US Patent 7499784 Method of selecting a transmission shift schedule

A method for selecting a shift schedule for a transmission in a motor vehicle is provided. The method includes the steps of determining whether a signal-to-noise ratio exceeds a threshold and calculating a tractive effort of the motor vehicle. A vehicle mass and a road grade is then estimated from the tractive effort using a recursive least squares estimator with multiple forgetting when the signal-to-noise ratio exceeds the threshold. A vehicle mass is selected and the road grade estimated from the vehicle mass and tractive effort when the signal-to-noise ratio does not exceed the threshold. A shift schedule is then selected based on the vehicle mass and the estimated road grade.