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

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.