1kHz is not enough — How to achieve higher update rates with a bilateral teleoperation system based on commercial hardware

Abstract

Teleoperation has a long history in the robotics community and numerous bilateral teleoperation systems employing manipulators have been proposed in the literature. On the one hand, systems have been designed which employ commercial hardware and hence generally suffer from low update rates and high delays due to restrictions of commercial manipulator controllers and haptic device controllers. On the other hand, bilateral teleoperation systems designed by research institutions often provide only few degrees of freedom. Our 6DoF bilateral teleoperation system, however, combines the amenities of commercial hardware with a high performance distributed control architecture which enables us to achieve update rates of more than 2kHz and delays in the range of only 100µs. This paper focuses on the architecture of our system and demonstrates how to achieve this performance using commercial hardware. Moreover, we show why update rates of more than 1kHz are essential for certain teleoperation tasks. Especially with high approach velocities and stiff environments, high update rates and low delays are key requirements for stability and thus for realistic haptic perception. We present experimental results demonstrating the influence of the update rate on system stability. These results not only highlight the benefits of high update rates but also give hints on how to estimate the update rate necessary to achieve stable teleoperation for a given environment stiffness.