Abstract: A tire pressure monitoring system for a vehicle having a plurality of inflatable tires includes a plurality of rotation sensors that generate rotation signals based on a rotation of each of the tires and a pressure sensor that is responsive to a pressure within one of the tires and that generates a pressure signal based on the pressure. A control module receives the pulse signals and the pressure signal and that detects a low pressure condition of at least one of the tires based on the pressure signal and the pulse signals.

Abstract: The present invention provides an apparatus and method for characterizing tire pressure on the four tires of a conventional passenger automobile. The method uses an apparatus disposed on a key fob. The key fob includes a tire valve stem interface that is capable of taking manual measurements of tire pressure. The fob further includes a pressure transducer that translates tire pressure into electronic form where it can be displayed on an LCD screen and transmitted by RF to an automobile computer. The automobile computer further includes a program that provides for the measurement of tire pressure in a sequential method thereby assuring that the tires are at placarded pressure or more. The method includes steps of using the key fob to measure the tire pressure and transmitting the tire pressure to the computer for processing.

Abstract: A method and apparatus of characterizing for tire pressure imbalances in a set of tires of vehicle, the vehicle having four wheels, and each wheel having a sensor generating a pulse for a predetermined amount of distance traveled by the wheel including entering a first characterization mode, accumulating a number of pulses from each sensor and adding the number of pulses from each sensor to generate a first record total pulse count in the characterization mode, generating a second record total pulse count in the characterization mode, determining if the first record is similar to the second record, and discarding at least one of the first and second records if the first and second records do not meet a criteria.

Abstract: Apparatus and methods are provided for controlling movement of an automobile in a pitched position. The apparatus has an attitude sensor that is configured to determine a pitch of the automobile and a speed sensor that is configured to determine a speed of the automobile. In addition, the apparatus has a braking mechanism that is configured to inhibit movement of the automobile and a controller that is configured to control the braking mechanism. The controller is configured to receive the pitch and the speed determined by the attitude sensor and the speed sensor, respectively, and control the braking mechanism based at least in part upon an evaluation of the pitch and the speed in order to inhibit movement of the automobile in the pitched position.

Abstract: Electrohydraulic braking applied to a plurality of automotive vehicle braking channels operates to drive brake pressure modulator position toward a position corresponding to a braking input and corrected for channel to channel braking variations and vehicle deceleration error. A function for adapting the braking input to a position command is provided for each channel and is periodically adapted in accord with a difference between the channel's brake pressure modulator position error and a desired position error.

Abstract: A regenerative and friction brake blend control method for use in a vehicle with at least one positionable hydraulic brake actuator for achieving friction braking and an electric propulsion motor with regenerative braking capability wherein an amount of regenerative braking achieved is indicated by a signal, wherein the method comprises the steps of determining a hydraulic actuator position command indicating a desired vehicle braking, determining responsive the hydraulic actuator position command a regenerative braking command, commanding the electric propulsion motor to regeneratively brake the vehicle responsive to the regenerative braking command, receiving the signal indicative of regenerative braking achieved, converting the signal indicative of regenerative braking achieved to an actuator position reduction signal, subtracting the actuator position reduction signal from the hydraulic actuator position command to determine a difference command, and commanding the hydraulic actuator according to the diff

Abstract: A method for determining the center position of a steering wheel for a vehicle equipped with electric power steering having a brushless motor. Vehicle operating conditions corresponding to a straight direction of vehicle travel are detected. An estimated center position of the brushless motor is determined while the vehicle operating conditions are detected. A range of angular positions about the estimated center position is established in which the actual center position of the steering wheel is determined to be the position of the brushless motor equal to a midpoint of the range of angular positions.

Abstract: An electric braking system controls the vehicle brake torque based on the pressure applied by the vehicle operator to the vehicle brake pedal and a moving vehicle brake system gain to provide normal power assisted braking while the vehicle is moving. The deviation of the vehicle braking condition from a level incline and lowest vehicle weight (LVW) is determined based upon a determined percent difference between the actual vehicle deceleration while the vehicle is being braked to a stop and an expected deceleration that would result from the total brake torque, a level road surface, and the vehicle weight at LVW. The expected deceleration is determined by determining the total vehicle brake torque represented by the sum of the brake torques applied by the individual wheel brakes and dividing by the LVW of the vehicle.

Abstract: The left and right rear brake systems of a vehicle each are controlled by a respective electric torque motor. A rear wheel braking system controls the current to each of the torque motors so that each rear wheel is controlled to a speed having a predetermined relationship to the corresponding front wheel. The relationship between the motor currents when each wheel speed has been established at the predetermined relationship is used to determine a bias current value used to equalize the gains of the left and right rear brake systems.

