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Conventional knee supporters generally reduce knee pain by restricting joint movement. In other words, there were no mechanical knee supporters that functioned powerfully. Considering this problem, we first devised a device in which a spring is inserted into the double structure of the cylinder and piston, and a braking action is applied to the piston. This mechanism retracts when the knee angle exceeds a certain level. Next, the knee and the device were modeled, and the dynamic characteristics of the device were investigated to find effective elements for knee shock absorption. Although various skeletal and muscular structures have been studied for the knee section, we kept the configuration as simple as possible to find effective elements for the device. A shock-absorbing circuit was devised, and air was used as the working fluid to facilitate smooth knee motion except during shock. Increasing the spring constant effectively reduced the knee load.

Conventional ergonomics utilizes second-order control systems and three-dimensional models, but their complexity makes them unsuitable for practical development. In this paper, a simple mechanism for lifting objects by temporarily setting the load to zero was devised by applying basic techniques of kobujutsu (Japanese ancient martial arts). The accuracy of this mechanism was confirmed by simulation and experiment. This mechanism reveals that the speed of reflection of signals by the brain is important to essentially increase the output of human muscles, enabling efficient and simple movements. It is suggested that the method of lifting objects revealed in this paper is not limited to martial arts and other sports fields but could be applied to a wide range of fields such as nursing care and agricultural work. The development and evaluation of the simple object lifting technique demonstrated in this paper is expected to activate and improve the motor skills of the public and have a positive impact on health maintenance activities.

Trawling is one of the most common fishing methods used by small vessels. This method requires the vessel to operate at a constant low speed because the depth of the trawl must be kept constant. In addition, the operation is often conducted by a small number of people, who must simultaneously maneuver the vessel and fish, making automation desirable. To develop this device, a mathematical model of the vessel was created based on data collected from actual operation of the vessel, and simulations were conducted to determine what type of control system would be suitable. As a result, it was possible to grasp effective control methods, effects of disturbances such as tides and waves, and how to deal with effective parts to improve response.