欠驱动假手手指抓取力的研究

Finger grasp force of underactuated prosthetic hand

为了满足欠驱动手进行复杂作业的需要,基于欠驱动原理建立了手指对物体的抓取力模型和基于力的阻抗控制策略.对应于任一手指姿态,抓取力模型可以准确得到基关节抓握力矩和手指各指节抓取力的关系;采用基于力的阻抗控制策略,实现了基关节抓取力控制.实验证明,手指能够稳定地抓取鸡蛋这样比较滑、容易碎、形状复杂且有一定质量,需要稳定和平衡抓取力的物体,其成功率达80%以上.而这是单纯用手指的基关节力控制很难做到的(成功率只有不到20%).手指抓取力模型和阻抗控制策略的建立大大增强了假手进行复杂作业,抓取复杂物体的能力.

In order to improve the operation capacity of an underactuated prosthetic hand,the static grasp model and the force based impedance control strategy of the finger were constructed based on the underactuated mechanism.According to the static grasp model,the precise relationship between the actuation torque and the support force from phalanges can be obtained corresponding to any grasp attitude.The force based impedance control strategy realizes the force control of base joint.According to experiments,the finger can stably grasp a slippery,fragile,complicated and comparatively heavy object such as an egg.Its success ratio reaches 80%,which can not be achieved only through the force control of base joint（the success rate was only less than 20%）.Therefore,the hand can realize complex operation with the construted static grasp model and the force based impedance control strategy.