Position Control of 3-DOF Underactuated Manipulators with Last Passive Joint Using Fuzzy Logic Control

Underactuated manipulator is one kind of second order nonholonomic dynamics systems. How to control this system is still an open problem. This paper proposes a fuzzy strategy to control three DOF underactuated manipulator with a last passive joint. Four measures are selected to construct the fuzzy logic controller. The four measures are divided into two classes; one class is concerning first link, another class concerning the second link. Four fuzzy logic processors are designed to deal with the measure errors, respectively. The four fuzzy logic processors are also divided into two classes according to the two measure classes. Then, the processed results from the four processors are composed to produce control signs to compensate the errors occurring in the manipulator motion. This method simplifies the design of the fuzzy logic controller. Finally, numerical simulation verifies the fuzzy controller.