Abstract: A traction control system for a vehicle in which the rate of reduction of the torque input to the driven wheels of the vehicle in response to an excessive spin condition is varied as a function of the road surface coefficient of friction. The rate of increase of wheel spin is measured as an indicator of the road surface coefficient of friction and the area of the air intake of the engine is reduced at a rate that is in inverse proportion to the measured rate of increase of wheel spin. The rate of torque reduction is also made a function of the magnitude of wheel spin. The area of the air intake following recovery from an excessive spin condition is increased at a rate that is in inverse proportion to the road surface coefficient of friction.

Abstract: A brake system using a pair of brake apply and release force units, the units having electric motors with non-backdriveable mechanical output members to supply the needed brake apply force to limit of capability of the motors. Piezoelectric elements that generate high forces with low expansion during rapid rates of change of applied voltage are positioned in brake apply force-transmitting series with the motor output members. These elements are alternately energerized with applied voltage and deenergized, in opposite phase relation. The piezoelectric expansion effect of each energized element is mechanically captured in each energization cycle by the motor unit having the deenergized element so that the brake apply forces actually applied to actuate the brake are increased well beyond the maximum output of the motors.

Abstract: A vehicle near obstacle detection system includes a plurality of radio frequency heads that can transmit and receive both frequency-modulated, continuous wave and two-frequency Doppler radar signals, such that the system operates in frequency-modulated, continuous wave radar mode and in two-frequency Doppler radar mode. The radio frequency heads used for transmitting the radar signals transmit their radar signals in accordance with commands from a system controller. The radio frequency heads are provided at various locations on the vehicle, directed at points around the vehicle which cannot easily be seen by the vehicle operator. The system controller switches between the two radar modes depending on which one is more appropriate to make use of one mode's strengths while avoiding the other mode's weaknesses. When there is no relative movement between objects and the vehicle, the frequency-modulated, continuous wave mode is used.

Abstract: A throttle valve diagnostic apparatus monitors the integrity of a throttle valve position sensor in an internal combustion engine using an engine parameter indirectly related to the value position. If the absolute pressure of the air in the intake manifold associated with the throttle valve is less than a predetermined pressure for a predetermined amount of time while the position sensor indicates a valve position greater than a predetermined position, the valve position sensor is assumed to be faulty.

Abstract: A schedule of brake pressure ramp rates is provided in a vehicle antilock brake controller as a function of predetermined wheel parameters. The ramp rates associated with the specific values of the wheel parameters are filtered by limiting the changes in ramp rate to a next higher ramp rate from the schedule of rates when the ramp rate called for by the wheel parameters is greater than the present ramp rate and to a next lower ramp rate from the schedule of rates when the ramp rate called for by the wheel parameters is less than the present ramp rate.

Abstract: The motor current in a vehicle antilock brake system motor driven pressure modulator is increased in stepwise fashion to ramp the brake pressure in the apply phase of an antilock braking cycle. At the beginning of each current step as the motor current is increased in stepwise fashion, the motor torque is increased momentarily at least by an amount to assure that the static friction of the pressure modulator is overcome and that motor rotation is initiated. The motor torque is increased to a value to initiate motor rotation at the beginning of each current step by momentarily increasing the motor current to a value greater than the current step value by a predetermined amount that assures that the increase of motor torque exceeds the static friction of the pressure modulator.

Abstract: In a vehicle anti-lock brake controller, a differential slip between the wheels on each side of an axle is sensed to detect a yaw condition and the wheel with the lower slip value is identified as the high coefficient wheel. In response to a detected yaw condition, the monitored value of slip of the high coefficient wheel is controlled about a target slip value that has an initial value less than the critical slip value at the beginning of antilock controlled braking to minimize longitudinal force imbalance and which is thereafter ramped to the critical slip value to maximize longitudinal braking forces.

Abstract: A vehicle speed estimation system estimates vehicle speed from wheel speed prior to an incipient wheel lockup condition. When an incipient wheel lockup condition is sensed, the estimated speed is increased by a determined amount and then decreased based on an estimated vehicle deceleration. The estimated vehicle deceleration during the incipient wheel lockup condition is based on wheel deceleration at a time preceding the time the incipient wheel lockup condition is sensed. When in incipient wheel lockup condition is sensed, a forgetting period during which wheel deceleration is not representative of vehicle deceleration is determined. The estimated vehicle deceleration during the incipient wheel lock condition is then based on wheel deceleration prior to the forgetting period.

