Vibration control of a telescopic handler using time delay control and commandless input shaping technique: Fid-Bau Portal

Vibration control of a telescopic handler using time delay control and commandless input shaping technique

Park, J.Y. / Chang, P.H.

A telescopic handler is a type of construction machinery used for the loading, transporting and unloading of various forms of cargo. To increase its productivity, the boom of the telescopic handler should be operated at high-speed mode without any occurrence of vibration. Residual vibration, however, in the boom often arises when lifting cargo to higher positions. To solve this problem associated with the occurrence of vibration, TDC (Time Delay Control) and commandless IST (Input Shaping Technique) were applied. In the case of small motion operation, the motion of the boom was controlled so that it did not excite the dominant vibrational mode. To this end, first a reference trajectory was designed that did not excite the natural frequency of the telescopic handler, then, the boom was controlled to follow the trajectory by using TDC, which is a well-proven and effective method for nonlinear systems. The experimental results indicate that TDC control performance was higher than that of a skilled human operator. The vibration occurring during unloading operations can be regarded as an impulse response caused by external disturbances. Considering the characteristics of the vibration, commandless IST was proposed. The experimental results indicate that commandless IST reduced about 77 % of the original vibration in the unloading operation. To use the proposed algorithm in actual applications under various working conditions such as the weights of the loads, the length of the boom and the boom angle, an additional algorithm, the gain map method, is required. That is, after detection of current working condition through infor-mation from sensors, its corresponding gains obtained from the gain map are applied. Through this algorithm, the methods proposed can be used under various working conditions. To this end, additional sensors has to be installed to detect current working condition and to perform the experiments under the each working conditions to make the gain map out. The effectiveness of the new method was confirmed through experiments. These promising results show that the proposed control schemes can improve productivity, safety and ride comfort of the telescopic handler, and that even a novice operator can easily operate its boom without vibration occurring.