Analysis of Variable Impedance Characteristics in Human Movements and Its Application to Control of Powered Prosthetic Arms

本研究的目的是建立一个新的人体运动阻抗模型，并将其应用于动力假肢的控制。本研究取得的主要成果如下：1.为了通过实验来估计人体阻抗，需要测量施加到人体四肢端点的外部干扰所对应的力。本研究开发了一种新型的阻抗测量实验装置，该装置可以在水平面内施加任意方向的外部干扰.通过对腕关节机械阻抗的测量，分析了骨骼肌激活水平与关节阻抗的关系。实验结果表明，腕关节的粘弹性变化取决于肌肉的激活水平。然后，提出了一种新的关节阻抗模型，该模型使用了肌肉激活水平的非线性回归模型。提出的关节阻抗模型实现了一个动力假肢与3自由度，这是由超声电机驱动。在该控制系统中，操作人员可以通过使用他/她的EMG信号来控制关节阻抗本身。假肢控制系统的实现相结合的建议阻抗控制系统和运动歧视系统，可以估计操作员的预期动作从肌电信号使用神经网络。所开发的控制系统的有效性，证实了截肢者的实验。

The purpose of this research is to make a new impedance model of human movements and apply it to the control of powered prosthetic arms. The obtained results throughout the research can be summarized as follows :1. In order to estimate the human impedance experimentally, it is necessary to measure force corresponding to external disturbance applied to an end-point of human extremities. In this research, a new experimental apparatus for the measurement of the impedance has been developed, by which the external disturbance with any direction in the horizontal plane can be applied.2. Measuring the mechanical impedance of the wrist joint, we have analyzed the relation between the activation level of skeletal muscles and the joint impedance. The experimental results show that the viscoelasticity of the wrist joint changes depending on the muscular activation level. Then, a new joint impedance model using a nonlinear regression model of the muscular activation level has been proposed.3. The proposed joint impedance model was implemented into a powered prosthetic arm with 3 degrees of freedom which are driven by ultrasonic motors. In this control system, a human operator can control the joint impedance itself by using his/her EMG signals.4. The prosthetic control system was realized by combining the proposed impedance control system and a motion discrimination system that can estimate the operator's intended motions from EMG signals using a neural network. Effectiveness of the developed control system was confirmed from the experiments by an amputee.