Dimitri: A Low-Cost Compliant Humanoid Torso Designed for Cognitive Robotics Research

This work presents Dimitri, an open-software & open-hardware robot torso equipped with modular low cost compliant joints, built to allow advanced research on human-robot interaction, force-aware object manipulation and environment exploration. The robot has 13 DOFs: 4 DOFs with series elastic actuators in each arm, 3 DOFs for roll, pitch and yaw of the waist, and 2 DOFs for head pan and tilt. Our main innovation is in the employment of a polyurethane based compliant spring system attached to conventional robotics servo motors, turning them into low-cost series elastic actuators (SEAs). To demonstrate the robot's capabilities in the context of cognitive robotics research and goal-directed behavior, we successfully employed a multiple timescale recurrent neural network (MTRNN), enabling the robot to reproduce combined prototypical movement patterns previously trained via interactive demonstration.