In this paper, the torque tracking control problem for a class of series elastic actuators(SEAs) in the presence of unknown payload parameters and external disturbances is investigated. The uncertainties/disturbances ...In this paper, the torque tracking control problem for a class of series elastic actuators(SEAs) in the presence of unknown payload parameters and external disturbances is investigated. The uncertainties/disturbances rejection problem for SEAs is addressed from the view of a continuous nonlinear robust control development. Specifically, based on the analysis of a nonlinear SEA, the generic dynamics of SEA systems is described and a novel nonlinear control framework for SEAs is constructed. Then a RISE(robust integral of the sign of the error)-based second-order filter is introduced to synthesize the control law. Moreover, the control performance is theoretically ensured by Lyapunov analysis. Finally, some experimental results are included to demonstrate the superior performance of the proposed control method, in terms of transient response and robustness.展开更多
A series elastic actuator(SEA) is a powerful device in the area of human-machine integration, but it still suffers from difficult position control issues. Therefore, in this paper,an efficient approach is proposed to ...A series elastic actuator(SEA) is a powerful device in the area of human-machine integration, but it still suffers from difficult position control issues. Therefore, in this paper,an efficient approach is proposed to solve this problem. The approach design is divided into two steps: feedback linearization(FL) and global sliding mode(GSM) controller design. The bounded analysis is presented and global asymptotic convergence is analytically proven. Simulation and experiment results illustrate the effectiveness of the proposed scheme.展开更多
Human-robot interaction(HRI) is fundamental for human-centered robotics, and has been attracting intensive research for more than a decade. The series elastic actuator(SEA) provides inherent compliance, safety and fur...Human-robot interaction(HRI) is fundamental for human-centered robotics, and has been attracting intensive research for more than a decade. The series elastic actuator(SEA) provides inherent compliance, safety and further benefits for HRI, but the introduced elastic element also brings control difficulties. In this paper, we address the stiffness rendering problem for a cable-driven SEA system, to achieve either low stiffness for good transparency or high stiffness bigger than the physical spring constant, and to assess the rendering accuracy with quantified metrics. By taking a velocity-sourced model of the motor, a cascaded velocity-torque-impedance control structure is established. To achieve high fidelity torque control, the 2-DOF(degree of freedom) stabilizing control method together with a compensator has been used to handle the competing requirements on tracking performance, noise and disturbance rejection,and energy optimization in the cable-driven SEA system. The conventional passivity requirement for HRI usually leads to a conservative design of the impedance controller, and the rendered stiffness cannot go higher than the physical spring constant. By adding a phase-lead compensator into the impedance controller,the stiffness rendering capability was augmented with guaranteed relaxed passivity. Extensive simulations and experiments have been performed, and the virtual stiffness has been rendered in the extended range of 0.1 to 2.0 times of the physical spring constant with guaranteed relaxed passivity for physical humanrobot interaction below 5 Hz. Quantified metrics also verified good rendering accuracy.展开更多
串联弹性驱动器(Series elastic actuator, SEA)是机器人交互系统中的一种理想力源.本文针对非线性SEA的力矩控制问题提出一种基于RISE (Robust integral of the sign of the error)反馈的最优控制方法,能够克服模型参数不确定和有界扰...串联弹性驱动器(Series elastic actuator, SEA)是机器人交互系统中的一种理想力源.本文针对非线性SEA的力矩控制问题提出一种基于RISE (Robust integral of the sign of the error)反馈的最优控制方法,能够克服模型参数不确定和有界扰动,实现SEA输出力矩在交互过程中快速平稳地收敛到期望值.具体来说,首先对SEA的模型进行分析和变换;然后假设模型参数和扰动均已知,并在此基础上基于二次型指标设计最优控制律;之后基于RISE反馈重新设计控制律抵消模型参数不确定性和有界扰动,基于Lyapunov理论分析控制器的收敛性和信号的有界性,实验结果表明这种基于RISE反馈的最优控制方法具有良好的控制性能和对有界扰动的鲁棒性.展开更多
基金supported in part by the National Natural Science Foundation of China(61573198)in part by the National High-tech R&D Program of China(863 Program)(2012AA041403)
文摘In this paper, the torque tracking control problem for a class of series elastic actuators(SEAs) in the presence of unknown payload parameters and external disturbances is investigated. The uncertainties/disturbances rejection problem for SEAs is addressed from the view of a continuous nonlinear robust control development. Specifically, based on the analysis of a nonlinear SEA, the generic dynamics of SEA systems is described and a novel nonlinear control framework for SEAs is constructed. Then a RISE(robust integral of the sign of the error)-based second-order filter is introduced to synthesize the control law. Moreover, the control performance is theoretically ensured by Lyapunov analysis. Finally, some experimental results are included to demonstrate the superior performance of the proposed control method, in terms of transient response and robustness.
基金supported in part by the National Natural Science Foundation of China(61573198)
文摘A series elastic actuator(SEA) is a powerful device in the area of human-machine integration, but it still suffers from difficult position control issues. Therefore, in this paper,an efficient approach is proposed to solve this problem. The approach design is divided into two steps: feedback linearization(FL) and global sliding mode(GSM) controller design. The bounded analysis is presented and global asymptotic convergence is analytically proven. Simulation and experiment results illustrate the effectiveness of the proposed scheme.
基金supported by the National Natural Science Foundation of China(61403215)the National Natural Science Foundation of Tianjin(13JCYBJC36600)the Fundamental Research Funds for the Central Universities
文摘Human-robot interaction(HRI) is fundamental for human-centered robotics, and has been attracting intensive research for more than a decade. The series elastic actuator(SEA) provides inherent compliance, safety and further benefits for HRI, but the introduced elastic element also brings control difficulties. In this paper, we address the stiffness rendering problem for a cable-driven SEA system, to achieve either low stiffness for good transparency or high stiffness bigger than the physical spring constant, and to assess the rendering accuracy with quantified metrics. By taking a velocity-sourced model of the motor, a cascaded velocity-torque-impedance control structure is established. To achieve high fidelity torque control, the 2-DOF(degree of freedom) stabilizing control method together with a compensator has been used to handle the competing requirements on tracking performance, noise and disturbance rejection,and energy optimization in the cable-driven SEA system. The conventional passivity requirement for HRI usually leads to a conservative design of the impedance controller, and the rendered stiffness cannot go higher than the physical spring constant. By adding a phase-lead compensator into the impedance controller,the stiffness rendering capability was augmented with guaranteed relaxed passivity. Extensive simulations and experiments have been performed, and the virtual stiffness has been rendered in the extended range of 0.1 to 2.0 times of the physical spring constant with guaranteed relaxed passivity for physical humanrobot interaction below 5 Hz. Quantified metrics also verified good rendering accuracy.
文摘串联弹性驱动器(Series elastic actuator, SEA)是机器人交互系统中的一种理想力源.本文针对非线性SEA的力矩控制问题提出一种基于RISE (Robust integral of the sign of the error)反馈的最优控制方法,能够克服模型参数不确定和有界扰动,实现SEA输出力矩在交互过程中快速平稳地收敛到期望值.具体来说,首先对SEA的模型进行分析和变换;然后假设模型参数和扰动均已知,并在此基础上基于二次型指标设计最优控制律;之后基于RISE反馈重新设计控制律抵消模型参数不确定性和有界扰动,基于Lyapunov理论分析控制器的收敛性和信号的有界性,实验结果表明这种基于RISE反馈的最优控制方法具有良好的控制性能和对有界扰动的鲁棒性.
