A Hybrid Differential Flatness and Sliding Modes Controller for Dynamical Structural Testing on Lower Limp Prostheses

Abstract

The standard ISO 10328 specifies the procedure for structural tests on lower limb prosthetic devices, as a method for quality control. Having the standard as reference, a machine is designed and implemented to follow the test routine, which if succeeded, shows the quality concept for the devices tested. Furthermore, it is shown the controller design process, which manage the application of a sinusoid force with specified amplitude, frequency and offset, in order to realize the dynamic test, by means of a double effect cylinder and proportional valves for pressure and flow.The dynamic model was calculated through a parametric identification technique in a pre-stabilized closed loop. Later, a hybrid control strategy was set using the differential flatness concept and a sliding modes controller, so that both identified model and real system could be properly controlled.