ‘cat utopia’ in their terms. At its centre, a robot arm
manipulated a variety of toys to try and entertain a small community of cats
who lived there for six hours a day for twelve days. During this time, the
robot offered over 500 play activities for the cats. In the background, the
artists, roboticist, animal-computer-interaction specialists, machine learning
experts, and animal behaviour experts worked tirelessly to ensure their
safety, wellbeing and hopefully, pleasure.

While Cat Royale was undoubtedly a unique experience, and not one that can be
directly transferred into people’s homes, and while an art project is an
unusual approach to designing robots and animal-computer interactions, we
propose that Cat Royale offers important insights into the design of robots
for companion animals. The artists’ meticulous attention to detail in
delivering a safe and entertaining experience for the cats drove them to ‘go
beyond’ many of the conventional aspects of robot design. Yes, they had to
choose and adapt robot hardware and implement software for motion control,
tracking the cats, and recommending games. However, they also had to carefully
embed these within a wider environment that allowed the cats to engage
appropriately, while humans could oversee safety and enjoy the spectacle. In
short, they needed to create an entire ‘robot world’.

We reflect on the design of Cat Royale, and how the experience unfolded with
the cats, to draw out wider implications for creating robot worlds (or, more
formally ecologies (Lyle et al., 2020)). We distil two key contributions.
First, we highlight the importance of world design for robots; of designing
key aspects of the places they inhabit alongside companion animals and humans,
including providing safe spaces and observation spaces for all parties,
enabling robots to flexibly interact with passive objects, and finding a
decoration scheme appropriate to all. Second, we reveal how designing a robot
to autonomously engage animals requires consideration of interspecies
interactions, from spectating, to overseeing, to cleaning up the resulting
mess. Our aim is to sensitise designers to the complexities of robot
encounters with animals—intended or otherwise.

##  2\. Related Work

Related work falls into two categories. First, with the immediate goal of Cat
Royale in mind, we review previous attempts to design digital technologies to
play with cats. Second, we consider a body of work that speaks to the wider
idea of designing robot worlds and digital ecologies that has emerged from our
reflections.

###  2.1. Playful digital technologies for cats

####  2.1.1. Commercial cat toys

Cats are specialised meat-eaters, who have evolved to hunt and consume small
prey, for which their sensory, cognitive and physical characteristics, and
behavioural aptitudes are supremely adapted, including for example a high
visual (Miller and Lights, 2001), auditory (Populin and Yin, 1998) and tactile
(Bradshaw, 2012) sensitivity to movement. Many commercial products for cat
care and entertainment are designed to leverage these characteristics and
aptitudes to enhance cats’ domestic experience as well as humans’ experience
with their feline companions. There is a significant global market for cat
toys and games (valued at around US$ 1 billion (Insights, 2023)) spanning a
great variety of mechanical devices: from simple canes to which feathered
objects are stringed for cats to paw at and catch as the cane oscillates under
their blows (e.g. (Shop, 2023)); to complex modular circuits featuring
perforated tunnels through which balls run for cats to ambush and catch at the
openings located along the tunnel tracks (Catit, 2023). A wide range of smart
toys can also be found on the market: from smart boxes that activate when cats
approach and that randomly poke feathers through holes for cats to try and
grasp before they disappear again (e.g. (Dream, 2023)); to wheeled mice that,
after periods of inactivity, wake up and zoom away at speed, avoiding
obstacles and resetting themselves as they roll over, so they can continue to
entice their feline users to chase them (e.g. (Petlibro, 2023)).

####  2.1.2. Digital screens for cats (and humans)

Despite the size and technological advances of the cat toy and games market,
Animal-Computer Interaction (ACI) research on computing-enabled toys for
multispecies play with cats has been relatively limited. One notable exception
concerns exploring how digital screens may enable cats and humans to share
play experiences. (e.g., (Noz and An, 2011; Kasuga et al., 2017; Mancini,
2013)). Noz and An (2011) developed and evaluated a game application for iPad,
designed to leverage cats’ chase drive, and to enable humans and cats to play
together. Its interface featured a mouse icon which ran randomly across a
screen, producing sounds and changing orientation, velocity and direction when
tapped; an associated application for iPhone also allowed the human to control
the virtual mouse’s motion variables. Human participants in a user evaluation
reported that the game had been enjoyed by the cats and that it had helped
them bond with them. However, these findings were based on the human
participants’ perceptions of the cats’ experience, rather than on expert
behavioural analysis over an extended period. A similar tablet game was
developed by Westerlaken and Gualeni (2014) to enable humans and cats to play
together via an interface presenting a virtual aquarium where fishes swam
around randomly for the cats to catch. The game provided both visual and audio
feedback for the cats and the interface allowed the human player to modify
some of the game’s variables. Consistent with cats’ sensory characteristics
and behavioural aptitudes (Haddon and Mills, 2023), behaviour analysis of
cats’ interaction with the artefact suggested that the cats were particularly
stimulated by the audio feedback and by variations in the speed of the fishes,
and that they especially focused on the sides of the tablet when the fishes
disappeared from that edge of the screen. However, while this kind of virtual
experience raised the interest of many cats, researchers have warned that
digital interactions which stimulate biologically important behaviours (e.g.,
hunting) and promise biologically significant outcomes (e.g., catching prey),
without providing the release that a physical interaction would afford, may
have a negative impact on the animals’ welfare (Haddon and Mills, 2023).

####  2.1.3. Intelligent environments and robots

Previous work by Pons et al. (2015) aimed to develop intelligent, multi-modal
playful environments which leverage machine learning and embodied
interactions, involving multiple technological elements, to engage cats
through the provision of adaptive experiences based on their responses. To
this end, the researchers developed a depth-based tracking system, using
sensor data from Microsoft Kinect, for detecting the location, body posture,
gestures and field of view of feline and other players within the environment
(Pons et al., 2015). They also conducted an observational study of cats
interacting with different technological objects, both digital (ground
projections of mice) and physical (robots Sphero and Jumping Sumo) (Pons et
al., 2017). The study aimed to assess the system’s ability to recognise cats’
interactions with the stimuli, which it did with varying degrees of success.
The authors also assessed the cats’ responses when presented with the
multimodal stimuli and found that the cats were more interested in tangible
ones than they were in digital ones.

We can consider general purpose robots to be a form of intelligent
environment, especially ones that learn and adapt. In the case of Animal-Robot
Interactions (Kim et al., 2009), whether or not animals are the target users,
pursuing this aim would require robots to correctly interpret animals’
communication modes, allowing them to provide input, and to respond safely and
appropriately according to the needs and wants animals might express. But, in
order to provide enriching experiences that can foster cats’ wellbeing, the
implementation of such intelligent environments might require the collection
and triangulation of large amounts of data from multiple sources, informed by
appropriate scientific knowledge on cat behaviour and welfare. In this regard,
Lawson et al. (2015) have highlighted how an imprudent use of quantifying
technologies may lead to an incorrect interpretation of and response to cats’
welfare needs, as well as to a weakening of the human-cat bond. The authors
conducted a qualitative study with cat owners and cat welfare experts who had
been asked to consider speculative designs of cat-quantifying technologies;
they found that cat owners were desirous and willing to trust information on
their animals provided by the technologies in question, even though this had
little scientific validity. This raises the question as to what might induce
people to trust these technologies and, more importantly, what conditions
these should meet before they can be trusted to have a positive impact on
animal guardianship, care and wellbeing, which is a key aim of the Animal-
Computer Interaction (ACI) field (Mancini, 2011).

