Mototaro Sato

A Study on Walking Support by Human Motion Analysis and a Leg Model in Walking at Gait Initiation

This paper describes a method of assisting muscle functions at gait initiation using a human leg model. We analyzed a human motion of walking mechanism at gait initiation by measuring 3D position data and force plate data and surface EMG. It is generally accepted that the backward shift of the COP at the center of pressure of the sole of the foot is very significant at gait initiation starting from the standing upright position. The mechanism generating the backward shift of the COP is discussed according to measured data. The human leg model with the same size and the approximation weight as those of a subject was constructed to simulate the condition beginning to walk from standing upright posture. Air cylinder actuators, serving as muscle functions, were installed in the part of muscle on the leg model. Further, a small actuator is equipped at the part of the heel to produce the backward shift of the COP at beginning of the walk. Gait initiation is well simulated when actuators were operated synchronizing with the surface EMG. Based on these results, a simple method for initiating the walk was discussed in relation to walking mechanisms analyzed.

Studies on drilling of aluminum cast alloy AC8B

The object of these studies is to examine the change in cutting conditions with the progress of drilling for determining the optimum conditions in the experiments of drilling deep holes in aluminum cast alloy AC8B.The results obtained were as follows:(1) The torque was linearly increased with the increase of hole depth. However, the thrust was nearly kept constant owing to the difficulty in removal of chips, except for temporary variations.2) The cutting resistances of heat-treated (T5 and T6) specimens were higher than that of as cast (F) specimen. In particular, the resistance of T6 was the highest among them. These results would be due to the fact that there is a relationship between cutting resistance and tensile strength or hardness of the material.3) The depth of holes per one step feed greatly depended upon the feeding speed and the twisting angle of the drill. According to the data in these experiments, the effective twisting angle and feeding speed of the drill in drilling of deep holes were about 30° and 0.05 mm/rev., respectively.