Enhancing the Tracking Performance of Passivity-based High-Frequency Robot Cloud Control

Fabian Jakob, Xiao Chen, Hamid Sadeghian, Sami Haddadin

Abstract: This paper addresses the migration of high-frequency robot controllers to remote computing services, which are connected via a communication channel prone to delays and packet loss. The stability of the networked system is guaranteed by ensuring passivity of each subcomponent in the interconnection, as well as the Time-Domain-Passivity-Approach (TDPA) for the communication channel. We reduce conservatism of the TDPA using the model knowledge on both sides of the communication system to identify passivity excesses. This is further used to avoid over-dissipation of energy in the passivity controller by augmentation of a tolerable passivity-shortage. Tracking offsets are eliminated with a position drift compensation algorithm, for which convergence guarantees are provided. The experimental validation of the results conducted on a 7-DoF Franka Research 3 robot demonstrates a substantial enhancement in tracking performance due to the proposed modifications, particularly in scenarios with high communication delays.