Dextrous manipulation of a micropart with multiple compliant probes through visual force feedback

In our recent work, we have demonstrated effectiveness of the concept of multi-probe microassembly for manipulating and inserting microscale, sub-millimeter, parts to create three-dimensional microstructures. However, the approach has been based on trial-and-error manual teaching of grasp points to ensure a stable grasp during motion. As a result, the part orientation is restricted (nearly aligned with the world reference frame and lying flat) to ensure successful grasping and manipulation. In this paper, we developed a kinematics based hybrid motion and force control based only on vision feedback. We first conduct a systematic analysis of the bending of the probes while they are in contact with the part, to estimate the grasp force based on the vision feedback of the probe configuration. A Jacobian based controller is then used for position manipulation while maintaining the desired squeeze force. Experimental results with two probes and two camera are included to demonstrate the effectiveness of the controller to move the part to specified position and orientation while maintaining sufficient squeeze force to prevent part slippage.