This study deals with a calculation method for the forward kinematics of a 3 DOF parallel link manipulator. As a method for such a calculation, up to the present, the Newton method, or Newton-Raphson method alternatively, has been generally used. Nevertheless, this method is difficult to apply to on-line control systems, since it requires significant computation time and a large capacity of computer memory for calculations. In this study, therefore, a new algorithm for calculating forward kinematics is proposed. Fundamentally, the algorithm consists of two processes. The first is to calculate in a very short time an approximate solution of the kinematics. The second is to compensate the approximate solution in order to obtain the accurate one. It was confirmed that the computation time for the new algorithm was decreased to as little as 1/69-1/81 that for the Newton method. It was also confirmed experimentally that the algorithm was successfully applicable to an on-line control system.

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This paper deals with dynamic characteristics of a balanced piston type relief valve for water hydraulic use. Mathematical model for the valve has been derived as ordinary differential equations of 8th order. Effects of various structural parameters on the stability of the system have been investigated by eigenvalue analysis. As a result, it has been shown that the system stability can be improved by making the middle chamber volume of the valve and the pilot valve mass as small as possible. Furthermore, it has been found that the existence of a drain pipeline markedly affects the instability of the valve mode.

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Vane pumps have been used mainly at medium rotational speeds and system pressures.By using dual-vanes instead of the usual single vanes, it is possible to operate them under more severe conditions. In this paper, we have focused on the jumping phenomenon that causes dual-vanes to detach from the cam ring during the compression process. Vane jumping was taken into consideration when the motion of the dual-vane and transient pressure of the pumping chamber were modeled. Measurement of the dual-vane movement and chamber pressure was conducted in order to compare it with the simulation results. A technique using an additional chamber was introduced to prevent the vane jumping.

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