# Research into performance optimization control strategy of a hydrostatic drive bulldozer based on the constant speed cruise

## TL;DR

This paper introduces a new control strategy to improve fuel efficiency in hydrostatic bulldozers by optimizing engine and hydraulic system performance during constant speed operations.

## Contribution

A novel performance optimization control strategy is proposed to enhance fuel economy in hydrostatic bulldozers during constant speed cruise.

## Key findings

- The POCS strategy reduced fuel consumption by 6.5% and 3.7% compared to constant-speed control at 1600 rpm and 1700 rpm, respectively.
- In experiments, POCS achieved a 4.1% reduction in fuel consumption compared to the 1700 rpm constant speed control strategy.
- The strategy results in a more concentrated distribution of working points, improving overall machine efficiency.

## Abstract

Hydrostatic bulldozers, mainly medium- and low-horsepower machines, are widely used in engineering, and improving their fuel economy is crucial under the global push for energy conservation. To address the poor fuel economy of the bulldozer during repetitive, precision tasks or idle transfers, a performance optimization control strategy (POCS) based on constant speed cruise(CSC) is designed. This strategy achieves optimal overall machine efficiency under cruise control by adjusting the engine throttle and the displacement of the hydraulic pump and motor. On one hand, engine performance is optimized by designing the operating modes and the optimal fuel consumption line based on the engine’s general characteristic curve. The engine operating point is switched according to this line, reducing fuel consumption. On the other hand, the hydraulic system performance is optimized by proposing a method for determining the optimal efficiency combination for the pump and motor, considering the efficiencies of the engine, pump, and motor. This method calculates the required engine power and the preset motor speed to determine the displacement settings of the pump and motor at maximum efficiency for each operating condition. The required engine power is derived by reversing the efficiency, while maintaining the motor speed (i.e., working point identification).Then, the engine and hydraulic system models are developed and co-simulated. The results show that, compared to the constant-speed control strategy at 1600 rpm and 1700 rpm, the POCS results in a more concentrated distribution of working points, with overall fuel consumption reduced by 6.5% and 3.7%, respectively. In the final experiment, compared with the 1700 rpm constant speed control strategy (CSCS), the total fuel consumption was reduced by 4.1%. This control strategy offers a novel and effective approach to optimizing bulldozer fuel consumption and provides valuable insights for other hydrostatic applications.