Servo control in joint space of biped robot using nonlinear H-infinity strategy

This paper present a solution to the problem of servo control in joint space of biped robot using a state feedback nonlinear H(infinity ) optimal disturbance attenuation, which guarantee robust stability against external disturbance and fluctuation of the system parameter. The design aims at finding a stabilizing nonlinear state feedback such that the close loop system is (gamma) dissipative. We know that the nonlinear H(infinity ) control can be reduced to solvability of the Hamilton-Jacobian-Isaccs partial differential problem, which is difficult to solve. Based on about fact and combining the work of Johansson and Chen, we are able deduce the problem of a state feedback nonlinear H(infinity ) optimal disturbance attenuation to solving a Riccati-like equation. After some manipulation by use of the skew symmetric property of robot, the Riccati-like equation can be further simplified algebraic matrix problem. Finally, the explicit global solution is presented.