The conventional force control has proposed load-side torque control based on the resonance ratio control (RRC) enhanced by an instantaneous state observer using the acceleration sensor; however, environmental stiffness variation ($K_e$ variation) is not considered in such systems. This article evaluates the robust stability of the conventional method based on open-loop characteristics and the stability analysis results indicate that the conventional method becomes unstable during $K_e$ variation. To realize superior high-robust stability, this article proposes a high-robust force control based on the duality of the two-inertia system. This article constructs an equivalent RRC (ERRC) combining the motor-side velocity control and the load-side velocity observer and demonstrates a torque-velocity duality. The results confirm that the load-side torque control based on ERRC is robust against $K_e$ variation through the analysis of open-loop characteristics, and illustrate that the ERRC has the same as the conventional RRC proposed in position or velocity controls. The effectiveness of the proposed control method is validated through numerical simulations and experiments.

中文翻译：

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基于二惯量系统对偶性的环境刚度变化高鲁棒力控制

传统的力控制提出了基于共振比控制（RRC）的负载侧扭矩控制，通过使用加速度传感器的瞬时状态观测器；然而，环境刚度变化（$K_e$在此类系统中不考虑变化）。本文基于开环特性评估了常规方法的鲁棒稳定性，稳定性分析结果表明常规方法在$K_e$变化。为了实现优越的高鲁棒稳定性，本文提出了一种基于二惯性系统对偶性的高鲁棒力控制。本文构建了一个结合电机侧速度控制和负载侧速度观测器的等效 RRC (ERRC)，并演示了转矩-速度对偶性。结果证实，基于 ERRC 的负载侧转矩控制对$K_e$通过开环特性分析的变化，并说明ERRC在位置或速度控制方面与传统的RRC具有相同的特性。通过数值模拟和实验验证了所提出的控制方法的有效性。