Sophia-Hubo's Arm Motion Generation for a Handshake and Gestures

Sophia-Hubo is developed to perform walking mobility on the Sophia robot, which is a human-like robot developed by Hanson Robotics Ltd. The robot has achieved walking motion to attach Hubo's lower body. Also, it needs arm motions to interact with people such as a handshake and gestures. To handshake with a person, we use inverse kinematics (IK) of Sophia-Hubo's right arm for stretching the arm to the person and torque control for handshaking. We use Levenberg-Marquardt method with Robust Damping to find a solution of the IK, and torque control of Dynamixel on shoulder pitch and elbow joint. The torque control input is calculated with the measured joint angular velocity. For making joints moving smoothly, we apply a 5th polynomial function trajectory. Through recursively adding the 5th polynomial trajectory to the end of the previous trajectory, we can make gestures.