Brake system with adaptive offset compensation

In a vehicle brake system comprising a depressible brake pedal, at least one hydraulic brake line and at least one pressure sensor providing an outputs signal responsive to a pressure in the hydraulic line, a method of controlling the brake system comprising the steps of:

• determining whether a brake pedal is depressed;
• if the brake pedal is depressed, controlling the brake system responsive to the output signal and a stored offset value representative of an offset of the sensor;
• if the brake pedal is not depressed, thereafter
• determining if the brake pedal has not been depressed for a predetermined time limit;
• if the brake pedal has not been depressed for a predetermined time limit, updating the stored offset responsive to the sensor output signal.

In a vehicle brake system comprising a depressible brake pedal, at least one hydraulic brake line and at least one pressure sensor providing an output signal responsive to a pressure in the hydraulic line, a method of controlling the brake system comprising the steps of:

• determining whether a brake pedal is depressed;
• if the brake pedal is depressed, controlling the brake system responsive to the output signal and a stored offset value representative of an offset of the sensor;
• if the brake pedal is not depressed, thereafter
• determining if the brake pedal has not been depressed for a predetermined time limit;
• if the brake pedal has not been depressed for a predetermined time limit and the sensor output signal is within a predetermined range indicative of an acceptable range of output values for the sensor when the pedal is not depressed, updating the stored offset responsive to the sensor output signal, wherein the offset for the pressure sensor in the brake system is continuously updated and is adaptive to sensor aging and the vehicle environment.

A vehicle brake system comprising:

• a depressible brake pedal;
• at least one hydraulic brake line;
• at least one pressure sensor providing an output signal responsive to a pressure in the hydraulic line;
• a brake actuator responsive to a brake command to command friction braking of the vehicle at a braking torque indicated by the brake command;
• a brake controller coupled to the pressure sensor and to the brake actuator comprising
• (a) means for determining whether the brake pedal is depressed;
• (b) means for determining the brake command when the brake pedal is determined to be depressed, wherein the brake command is determined responsive to the output signal and a stored offset value for the pressure sensor;
• (c) means for applying the brake command to the brake actuator;
• (d) means for determining whether the brake pedal has not been depressed for a predetermined time period and
• (e) means for updating the offset value when the brake pedal is determined to have been not depressed for the predetermined time period, wherein the means for updating the offset value comprises means for receiving the output signal, means for comparing the output signal to a predetermined limit, and means for storing the received output signal in memory as the updated offset value,
• wherein the brake unit adaptively updates the sensor output signal, compensating for sensor aging and environmental conditions of the vehicle.