Interactive Co-Design of Form and Function for Legged Robots using the Adjoint Method

Our goal is to make robotics more accessible to casual users by reducing the domain knowledge required in designing and building robots. Towards this goal, we present an interactive computational design system that enables users to design legged robots with desired morphologies and behaviors by specifying higher level descriptions. The core of our method is a design optimization technique that reasons about the structure, and motion of a robot in coupled manner in order to achieve user-specified robot behavior, and performance. We are inspired by the recent works that also aim to jointly optimize robot's form and function. However, through efficient computation of necessary design changes, our approach enables us to keep user-in-the-loop for interactive applications. We evaluate our system in simulation by automatically improving robot designs for multiple scenarios. Starting with initial user designs that are physically infeasible or inadequate to perform the user-desired task, we show optimized designs that achieve user-specifications, all while ensuring an interactive design flow.Comment: 8 pages; added link of the accompanying vide

Choreographic and Somatic Approaches for the Development of Expressive Robotic Systems

As robotic systems are moved out of factory work cells into human-facing environments questions of choreography become central to their design, placement, and application. With a human viewer or counterpart present, a system will automatically be interpreted within context, style of movement, and form factor by human beings as animate elements of their environment. The interpretation by this human counterpart is critical to the success of the system's integration: knobs on the system need to make sense to a human counterpart; an artificial agent should have a way of notifying a human counterpart of a change in system state, possibly through motion profiles; and the motion of a human counterpart may have important contextual clues for task completion. Thus, professional choreographers, dance practitioners, and movement analysts are critical to research in robotics. They have design methods for movement that align with human audience perception, can identify simplified features of movement for human-robot interaction goals, and have detailed knowledge of the capacity of human movement. This article provides approaches employed by one research lab, specific impacts on technical and artistic projects within, and principles that may guide future such work. The background section reports on choreography, somatic perspectives, improvisation, the Laban/Bartenieff Movement System, and robotics. From this context methods including embodied exercises, writing prompts, and community building activities have been developed to facilitate interdisciplinary research. The results of this work is presented as an overview of a smattering of projects in areas like high-level motion planning, software development for rapid prototyping of movement, artistic output, and user studies that help understand how people interpret movement. Finally, guiding principles for other groups to adopt are posited.Comment: Under review at MDPI Arts Special Issue "The Machine as Artist (for the 21st Century)" http://www.mdpi.com/journal/arts/special_issues/Machine_Artis

Automated gait generation based on traditional animation

This thesis describes the development of a tool to assist animators in doing walk cycles. In traditional animation, animators create expressive walk cycles with key poses. The process of generating walk cycles by hand is tedious and repetitive. To help animators, many researchers in computer graphics have worked on automating gait generation. However, almost all of them used methods that eliminate animator defined key poses. Although they produce realistic results, their methods are not suitable for expressive walk cycles that can be found in cartoons. The tool described in this thesis attempts to incorporate practices of traditional animators such as comparison of key poses and the use of arc into the program interface. With this tool, animators can concentrate only on setting key poses, which is the most creative task in animating expressive walk. The gait generation program can produce highly expressive walks like the double bounce walk and the sneak. With automated features of the developed tool, animators can save time and effort when animating expressive walk along a curved path

Learning recurrent representations for hierarchical behavior modeling

We propose a framework for detecting action patterns from motion sequences and modeling the sensory-motor relationship of animals, using a generative recurrent neural network. The network has a discriminative part (classifying actions) and a generative part (predicting motion), whose recurrent cells are laterally connected, allowing higher levels of the network to represent high level phenomena. We test our framework on two types of data, fruit fly behavior and online handwriting. Our results show that 1) taking advantage of unlabeled sequences, by predicting future motion, significantly improves action detection performance when training labels are scarce, 2) the network learns to represent high level phenomena such as writer identity and fly gender, without supervision, and 3) simulated motion trajectories, generated by treating motion prediction as input to the network, look realistic and may be used to qualitatively evaluate whether the model has learnt generative control rules

