MODELING AND CO-SIMULATION OF HYBRID OFF-ROAD MACHINERY

Co-simulation is a modeling approach that can be used to simulate systems that combine multiple physical domains in a computationally efficient manner. Hybrid off-road machinery can be modeled with required complexity by using multibody dynamics approach. The model of the machinery body can be combined with a hybrid electric powertrain which includes electrical and mechanical components in the powertrain through cosimulation. This paper describes a co-simulation platform that combines system-level hybrid electric powertrain models with detailed models of off-road machinery with hydraulic implements. This platform can help in comparing various powertrain concepts for off-road machinery. As a case example, two powertrain concepts for a tractor with a hydraulically operated front loader are compared. The dynamic traction and hydraulic loading of the tractor are simulated from user inputs given by a human operator and the resulting interactions of the tractor with a deformable terrain. A double planetary gear powertrain is combined with hydraulic actuators that are coupled, in the first case, directly to the engine, and in the second case, to the battery through a second electric motor. The model with electrically coupled hydraulics is observed to consume lower energy and fuel due to efficient distribution of the demanded power between the diesel engine and the electric battery.