A self-contained, elastic joint drive for robotics applications based on a sensorized elastomer coupling—Design and identification

•A novel, sensorized, elastomer coupling based on the principle of jaw couplings is presented.•The elastomer coupling is integrated into a self-contained, rotatory joint drive.•Integrated rotary position sensors measure the torsion angle of the coupling.•A system identification of the elastomer coupling is realized and models are derived.•Using these models with the torsion measurement the acting torque can be estimated.

While classical robotics traditionally makes use of stiff constructions in order to achieve a high precision, there is on-going research in development and control of new compliant robotic systems. These systems are suitable for direct human–machine-interaction due to their elastic behavior. The compliance is mostly achieved by control or by the integration of steel springs into the joint drives. This paper proposes a novel approach based on a sensorized elastomer coupling. Due to its damping characteristics, the interaction-safety can be improved in comparison to steel spring or purely control based approaches. The presented coupling is an integral part of a self-contained drive system which is also introduced. Simulation results of the strain/torsion and torque/torsion relationship for different geometrical variations of the elastomer coupling and experimental data of a prototype are presented. Since the sensorized coupling provides torsion measurements of the elastomer inlay, a system identification approach was employed to derive nonlinear and linear models of the coupling which can later be used in model-based joint-control.