A Three Dimensional Method for Determining Vehicle Load in a Powershift Transmission Application 952132
A control need for powershift transmissions exists to determine vehicle load under a variety of conditions experienced by off-road vehicles. Conditions include fully-loaded, partially-loaded, full-throttle and part-throttle. For this vehicle application, agricultural tractors produced by AGCO, the only parameters available to the electronic transmission control unit were engine speed and intake manifold turbo boost pressure. From sparsely populated data, a 3-D torque map was developed to represent engine speed, turbo boost pressure and PTO torque. Filtered data were then placed into the electronic transmission control as a representation of vehicle load. This 3-D torque map allows the microcontroller to approximate the vehicle's load, using engine speed and turbo boost pressure as input parameters. This method of determining vehicle load allows the electronic transmission control (ETC) to maintain a consistent acceleration through all shift conditions. This methodology contributes to reduced operator fatigue and mechanical stress of the vehicle.