Cat Royale occupies a distinct position at the intersection of this body of
related work. It responds to the importance of tangible play and the market
for interactive physical toys, but aims to extend their possibilities by
having an autonomous robot deploy the toys, albeit with a human-in-the-loop
(Kim et al., 2009) to moderate the robot’s decisions and ensure safety. It
also embeds this robot, toys and cats into an intelligent environment that
monitors the resulting play and tries to learn the cat’s individual
preferences. Finally, it recognises questions of trust, exploring these
through dialogue with its public audience.

###  2.2. Robot worlds and digital ecologies

A key reflection that emerges from our experience of Cat Royale concerns the
importance of carefully designing the wider world within which a robot must
operate beyond designing the robot itself.

There is much research in Human-Robot Interaction (HRI) on investigating and
designing direct dyadic interactions between humans and robots (e.g.,
(Anderson-Bashan et al., 2018; Schneiders et al., 2022)). While this will
remain important, here we focus our attention on the far fewer examples of
also designing the world within which such interactions occur. The Moxi robot
by Diligent Robotics (Inc, 2023) is an assistive technology deployed in a
variety of hospitals, all with different spatial constraints. A key challenge
for Moxi concerns opening the various doors it encounters. The solution was to
customise the environment, deploying robot-readable (Higginbotham, 2019)
stickers at doors to allow Moxi to interact correctly. Another example is the
SN robot, designed to mediate social interactions between lonely individuals,
and ultimately reducing the feeling of loneliness (Jeong et al., 2018). A
robot who, through sensors placed within the environment, detects activities
performed in the household (e.g., opening of doors or using the washing
machine). More generally, Jeong et al. (2018) show how the design of the
environment, and not ‘just’ the robot design, impacts robots’ capabilities,
ultimately informing the entire interaction. In a similar vein, Higginbotham
(2019) writes of the challenges of robots and other emerging devices changing
faster than the environments in which they are deployed and the infrastructure
on which they depend and argues for the importance of redesigning both to
create a ’robot readable world’ (using a phrase credited to designer Carla
Diana) (Higginbotham, 2019).

Looking beyond robots, various researchers have drawn attention to the need to
understand and design interaction as part of a wider context within which it
is situated. The concept of an ‘ecology’, in various forms, has often been
raised as a way to describe this broader perspective beyond the immediate
device (e.g., (Raptis et al., 2014; Bødker et al., 2016)). In reviewing 129
works on ecological approaches to digital technology, Lyle et al. (2020)
identify four key types: information ecologies as systems of people,
technologies, practices and values in a local environment; device ecologies as
systems of interconnected devices; artifact ecologies as foregrounding the
relationship of artefacts to practices; and communication ecologies as
foregrounding on communication practices. They further propose that ecologies
can be considered at three levels of scale: the micro scale of individuals,
artefacts and tasks); the meso scale of people and practices; and the macro
scale of organisations and activity systems. Others have employed the term
‘ecosystem’ to describe the wider organisational contexts within which digital
technologies exist, including the regulatory and governance structures that
underpin trust (Stahl, 2022). In short, consideration of the wider ecology
within which technology exists can take numerous shapes and forms, but in its
essence involves looking far beyond the design of ‘just’ the technology.

Figure 1.  Left: The control room (front to back): robot operator, artists,
vision mixer. Centre: Inside the Cat Royale enclosure, in the centre of the
room is Clover playing with the String deployed by the Robot. In the upper
left corner Pumpkin is resting on one of the high perches. Behind the robot
are the four toy racks used to store end-effectors. Two of the high dens are
visible, allowing the cats to retreat. On the left, a scratching post, as well
as the ball run tube system is visible. Within the enclosure a multitude of
plants are distributed. Right top: The robot control system. The activity
library is on the left. Each blue box (52 visible) represents one of the many
possible robot actions. Right bottom: The iPad based interface for documenting
the cat stress score (Kessler and Turner, 1997), this is based on a seven
point scale (1: Fully Relaxed to 7: Terrified).

Turning to the home as a distinctive ecology, the architect Stewart Brand
offered a framework to express the evolution of a building over many years in
terms of so-called ‘shearing layers’. He presents six distinct layers: 1) the
physical ‘site’ characterised by the geographical site which defines the
boundaries of the structure; 2) the ‘structure’, which is the building or
structure itself; 3) the ’skin’, which is embodied in the facade and walls of
the structure; 4) the ‘services’ that are embedded into these, including
wiring and other infrastructure needed to operate and maintain it; 5) the
‘space plan’ which is the layout of the space including placement of walls,
doors, and floors; as well as 6) and the ephemeral ’stuff’ such as furniture
and decorative items which is less static and permanent (Brand, 1995). Rodden
and Benford (2003) build on this framework to consider how digital
technologies become integrated into and co-evolve with the home. While digital
technologies might impact on (and be impacted by), all six layers, skin,
services, space plan and stuff are most immediately obvious to consider in the
design and deployment of any new technology. Moreover, they may come into
conflict with each other due to the different rates at which they evolve,
consistent with Higgenbotham’s line of argument highlighting the tension
between robots, robot environments and infrastructure (Higginbotham, 2019).

##  3\. Approach

With Cat Royale, we have followed the approach of Performance-led Research in
the Wild (Benford et al., 2013) as a distinctive way to engage HCI research
with the performing arts to the benefit of both. Falling under the broad
umbrella of Research Through Design, this is design-led, unfolding through the
practical creation of public performances and installations and subsequent
reflection on these to generalise design knowledge. It also sits within a
broader history of HCI engaging the arts, both to address their distinctive
challenges with regard to engagement, presence and other matters (Edmonds,
2014), but also to surface fresh perspectives for the field, such as:
provoking interpretation through ambiguity (Sengers and Gaver, 2006);
deliberately designing uncomfortable interactions (Benford et al., 2012);
promoting environmental sustainability through activist art (DiSalvo et al.,
2009) and various provocations arising from artistic speculative design
(Andersen et al., 2018).

Papers grounded in Performance-led Research in the Wild have appeared in HCI
for more than 20 years with the approach being explicitly named and
articulated in 2013 (Benford et al., 2013). Its distinctiveness arises from
the particular relationship it establishes between art practice and HCI
research. Typically, the process begins with a team of professional artists
and computer scientists, including HCI researchers, building a relationship.
At some point the artists propose a creative vision and/or opportunity to
create a new artwork. While this may be in part grounded in the technical
capabilities of the researchers, and perhaps even broadly inspired by their
research (especially if the collaboration is partly funded by a wider research
grant), the vision is essentially an artistic one, and often takes the
technology in an unexpected direction, sometimes offering a critical
perspective on it. The first role of the researchers is to help the artists
realise their vision, collaborating with them to iteratively develop software
and hardware, and enable early public performances. In return, the researchers
get to study the artists’ rationale and process, and the audience’s
experience. Reflection across these often yields unusual perspectives on
interaction.

Figure 2. Left: Public installation as presented during Curiocity Brisbane
World Science Festival5 (day five). Right: Installation currently on display
at the National Science Gallery in London (June 2023 - January 2024).

