An Integrated Programmable CPG With Bounded Output

• 成果类型: Article
• 署名作者: Pasandi, Venus; Sadeghian, Hamid; Keshmiri, Mehdi; Pucci, Daniele
• 署名单位: Istituto Italiano di Tecnologia - IIT; Isfahan University of Technology; Technical University of Munich
• 刊物名称: IEEE TRANSACTIONS ON AUTOMATIC CONTROL
• ISSN/ISSBN: 0018-9286
• DOI: 10.1109/TAC.2022.3166715
• 发表日期: 2022
• 页码: 4658-4673
• 关键词: trajectory; oscillators; robots; Legged locomotion; Synchronization; Limit-cycles; Trajectory optimization; Cyclic motions; integrated central pattern generator (CPG); programmable oscillator; smooth motion modulation; state-constrained dynamical system

摘要

Cyclic motions are fundamental patterns in robotic applications, including industrial manipulation and robot locomotion. This article proposes an approach for the online modulation of cyclic motions in robotic applications. For this purpose, we present an integrated programmable central pattern generator (CPG) for the online generation of the reference joint trajectory of a robotic system out of a library of desired periodic motions. The reference trajectory is then followed by the lower level controller of the robot. The proposed CPG generates a smooth reference joint trajectory convergence to the desired one while preserving the position and velocity joint limits of the robot. The proposed CPG consists of one novel bounded output programmable oscillator. We design the programmable oscillator for encoding the desired multidimensional periodic trajectory as a stable limit cycle. We also use the state transformation method to ensure that the oscillator's output and its first time-derivative preserve the joint position and velocity limits of the robot. With the help of Lyapunov-based arguments, we prove that the proposed CPG provides the global stability and convergence of the desired trajectory. The effectiveness of the proposed CPG for trajectory generation is shown in a passive rehabilitation scenario on the Kuka iiwa robot arm, and also in walking simulation on a seven-link bipedal robot.