Manipulation with soft fingers: contact force control

The issue of controlling contact forces generated when the fingers of a dextrous device first close on an object is addressed. The use of active fingertips is proposed to enhance the system performance and avoid contact instability problems resulting from noncollocated sensors and actuators. A first step towards exploring this issue is the study of an idealized controllable fingertip making contact with an object. The authors provide analytical and simulation studies to identify ideal fingertip characteristics to achieve a desired performance for a simple contact problem. An investigation of the performance of more realistic fingers with limited controllability follows. Preliminary experimental results for a prototype semi-active fingertip that uses an electrorheological fluid to achieve active damping control are provided. A brief summary of future experimental plans to implement such active fingertips in simple manipulation tasks is presented