In this case, the artists—who have been collaborating with some of the authors
on multiple projects for decades—were invited to make some form of artwork
that would explore the question of trust in autonomous systems. The artists
have over 30 years of experience using new technologies to create a variety of
artworks, including performances, games, films, apps, and artistic
installations. Following exploratory workshops at which they experienced
various robots, their artistic response was Cat Royale, which the researchers
then helped implement over a period of 18 months. The following account draws
on design documents, meeting notes, observations, and autoethnographic field
notes and video recordings (especially from the ‘robot operator’) to reflect
on the process, up to and including what happened when the cats played with
the robot. Observations and autoethnographic field notes used to give the
account of Cat Royale were made by various members of the team including the
artists, the robot operator, and members of the research team who observed the
activities taking place. This material does not cover public reaction to
watching the final edited film, which is still being deployed in museums and
galleries and will be reported in subsequent papers. Instead, the contribution
of this paper is to report on the lessons that emerged through designing a
unique and challenging artefact.

Our project was advised by, and received ethical approval from, three ethical
review boards at the lead researchers’ University. The Animal Welfare and
Ethical Review Body (AWERB) ensured compliance with the regulations and law
governing research involving animals in our country; the Committee for Animals
and Research Ethics (CARE) in the School of Veterinary Science shaped and
approved our cat welfare protocol. The Computer Science research ethics
Committee (CSREC) approved the human-facing aspects of the project including
consent, anonymity and data collection and management (Benford et al., 2024).

##  4\. Cat Royale: The Multispecies World

To investigate multispecies interaction between human and non-human actors
with a (semi)autonomous system, the artist-led Cat Royale project team,
comprising artists and a multidisciplinary set of researchers, asked itself
the following question:

> “How do we situate an autonomous system within a wider environment, which is
> simultaneously engaging for spectators, ensures cat well-being, and is
> suitable for the autonomous system to operate in?”

This section outlines the project and its non-human and human components and
actors. The design process and the accompanying challenges of Cat Royale,
which this paper focuses on, were developed over the course of eighteen
months.

The Enclosure. The project’s centrepiece was a bespoke enclosure, built for
and inhabited by three cats. The three cats, a parent and two offspring, spent
six hours a day (two periods of three hours) over twelve consecutive days
within the enclosure, a total of 72 hours. As we describe below, the enclosure
was designed, in the artists’ words, to be a ’utopia’ for the cats, a
luxurious space that could cater to their various needs, including play. Its
striking visual design was also intended to convey the idea of luxury to the
audience when filmed via the eight cameras embedded inside.

The Robot. Placed in the centre of the enclosure was the robotic arm, whose
sole purpose was to play with Ghostbuster, Clover, and Pumpkin, the three
inhabitants of the enclosure. Provided with access to a series of custom end-
effectors and a wide range of different toys and attachments, the robot was
able to offer a variety of games and treats. At regular intervals, the robot’s
underlying system proposed a robot action aimed at maximising a specific cat’s
assessed happiness (see Section 4.5). If approved by the lead artist of the
installation, the robot would execute a playful activity targeted at
increasing the cat’s happiness, while being monitored by the robot operator to
ensure safe robot movement in close proximity to the cats. To further ensure
animal welfare, each cat’s individual stress score (Kessler and Turner, 1997)
was ranked at 15-minute intervals by the team’s specialist in feline
behaviour. The robot performed more than 500 activities over the course of the
12 days, ranging from providing small cat treats222Regular food and water was
available to the cats at all times, regardless of their engagement with the
robot., to simple toys like a cardbox or a string, all the way to more
elaborate toys such as an orange bird toy or a battery powered wiggling fish
toy. Following each activity, each cat’s engagement—as a proxy for positive
attitude towards the robot’s provided entertainment—was ranked using the
Participation in Play scale (Ellis, 2022). The task executed (i.e., ‘present a
prey game with a toy bird’), the targeted cat, and the impact on happiness
where subsequently fed back into the robot’s machine learning system (i.e.,
the decision engine) informing future proposed activities.

Figure 3. Top left to bottom right: A selection of iterations showcasing the
enclosure design from initial inspiration by the art of Verner Panton, to 3d
renderings and scale models, to the final full sized installation.

The Installation. All cat and robot activities within the enclosure were
constantly filmed using eight cameras (see Figure 5 1), the output of which
were mixed in real-time by an experienced television vision mixer to capture
the best possible view of the action and to add descriptive captions to it.
The footage was subsequently edited into an eight-hour long film that was
exhibited to public audiences at the Curiocity Brisbane World Science
Festival333https://www.worldsciencefestival.com.au/news/cat-royale-twelve-
days-three-cats-one-ai-trained-robot (see Figure 2 left), and at the National
Science Gallery in London444https://london.sciencegallery.com/ai-artworks/cat-
royale (see Figure 2 right) for six months. Short highlight videos (2 – 5
minutes) were also edited and released online during filming.

The remainder of this section, elaborates on core elements of the design of
the cat and robot world that is Cat Royale.

###  4.1. Designing the enclosure

Inspired by art from the 70s, e.g., Verner Panton Visiona II
exhibit555https://www.verner-panton.com/en/collection/visiona-2/, Cat Royale’s
vision was to create a luxurious environment using organic shapes and colours,
which would be of interest to and appropriate for the cats that would use the
space, as well as of interest to the audience who would watch the cats in the
space. The design of the enclosure was informed by cat-centric criteria to
provide for their needs, entailing the presence of high perches, resting dens
and viewing-platforms, suspended walkways, rolling floors (which provided
hiding places to ambush the toys during prey-behaviour games with the robot),
and soft—and claw-able—textures. The audience’s input, provided through the
audience advisory panel (see Section 4.5) and the artists’ vision for the
enclosure , had to be aligned with the cats’ needs, consistent with advise
from the animal welfare and behaviour experts (i.e., a veterinarian as well as
an expert in feline behaviour).

To this end, the enclosure went through numerous iterations, sketches, mock-
ups, 3D renderings, physical scale models, until the final design was
installed (see Figure 3 for a selection of different stages of the enclosure
design). With the enclosure being a crucial part of the success of the
installation, we had to make sure that it allowed the cats enough agency to
prioritise their well-being by, e.g., allowing them to engage with the robot
or withdraw from it, using the many perches, walkways, dens and other
resources provided, consistent with ACI research ethics guidelines (Mancini,
2017). Furthermore, apart from being entertained by the robot, the cats had
species-specific and individual needs, identified by experts in feline
behaviour, veterinarians and their owner. Accordingly, the enclosure was
equipped with numerous cat friendly plants, a scratching post, a ball run, and
a water fountain as forms of enrichment, as well as multiple feeding stations
and secluded litter boxes, to prevent resource-based competition among the
cats. While the enclosure was built for the cats as primary
stakeholders—making traversal on the sloped surfaces suboptimal for
humans—accessibility for humans was still vital. Following each three-hour
session, members of the team had to be able to enter the enclosure, after the
cat owner had safely removed the cats, in order to perform regular
maintenance, such as vacuuming, refilling the water fountain, emptying the
litter boxes, or making smaller adjustments to the robot, cameras, or
enclosure. In addition to the entrance to the enclosure, two-way mirrors on
both sides allowed for viewing from both the control room and the viewing
area.

Figure 4. From left to right: Clover, Pumpkin, and Ghostbuster.

###  4.2. The Cats

As non-human stakeholders, such as cats, are increasingly encountering
autonomous systems, and vice-versa, it is important to understand how to
design these systems for, and with, them. The cats’ involvement was an ongoing
process, from the recruitment of the specific animals, i.e., Clover, Pumpkin,
and Ghostbuster (see Figure 4, left to right), to their safe return home
following the conclusion of the installation, all the way making sure that
they thrived.

