Closed loop velocity control of a small teleoperated hydraulic machine

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Closed loop velocity control of a small teleoperated hydraulic machine

Raneda, A. / Vilenius, J. / Huhtala, K.

The goal of this paper is to develop a closed loop velocity control for a small teleoperated hydraulic mobile machine. The mobile machine subject to study is a skid steered leader equipped with boom and bucket for load handling. After carrying out modifications to convert the normal leader into a teleoperated machine (installation of electrohydraulic valves, pump and multiple sensors) the mobile machine is, at first, remote controlled by directly actuating the valves in an open loop manner using steering wheel and gas pedal for motion control and a joystick for boom and bucket control. This type of control was very fast to implement and provided reasonably good results. However several drawbacks were experienced such as undesired motion due to valve leakage in the null position and low efficiency of the machine. In order to increase the controllability of the machine, a closed loop velocity control was implemented in the mobile machine. In the velocity control scheme the diesel engine, the pump and the valves were regulated to provide the required flow to the hydraulic motors in order to achieve the reference velocity set by the operator. The velocity control also allows use of smooth velocity profiles in acceleration and braking and a more efficient use of the hydraulic power.