FUZZY ADAPTIVE FORCE CONTROL OF INDUSTRIAL ROBOT MANIPULATORS WITH POSITION SERVOS

A fuzzy adaptive force control algorithm is suggested for commercializ ed industrial robots equipped with position servo drives in cascade wi th a software filter for the control of acceleration/deceleration prof ile to avoid vibrational shocks due to a sudden start or stop, where t he control algorithm is composed of a Fuzzy Interpolation Logic Contro ller (FILC) and a Fuzzy Adaptive Stiffness Estimator (EASE). FILC dete rmines a control action according to the magnitude of an environmental stiffness in such a way that good force response is maintained regard less of changes of environmental stiffness. Specifically, some fuzzy c ontrollers are designed for several representative environmental stiff ness values, and then a control action for an estimated environmental stiffness value which is not the same as any representative stiffness values is decided by fuzzily aggregating different control actions of those fuzzy controllers. Here, FASE plays the role of estimating an en vironmental stiffness value and transfers the estimated stiffness valu e to FILC. To show the validity of the proposed adaptive fuzzy force c ontroller, several numerical examples and some experimental results ar e illustrated, where soft, medium and hard environments are considered .