Experimental Verification of Discretely Variable Compression Braking Control for Heavy Duty Vehicles

In this report a recursive least square scheme with multiple forgetting factors is proposed for on-line estimation of road grade and vehicle mass. The estimated mass and grade can be used to robustify many automatic controllers in conventional or automated heavy-duty vehicles. We demonstrate with measured test data from the July 26-27, 2002 test dates in San Diego, CA, that the proposed scheme estimates mass within 5% of its actual value and tracks grade with good accuracy. The experimental setup, signals, their source and their accuracy are discussed. Issues like lack of persistent excitations in certain parts of the run or difficulties of parameter tracking during gear shift are explained and suggestions to bypass these problems are made. Finally, the steps taken for developing the compression brake map, transmission map and tuning a controller for coordinated use of service and compression brake are explained. Using the data from the July 26-27, 2002 test dates in San Diego, CA, we show in simulation that the inclusion of the splitting torques scheme resulted in a service brake use decrease of 90 percent.