Analytical Solution of Pepper’s Inverse Kinematics for a Pose Matching Imitation System

Abstract

In this paper, a human-humanoid imitation system is proposed, with a focus on the kinematic model used for translating end effector positions to joint angles. The overall system comprises the humanoid robot Pepper and a Kinect v2 camera for capturing human 3D joint positions. The presented kinematic model is based on analytical solutions of Pepper’s inverse kinematics and also uses the forward kinematics. The aim of the paper is to provide insights into deriving the kinematics of robotic chains for the purpose of pose matching imitation, as well as accuracy evaluation of the derived forward and inverse kinematic solutions. The solutions of the inverse kinematics provide results with a mean error of approximately 0.2° for the angle solutions of the head joints, 0.7° for the arm joints, and 4° for the torso (leg) joints. The evaluated speed lies within a range of 0.002 to 0.08 ms. These results indicate that the presented kinematic model is an effective method for translating end effector positions to joint angles for our pose imitation application in real-time or close to it. Finally, we show preliminary results of the proposed imitation system and discuss future work.