Animal welfare was a constant priority throughout. To ensure this, among other
considerations, the cats needed to be familiar with each other (so they would
be comfortable sharing the enclosure) and live within close proximity of the
art studio in which the enclosure was to be built, ensuring that their
transport would have minimal impact. Furthermore, in order to make sure that
the cats were not deprived of contact with their owner, the owner needed to be
able to move to the art studio for 17 days, including the twelve days of the
installation’s deployment and a five-day habituation period prior to the
deployment. Moreover, the capacities of the underlying computer Computer
Vision (CV) System needed to be considered. To this end, three visually
distinct cats were chosen to improve the ease of detection for the CV System.
In line with ACI ethics principles proposed by Mancini (Mancini, 2017), we
sought two complementary forms of consent for the feline participants.
Firstly, we secured mediated consent from the cats’ owner, as the agent with
the authority to represent the best interests of the cats, and secondly by
designing the enclosure and the robot (as well as its placement) in a way that
allowed the cats to provide or withdraw their contingent consent, by choosing
to either engage with the robot, and how, or not to engage with it and instead
retreat to the many protected and comfortable spaces provided by the
enclosure.

###  4.3. The Robot and its Underlying Systems

Just as the cats’ recruitment was vital, so was the selection of the robot
used in the enclosure. The robot’s morphology, range, movement speed, and
lifting capacity endowed, or deprived, the artist of different affordances in
relation to the movements that could be executed. Furthermore, the robot, as
instantiation of a physically embodied autonomous system, had a potentially
tangible impact on the cats’ wellbeing and safety. For Cat Royale, the choice
was to use a lightweight robot with a small payload and reach, thereby
allowing the cats to easily withdraw from it. The choice for the project fell
on the Kinova Gen3 lite robot
arm666https://www.kinovarobotics.com/product/gen3-lite-robots, a small
collaborative robot with 6 degrees of freedom, 0.76 meters reach, an
integrated two-finger gripper providing it with a maximum payload of only 0.5
kilograms.

Alongside the hardware, three software components were developed to drive the
robot: 1) the above-mentioned CV System, 2) a decision engine, and 3) a robot
control system.

Figure 5.  1. One of the eight iPhones mounted in the enclosure. 2. Close up
of the decision engines recommendation. Visible is the proposed cat (Clover),
the task (Helicopter game), the toy (Helicopter), as well as some meta data
for the log files. 3. Computer Vision System identifying Pumpkin and Clover,
each one highlighted with a boundary box. 4. Emergency stop button desk
mounted next to operator.

The CV System identified the individual cats (see Figure 5 3) and their
positions in the enclosure so that the system could target games at specific
cats. The data set that was used to train the system for this classification
task included 7353 videos of cats, labelled by volunteers using the Zooniverse
crowd-sourcing platform777https://www.zooniverse.org/projects/blasttheory/cat-
royale. The decision engine was the core system which provided the robotic
system with autonomy. At regular intervals, approximately six minutes after
the previous activity was completed, the decision engine would propose an
activity for the robot targeting any of the three cats, e.g., ‘Prey game with
bird colours, target: Ghostbuster’. To ensure that a balance was struck
between offering the preferred activities and providing sufficient activity
variation, the decision engine varied the so-called exploration-to-
exploitation ratio throughout the course of the project. That is, during the
early days, when no or little training data existed to determine the
performance of the robot’s activity, the system would rely on exploration,
i.e., trying random activities to collect training data. With the increase in
collected training data, the system learned which activities had a positive
impact on each of the cats’ happiness score, allowing the decision engine to
propose specific activities and toys depending on the individual cats’
preferences. This led to a higher degree of exploitation, i.e., the use of
specific activities that were proven to have a positive impact on cat
happiness. The robot, once the specific activity was approved by the artists,
would execute the movements. This was done by the robot operator (see Section
4.5) using the robot control system. The control system acted as the interface
between control room and robot, and allowed the robot to autonomously plan
trajectories for moves, which could be executed—under human supervision as
discussed below—at will.

###  4.4. Toys, Racks, and Robot Movement

With the robot selected, the next step was to provide it with additional
affordances so that it could play a variety of games. These needed to allow it
to manipulate a wide range of items (e.g., feathers, pillows, treats, bells,
or balls) in order to attempt to engage the cats (see Figure 6). To provide
the artists with greater artistic freedom, we designed and 3D printed custom
end-effectors. These were supports to which a range of objects could be safely
secured and which the robot arm’s two-finger gripper could securely grab, from
custom-built racks, and hold. This way, the end-effectors augmented the
robot’s capabilities beyond the limitations of the two-finger gripper,
enabling the artists to prototype and experiment with different toys and
movements, expanding the repertoire of playful experiences available to the
cats—including some that allowed the cats to, in some regard, overpower the
robot. Thus, the customisation allowed a wider range of creative possibilities
for the artists and enrichment activities for the cats.

Figure 6. Left top: Four of the wide variety of balls for available to the
robot. Left bottom: The toy rack with four end-effectors used for balls and
treats (rack on the right) as well as attaching various toys to (three racks
on the left). Right: Various feather toys which can be used with the three
most end-effectors.

Perhaps, the most vital capacity of the robot was its movement. We needed to
be able to generate movements with the robot that struck a balance between
predictable routine and exciting novelty for the cats. In addition to engaging
the cats, the art installation needed to captivate audiences. So, while the
installation started with a set of supported robot movements, the robot
operator—directed by the artists—added new movements on a daily basis,
gradually increasing the repertoire of the robot. The initial set of movements
included the controlled picking-up and putting-down of toys from the toy
racks. During the twelve days, the movement library available to the robot
grew through the addition of new ways of performing, for example, ‘dragging’,
‘dangling’, ‘dropping’, ‘throwing’, and ‘offering’ motions. The need to add
new movements on a daily basis, necessitated the robot—and its underlying
systems—to allow for rapid prototyping and development of new sequences.
Furthermore, it was vital to design and implement a variety of movements, as
not all movements made sense with all toys, e.g., a ‘throwing’ movement made
sense with a ball, while not being applicable with a feather toy. This
customisation of movements allowed the robot to engage the cats differently
depending on the specific toy used, and the individual cats’ preferences.

###  4.5. Humans-in-the-loop

While, in line with ACI research ethics recommendations (Mancini, 2017), the
Cat Royale project placed the animals at the centre, a multitude of human
stakeholders were involved and therefore had to be accounted for during the
conceptualisation and deployment of the artistic installation. This included,
the artists, two robot operators, and the audience, an animal welfare officer,
a toy wrangler, the cats’ owner, a vision mixer, and the members of three
ethics panels who conducted the project’s ethical review and approved the
proposed work. While the human actors in some sense collaborated on the same
tasks—i.e., ensuring the cats’ welfare and increasing their happiness, and
successfully delivering an artistic installation for the audience—their impact
on the installation varied.

The audience had no direct impact on the execution of the project but were
involved in its conceptualisation—represented by 15 members from the general
public who formed an audience advisory panel. This had an impact upon the
design of the environment by, e.g., conceptualising how a cat utopia would
look and providing input as to how related information was to be presented to
audiences around the world. The latter included, e.g., how to convey
information about the cats’ happiness scores and the decisions made by the
robot. Through the panel’s representation, the general public was given a
voice in the design of the project.

