Affective robotics centers on recognizing emotional states and generating artificial emotions through embodied robotic systems. This paper surveys the current state of the field, with a particular focus on bodily expressed emotion—both in recognizing affect through body movements and postures, and in generating movement that is parsed as affect by human observers. Framed through the lens of the performing arts, this examination provides insights into the expressive potential of robots, motivates key open questions, and highlights challenging problems, as presented through an art-inspired case study and foundational background material. A close engagement with the performing arts suggests intense malleability and diversity of bodily expression, challenging some of the field's prevailing goals—such as designing generally “happy” robotic movement—and emphasizing the importance of variables such as context and interactional intent. The paper concludes by proposing future directions for bodily expressed affective robotics that integrate advances from both robotics and the performing arts.

This paper presents artistic work that comments on the exploitation of feminine gender performance in technology, from the point of view of a particular artist, enabled by a wearable robotic device that creates an onstage cyborg character. The piece, entitled "Babyface'' was created in residence in a robotics lab and has catalyzed the development of a motion-activated wearable robot. This paper reports on the creation of this piece, its accompanying device, along with initial responses that have been shared informally. Iterations of multiple flexible attachment structures, a clear plastic dress that references the hyperbolic representation of the female sex, as well as the electronic subsystems are presented alongside discussion of the somatic and choreographic investigations that accompanied prototype development. These fabricated elements alongside the actions of the performer and a soundscape that quotes statements made by real "female'' robots create an otherwordly, sad cyborg character that causes viewers to question their assumptions about and pressures on the female ideal. This work is an important first step in the development of a wearable robot with embodied connection to the performer and, eventually, audience members.

In some applications, operators may want to create fluid, human-like motion on a remotely-operated robot, for example, a device used for remote telepresence. This paper examines two methods of controlling the pose of a Baxter robot via an Xbox One controller. The first method is a joint- by-joint (JBJ) method in which one joint of each limb is specified in sequence. The second method of control, named Robot Choreography Center (RCC), utilizes choreographic abstractions in order to simultaneously move multiple joints of the limb of the robot in a predictable manner. Thirty-eight users were asked to perform four tasks with each method. Success rate and duration of successfully completed tasks were used to analyze the performances of the participants. Analysis of the preferences of the users found that the joint-by-joint (JBJ) method was considered to be more precise, easier to use, safer, and more articulate, while the choreography-inspired (RCC) method of control was perceived as faster, more fluid, and more expressive. Moreover, performance data found that while both methods of control were over 80% successful for the two static tasks, the RCC method was an average of 11.85% more successful for the two more difficult, dynamic tasks. Future work will leverage this framework to investigate ideas of fluidity, expressivity, and human-likeness in robotic motion through online user studies with larger participant pools.

In this paper we examine a novel method of core-located actuation that we believe can be used to vary gaits in a compass-gait walker, using critical analysis of a ball-in-tray mechanism to apply forces at the robot's "pelvis". The dynamic equations of motion of a tilting ball-tray system with several design parameters are developed and simulated for various tray designs. Results show that changes in tray design do indeed significantly affect the trajectory. When compared to a hardware ball-tray system, the results show good agreement with the simulation. The sagittal plane component of the ball's trajectory is applied to the motion of a corresponding mass at the "pelvis" of a compass-gait walker. Simulations of the compass-gait walker show that this trajectory generates a feasible gait.

Variable walking styles in bipedal robots may be used to communicate information about purpose and/or personality to human viewers- and may also help accommodate features of the environment. This paper presents variable gait in a simulation and results from a hardware prototype for gravity-driven rolling ball mechanism in a previously proposed bipedal design. First, optimal control inputs that produce a range of variable feasible gaits is generated on a simplified under-actuated planar model. Then, a tray-like mechanism that provides a curved path for a ball to roll on is presented. This mechanism is designed to replicate a notion of pelvic shift, described in Bartenieff Fundamentals, with movement of the ball (which is shaped by the tray) creating a shift of weight. Analysis of two gait styles and two tray designs shows comparable ranges of forces in the direction of travel between the simulated planar model and the hardware mechanism. This work is an important first step in generating feasible, stable- and variable- bipedal gaits using this hardware design.

The behavior and aesthetics of robots can impact perception by human viewers, and prior work has shown that context influences this judgement. This paper presents an experiment to better understand what sort of gait label can best explain human estimate of an internal state based on external changes, despite effects of variable context on the perception of gait. The study analyzes how a user's perception of movement in a simple two degree-of-freedom mechanism changes through the use of varying environments via more emotive or more descriptive labels. Specifically, five bipedal gaits were overlaid onto illustrated backgrounds that were created to reflect various affective inclinations and given labels with and without emotive implications. Users were then asked to rate the accuracy of the descriptive or emotive labels of these videos, and the differences between their ratings were compared throughout the multiple backgrounds. It was found that while both sets of labels scored well, emotive labels were slightly preferred overall. However, although the addition of an environment positively affected the user perceptions in rating the suggested descriptive labels, it was more likely to negatively affect the ratings of emotive labels. The results of this analysis suggest that lay end-users prefer to make judgements about motion behavior in an emotive space but that descriptive labels may be more stable identifiers across various contexts for robot designers. These results highlight the emotional connection that humans make with motion and the role the context plays in helping to create this experience.

Performance is a vehicle to explore and modify audience experiences. The design of expressive robotic systems shares a similar goal. Toward the end of uniting these two approaches, this paper presents a collaborative academic and artistic effort to design an experimental testbed for studying human perceptions of robots, and changes therein, through dance performance. The elements of the testbed design, which allow for multiple audience experiences inside the same live event, will be outlined. Then, one instantiation of a performance using this testbed design will be summarized. In developing this testbed and instantiation, synergistic academic and artistic goals included measuring the audience's initial perception of existing technologies and further priming the audience about these technologies through the performance. These perceptions were framed through the lenses of power, valence, and acceptability; comparisons between the Rethink Robotics Baxter, Softbank NAO, and a human performer are presented. This piece (and excerpts of it) will be used to gather audience perceptions at multiple events to bring lay audience members the experience of robotics researchers and understand how that modifies their impressions of these systems.

This paper presents a method for segmenting human motion based on a notion of quality and the movement of a user such that the exact segmentation is tailored for different subjects. The problem is solved via an inverse optimal control problem where the parameter of optimization is a time along the movement trajectory that splits the longer trajectory into distinct “moves.” First, trajectories are generated using a “forward” optimal control problem; then, the match of these generated trajectories is optimized via a second, “inverse” optimization, which determines the appropriate point of segmentation. An analytical solution to this set up, its numerical implementation, and an application to real data are presented. A key novel contribution of this paper is the analytical derivation of first order necessary conditions for optimality. The segmented movements may populate a library of movement primitives in order for robots and automated systems to perform and interpret novel tasks.