Compliant Motion of a Mobile Manipulator

Mobile Manipulator: Mitsubishi PA-10, 7 DOF manipulator. We have modified the controller to allow open access to the motor amplifiers and encoders. We use a standard data acquisition card, sending torque commands (voltage translated to current by motor amplifiers), and reading encoder signals.

Omnidirectional Mobile base: Designed and built in-house. It has 4 powered caster wheels (2-axis wheels with an offset in steering). It has 8 motors and allows full 3-axis omnidirectional motion in the horizontal plane.

The end-effector is "freed" in the x, y (horizontal), and rotation about z axes (vertical). These axes are force controlled to a desired zero force. The rest of the axes are motion controlled to maintain its current position. The robot is therefore easily moved by a human operator, while mantaining the position along the motion controlled axes. Click here for video.