Robust control of robot manipulators under time-varying parametric uncertainty and disturbance with adaptive gravitational compensation

We consider the tracking problem for robot manipulators with unknown and time-varying physical parameters and disturbances which belong to L₂. Proposed state feedback adaptive robust controller consists of a nonlinear compensation based on nominal physical parameters, a linear and a nonlinear state feedback, and an adaptation algorithm for adjustment of the gravitational parameters. The effects of time-varying parameters and disturbances on the tracking performance can be attenuated within a prescribed level. Exact asymptotic tracking can be achieved for vanishing disturbances, constant parameters, and set point problem. By adding feedback input to penalty variable, high gain feedback can be strategically avoided.