Payload oscillation reduction in load-handling machines: A frequency-based approach

This article presents an innovative pressure feedback method to address undesired payload oscillations in hydraulic load-handling machines, which have a negative impact on both machine productivity and safety. Tracking control techniques in these machines are often not applicable due to the difficulty or the cost associated with the installation of the feedback sensors on the payload. In this work, by means of pressure sensors installed on the hydraulic system, the payload oscillation frequency is first detected by analyzing the frequency content of the measured pressure and then counteracted through a sinusoidal-based excitation command on the machine actuator. The work particularly addresses the challenges related to the use of the same actuator for detecting and quantifying the oscillation (in both frequency and amplitude) and for reducing the payload oscillations. In fact, interference on the feedback pressure signal due to the control action is present. Experimental results on a truck-mounted hydraulic crane show how the proposed technique permits to reduce payload oscillation in order of 50%, which is comparable to other less-practical tracking control techniques.