Perception Based Gait Generation for Quadrupedal Characters

With the rapid expansion of the range of digital characters involved in film and game production, creating a wide variety of expressive characters has become a problem that cannot be solved efficiently through current animation methods. Key-frame animation is time-consuming and requires animation expertise. Motion capture is constrained by equipment and environment requirements and is most applicable to humanoid characters. Simulation can produce physically correct motion but does not account for expressiveness. This thesis focuses on developing a more efficient animation system using a procedural approach in which the skeletal structure and characteristics of motion that communicate weight and age in quadrupeds have been isolated and engineered as user-controlled tools and modifiers to build creature shape and synthesize cyclic gait animation. This new approach accomplished the goal of quick generation of expressive characters. It is also successful in achieving real-time animation playback and adjustment

Customisation and Context for Expressive Behaviour in the Broadband World

The introduction of consumer broadband makes it possible to have an emotionally much richer experience of the internet. One way of achieving this is the use of animated characters endowed with emotionally expressive behaviour. This paper describes Demeanour, a framework for generating expressive behaviour, developed collaboratively by University College London and BT plc. The focus of this paper will be on two important aspects; the customisation of expressive behaviour and how expressive behaviour can be made context dependent. Customisation is a very popular feature for internet software, particularly as it allows users to present a specific identity to other users; the ability to customise beahviour will increase this sense of identity. Demeanour supports a number of user friendly methods for customisng behaviour, all of which use a character profile that ultimately controls the behaviour of the character. What counts as appropriate behaviour is highly dependent on the context, where you are, who you are talking to, whether you have a particular job or role. It is therefore very important that characters are able to exhibit different behaviours in different contexts. Demeanour allows characters to load different profiles in different contexts and therefore produce different behaviour

Using Fourier Analysis To Generate Believable Gait Patterns For Virtual Quadrupeds

Achieving a believable gait pattern for a virtual quadrupedal character requires a significant time investment from an animator. This thesis presents a prototype system for creating a foundational layer of natural-looking animation to serve as a starting point for an animator. Starting with video of an actual horse walking, joints are animated over the footage to create a rotoscoped animation. This animation represents the animal’s natural motion. Joint angle values for the legs are sampled per frame of the animation and conditioned for Fourier analysis. The Fast Fourier Transform provides frequency information that is used to create mathematical descriptions of each joint’s movement. A model representing the horse’s overall gait pattern is created once each of the leg joints has been analyzed and defined. Lastly, a new rig for a virtual quadruped is created and its leg joints are animated using the gait pattern model derived through the analysis

Semi-Autonomous Avatars: A New Direction for Expressive User Embodiment

Computer animated characters are rapidly becoming a regular part of our lives. They are starting to take the place of actors in films and television and are now an integral part of most computer games. Perhaps most interestingly in on-line games and chat rooms they are representing the user visually in the form of avatars, becoming our on-line identities, our embodiments in a virtual world. Currently online environments such as “Second Life” are being taken up by people who would not traditionally have considered playing games before, largely due to a greater emphasis on social interaction. These environments require avatars that are more expressive and that can make on-line social interactions seem more like face-to-face conversations. Computer animated characters come in many different forms. Film characters require a substantial amount of off-line animator effort to achieve high levels of quality; these techniques are not suitable for real time applications and are not the focus of this chapter. Non-player characters (typically the bad guys) in games use limited artificial intelligence to react autonomously to events in real time. However avatars are completely controlled by their users, reacting to events solely through user commands. This chapter will discuss the distinction between fully autonomous characters and completely controlled avatars and how the current differentiation may no longer be useful, given that avatar technology may need to include more autonomy to live up to the demands of mass appeal. We will firstly discuss the two categories and present reasons to combine them. We will then describe previous work in this area and finally present our own framework for semi-autonomous avatars

Creating Procedural Animation for the Terrestrial Locomotion of Tentacled Digital Creatures

This thesis presents a prototype system to develop procedural animation for the goal-directed terrestrial locomotion of tentacled digital creatures. Creating locomotion for characters with multiple highly deformable limbs is time and labor intensive. This prototype system presents an interactive real-time physically-based solution to procedurally create tentacled creatures and simulate their goal-directed movement about an environment. Artistic control over both the motion path of the creature and the localized behavior of the tentacles is maintained. This system functions as a stand-alone simulation and a tool has been created to integrate it into production software. Applications include use in visual effects and animation where generalized behavior of tentacled creatures is required