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 incorporated stiffness regulation into their feedback control design; however, this is one of the initial motivations to develop continuum robots. This paper addresses the crucial challenge of controlling both the position and stiffness of underactuated continuum robots actuated by antagonistic tendons. We begin by presenting a 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 that adheres to the non-negative tension constraint. Comprehensive experiments on our continuum robot validate the theoretical results and demonstrate the efficacy and precision of this approach.

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，尤其是其针对不同应用场景的可调节刚度水平。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其反馈控制设计中——然而，这恰恰是开发连续体机器人的最初动机之一。本文致力于解决由拮抗肌腱驱动的欠驱动连续体机器人位置与刚度控制这一关键挑战。我们首先提出一个刚性连杆动力学模型，用于分析肌腱驱动连续体机器人的开环刚度调节能力。基于该模型，我们设计了一种新颖的、遵循非负张力约束的基于无源性的位置-刚度控制器。在我们开发的连续体机器人上进行的全面实验验证了理论结果，并展示了该方法的有效性与精度。