Behind the scenes of Cat Royale (see Figure 1 left) the artists and the robot
operator collaborated closely to ensure the successful operation of the robot.
The system, specifically the decision engine as described in Section 4.3,
proposed concrete actions for the robot to carry out in order to increase the
happiness of the cats. It was then up to the directing artist to make a
judgement call—trusting and accepting the system’s recommendation, executing
the proposed action and hoping it would lead to increased happiness for the
cats and excitement for the audience; or rejecting the proposed action and
requesting a new one.

To ensure safety, the system relied on a human-in-the-loop mediating between
artist and robot, namely a robot operator. The robot operator would, following
the decision of the artist, initiate and monitor the robot during task
execution. Their primary responsibility was to ensure that the robot’s
trajectories would in no way put the cats at risk. To ensure that every action
of the robot was monitored and that the operator could intervene instantly, if
needed, the system relied on a dead man’s switch. This was a designated button
that enabled the robot to move as long as the operator pressed it but that
stopped all robot movement when released. This was a safety precaution to
ensure that the operator was in control at all times. Therefore, as the one
who held ultimate control behind the scenes, the robot operator could—against
the artists and the decision engines recommendation—stop any robot action, if
they perceived it as posing a risk to the cats. As an additional safety
measure, the robot operator had access to an emergency stop (see Figure 5 4)
that would cut all power to the robot.888At no point was it necessary to use
the emergency stop button in order to ensure cat safety.

Following each performed robot activity, the system needed information
regarding the cats’ happiness score, i.e., the impact of the given activity on
each individual cat’s happiness score. To achieve this, the lead artists—who
closely monitored the environment, focusing on the cats’ engagement—used the
Participation in Play scale (Ellis, 2022) to rank each cat’s engagement, which
acted as a proxy for happiness on a scale from 0 to 5 (e.g., ‘No interest in
playing or retreats from attempts at play’ to ‘Enthusiastically playing,
moving around the environment’). Furthermore, the cats’ stress score (Kessler
and Turner, 1997) for each cat was recorded using instantaneous sampling
(i.e., at predetermined time intervals of 15 minutes) by the animal welfare
officer. At each 15-minute key point, a tablet would prompt them to evaluate
the facial expression and body language of each cat (stomach, tail, eyes,
pupils, ears, whiskers, and vocal behaviour), and identify the current stress
score for each cat on a 7-point scale (1: Fully Relaxed to 7: Terrified).

During the entire 12-day installation period, the vision mixer, in real time,
switched between the eight different camera angles and a series of overlay
screens (e.g., ‘Pumpkin happiness score increased by 2%’ or ‘Coming next:
Helicopter game for Clover’). This edited 6-hour daily video, cut in real
time, was presented to the audience at the Curiosity Brisbane World Science
Festival in Brisbane, Australia. Therefore, the vision mixer had the important
function of creating the final perspectives made available to the public.

##  5\. The Narrative Unravelled

We now turn our attention to the events that transpired during the deployment
of Cat Royale. While our aim in this paper is not to evaluate the success of
Cat Royale in terms of effectively playing with the cats, we do note that,
from the perspective of the artists and wider team, the experience was judged
to be successful. The successful completion of Cat Royale, while not formally
evaluated in this paper, is multilayered. Firstly, the cats safely inhabited
the enclosure for twelve days without needing to be withdrawn due to stress or
injury. The cats waited in front of the door to the enclosure, seemingly
awaiting to gain access to it. Secondly, within the enclosure, they
voluntarily chose to engage with the robot’s games, typically descending from
their perches to play for several minutes at a time. Thirdly, the team were
informally (i.e., not backed up by a scientific analysis), of the view that,
on the whole, the play was pleasurable and not frustrating for the cats. This
sentiment was shared by the animal welfare officer based on the cats’ body
language, as well as the cat owner. Lastly, Cat Royale seemed enjoyable for
humans to watch. With countless visitors at the installation in Brisbane, tens
of thousands of views on YouTube, thousands of likes on social media, and
extensive engagement in comment threads across various platforms, the project
effectively captured public attention.. However, there were revealing
incidents along the way. In the following, we draw on autoethnographic field
notes and video recordings from the team, especially from the two robot
operators and the lead artist, to paint a picture of how Cat Royale unfolded.
We present a range of vignettes from typical operation to more challenging
examples—requiring careful management—all of which presents the orchestration
of Cat Royale.

###  5.1. Typical Robot Engagement

This section presents a cat-centric perspective by highlighting what typically
happened within the enclosure. Vignette 5.1) describes a representative
example of the robot activity in which some—but not necessarily all—cats
engaged in playful behaviour. This type of activity, with a variety of
different toys and movement sequences, occurred several hundred times over the
course of the twelve days.

> 17:47:  Just over halfway through the second session of the ninth day, the
> decision engine proposes ‘Helicopter prey game, target: Ghostbuster’.
>
> 17:48:  Around thirty seconds later, once the activity has been announced to
> the audience watching in Brisbane, the robot awakens and moves towards the
> helicopter toy999A small three winged propeller with feathers at the end of
> a string connected to a support, which is currently mounted on the second
> toy rack.
>
> 17:48:  With a circular motion of its first joint (i.e., the base) the robot
> rotates the helicopter toy towards the centre of the room. While all three
> cats are following the toy’s movement with intensity, Pumpkin is the first
> to lower his posture and wiggle his entire body, indicating an impending
> pounce. Indeed, one minute and four seconds after the robot has picked up
> the toy, Pumpkin pounces on it.
>
> 17:49:  After an initial period of observation, Ghostbuster joins Pumpkin in
> attacking the toy, all the while Clover continues to monitor the situation
> from the elevation of one of the resting dens located under the ceiling of
> the enclosure.
>
> 17:49 - 17:52:  While Pumpkin disengages and retreats to one of the high
> walkways, Ghostbuster continuously follows the toy as the robot slowly drags
> it around itself. As the robot lifts the toy [17:52], Ghostbuster jumps
> towards it and continuously hits it with his paws, only to disengage shortly
> after. Throughout the entire engagement, the cats pay attention to the toy,
> while being seemingly disinterested in the robot itself.
>
> 17:54:  Once Ghostbuster stops engaging with the Helicopter toy, the robot
> carefully places the toy back onto the rack before gracefully going back to
> its retracted stand-by position, awaiting the next command. Based on his
> interaction with the toy, Ghostbuster’s happiness score is updated as having
> increased by 3%.
>
> 17:48 - 17:54:  During this entire time, the various humans-in-the-loop
> follow the action intensely. In the control room, the vision mixer stares at
> the overview screen with the eight cameras, making sure that the audience is
> presented with the most interesting angle available. The artist observes the
> cats through the two way mirror, excited about every cat-robot engagement.
> The robot operator, whose finger is pressed onto the dead man’s switch,
> observes the robot—and its surroundings—should they need to pause the
> robot’s trajectory. On the other side of the installation—in the viewing
> area—the animal welfare officer pays attention to every little signal the
> cats’ body language express, ready to estimate their emotional states.
>
> Cat Royale, a regular occurrence. Day 9, afternoon session.

The activity described above could be considered a success. Most importantly,
no interventions by the robot operator or animal welfare officer were needed,
as the cats’ welfare was at no point at risk. Furthermore, two of the cats
engaged in the activity, especially Ghostbuster, who was the decision engine’s
target for this specific activity. During Ghostbusters and Pumpkin’s
engagement with the toy, Clover continuously used the high platforms and dens
to monitor the situation below. Since this activity was successful in safely
engaging the cats, it provided—based on the artist’s judgement—interesting
footage for the video to be presented to the audience. Thus, this is a good
example of an activity that achieved the primary task Section 4 of ensuring
cat well-being while engaging both the cats and the audience.

