버킷 위치 제어용 입력성형기에 관한 연구

Abstract

To perform work of unmanned excavator, such as leveling, stumping and digging, working paths had to generate and motion of bucket had to follow this generated paths. However the motion of bucket had moved like undamped system when bucket was far from the body of excavator. In this condition, the movement of bucket couldn’t follow the suggested path easily due to relatively huge mass and spring constant. To adjust the path of bucket, the unmaned excavator needs extra controller that can control a displacement of the bucket with feed back signal. However, this solution requires extra cost and it also increases energy loss to control itself. An input shaper is a feed forward controller that can reduce the residual vibration with reference input modification. This controller doesn’t need any extra equipment and energy that improve the performance of the system. However, hydraulic cylinder system still has problem where it has a huge difference between natural frequency of the system and frequency response of actuator. Indeed, hydraulic actuator is too slow to use an input shaperBR The purpose of this paper is to suggest an input shaper that can import a hydraulic system. To satisfy this purpose, at first, kinematics and inverse kinematics of the excavator was induced. The position of the bucket was controlled by hydraulic cylinders which can be assumed like 3-axis robot. This mechanical analysis can be used to set up the command signal. After that, an input shaper was designed to reduce the residual vibration. A boom cylinder has residual vibration when bucket cylinder was moved despite a damping effect of this system. A residual vibration can be assumed a second order system and it can be adjusted by an input shaper. This result was compared with path trajectory on a fifth order polynomial. After that, the suggested input shaper was induced from the principal of the input shaper. Consequently, the suggested input shaper was verified with computer simulation.