Analysis and Control of Variable Stiffness Robots
Analysis and Control of Variable Stiffness Robots
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变刚度机器人的分析与控制
DOI：
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发表时间：
2014
期刊：
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通讯作者：
Florian Petit
中科院分区：
文献类型：
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作者：
Florian Petit
该论文介绍了可变刚度激活的机器人的分析和控制，目的是与其环境，尤其是人类的精确，敏感，健壮和动态相互作用。抑制作用是通过开发新的控制概念的最高需求，而最先进的技术是从相关领域的。机器人系统的共同任务是机械合规性的作用，因为它可以衰减接触力，并且可以保护环境和机器人。使用联合扭矩信息的合规性提供所需的合规性：它通过吸收冲击冲击而增加了机制，其能量存储功能可以实现高度动态的动作弹簧刚度可以调整，因此，机器人可以在机械水平上调整到任务。探索可变刚度机器人的全部潜力的技术。 DLR手臂系统的集成刚度机器人已开发出本论文的简介部分。描述了可变的刚度执行器和在多关节机器人系统中的集成加深执行器的理解，在案例研究中评估了双向拮抗变量（BAV）的设置。允许完全利用关节的扭矩功能的帮助模式。刚度的性质用于合成基于CAM的BAV设置，这些设置是在实验中评估的。它允许控制算法调整机器人的阻抗属性通过提供机器人特性的灵活调整，例如平衡位置，刚度，刚度，
This dissertation addresses the analysis and control of variable stiffness actuated robots aiming at precise, sensitive, robust, and dynamic interaction with their environment and especially humans. The focus is the adjustment of impedance properties, namely adjusting the robot equilibrium position, the stiffness, and damping. Highest demands are met by the development of new control concepts and the transfer of state-of-the-art techniques from related fields. Physical interaction is a common task of robotic systems. Aiming at providing service and support for humans, robots need to be able to collaborate with humans and in human environments. The ability to perceive the surrounding and react in a sensitive way is a key factor for robots. Another one is the role of mechanical compliance as it allows to attenuate contact forces and both the environment and the robot can be protected. A step towards this goal is the class of torque controlled robots, where active control generates the compliant features using joint torque sensory information. A further advancement of this technology are the recently developed variable stiffness (VS) robots. There, a main feature is the deliberate introduction of a mechanically variable, elastic element in the robot joints. This passive spring provides the desired compliance properties: it increases the mechanism robustness by absorbing shock impacts and its energy storing capabilities allow to achieve highly dynamic motions. Additionally, the spring stiffness can be adjusted and thereby, the robot can be tuned to the task on a mechanical level. A further important property of the elastic elements is its joint torque sensing capability. In this work new control methods are developed and combined with well-established techniques to exploit the full potential of variable stiffness robots. The research has been conducted at the Institute of Robotics and Mechatronics of the German Aerospace Center (DLR), where an integrated variable stiffness robot, the DLR Hand Arm System, has been developed. An introductory part of this thesis is dedicated to the analysis and modeling of variable stiffness actuators (VSA) which is a basis for the later controller designs. An abstract dynamic model is presented describing the variable stiffness actuators and the integration in the multi-joint robot system. The properties of the model and the nonlinear and varying elastic elements are elaborated. To further deepen the actuator understanding, the bidirectional antagonistic variable stiffness (BAVS) setup is evaluated in a case study. Furthermore, the functionality of the BAVS joint and torque and stiffness properties are analysed. Major results are the existence, transition, and stiffness properties of a helping mode, which allows to fully exploit the torque capabilities of the joint. An analytical model of this mode is developed, which facilitates analysis and design of the joint’s stiffness properties. This model is used to synthesize cam disc-based BAVS setups, which are evaluated in experiments. Such, an insight into VS joint design and realization is given and additionally a contribution to actuator development is provided. The major part of this thesis is dedicated to the development of control algorithms to adjust the impedance properties of robots. The impedance control formulation is a main reason for the success of torque controlled robots. It allows to solve many tasks in an intuitive manner by providing flexible adjustment of the properties of the robot such as equilibrium position, stiffness,