###  5.2. Intervening with the Robots Autonomy

The movement executed by the robot happened in an autonomous (but monitored)
manner. If everything went according to plan, the robot operator initiated the
movement—by keeping the dead man’s switch pressed—until the entire movement
sequence was successfully completed and the toy was placed back on the rack.
However, as autonomous agents, the behaviour of the cats could not be
predicted nor controlled; similarly, several of the toys responded
unpredictably to the cats’ interaction due to, e.g., different lengths in the
string to which they were attached or slight variations in the angle at which
the toy had been placed onto the rack following a previous activity and prior
to initiation of a new activity. Therefore, at times, there was a need for
manually overriding parts of the system. This was done in several different
ways, both by the artists and by the robot operator.

Figure 7. Robot control interface for the manual adjustments of the six
degrees of freedom and the opening/closing of the gripper.

####  5.2.1. Artistic intervention

Following the proposal of an action for a specific cat by the decision engine,
the artists could chose to request a new activity, rejecting the initial
proposition. This happened frequently (226 times), for a variety of reasons.

One reason for rejecting a specific action could be that the action was being
performed too frequently (e.g., ‘Ping pong ball run, target: Clover. REJECTED
- repetition’). Other reasons included the lack of correct calibration of the
activity, which could lead to robot failure—necessitating a restart (e.g.
‘Kicking toy in animal print, target: Ghostbuster. REJECTED - ‘breaks’ the
robot arm’). A third reason for rejection was related to the ‘status’ of the
enclosure. Dropping a ball in the ball-run, for instance, was eventually
rejected as a previous ball had become stuck, i.e., ‘Perforated ball tube run,
target: Ghostbuster. REJECTED - ball run is blocked’. Lastly, but most
importantly, some actions were rejected to ensure animal welfare. While, the
cats might have been interested in receiving frequent treats, eating too many
treats would not have been beneficial for their health. Therefore tasks like
‘Meaty stick treat, target: Clover. REJECTED - received enough treats this
session’ were at times rejected. Furthermore, the artists could reject a
proposed action, and instead request another specific action. This happened
much less frequently (17 times) and was typically related to the desire to (i)
try out a newly implemented task, or (ii) take advantage of the momentary
position of one (or more) of the cats. An example of the latter occurred in
the second session on day eight: ‘Perforated ball run for Clover. REQUESTED -
Clover is looking at the ball run.’

####  5.2.2. Operator intervention

In addition to the artists’ intervention, other types of interference with the
system’s autonomy could occur, namely by intervention from the animal welfare
officer—which never occurred—or from the robot operator. Both could, at their
own discretion, interrupt the installation or specific robot movements, if
they deemed that the cats’ welfare was at risk (e.g., to avoid a collision
with any of the cats). Vignette 5.2.2 highlights one such occurrence by the
robot operator.

> 12:37: Towards the end of the morning session the decision engine proposes
> ‘Simple game with feather boa, target: Pumpkin’. This activity has been
> successfully used once before the previous day, resulting in a maximum
> happiness score for Pumpkin.
>
> 12:38:  Shortly after it successfully picks up the toy, the robot moves the
> feather boa in a counter clockwise fashion towards the centre of the room,
> rotating around its base. While passing the ball run system, which some of
> the smaller balls can roll through, the soft feather boa collides with one
> of the pipes. Continuing the movement along the current trajectory could
> break the feather boa or, worse, it could break the tubes which might then
> hit the cats.
>
> 12:38 At the onset of the collision, the robot operator releases the dead-
> man’s switch, effectively stopping the robot’s motion mid trajectory.
> Utilising the six virtual sliders, which are part of the control interface
> (see Figure 7), the robot operator is able to manipulate each robot joint in
> isolation, allowing them to untangle the feather boa, bring the end-effector
> to a safe position, and continue the trajectory of the planned task.
>
> 13:10  Following the morning session, the stick to which the feather boa is
> stringed is shortened, which prevents future collisions with the tube
> system.
>
> Cat Royale, manually control to recover from collisions with objects in the
> enclosure. Day 3, morning session.

As Vignette 5.2.2 highlights, manual overrides to prevent damage to the
enclosure, the robot and, most importantly, the cats were possible. However,
none of these interferences—be it by the artists or the robot operator—were
without consequences. Artists’ rejections of specific tasks, for a variety of
reasons, could lead to a shortage of training data for the decision engine on
this particular activity, thereby influencing future proposed activities. In
the same fashion, operator interference with toys’ trajectories changed the
activity. This had the potential to alter the cats’ engagement with the
activity and ultimately the activity’s impact on their happiness score (using
the PIP scale (Ellis, 2022)), whether positively or negatively. This, just as
the artists’ interference, had implications for the data fed back to the
decision engine, thereby potentially affecting future activities.

###  5.3. The Cat is in Control

Figure 8. Day 10: Clover forcefully pulling at the right angle, leading to
loosening of the joint and an error occurrence in the control interface.

While many interactions between the cats and the robot went as expected (see
Section 5.1), at times unanticipated events occurred. One of these is the loss
of human control, as it could be removed from the operator by the cats’
forceful intervention. At 10:45 in the morning session on day 10, Clover
discovered that, when pulling from a particular angle, she was able to
physically overpower the robots joints, leaving the operator powerless for a
brief moment. Figure 8 illustrates an occurrence of Clover’s ‘forceful taking
of control’. This encounter occurred just as the play activity was about to
conclude, at least from the robots’ perspective. However, for Clover, the
orange bird toy was far more popular than most other toys and play activities,
and she was not ready to part with it just yet. As visible from Figure 8
picture 1–6, Clover pulls the Kinova while the arm’s last section is
positioned vertically (i.e., when it can be moved towards the floor or towards
the ceiling). Following a short pull by Clover, the joint unlocks, which
results in it dropping down (due to gravity). This overpowering of the robot
by one of the cats has an effect well beyond the cats’ enclosure: in the
control room, the robot operator receives an error code that demands to be
acknowledged because, during this brief period, no manipulations of the
robot’s joints are possible. Furthermore, when the trajectory of the robot is
abruptly disrupted, the activity it was performing is cancelled and the robot
has to re-initiate the proposed movement.

This—hunting or attacking the toys—behaviour persisted, with Clover ultimately
being rewarded by managing to strip the robot of the orange bird toy and
dragging it away. All the while, the string which connected the bird toy and
the stick the robot was holding, became stuck in the water fountain, tipping
it over. Unlike many digital interactions, the physical embodiment of the
robot allowed the cats to ‘disassemble’ it by taking the toys from it. This
allowed the interaction to fulfil the cats’ biological drive stimulated by the
robot (i.e., hunting), allowing them to grab, manipulate and drag objects
(i.e., prey), thus positively impacting Clovers’ welfare (Haddon and Mills,
2023).

##  6\. Discussion - Designing Robot Worlds

Reflecting on the artists’ final design and the experience of the cats, we
suggest that Cat Royale provides an existence proof that it is indeed possible
to design a general purpose robot to play a variety of games that repeatedly
engage cats in what appear to be naturally playful behaviours (e.g., that at
first sight appear to engage their natural hunting behaviours). The cats did
not appear to get bored, but rather to become confident, even assertive, in
engaging the robot in such play. It may even be possible for a future robot to
learn the preferences of individual cats and to adapt its play to them.

