Robust control synthesis of elastic structures based on variable structure control combined with optimal interpolation technique

A variable structure control technique combined with an operator spline for bilinear systems is investigated to control the moving elastic structure for purposes of achieving high performance tracking and precision pointing of a fast moving flexible structure (such as the agile motion of a robot manipulator with flexible links or the slewing maneuvers of a large space structure). The control torque applied to the structure is based on estimates of the structure parameters and on upper bounds of the model errors. It is shown through a simulated example how the chattering behavior of the controller, which involves high actuator activity, is avoided at the expense of tolerating a known tracking error in such a way that the closed loop dynamics in the boundary layer is approximated by the response of a critically damped oscillator with designer-selected bandwidth. A tradeoff is then to be set by the designer by taking into account the main requirements of a given task and the hardware available that is capable of achieving it