Computed Torque Posture Control for Robotic-Assisted Tele-Echography

The paper presents a robotic tele-manipulation setup for remote ultrasound echography. The master station sends position and orientation commands through the Internet to the remote robot to control the probe. Geometric, kinematic and dynamic models are used to control the robot through computed torque techniques, including gravity compensation. Proportional and derivative control in 6-DOF task space is described, focusing the orientation error computation through angle axis representations. Mapping between master commands and control reference is analyzed, taking into account arbitrary initial robot postures. A user interface for echographic image reception with keyboard/mouse or haptic input control is described. Experiments with a 7-DOF WAM (TM) robot and a haptic device, featuring force feedback are presented.