However, as we saw in the many details of the artists’ design, this was far
from being a simple proposition. Delivering Cat Royale required the artists to
innovate solutions to a wide variety of challenges, including: choosing an
appropriate robot; designing its movements; introducing systems to make these
safe; developing a decision engine to recommend games; choosing suitable
(passive) toys and adapting them so the robot could deploy them; building a
magnetic rack storage system for the toys; creating a surrounding enclosure
with spaces and facilities to make the cats comfortable and meet their other
needs; appropriately decorating this for the cats, computer vision system and
human audience; creating an external control room from which the play could be
monitored and broadcast; and putting in place a wide variety of supporting
humans roles. Furthermore, to make Cat Royale a success they had to ensure
that all of these elements worked together as a coherent whole.

What is notable about this list of activities is just how much of it extends
beyond designing the robot itself or its direct interactions with the cats
(though these certainly appear). Rather, the artists designed an entire ‘robot
world’. This reflects the idea of understanding and designing interaction in
terms of entire ecologies, not just devices, as we reviewed earlier. Cat
Royale provides an extreme example of designing an entire information ecology
of people, technologies, practices and values in a local environment, now
extended to also include animals. However, it is also a highly unusual
example; in this art project, the artists had more or less free licence to be
creative with the design of their robot world. They also had the luxury of
starting with a blank page. Cat Royale seems unlikely to directly transfer to
people’s homes due to its size, cost, need for a humans in supporting roles,
and the fact that most homes are already replete with other ‘stuff’. So what
broader lessons can we generalise from this example. What does Cat Royale tell
us about designing more everyday robot worlds for cats or other animals?

We now look under the surface of its design to distil underlying principles,
grouping them under two broad themes that capture the essence of how the
artists approached their robot world: designing the robot’s physical world and
designing multispecies interactions also involving humans.

###  6.1. Designing the Robot’s Physical Worlds

In order to bring some coherent structure to the many details of designing the
robot’s physical world, we return to Brand’s framework (as introduced in
Section 2.2) for the evolution of buildings (Brand, 1995) as previously
introduced to HCI (Rodden and Benford, 2003). Cat Royale reveals how the
creators of robot worlds need to pay attention to stuff, space-plan and
services (as exemplified by the toys the robot wielded, the enclosure and the
surrounding service space).

Designing passive stuff to mediate interaction. Although it may seem trivial
to point out that robots will often interact with animals via passive objects,
it is worth reflecting on important facets of their design. It was easy to
extend the robot’s repertoire of actions by simply introducing new toys.
Moreover, the movements of strings and similarly flexible materials afforded a
range of natural and somewhat unpredictable movements that would have been
difficult to programme. The toys were safe to lick, bite, claw and carry away.
They also draw attention away from the arm itself, in the interests of both
animal and robot safety. Toys simultaneously made the possibility of
collisions more likely, but also much softer and safer. They could even be
released into the environment to create more playful effects and again to
distract the animals away from the robot. However, they introduced their own
challenges: requiring a storage system that was accessible to the robot but
animal-proof, while their flexibility allowed the animal to take control,
making it difficult to know when and how to best release them and thus
introducing a point of vulnerability—e.g., allowing Clover to ‘break’ the
robot (see Figure 8). While Cat Royale’s objects were passive, we envisage
that future work could endow ‘smarter’ end-effectors with greater agency
through local sensing and actuation, for example being able to detect when
they were under strain or engaging in locally autonomous behaviours (Pons et
al., 2015).

Designing robot space plans. An important feature of Cat Royale’s enclosure
was that it provided a safe space for both animals and robot. Feeding trays,
litter trays and sleeping areas were out of the robot’s reach (see Vignette
5.1 and Section 5.1). Animals could traverse the space via raised walkways
that similarly avoided the robot. Importantly, they could also watch it from
an elevated position, choosing when to descend and engage, which both
preserved their autonomy and facilitated their spontaneous (i.e., hunting)
behaviour, and drew them into engagement, in a similar manner to the Honeypot
effect reported for humans using public displays (Hornecker et al., 2007). The
robot too had its own safe space in the form of the raised racks where it
could store the toys. A second important aspect of the space plan was the
visual decoration which involved a balancing act between being aesthetically
pleasing to humans (especially when seen through a camera), suitable for the
cats, and also convenient for the vision system (including being able to
discriminate the distinct visual markings of individual animals). Future
opportunities might build on the experience of the Moxi robot and the idea of
‘robot readable worlds’ (Higginbotham, 2019) by deploying visual markers that
could be read by the robot while utilising aesthetically pleasing graphic
designs (Getschmann and Echtler, 2021; Benford et al., 2017).

Designing robot services. Deploying technologies brings requirements for
services such as power, cabling, networking and physical access for monitoring
cleaning and repairing. Cat Royale established an extensive space surrounding
the enclosure from which such services could be provided, including access
hatches through which human wranglers could reach in without the animals
exiting.

To generalise further, interior design—which broadly encompasses stuff, space
plan and the visible aspects of services—is an important part of the ecology
of the home. On the one hand, it is a necessary part of making the home
comfortable, maintaining it, and installing new technologies, and so must be
considered when introducing a robot (and indeed an animal). As previous
studies have shown, people already do this; the owners of domestic robots
(e.g., lawn mowing or vacuuming cleaning robots (Schneiders et al., 2021;
Verne, 2020)) already re-structure and decorate their homes and gardens in
order to make them more robot accessible. On the other hand, interior design
can be a creative and rewarding activity enabling people to personalise their
homes, and is something that many enjoy doing and are skilled at. Thus, while
it might seem technically trivial to focus on interior design for robots
rather than developing their hardware and software to adapt to prevailing
conditions, doing so may well prove to be an empowering strategy for those who
live with them. Interior design of the robot world, e.g., (Jeong et al., 2018;
Schneiders et al., 2021), might allow for new ways of robot interactions
regardless of robotic expertise.

In this paper, we have presented a case in which not only we designed for
interactions with the robot, but we also designed three of the six shearing
layers (Brand, 1995). Specifically, the stuff, space, and services surrounding
the deployment of the installation. We acknowledge that—in a less controlled
environment—this might not always be possible; however, at the same time, we
argue that considering if, and when, the shearing-layers can inform the
implementation and design of digital technologies can be useful—especially in
the case of physically embodied technologies such as robots. Prior examples of
how to design robots and, for example, their spaces (Schneiders et al., 2021)
to accommodate them in environments shared with human and non-human actors
(Bendel, 2017) have further shown the importance of this. An extreme case of
emergent interaction between animals (hedgehogs) and technology (lawn mowing
robots) in a shared environment is described by Rasmussen et al. (2021). The
lawn mowing robots, designed to replace human labour, lack consideration for
the non-human actors in their ecosystems leading to, in extreme cases, severe
injuries to the hedgehogs with which they share an environment. To prevent
negative consequences for non-human actors, we argue that it is important to
consider the adoption of technology from an ecological perspective expanding
beyond the human- and technology-centred viewpoints.

