ACTIVE VIBRATION DAMPING FOR AN OFF-ROAD VEHICLE
WITH DISPLACEMENT CONTROLLED ACTUATORS

Christopher Williamson1, Shinok Lee2, and Monika Ivantysynova1,2 
 

1) Purdue University, Department of Agricultural and Biological Engineering, 225 S. University St., West Lafayette, Indiana 47907, USA 

2) Purdue University, School of Mechanical Engineering, 225 S. University St., West Lafayette, Indiana 47907, USA 

williaca@purdue.edu, lee20@purdue.edu, mivantys@purdue.edu

Abstract

       Mobile earthmoving machines typically do not have wheel suspension. Consequently, vehicle dynamics are underdamped, and operators experience vibrations of low frequency and high amplitude which are detrimental to health, comfort and productivity. For most vehicles, the state of the art for improving ride quality is passive energy dissipation via seat dampers and hydraulic accumulators connected in parallel to the actuators. Alternatively, ride quality may be enhanced by active control of the seat or working actuators. In the present work, active vibration damping is considered for a skid-steer loader based on control of the flow rate to the boom lift cylinders with a variable displacement pump. A four degrees of freedom vehicle dynamic model is derived for linear motion in the vertical and horizontal directions, pitching angle, and boom motion with respect to the chassis. Dynamics of the hydraulic pump and actuator are also modelled. Considering the requirements of the intended application, the feedback control design emphasizes simplicity of implementation. The control law is a multi-DOF version of the well-known “skyhook damper” principle, where the control force is proportional to the vehicle velocity. Cascaded feedback loops of pump displacement and pressure produce the required force. An experimental evaluation was conducted according to ISO 2631-1 (1997) to measure the effect of the active controller on whole-body vibration as perceived by the operator. The active damping system reduced total vibration by as much as 34% and was consistently superior to a commercially available passive damping solution. Another controller with only pressure and position feedback was also tested; its performance was similar to the passive accumulators.

Keywords: activevibrationdamping,activesuspension,displacementcontrol,pumpcontrol,pressurecontrol,loader



 

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