Abstract
In this paper, a power assisted system for an overhead crane is presented. This system is realized by measuring the swing angle of a crane and moving the trolley and girder in the desired direction. Therefore, operators can move a heavy object freely using only slight force. In this paper, two kinds of controllers are proposed. One is a PD controller that emulates the dynamics of object with damping and it moves the object in proportional velocity to the operating force in steady-state. Another is a PID controller that maintains the velocity of object continuously after operators cease the application of their force. Its dynamics, damping characteristics, steady-state and admissible condition of controller gain are discussed in regard to the respective controllers. This system is applied to an experimental overhead crane in the laboratory, and the effect of energy saved by the power assist is shown by measuring the heart rate of operator.
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