H∞-force control of a hydraulic servo-actuator with environmental uncertainties

This paper deals with the application of the H_∞-approach to robustly control the force exerted by a hydraulic servo-actuator on its environment. In order to evaluate the system stability and the performance, large environmental uncertainties and disturbances are introduced by use of a particular workpiece. The major nonlinearities of the system are pointed out through experimental tests and parameters estimation results. Then, a linear time-invariant model for control is defined with respect to both system dynamics and application requirements. Experimental and simulation control results are presented and the achievement of a stability/performance trade-off is discussed