Design and Feasibility Verification of a Knee Assistive Exoskeleton System for Construction Workers

Robotic-powered exoskeletons and body joint-adapted assistive units are currently under development for the enhancement of human locomotor performance in the military, in industries, and in patients and the elderly with mobility impairments [1]. They free people from much labor and the burdens of many kinds of manual work. For example, when it comes to automation in the industrial field, factory automation has made good progress. Operators (humans) can be included in a conventional manufacturing process with respect to a formal production line and uniform working conditions. Automation outside the production line, however, especially in common manufacturing stages, has several limitations and difficulties in adapting to actual conditions because the industrial field has but a small part in the process due to its operating characteristics. There have been many approaches to the reduction of labor that do not only fully assist but also partly aid workers, such as in the use of extremely heavy payload-oriented construction equipment, which are manipulated by humans. Manual or semi-automatic machine tools are mostly used in contemporary industries. In particular, without manpower, especially without the manipulability and mobility of the upper and lower human limbs, full automation will be incompatible with today’s technologies [2]. Exoskeletons have strong advantages given their unique features such as their outstanding physical performance, exceeding that of humans, and their agility, which is utilized by operators’ nerve systems. As a result, attempts to adopt exoskeletons in the industrial field, especially at construction sites, indicate the use of feasible approaches to factory automation. The strategy and support method for exoskeletons that amplify human muscle power can be divided into four main categories: (1) exoskeletons that totally alternate with both the upper and lower parts of the muscle power system, (2) assist the all extremities not alternate (here, assist means the human share the load with the exoskeleton and alternate means the human just input operation command using his own motion into exoskeleton system and it totally handles the load), (3) alternate with the part of all extremities (4) assist the part of all extremities of muscle power system. The first type of exoskeleton which alternates with the entire muscle power still has many limitations, as with its size and electric power supply. Due to these constraints, exoskeletons are usually bulky and cannot freely move out of the range of the power source line. One of the representative studies of the second type which assists the whole body is the HAL series.