System and method for determining a vehicle velocity parameter

A method for estimating longitudinal velocity of a vehicle that is operating on a longitudinally-extending road surface, the vehicle having a plurality of wheels including a first set of wheels and a second set of wheels, the first set of wheels being spaced apart from the second set of wheels along a longitudinal axis of the vehicle, the longitudinal velocity of the vehicle being parallel to the longitudinal axis of the vehicle, and the road surface having a slope that is associated with changes in elevation of the road surface as the vehicle travels along the road surface, the method implemented by instructions stored on a non-transitory computer-readable medium and executed on a processor, the method comprising:

• obtaining a measured value of vehicle acceleration from an acceleration sensor, wherein the measured value of vehicle acceleration is based on (i) longitudinal acceleration of the vehicle as well as on (ii) vertical acceleration of the vehicle when the slope of the road surface is non-zero, wherein the longitudinal acceleration of the vehicle is acceleration of the vehicle in a direction parallel to the longitudinal axis of the vehicle;
• determining an initial estimate of the slope of the road surface;
• determining a difference between the initial estimate of the slope of the road surface and a prior estimate of the slope of the road surface;
• determining, for each wheel of the plurality of wheels, a wheel slip value for the wheel with respect to the road surface;
• in response to all of the wheel slip values being greater than a predetermined threshold, setting a current estimate of the slope of the road surface equal to the prior estimate of the slope of the road surface;
• in response to at least one of the wheel slip values being less than or equal to the predetermined threshold, setting the current estimate of the slope of the road surface equal to the initial estimate of the slope of the road surface;
• estimating the longitudinal velocity of the vehicle based on (i) the current estimate of the slope of the road surface and (ii) the measured value of vehicle acceleration;
• and
• controlling at least one wheel of the plurality of wheels based on the longitudinal velocity of the vehicle.