Simulative controller evaluation for an electro-hydrostatic excavator actuator with load-holding capability using active hysteresis and throttling control

Abstract

In recent years, the electrification of mobile machinery has progressed.Due to the change of the primary energy source, the hydraulic system must be more efficient and sustainable.In this context, the use of decentralized electro-hydrostatic actuators (EHA) is highly promising.Still, a widespread use cannot be observed.Reasons for this might be the higher initial component costs, worse dampening, as well as higher expenditure in the implementation of the required controls.This paper presents a simulative evaluation of an electro-hydrostatic actuator with a hydraulic high-speed unit for use in mobile machinery.The circuit layout was selected based on cost considerations and includes load-holding capabilities.Furthermore, the load-holding valves are a key aspect of the control scheme.They are used to introduce a small active throttling at the discharge side of the cylinder in both pumping quadrants, thereby extending their load pressure range and enabling full operational coverage of the four-quadrants.The developed controller is mainly based on two state machines.It aims to synchronize the switching times of the valves with motor speed to enhance system performance and prevent system excitation.The controller is implemented in Matlab Simulink.For the aspired evaluation, it was coupled with a lumped parameter model of the circuit.The simulated cylinder velocities for several different speed and load combinations are evaluated to determine the control performance.Special focus is placed on the quadrant changes.

Authors 2

1. Felix Figge Aachen Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   Institute for Fluid Power Drives and Systems (ifas) , RWTH Aachen University , Aachen , Germany

2. Katharina Schmitz Aachen Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   Institute for Fluid Power Drives and Systems (ifas) , RWTH Aachen University , Aachen , Germany