Hierarchical fuzzy logic controller for a flexible link robot arm performing constrained motion tasks

Abstract

An examination is performed on the dynamics and control issues for a robotic manipulator with link structural flexibility modelled during the execution of a task that requires the robot tip to contact fixed rigid objects. A multi-time-scale fuzzy logic controller is applied to this system. The large-scale system is decomposed into a finite number of reduced-order subsystems using the singular perturbation approach. A hierarchical ordering of fuzzy rules is used to reduce the size of the inference engine. Real-time implementation of fuzzy controllers can help reduce the burden of large-sized rule sets by fusing sensory data before input and the system's output to the inference engine. Using this approach the control of the force and position of the robot end point is possible while the end-effector moves on the constraint surface.