Realization of Mechanical Gravity Canceller equipped with passive adjustment mechanism for arbitrary load

Abstract

This study aims at realization of passively adjustment of compensation force generated by Mechanical Gravity Canceller (MGC). If an object attached to MGC is changed, it needs to adjust spring force for accurate balance. In the previous studies, self-tuning load compensable mechanism for MGC is developed. The mechanism can compensate torque of both manipulator's weight and load by using springs. However, the mechanism has a weak point that is necessary to rehang the spring as the load changes. More energy is required to rehang the spring than to lift the object which isn't compensated. For a solution of this problem, a passive adjustment mechanism is developed. The passive adjustment mechanism has two springs. One of the springs (spring 1) compensate its weight and another spring (spring 2) compensate load. Then spring 2 weigh load by changing displacement and the displacement change the compensation force of spring 2 passively. Therefore, the passive adjusting Mechanism can compensate its weight and arbitrary load completely. Moreover, to improve safety, the mechanism applies to an up-and-down system of the arbitrary load. The testing machine realizing proposed mechanism is 19 kg and can compensate from 0 kg to19 kg arbitrary load. Relative errors of compensation power of the machine are under 10 % and relative charged energy converges 10.5 % as increasing weight of load.