Drive Line Control for Off-Road Vehicles Helps to Save Fuel

A new control concept was developed to minimize the power losses of a hydrostatic drive line for off-road vehicles. The drive line control concept is based on two separate closed loop controls, one for the hydrostatic transmission and another for the combustion engine. The command values for both control loops are calculated under consideration of the characteristic curves of the combustion engine and the losses within the hydrostatic transmission, using an on-line optimization procedure. This paper discusses the benefits of this control concept based on a comparison of typical realistic driving manoeuvres. Objective of the investigations for different output powers is the potential of fuel savings under different operating conditions. A hardware-in-the-loop test rig for the investigated hydrostatic propel drive is used for the experimental validation.