Abstract: A vehicle antilock control system provides for selectively enabling the rear wheels of a vehicle to free-wheel and thereby attain vehicle velocity to provide an accurate measure of the vehicle speed during antilock controlled braking.

Abstract: A brake system for the rear wheels of a vehicle applies brake pressure to each rear wheel so as to establish the rear wheel speed at a predetermined relationship to the speed of the front wheel on the same side of the vehicle. The brake pressure applied to each of the front and rear wheels is limited by antilock controlled braking in response to a sensed incipient lockup condition of the wheel. When a front wheel first enters into an antilock controlled braking, in response to an incipient wheel lockup condition, the brake pressure to the rear wheel on the same side of the vehicle is rapidly increased to induce an incipient wheel lockup condition thereby inducing antilock controlled braking of the rear wheel.

Abstract: A vehicle parking brake system automatically adapts to the road surface condition when operated while the vehicle is moving. The parking brake pressure is automatically controlled, in response to an operator command to initiate the parking brake function or in response to a failure of the hydraulic front brakes while the vehicle is moving, to establish and limit wheel slip at a desired controlled slip between each of the braked wheels and the road surface so as to automatically adapt to the road surface coefficient of friction.

Abstract: Controlled movement of a motor driven pressure modulator is provided by commanding maximum current to the motor by application of system voltage resulting in the motor current initially rising rapidly to the motor stall current. The motor accelerates at a rate that is a function of the difference between the motor torque and the load torque represented by the load on the modulator. As the motor speed increases, the motor current decreases. When the motor current decreases below the stall current by a predetermined amount representing a predetermined speed of the motor, the motor current is turned off for a wait period that is based upon the time that it took for the motor speed to attain the predetermined speed. Thereafter, maximum motor current is again commanded and the cycle repeated to provide for motor speed control.

Abstract: A brake control system is described that maximizes the braking efficiency of an under-damped actuator, such as a motor-driven linear screw. When an incipient lock condition is detected, the system determines the optimal brake pressure, relieves brake pressure and measures the duration of the pressure release. When the wheel is approaching recovery, but has not yet substantially recovered, the system holds brake pressure constant at a value calculated to represent the amount of pressure remaining at the wheel brake. This calculated hold value is based upon the measured optimal pressure and the measured release duration, and allows the wheel to continue to reaccelerate towards recovery while preventing unnecessary pressure relief. Once the wheel recovers, the system reapplies brake pressure to a substantial fraction of the optimal pressure without over-exciting the actuator and over-shooting the desired pressure.

Abstract: A brake control system is described that maximizes vehicle braking efficiency by first determining, and then cycling wheel brake pressure and consequently wheel slip about, the critical slip value for the road surface. As each road surface has unique tractive characteristics, the amount of brake pressure required to produce critical wheel slip, and hence maximum brake force, varies for different coefficient of friction road surfaces. This invention determines the coefficient of friction for the operating surface and adjusts the system slip threshold to accurately mimic the actual critical slip value for the road surface. The invention then applies and releases wheel brake pressure so as to cycle wheel slip about this critical slip value.

Abstract: Vehicle wheel slip is controlled by an add-on brake pressure modulator that may function in addition to limit the brake pressure applied to the vehicle wheels during anti-lock braking. A piston is moved in a cylinder to regulate the braking pressure. During non-operating conditions of the modulator the piston is moved to provide minimum cylinder volume to be in condition to be moved to withdraw fluid from the brake system to limit brake pressure. When a potential for excessive slip of a driven wheel is detected, the piston is moved to increase the volume of the cylinder to draw in braking fluid from a reservoir. The modulator is then in condition to apply regulated brake pressure to limit excessive slip. When the potential for excessive slip no longer exists, the piston is controlled to provide minimum volume while returning the brake fluid to the reservoir. The modulator is then again in condition for limiting brake pressure.

Abstract: An excessive slipping condition of one of the driven wheels of a vehicle that is indicative of a loss of traction of that wheel is sensed based on the difference in the driven wheel speeds. An increasing braking force is applied to the wheel with excessive slip to transfer driving torque through the differential to the non-slipping wheel so as to equalize the driven wheel speeds. In order to provide for compensation of the difference in wheel speeds that is not due to slip that occurs as the vehicle is turning, the speeds of the driven wheels are compensated based on the difference in speeds of the undriven wheels.