A new robust stability analysis and design tool for bilateral teleoperation control systems

In this paper, a powerful robust stability analysis technique is introduced and developed for teleoperation systems. The methodology is based on wave parameters and discusses absolute stability and potential instability using scattering and is originally used in microwave systems [1], The proposed method provides suitable mathematical and visual aids to determine bounds or regions of passive environment impedances for which a potentially unstable system connected to any passive operator is stable, and vice-versa. Furthermore, a novel stability parameter is proposed to maximize the derivation of the above bounds or regions. This results in less conservative guaranteed stability conditions compared to the Llewellyn´s criterion; thus, achieving a better compromise between stability and performance. The proposed methodology allows for the design of bilateral control systems when such bounds are known or even when the operator or environment dynamics are active. The new robust stability analysis and Llewellyn´s criterion are numerically evaluated and compared with each other on two common teleoperation control architectures.