Open-Loop Position Control in Collaborative, Modular Variable-Stiffness-Link (VSL) Robots
Open-Loop Position Control in Collaborative, Modular Variable-Stiffness-Link (VSL) Robots
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DOI：
10.1109/lra.2020.2969943
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发表时间：
2020-01
影响因子：
5.2
通讯作者：
J. Gandarias;Yongjing Wang;A. Stilli;A. García-Cerezo;J. Gómez-de-Gabriel;H. Wurdemann
中科院分区：
文献类型：
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作者：
J. Gandarias;Yongjing Wang;A. Stilli;A. García-Cerezo;J. Gómez-de-Gabriel;H. Wurdemann
协作机器人为工业机器人和物理人机交互（pHRI）领域开辟了新的途径，因为它们适合与人类密切合作。可变刚度元件的集成和控制允许固有的安全交互：除了在可变刚度执行器上的显著工作外，可变刚度连杆（VSL）机械手的概念承诺在意外物理碰撞的情况下提高安全性。然而，这些类型的机器人机械手的位置控制是具有挑战性的关键任务为导向的运动。在这封信中，我们提出了一种混合的，基于学习的运动学建模方法，以提高传统开环位置控制器的性能，用于模块化，协作式VSL机器人。我们表明，我们的方法提高了传统的开环位置控制器的性能，并补偿了位置误差，特别是对于链接内的较低刚度值：使用我们的升级和模块化机器人，已经进行了两个实验来评估机器人在任务导向运动中的行为。结果表明，传统的基于模型的运动学方法不能精确地控制末端执行器的位置，随着VSLs内载荷的增大和压力的减小，末端执行器的位置误差增大。另一方面，我们证明，使用我们的方法，与具有3D打印刚性链接的机器人机械手相比，VSL机器人可以优于位置控制。
Collaborative robots open up new avenues in the field of industrial robotics and physical Human-Robot Interaction (pHRI) as they are suitable to work in close approximation with humans. The integration and control of variable stiffness elements allow inherently safe interaction: Apart from notable work on Variable Stiffness Actuators, the concept of Variable-Stiffness-Link (VSL) manipulators promises safety improvements in cases of unintentional physical collision. However, position control of these type of robotic manipulators is challenging for critical task-oriented motions. In this letter, we propose a hybrid, learning based kinematic modelling approach to improve the performance of traditional open-loop position controllers for a modular, collaborative VSL robot. We show that our approach improves the performance of traditional open-loop position controllers for robots with VSL and compensates for position errors, in particular, for lower stiffness values inside the links: Using our upgraded and modular robot, two experiments have been carried out to evaluate the behaviour of the robot during task-oriented motions. Results show that traditional model-based kinematics are not able to accurately control the position of the end-effector: the position error increases with higher loads and lower pressures inside the VSLs. On the other hand, we demonstrate that, using our approach, the VSL robot can outperform the position control compared to a robotic manipulator with 3D printed rigid links.