Transmission shift control - Off-highway

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Customer: 1st Tier supplier to Automotive Industry

Market: Off-highway - Worldwide

BRACE execution: Model Based Design & Auto-coding competence cluster

Location: BRACE office & Customer site

The considered transmissions contain several gear sets, which are each (dis)connected by hydraulic actuated clutches. During shifting, the transmission output torque may not be interrupted to prevent unwanted vehicle behavior. Therefore this transmission shifts as an overlap shift, where the output torque is maintained during the shift. In addition the clutches are used as well for vehicle braking. The shifts had to be smooth with very different load conditions to maintain cargo stability which made the requirements harder to fullfill than in a passenger car environment.

The current shift control and strategy of these transmissions are outdated. Also after a while in operation, the transmission controller must be recalibrated to cover up some (clutch) wear. The goal of this project is to update the shift controls and strategy to improve the performance and comfort, without changing the hardware. The need for recalibration after a given operation time must absolutely be prevented with the new controls.

The following were part of the project:

• Modelling and simulating of transmission components with Matlab. • Modelling and simulating of a complete driveline with Matlab. • Test bench operation with dSpace. • Performing different kind of experiments on a test bench. • Model validation on a test bench. • Control development. • Prototype testing. • Transfer of results to a production level.