Abstract: A control for an inductive load switches current on and off to regulate about a command value, a decaying recirculation current flowing through the load during the switch off periods. The current is sensed during the switch on periods and charges a capacitor to provide a simulation signal representing the motor current. The capacitor is allowed to discharge through a resistor during the switch off periods at the rate of the decaying recirculation current. The simulation signal is compared to the command value to control the switching. The simulation signal is sensed during a command value of zero current to determine offset errors for calibration purposes.

Abstract: An idle speed control motor under computer control positions a throttle stop for setting minimum throttle angles. The motor response to actuating pulses varies from motor to motor so that a gain factor is determined for each motor and is used to calculate the required pulse width to attain a desired throttle displacement. A gain learn program in the engine control computer runs when the ignition is turned off and is effective to extend the motor with a number of pulses of known width, measure the throttle displacement, and determine the gain factor by dividing a standard displacement by the measured displacement. The same program is applied to learning the gain of a throttle motor in an electronic throttle control system.

Abstract: A method for recalibration of parametric relationships used in exhaust gas recirculation EGR control. When such recirculation would typically be inactive, relationships between parameters are measured, such relationships being normally measurable only with inactive EGR. New information from those measurements is combined with information from previous calibrations to provide update information necessary for subsequent EGR control.

Abstract: An electromechanical XY carriage sweeps a magnetic or electrical field probe across a circuit board line by line to acquire field strength data as a function of probe position relative to the board. Colored field maps are produced. The carriage is controllable to obtain very high resolution data. A magnetic probe includes a single loop oriented parallel to the board or a loop oriented perpendicular to the board and selectively parallel to or perpendicular to the x axis of the carriage. Different field maps are produced by different probe orientations and each provides information regarding the circuit traces which carry rf currents.

Abstract: A vehicle acceleration wheel slip control system monitors wheel slip and when a wheel slip condition becomes excessive as wheel slip increases during vehicle acceleration, engine torque output is initially reduced in accord with the rate of change in wheel slip. This derivative adjustment produces a significant correction to the engine torque output before the slip condition becomes very large. Thereafter, when the slip condition represents recovery from the excessive slip condition, the engine torque output is controlled in accord with the error in wheel slip from a desired value. This proportional adjustment maintains a desired slip value while maintaining stable acceleration slip control.

Abstract: In a method of traction control, fuel injectors are selectively disabled to unfuel respective cylinders of an engine to reduce engine torque output. The method provides for limiting the number of cylinders that can be disabled for acceleration spin control based on engine and vehicle operating parameters to improve traction control performance and provide protection for the vehicle catalytic converter.

Abstract: A transmitted and received beam of a forward looking sensor of a source vehicle is steered as the source vehicle travels through a curvilinear path so that the steering angle is controlled to prevent the loss of detection of a target vehicle resulting from the effective lateral shaft of the beam relative to the path as the beam is steered into the curvilinear path. The beam is steered at an angle that limits the effective lateral shift of the beam relative to the curvilinear path such that a predetermined minimum target vehicle detection criteria is achieved.

Abstract: A communication method provides for an exchange of a multiple byte message between two processors. Interrupt suppression associated with the message transfer is minimized by alternating the processors between master and slave operating modes with each byte exchanged.

Abstract: Torque proportioning between the front and rear wheels of a vehicle is achieved by controlling the speed of each rear wheel, via modulation of the hydraulic brake pressure of the rear wheel during braking, to be the same as the speed of the front wheel on the same side of the vehicle.

Abstract: An adaptive cruise system for a vehicle maintains a desired selected operator-set speed in the absence of a detected preceding target vehicle and adjusts the vehicle speed when a target vehicle is detected to maintain a following distance that is set by the vehicle operator. An alert distance is computed that is a predetermined function of a distance based on driver reaction time. To provide for the driver selectable trailing distance, the driver reaction term of the alert distance is adjusted by the vehicle operator to achieve a desired distance to the target vehicle.

Abstract: The application of brake pressure to limit the spin of a driven wheel in a traction control system is made adaptive to the torque demand on the engine. This is accomplished by increasing the brake pressure when an excessive spin condition is sensed at a rate that is proportional to a parameter related to engine torque. The ramp is then terminated when the wheel parameters attain certain predetermined conditions. The brake pressure ramp is terminated when the wheel jerk is negative while at the same time the wheel deceleration is below a predetermined value. After the ramp is terminated, the brake pressure of the spinning wheel is controlled based on wheel parameters such as wheel spin ratio or the difference between the speed of the spinning wheel and vehicle speed.

Abstract: A wheel lock control system is described for a wheel braking system that includes a motor driven actuator for applying controlled hydraulic brake pressure to the wheel brake that is determined by motor current. The motor current corresponding to the brake pressure producing the maximum possible braking effort during each brake pressure application is identified and a value related thereto is reapplied to the motor after an incipient wheel lockup condition is sensed.