This paper presents an optimal algorithm to enhance the performance of an On-demand All Wheel Drive (ODAWD) vehicle by traction improvement through regulation of wheel slip. A 'Minimum Fuel Problem' is developed with a cost function minimizing the slip error and the control action which is the ratio of the torque transmitted to the non driven wheels (rear wheels) to the total torque from engine. A simplified vehicle model (bicycle model) is used for the derivation and the system produces a Two Point Boundary Value Problem (TPBVP) once the Hamiltonian is formed and Pontryagin minimum Principle is used. An iterative algorithm based on the 'Shooting Method' is then used to arrive at the optimal control action. The proposed controller optimally reduces the wheel slip error by engaging and dynamically controlling a hydraulic clutch which transmits the optimal torque to the rear wheels, thus reducing the vehicle longitudinal slip and enhancing vehicle traction. The controller was simulated in two phases where the first phase was an open loop simulation for a desired vehicle speed profile and the second phase, a closed loop system where the controller was integrated on a validated 14 degree-of-freedom detailed vehicle model in SIMULINK. The two phased simulation results provide high promise of the controller performance on low friction coefficient surfaces with enhanced traction and reduced vehicle longitudinal slip in an acceleration event.


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    Title :

    Optimal control of a quasi-linearized on demand all wheel drive system


    Contributors:


    Publication date :

    2008


    Size :

    7 Seiten, 15 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English