Pneumatic Position Control of Shift and Select Operation in Heavy Duty Vehicles
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The aim of the thesis is to find out if it's feasible to use on/off solenoid valves and pneumatic actuators to operate heavy duty manual transmissions. The shift and select operations in the transmission will be position controlled to reduce wear and tear. The on/off solenoid valves are more complicated to control than proportional valves, but are cheaper, smaller and more robust. Production cost is a crucial factor in all parts of automotive industry. This lead to limiting sensory inputs to only a position sensor for each of the two actuators.The gear change dynamics of a heavy duty transmission with the added pneumatics was modeled in MATLAB-Simulink. This enabled the development of a gain scheduled controller for the system. The pneumatics and control system was then implemented in a test rig consisting of a transmission driven by an electric motor, and the results were compared to those of the simulations. The results show that full gear changes with both shift and select actuation can be done in under 350 ms, and that the model replicates the dynamics in a realistic manner. It was found that one should implement RPM-matching in the system. This would lead to less wear and tear on the transmission, lower shift times and higher consistency in shift times. These results show that the use of on/off solenoid valves are a feasible choice of control method for the system.