Fuzzy Adaptive Control of Free-Floating Space Robot Based on Dead-Zone Compensator

This paper proposes a fuzzy adaptive controller based on dead-zone compensator for a free-floating space robot (FFSR) in the presence of the unmodeled nonlinear dynamics and additional disturbances. In the micro-gravity space environment, the FFSR lacks a fixed base. As a result, there is high dynamic coupling between the manipulators and the free-floating base, which leads to two inherent difficulties, which are non-linear parameterization of the dynamic equation and both kinematic and dynamic parameter uncertainties. These uncertainties make the dynamic equation of FFSR more complicated than that of the fix-based comparisons. And the control method for fixbased robot can not be applied directly for the FFSR system. In order to overcome these obstacles, we use the dead-zone compensator including a fuzzy control system to approximate the nonlinear dynamic function. The proposed controller could not only overcome the uncertainty but also efficiently track the desired trajectory of the manipulator joints in a finite time. The stability of the whole system is analyzed and then the structure of the controller is given. Through numerical simulations, the validity of the proposed scheme is also demonstrated.