An optimal-pressure control strategy for hydrostatic wheel loader

Mobile machines consume a large amount of fossil fuel each year; therefore, it is critical to reduce their fuel consumption. A wheel loader is a typical mobile machine of great research interest. Most compact wheel loaders are usually equipped with hydrostatic transmissions. To reduce the fuel consumption of the powertrain, a min-rpm strategy where the engine speed is maintained as low as possible is usually applied. It is a rule-based control strategy, however, cannot achieve minimum engine fuel consumption. Therefore, an optimal-pressure control strategy is proposed for hydrostatic wheel loaders, where the minimum fuel consumption is achieved by selecting optimal system pressure at each time step. To show the advantages of the proposed strategy, the powertrain operation and engine fuel consumption are compared with the min-rpm strategy through simulation studies. To further verify the effectiveness of the proposed strategy, comparisons are conducted using three loading cycles (30s, 57s and 90s). Results show the engine fuel savings in three loading cycles, with fuel saving up to 27% in the 90s loading cycle.