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Journal of Zhejiang University SCIENCE C

ISSN 1869-1951(Print), 1869-196x(Online), Monthly

Human-machine interaction force control: using a model-referenced adaptive impedance device to control an index finger exoskeleton

Abstract: Exoskeleton robots and their control methods have been extensively developed to aid post-stroke rehabilitation. Most of the existing methods using linear controllers are designed for position control and are not suitable for human-machine interaction (HMI) force control, as the interaction system between the human body and exoskeleton is uncertain and nonlinear. We present an approach for HMI force control via model reference adaptive impedance control (MRAIC) to solve this problem in case of index finger exoskeleton control. First, a dynamic HMI model, which is based on a position control inner loop, is formulated. Second, the theoretical MRAC framework is implemented in the control system. Then, the adaptive controllers are designed according to the Lyapunov stability theory. To verify the performance of the proposed method, we compare it with a proportional-integral-derivative (PID) method in the time domain with real experiments and in the frequency domain with simulations. The results illustrate the effectiveness and robustness of the proposed method in solving the nonlinear HMI force control problem in hand exoskeleton.

Key words: Interaction force, Adaptive control, Exoskeleton, Human-machine interaction (HMI), Impedance

Chinese Summary  <33> 人机交互力控制:针对食指外骨骼控制的模型参考自适应阻抗控制策略

研究目的:在手部外骨骼的力控制问题中,由于动作变化引起的模型参数变化以及人手自身非线性的力学特性,常规的线性控制器难以很好地解决外骨骼和人手之间的交互力控制问题。本文提出将阻抗控制与模型参考自适应控制方法结合,即模型参考自适应阻抗控制(MRAIC),以解决上述困难,并进行仿真分析和实验验证。
创新要点:将阻抗控制用于外骨骼人机交互力控制,并与模型参考自适应控制结合,推导出相应的自适应控制律,从而解决动作变化引起的模型参数变化以及人手自身力学阻抗特性的非线性问题。
方法提亮:采用阻抗控制进行力控制,不仅仅控制接触力,也控制力和位移之间的动态关系,更适合于人机交互界面;模型参考自适应控制使得非线性难题得以化解,并且模型参考提升了系统整体性能。
重要结论:方波跟踪实验和正弦跟踪实验表明,与PID线性控制器相比,MRAIC控制器具有更好的稳定性,响应更快;频域仿真分析发现,MRAIC控制器在0.1~5 Hz频段具有较好品质,这与人体动作的常规频率范围相符。

关键词组:交互力;自适应控制;外骨骼;人机交互;阻抗


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DOI:

10.1631/jzus.C1300259

CLC number:

TP242.3

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On-line Access:

2014-04-10

Received:

2013-09-16

Revision Accepted:

2013-12-29

Crosschecked:

2014-03-17

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