Nonlinear robust variable structure control of pointing and tracking with operator spline estimation

Summary form only given. Variable control (VSC) in effect consists of designing a control input based on a simplified or inaccurate dynamic model, to which a variable correction is added, based on estimates of the model errors, sufficient incipiently to overshoot the desired controlled trajectory (sliding manifold). To suppress chattering, an optimally time-varying boundary layer can be generated to contain the sliding surface, within which the corrected control is continuously interpolated. An explicit design rule (tradeoff) can then be established between tracking error tolerance and effective control bandwidth, determined by the imposed model error bounds. For rapid rotation of a deformable body, the elastic response can be moded by oscillators driven by angular acceleration, where stiffness and damping coefficients are also angular-velocity- and acceleration-dependent. Bandwidth-limited VSC has been generated for pointing and tracking with such deformable vehicles, with the operator spline estimate used in the design of the nominal part (the equivalent control estimate), and the operator spline error bound in that of the control correction