Improving performance of task space controllers using an inner PD joint controller: an application to visual sevoing

This paper presents a comparative study of two task space control approaches. The first approach, similar to most of task space controllers, makes use of an inner velocity loop. The second proposed approach employs an inner proportional derivative (PD) joint position-velocity loop. A stability proof for the second apprach is provided together with experiments using a visual servoed robot. It is shown that the proposed control law needs less gain at the task space level then precluding amplification of the measurement noise; moreover, it is shown that the first approach produces uncontrolled movements when the task space sensor fails whereas the proposed controller avoids uncontrolled behavior