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
.