An Adaptive Reaction Force Observer Design

TL;DR

This paper introduces an adaptive design method for reaction force observers that enhances robustness and stability in force control systems without relying solely on force sensors, validated through simulations and experiments.

Contribution

It presents a novel adaptive design approach for RFOB-based force control systems, enabling automatic tuning of parameters for improved stability and performance.

Findings

Enhanced stability and robustness demonstrated in simulations.

Automatic parameter adjustment improves force control performance.

Validated effectiveness through experimental results.

Abstract

In this paper, a new adaptive design method is proposed for reaction force observer (RFOB) based robust force control systems. It is a well-known fact that an RFOB has several superiorities over a force sensor such as higher force control bandwidth, stability improvement, force-sensorless force control, and so on. However, there are insufficient analysis and design methods for an RFOB based robust force control system; therefore, its stability and performance highly depend on designers own experiences. To overcome this issue, new stability analysis and novel adaptive design methods are proposed for RFOB based robust force control systems. In the proposed adaptive design method, the design parameters of the robust force control system, i.e., the bandwidths of a disturbance observer (DOB) and an RFOB, the nominal and identified inertias in the design of a DOB and an RFOB, respectively, and the force control gain, are adjusted automatically by using an adaptive control algorithm which is derived by estimating the plant parameters and environmental impedance. The proposed adaptive design method provides good stability and performance by considering the design constraints of a DOB. The validity of the proposals is verified by simulation and experimental results.