Analysis of Grasping Force Control by Human and its Application to Pneumatically Controlled fingers

人类的手指可以很容易地握住各种物体。气动控制灵活，过载、清洁，对爆炸性环境安全。因此，为了利用气动的这些优良特性来加工海产品，对人的抓取力进行了实验分析。实验的目的是为了反映气动伺服系统驱动机械手指的实验结果。利用手套扫描系统对硬、软和各种物体进行了实验。手套扫描系统有320个测力点，可以近距离研究人类的抓取机制。实验结果表明，拇指、食指和中指的指尖对物体的抓取起主要作用。因此，可以得出结论，指尖在抓取物体时有助于力量的调节。在此基础上，改进了机械手指的运动方式，即只有拇指平行运动，食指和中指的指尖可以60度弯曲。通过这些改进，实现了机械三指气动抓取控制。但如果物体太小，三个手指就不能捏住，往往会把它包起来。研究发现，如果这些改进的机械手指握住一个小物体，则需要增加发挥手掌的机构，尽管这些问题有待解决，但本研究表明，气动驱动的机械手指可以实现像人类手指一样的力控制作用。

Human's fingers can easily hold various objects. And pneumatic control is flexible to overload, clean, and safety to explosive environment. So, in order to utilize these good features of pneumatics to process sea foods, the Human's grasping force have been analyzed experimentally. The purpose of experiment is to reflect its results for developing mechanical fingers actuated by a pneumatic servo system.Experiments were made on hard, soft, and various objects by using Glove Scan System. Glove Scan System has 320 force detection points, so it can make possible to closely investigate human's grasping mechanism. Experimental results show that tip of a thumb, a forefinger and a middle finger mainly contribute to grasp object. Thus, it is concluded that fingertips contribute to force adjustment in grasping of the object. The prototype mechanical fingers were moved parallel to pinch object.From this result, the movement of the mechanical fingers have been improved to be able to force control, that is, only thumb finger move parallel, and the tips of the forefinger and the middle finger can be bend at 60 degree. By these improvements, the grasp control is possible to realize by mechanical three fingers actuated pneumatically. But if the object is too small, three fingers could not pinch and tend to enclose it. It is found that if these improved mechanical fingers hold a small object, the mechanism to play the palm of hand should be added.Although these problem should be resolved, this research could show that the mechanical fingers actuated by pneumatics could realize the role the force control like Human's fingers.