19th Asia-Pacific Vibration Conference (APVC2021)

 The automation of hydraulic excavators has been required because there are serious problems such as labor shortage and an improvement of the productivity in construction sites. In various operations of hydraulic excavator, the leveling operation on the ground needs skilled technique to operate because it required a high accuracy. For the automation of the operation, the trajectory tracking control of hydraulic excavator’s bucket tip by cascade type PID control by cylinder displacement and velocity is one of the effective methods. However, a hydraulic system has a response delay from a controller input to each cylinder motion, and it complicates to improve an accuracy and stability of feedback control. As the solution to this problem, there is the Smith Predictor which an appropriately control system which has a response delay like hydraulic system. Accordingly, this study investigates to utilize Smith Predictor for the leveling operation with 1/14 scale model of hydraulic excavator which is able to experiment at low cost. This scale model has the hydraulic circuit, which composed of hydraulic cylinder, a pump, and valves, and is able to represent the behavior similar to a real machine. To apply Smith predictor to controller, the hydraulic system of the scale model excavator is modeled by using time-delay and the second order transfer function. By the experiment in which the leveling operation is controlled using a scale model, we verified the performance of the Smith Predictor.
 

hydraulic excavator,trajectory tracking control,PID control,leveling operation,smith predictor