Abstract
Recently, the attention has been focused on developing a wearable power assist robot by installing an actuator, such as motors, in the body and assisting and enhancing muscular power; there has been a considerable increase in research and development in some institutes and companies worldwide. Various types of wearable power assist robots have been proposed to support the upper and lower limbs, waist, and so on, which are to be used for the operational support of elderly and disabled people, nursing care work, and heavy lifting work in production sites. Some of them have been commercialized and their promotions have been advanced. Their social needs are extremely high, and there is an expectation of further improvements of assisting effect, installation performance, safety and convenience and affordability. In this paper, after the current state of research and development of this kind of robot is outlined, and our researches on pneumatic rubber artificial muscles, exoskeleton type standing motion assist devices, and wearable, lightweight, and soft power assist robots without an exoskeleton are introduced.
Top2. Current Research And Development Of Power Assist Robots
The research and development of power assist robots is very active. Assistance in welfare, nursing, rehabilitation, and heavy manual labour are the main usages of these kinds of robots (excluding BLEEX of DARPA in United States). The assisted body part is different according to each research institute such as upper limbs, lower limbs, shoulders, waist, or the whole body. Although an electric motor is mainly used for the actuator, there is also a lot of research and development using pneumatic rubber artificial muscles on account of their lightweight and softness. Moreover, a supersonic wave motor has been used due to its lightweight; with the use of elastic power of rubber materials. Various power assist robots are being developed at a large number of universities and institutions, which can be seen in related journals and so on (Jose, 2008). In Japan, recently, the power assist robot has been attracted in agriculture and manufacturing and so on (Yagi, Harada, & Kobayashi, 2009).
Depending on the usage, this kind of power assist robot is required to satisfy the following conditions: 1) effective assistance; 2) safety; 3) wearability and comfort (small size, lightweight and soft); 4) convenience of attaching and detaching (simple mechanism); 5) possibility of wearing during long periods of time and at any time and 6) low price. In particular, the balance of the assist effect with safety and wearability is the important issue. If using the exoskeleton type driven with a high power actuator, the assist effect can be increased, but the safety and wearability decreases. Moreover, in welfare and nursing fields, the hard exoskeleton type is not favourable for the patient or nurse to have installed for long periods of time. It is necessary to select the mechanism and structure of the robot appropriately according to the assisted body part and the operation.
A small sized, lightweight, and soft pneumatic rubber artificial muscles are useful as the actuator for this kind of robot. A human friendly power assist robot can be achieved by making use of the softness of pneumatic rubber artificial muscles.