Three wheel vehicle electronic stability system and control strategy therefor

A three wheel vehicle having:

• a frame,
• a pair of front wheels, the front wheels being connected to the frame via a front suspension, each of the front wheels having a tire, the tire having a tire grip threshold,
• a single rear wheel, the rear wheel being connected to the frame via a rear suspension, the rear wheel having a tire, each of the tires having a tire grip threshold,
• an engine supported by the frame and operatively connected to at least one of the wheels to provide power to propel the vehicle,
• a braking system including brakes associated with each of the wheels to brake the vehicle,
• a steering system including a handlebar operatively connected to the front wheels to steer the vehicle,
• a straddle seat disposed on the frame, the seat being suitable for accommodating at least a driver of the vehicle sitting in straddle fashion,
• the tire grip thresholds of tires being, for a set of combinations of lateral and longitudinal accelerations that the vehicle may undergo, greater than a wheel lift threshold of a vehicle, such that the vehicle experiences wheel lift before the tires lose grip,
• a plurality of sensors arranged on the vehicle so as to provide electronic signals related to vehicle information including at least engine speed, engine throttle position, lateral acceleration, and longitudinal acceleration, and
• an electronic stability system (ES S) including a processor and memory, the ESS being electronically connected to at least the engine, the sensors, and the braking system, the memory including instructions that when executed by the processor:
• cause a determination, using information from the sensors including information related to the longitudinal acceleration of the vehicle, information related to the lateral acceleration of the vehicle, and data from the memory, of whether (i) a precursory condition indicative of a wheel lift before the tires lose grip exists and (ii) the tire grip threshold of any of the tires has been exceeded;
• and
• cause a reduction of the longitudinal acceleration of the vehicle by a first amount less than that which would cause the tire grip threshold of any of the tires to be exceeded when a precursory condition indicative of a wheel lift before the tires lose grip exists and the tire grip threshold of none of the tires has been exceeded, thereby increasing an amount of lateral acceleration that the vehicle can undergo before experiencing wheel lift other than by reducing the lateral acceleration of the vehicle.