H.INF. Control of Robot with Linearized Model.

Dynamic models of mechanical manipulators consist of highly nonlinear coupled second-order differential equations. Linear time-invariant control laws which utilize the linear model of robot dynamics are often used for industrial robots because of the simplicity of the control algorithms. However, due to the fact that nonlinearity is not considered and uncertainity exeists in the manipulator models, linear time-invariant control schemes cannot achieve satisfactory control performance. Therefore, a control scheme which is robust against the errors caused by the linerization procedure is required. In this paper we propose an H∞ control approach to the position control of the manipulator. The H∞ controller is linear and time-invariant and it guarantees the closed-loop robustness against the modeling error. Simulations and experiments on the two-link direct-drive manipulator demonstrate the effectiveness of the proposed H∞ control scheme.