RoboGroove: Creating Fluid Motion for Dancing Robotic Arms

Robotic motion has been studied for many purposes, such as effective fast movements, communicative gestures, and obstacle avoidance. Through this study, we are able to improve the perceived expressivity of a robot performing a task by generating trajectories. So far, robots have been very rigid in their movements, making them feel more robotic and less human. The concept of follow through, and smooth movement, can be used to increase animacy for a robot which leads to a more lifelike performance. In this paper, we describe the use of follow through to improve dances and grooves that can match the elegance of human dancers. We created two techniques using a non-humanoid robotic arm, to simulate this for a robotic dancer. Our first technique uses forward kinematics with trajectories that are generated based on a dancer moving to a beat. We mapped various movements of a human dancer to a set of joints on a robotic arm to generate the dancing trajectory. This technique allows a robot to dance in real-time with a human dancer, and also create its own smooth trajectory. The time delay that each human body part uses is implemented as time delay in the robot movements. The second method uses impedance control with varied damping parameters to create follow through. Robotic joints with low damping can passively move in response to other movements in a robot. The arm had high damping for any active moving joints, while the rest of the arm would passively react to this excitation; similar to how a human body responds to our own movement. These two methods were compared in a study where the robot would dance to a beat and users would qualitatively and quantitatively rate the robotic movement. The results of the survey showed that both methods provided an increase in animacy and anthropomorphism of a robot dancing to a beat. Impedance control had the highest rating for animacy, anthropomorphism, full body, and individual body rating. The use of impedance can provide a simple way for a robot to dance like a human, without a change to the primary trajectory.