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Optimization of Powertrain Performance Using Dynamic Scheduling of Engine Torque and Transmission Ratio
Published September 25, 1997 by Institution of Mechanical Engineers in United Kingdom
This paper considers the problem of computing engine and transmission control strategies which optimize fuel economy and exhaust emissions. The study is based on an idealized state variable model, in which it is assumed that the engine torque can be modulated instantaneously. With this idealized model, the available engine power is represented by inequality constraints, which define the maximum and minimum allowable engine speeds, and which bound the available engine torque by a peak torque curve and peak overrun torque curve, both of which are dependent on engine speed. The approach involves the multi-objective minimization of cost functions involving the fuel flow and emissions rates, which are nonlinear functions of engine torque and speed. The computational technique is based on a Goal Attainment formulation involving an iterative gradient algorithm for constrained multi-objective optimization.