Abstract

Typically, off-road construction machines are not equipped with suspensions at the wheel axles. This has led to alternative concepts that uses the working implement to mitigate the vibration transmitted to the cabin. The most common solutions are based on passive ride control (PRC) methods. A PRC usually requires a hydraulic accumulator and dissipating valves properly connected to the working hydraulics. In this way, the PRC is able to dissipate the fluid energy and damp the oscillations of the pressure inside the hydraulic actuators, with clear benefits on the machine vibration. This paper focuses instead on an active ride control (ARC) methodology, which controls the working hydraulic motion to counter-reach the machine vibrations, avoiding the use of an accumulator.

The paper addresses the main challenge of designing the controller for the ARC for the reference case of a wheel loader. A high pass pressure filter control with pressure feedback is proposed for this application. The controller is first studied in a simulation model and then validated through experiments on a stock machine.

The bandwidth limitation of the standard hydraulic system does not permit to achieve the same performance of a state-of-art PRC system considered as baseline. Notwithstanding, the experimental results on the proposed ARC shows significant improvements with respect to a case where no controller is used. Moreover, the proposed method could be applied with more effectiveness in hydraulic systems with higher dynamic response.

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