Earthmoving vehicle powertrain controller design and evaluation

Previous work examined the control of a nonlinear Multi-Input Multi-Output electrohydraulic system representative of an earthmoving vehicle powertrain. The system layout incorporates a prime mover, a variable displacement pump, several flow valves and motors representing different loads on the powertrain. A gain-scheduled H_∞ controller was successfully developed and tested on a Hardware-in-the-Loop (HIL) system. However, previous results were for relatively simple reference tracking tasks. In this paper, the previously developed systems and load emulation environments are implemented and used to provide a test environment for the human-centered evaluation of powertrain controller designs. Measures for performance and efficiency are first discussed and defined for the earthmoving powertrain. The H_∞ control problem is then presented along with a brief summary of the Earthmoving Vehicle Powertrain Simulator (EVPS) plant model developed previously. Various design plant models (DPMs), based on maximizing performance and/or efficiency, are described and controllers are synthesized using commonly available H _∞ control design software. Experimental comparisons of working cycle times, tracking performance, system efficiencies, and component efficiencies are made between the different controller designs. The task used for comparison is a 180-degree closed-loop working cycle for a medium sized wheel loader.