###  6.2. Enhancing Multispecies Interactions

Adopting an ecological perspective on computer systems foregrounds the often
diverse roles played by people in these systems. The robot in Cat Royale was
designed to appear, to the audience, to autonomously interact with animals
without humans ‘being in the room’. However, we have seen (e.g., Section 5.2)
that, behind the scenes, various human roles were implicated in realising
these interactions and ensuring they were as engaging and safe as possible:
the robot operator, animal welfare officer, toy wrangler, artists, vision
mixer, cat owner, and also the audience who watched the edited recordings. One
might be tempted to argue that many of these human roles were only required
due to the prototypical nature of Cat Royale, with humans initially delivering
system functions that would eventually be automated. Perhaps, for example, the
operator’s role and the ‘happiness’ scoring of the cats’ engagement (as
described in Section 4) could be subsumed by a future more autonomous AI-
driven robot. Under this view, the various roles humans played in the project
could be seen as revealing gaps in the technology and clarifying requirements
for further development. However, our ecological approach leads us to take an
alternative view: that humans, just as the three cats, are a vital part of the
ecosystem and that we need to design to support and even enhance their
involvement in it rather than design to remove them. The approach of designing
computer ecosystems to create opportunities for rewarding engagement, rather
than to reduce human labour, has previously been explored in the context of
providing support at online festivals (Benford et al., 2023); while owning
animals is not formally ‘volunteering’ of this kind, it is often ‘voluntary’,
perhaps similarly implying that we should seek to maximise opportunities for
rewarding human engagement. This insight also reflects Lawson et al.’s (Lawson
et al., 2015) concern that digital technologies developed for animals may
potentially weaken human-animal bonds. With this in mind, we generalise from
the specific human roles in Cat Royale to propose key directions for enriching
human involvement in robot worlds.

Enriching human-animal relationships. Cat Royale showed how both a robot
operator and the lead artists needed to be closely involved in getting the
robot to successfully play with cats, the former to finesse its physical
movements by using the deadman’s switch to advance or stop it in its pre-
planned sequence and sometimes to improvise new moves, and the latter to
review its recommendations for games to play. An interesting strategy would be
to extend rather than replace such roles. Might a mixed-initiative system
(Allen et al., 1999) that combined the strengths of a robot (precise, slow and
patient movements) and human (fine judgement of animals’ reactions and ability
to improvise) deliver better experiences for the animal, but also for the
human, involving them in creating and delivering new experiences? And might
this extend to other functions beyond play? Could we similarly enhance human
engagement with animal care activities such as feeding and grooming? An
important topic for future research concerns better understanding how animals
(and possibly humans too) might view the robot as an interlocutor in their
interactions. In Cat Royale, while the behaviour of the toys clearly elicited
playful responses, at this stage it is not possible to tell how the cats
perceived the robot itself as an actor. However, researchers have observed the
emergence of social behaviour in dogs who encountered autonomous robots
(Gergely et al., 2013), demonstrating that at least some animals perceive
robots as social actors.

Even in situations where we might want robots to interact autonomously with
animals, such as when humans cannot be present, Cat Royale reveals
opportunities for enhancing human offline involvement. Might the role of the
audience in Cat Royale (supported by the vision mixer), be transformed into
something more personal and interactive, with humans enjoying watching footage
of their animals, but also categorising and rating their interactions so as to
better train the robot? While we want to avoid the risks of inappropriately
‘quantifying’ animals through over-use of tracking technologies as discussed
by Lawson et al. (2015), might engaging with data to directly help train
autonomous systems potentially enrich the experience of both animals and
humans?

We conclude by noting two further and more pragmatic aspects with regards to
which we should support human involvement concerning the care of animals and
robots respectively.

Ensuring animal welfare. While animal engagement to some extent can be
provided through autonomous systems, ultimately every system depends on human
involvement to take responsibility for monitoring, approving and overseeing
its interactions. Responsibility for the welfare of the cats spread across
multiple roles in Cat Royale: the operator and artist for immediate safety
around the robot, and the animal welfare officer, owners and vet for general
wellbeing. Similar functions will need to be supported for other systems that
engage animals with robots, either through real-time monitoring and
intervention or offline review and reconfiguration.

While during the design of Cat Royale we focused on the design of more than
human-centred worlds (Wakkary, 2021) , we emphasised the cat’s as primary non-
human actors. While not focusing on every possible actor within a domestic
ecology, we made deliberate choices to introduce cat grass and other, animal
friendly, plants within the environment. This multispecies ecology could be
understood to comprise an even broader flora & fauna, emphasising the
interaction with other non-human actors beyond the cats. While, during the
analysis of Cat Royale, resulting in the findings presented in this paper, we
focus on the cats as the sole non-human actor, other work has considered a
range of other actors, including house plants and insects. One example is
presented by, e.g., (Bendel, 2017) who has investigated insect friendly
robotic vacuum cleaners, in the context of the home, and the impact these have
on the animals’ welfare, which is typically disregarded. Further research,
could expand this project’s focus to encompass multispecies interactions
within a broader ecological context in the home.

Robot wrangling and restoring order. Some of the chaotic goings-on in Cat
Royale that emerged from the cats’ enthusiastic play with the robot reveal
that humans will routinely need to intervene to find (e.g. Vignette 5.2.2),
gather and repair/replace objects; disentangle, reset, or re-calibrate the
robot; and generally tidy up the mess that ensues animal-robot interactions.
This is particularly the case as we cannot expect animals to do so for
themselves—they will not judge or respect the limits of the robot, nor be able
to fix any problems that occur. They are non-responsible users unconcerned for
the robot as an actor in the system. While ideally the robot would be able to
perform some of these tasks by itself (or perhaps other robots would), it
seems that current robotic systems are nowhere near having the capabilities
required to do so yet. The implication here is that everyday robot owners need
to be enabled to wrangle the robot, for example by disentangling, resetting
and re-calibrating it.

###  6.3. Limitations

The study focused on the design of a multispecies world with a bespoke
enclosure for the interaction between three cats and a robotic arm. Behind the
scenes, a control room with a variety of humans-in-the-loop (including
artists, robot operator, and the animal welfare officer). However, while this
robot world, or robot ecology, deliberately introduced other non-human actors,
i.e., plants, into the ecology, the findings presented in this paper focus on
the cats. Future domestic robots will encounter a wide variety of non-human
actors including insects and plants. Future work might consider widening the
meaning of the multispecies ecology view, and investigate how these worlds
might be shaped to include a multitude of non-human actors.

Would a system like this be able to provide animal happiness in the wild,
i.e., in an actual home? While Cat Royale probed questions related to
autonomous systems, and investigated their capacity to take care and
ultimately increase animal happiness, the project, by design, cannot provide
results in relation to the system’s capacity to replicate the observed effects
in the wild. This investigation, informed by projects such as the one
presented in this study, remains open for future work.

##  7\. Conclusion

In this paper, we have presented the artist-led project Cat Royale, an
exploratory investigation at the intersection between art and human/animal-
robot interaction. We presented a detailed account on the design of the
project, emphasising both the robot design and the design of the wider context
in which it was situated, i.e., its ’robot world’. We also revealed that the
importance of humans-in-the-loop cannot be understated. We described the
unravelling of the events that transpired as part of the twelve day long
installation, aiming to offer the reader insight into both the routine and the
more challenging animal-robot interactions of Cat Royale. We then present two
key implications which emerged through the Cat Royale project, which could
inform future research and development of domestic robots. Firstly, we stress
the importance of considering the environment beyond the robot design to
include the design of the wider context, i.e., the physical world the robot
and other actors are expected to share. Secondly, we highlight the need for
designing multispecies interactions to include human involvement during robot
supported enrichment for companion animals, as necessary functions implicated
in animal-robot interaction (e.g., holding responsibility for animal welfare
or recovering from breakdowns) cannot be outsourced to autonomous systems.

###### Acknowledgements.

This work was supported by the Engineering and Physical Sciences Research
Council [grant number EP/V00784X/1] UKRI Trustworthy Autonomous Systems Hub.

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