Displacement control optimization of hydro-static transmission system containing variable displacement pump and hydro-motor of a front-end loader

The article focuses on optimizing the Front-End-Loader (FEL) machine’s hydro-static transmission (HST) system, which comprises a variable displacement hydraulic pump and hydro-motor. These components enable 2-DOF controlled operation, adjusting both pump and hydro-motor displacements simultaneously. In off-road applications, fluctuating load and speed disrupt the FEL’s efficiency. To address this, the article introduces a novel Look-up table-based MIMO controller. This controller algorithm dynamically adjusts displacement of pump <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>p</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> and displacement of hydro-motor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> based on speed or load demands, aiming for maximum overall efficiency. Integrated into the control hardware, the system optimizes performance within specific speed and torque ranges. Additionally, a sensitivity analysis highlighted the pump and hydro-motor’s higher responsiveness to displacement and operating pressure, emphasizing their crucial role in efficiency optimization. This approach ensures the FEL operates within its efficiency zone, particularly beneficial for off-road applications. Also, the solution may be directly implemented as a software update solution on the transmissions with an electronically controlled variable displacement pump and motor to operate it at high efficiency.