Continuum robots have gained widespread popularity due to their inherent compliance and flexibility, particularly their adjustable levels of stiffness for various application scenarios. Despite efforts to dynamic modeling and control synthesis over the past decade, few studies have focused on incorporating stiffness regulation in their feedback control design; however, this is one of the initial motivations to develop continuum robots. This paper aims to address the crucial challenge of controlling both the position and stiffness of a class of highly underactuated continuum robots that are actuated by antagonistic tendons. To this end, the first step involves presenting a high-dimensional rigid-link dynamical model that can analyze the open-loop stiffening of tendon-driven continuum robots. Based on this model, we propose a novel passivity-based position-and-stiffness controller adheres to the non-negative tension constraint. To demonstrate the effectiveness of our approach, we tested the theoretical results on our continuum robot, and the experimental results show the efficacy and precise performance of the proposed methodology.

翻译：连续体机器人因其固有的柔顺性和灵活性而广受欢迎，尤其因其在不同应用场景下可调节的刚度水平备受关注。尽管过去十年在动力学建模与控制综合方面取得了诸多努力，但很少有研究将刚度调节纳入反馈控制设计中——然而这恰恰是发展连续体机器人的最初动机之一。本文旨在解决一类由拮抗肌腱驱动的高度欠驱动连续体机器人的位置与刚度协同控制这一关键难题。为此，首先提出一个高维刚体连杆动力学模型，该模型能够分析腱驱连续体机器人的开环增刚度效应。基于该模型，我们提出一种新型基于无源性的位置-刚度控制器，该控制器严格遵守非负张力约束。为验证所提方法的有效性，我们在自研连续体机器人上开展了理论成果的测试实验，实验结果证明了所提方法的优越性能与精确控制能力。