Sensor Fusion for Compliant Robot Motion Control

In English Force feedback control is necessary for accurate force control in robotic manipulators and, thus far, wrist force/torque (F/T) sensors have been used. An important problem arises when only these types of sensors are used. In a dynamic situation where the manipulator moves in either free or constrained space, the interaction forces and moments at the contact point and also the non-contact ones are measured by the force/torque sensor. In this work, an estimator based on a sensor fusion strategy integrating the measurements of three different sensors (a wrist F/T sensors, an inertial sensor and joint sensors) was developed to determine the contact force and torque exerted by the manipulator to its environment. The resulting observer helped to overcome some difficulties of uncertain world models and unknown environments since it reduces the high-frequency and low-frequency spectral contents—i.e., the low-frequency component due to inertia of a heavy tool mass and the high-frequency component due to impacts. The new improvement was experimentally validated in a force/position impedance control loop applied to a Stäubli RX60 industrial robotic platform.