David Fenstermacher is currently working on developing a hybrid velocity/force controller for the electro-hydraulic piston. The final controller will be able to regulate the velocity of the piston in unconstrained motion. However, if the force being exerted by the piston exceeds a certain, pre-set level (for instance if the piston impacts an object or the ground), the controller will smoothly transition to a force control mode. Under these circumstances, the piston force will not exceed that pre-set level until it is commanded to move in the opposite direction.

Jeff Lentz is currently working on adaptive parameterization of a pilot valve. This work is motivated from the need to eliminate costly calibration procedures to determine the dead zone nonlinearities in the valves. The adaptive parameterization is advantageous in that the calibration procedure is eliminated and the performance level is maintained even when the system undergoes changes, due to factors such as wear or temperature. The methodology being developed is applicable to many other nonlinear systems.