Simulation of an Electrohydraulic Draft Control System for an Agricultural Tractor

The agricultural tractor/implement system is well understood and hence relatively easy to model. Addition of models for an electrohydraulic valve and control algorithm provides a good tool for hitch control development. Simulation provides a number of advantages in the development of a hitch control system for an agricultural tractor. A wide range of operating conditions can be studied that would be difficult, expensive, unsafe, or even impossible to produce in the field. Conditions can be repeated allowing study of subtle effects that would be lost in the random nature of field testing. Any variable involved can be observed to further understanding of the problem. The most difficult aspects of control algorithm design for these types of systems are involved in handling transients. These effects are not easily investigated with other forms of analysis. Experience gained with the simulation will allow tailoring of the developed control system to other models and makes of tractors. Additional features such as power shift control can be easily done leading to a long-range goal of an integrated powertrain control system.