Abstract: An interface circuit between a microcomputer and a MOSFET driver for motor control includes logic for failsafe motor control particularly to protect the driver. AND gates supply driver signals when a set of conditions are met. Certain conditions are mandated directly by the microcomputer. An analog oscillator and digital counter are used to time data signals from the microcomputer to assure continual computer operation. Other conditions are determined by the logic and include monitoring faulty motor current conditions, assuring that forward and reverse signals are not given concurrently, and assuring that there is a dead time between forward and reverse signals to the driver.

Abstract: A method and means are described for determining the mass of air available for combustion within a cylinder of a crankcase scavenged two-cycle engine, without the use of a mass-air flow sensor. This is achieved by estimating the mass of air under compression within a crankcase chamber, prior to its transfer to a cylinder combustion chamber during the engine operating cycle. The estimate for air mass is based upon the polytropic behavior of a portion of the crankcase compression process, and the pressure, volume and temperature of the air at two predetermined engine rotational positions during the polytropic phase of compression. The volume of the air within the crankcase chamber is determined as a function of engine rotational angle, with crankcase air temperature being derived as a function of intake air temperature. Air pressure during the polytropic phase of compression is sensed with a pressure sensor disposed within the crankcase chamber.

Abstract: A method and means are described for determining the mass of air available for combustion within a cylinder of a crankcase scavenged two-cycle engine, without the use of a mass-air flow sensor. This is achieved by estimating the mass of air under compression within a crancase chamber, prior to its transfer to the cylinder combustion chamber. The estimate for air mass is based upon the integration of crankcase pressure over the interval of decreasing crankcase volume, while air within the crankcase is under compression. The volume of the air within the crankcase chamber is derived as a function of engine cycle position, with crankcase air temperature being derived as a function of intake air temperature. Air pressure during compression is monitored with a crankcase pressure sensor. The estimate for air mass is corrected to account for air leakage and incomplete transfer of the air between the crankcase and combustion chambers.

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 system and method of limiting the wheel slip of a driven wheel of a vehicle to a maximum allowable value so as to maximize the driven wheel tractive force is described. The driven wheel tractive force represented by an expression including the engine intake air flow area, a load variable function and the speed of an undriven wheel is continually monitored. The value of the monitored tractive force at the time the driven wheel slip reaches a maximum allowable value is identified and stored. When the slip exceeds the maximum allowable value, an intake air flow area is limited to a value determined to return the driven wheel tractive force to the identified tractive force at the maximum allowable wheel slip value.

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: In an engine having direct fuel injection or injection at individual intake ports, the fuel injectors are of the positive displacement type and are equipped with plunger displacement sensors to yield a displacement signal representing the quantity of fuel injected. This signal is used as feedback to a closed loop PID control which compares the injected quantity to a demand quantity to determine an error and calculates a control pulsewidth which reduces the error eventually to zero. An open loop injector calibration of pulsewidth versus approximate fuel quantity is used as a base pulsewidth to which the closed loop adds a correction value.

Abstract: A dual slope drive-by-wire device circuit is used for controlling the position of the throttle of an engine. The circuit generates a command such that the response is a low gain for low values of throttle position for providing a desired resolution at low throttle angles such as idle, and a high gain for higher throttle angles, producing a desired range of throttle angle control. The throttle is positioned in response to the command signal.

Abstract: In a radar system, an RF signal is transmitted at a frequency modulated by a sawtooth signal. The transmitted RF signal is mixed with the transmitted signal reflected from an object. The resulting IF signal is analyzed into a Fourier series having a DC coefficient and harmonic frequency coefficients. The range to the object is determined from the harmonic frequency coefficients in multiples of the range resolution determined by the RF bandwidth of the system when the DC coefficient is less than each of the harmonic frequency coefficients. The range to the object is determined to be within 1/2 the range resolution determined by the RF bandwidth when the DC coefficient is greater than each of the harmonic frequency coefficients.

Abstract: A microprocessor based electronic spark control for an internal combustion engine is programmed to determine spark time using a prediction of engine speed during the spark period in which the next spark should occur and to make the calculations immediately prior to that period. The prediction is based upon the most recent speed information including a reference period value just prior to the next spark period. Reference pulses produced from a crankshaft driven transducer determine the measured reference periods and preferably comprise a plurality of pulses per spark event. One reference period is chosen as a base period and a weighted difference of recent periods is used to adjust the base to predict the spark period. The spark period or the corresponding engine speed is used in calculating the spark angle and the conversion to spark time. A hardware interrupt to the microprocessor causes the calculations to be made when the reference pulse nearest the next spark occurs.

Abstract: A vehicle near-obstacle detector in the form of a diplex Doppler radar system provides range information between a vehicle and an object based on the phase shift between a pair of Doppler signals derived from two transmitted radar signals at slightly different frequencies. A speed dependent error introduced by the time constant of a filter circuit converting duty cycle range information based on the phase shift to an analog signal is compensated by introducing a small time shift in the signal path of one of the Doppler signals to effect a shift in the duty cycle range information.

Abstract: A method for calculating actual air charge temperature uses values of coolant temperature, ambient temperature and engine air flow. These parameters affect the intake manifold temperature which, in turn, affects the amount of heat that is transferred to the air from the manifold. The time constant associated with the manifold temperature keeps the actual air charge temperature from instantaneously achieving a steady state condition. A time constant in the actual air charge temperature calculation substantially tracks the time constant associated with the change in temperature of the manifold as it responds to changes in air flow conditions. This actual air charge temperture value can then be used to calculate an accurate air-fuel ratio.

Abstract: Apparatus for providing tactile feedback in response to the touch input command of a user to the touchscreen of a cathode ray tube in a CRT command and display system. An actuator is provided for imparting motion to the CRT when the actuator is energized. Energization occurs in response to a touch input command of the user to the touchscreen of the CRT. When energized, the actuator provides tactile feedback to the user by imparting motion to the CRT.

Abstract: A system and method determines the rotational speed of a rotating member by determining speed from signals having a frequency directly proportional to the rotational speed. The system provides for the estimation of rotational speed even if no speed signals are detected over a sampling interval.

Abstract: A brake control system is described that maximizes vehicle braking efficiency by maximizing the amount of time spent cycling pressure at or near the optimal pressure for the road surface. Upon detecting an incipient wheel lock condition, the system measures the optimal pressure for the road surface and relieves pressure. Once wheel recovery is sensed, the system reapplies pressure to a significant fraction of the optimal pressure and increases pressure gradually from that point. If a change to a higher coefficient surface occurs while the system is modulating brake pressure, the system detects that surface transition and rapidly increases brake pressure to quickly arrive at the new optimal pressure.

Abstract: An engine control system monitors the force applied to the accelerator pedal and normal engine operating conditions during which the force applied to the pedal is normally zero and provides for normal engine operation if these conditions exist. When the force applied to the accelerator pedal is zero and none of the normal engine operating conditions at which the force applied to the accelerator pedal is normally zero exist, the engine is forced into a back-up control mode.

Abstract: An adaptive ignition controller for an internal combustion engine provides for engine operation at substantially peak thermal efficiency for all engine operating conditions by controlling the ignition advance angle intiating combustion to a crankshaft angle before top dead center that is substantially equal to the crankshaft angle after top dead center at which combustion is completed.

Abstract: An adaptive ignition controller for an internal combustion engine provides for engine operation at substantially peak thermal efficiency for all engine operating conditions by controlling the ignition advance angle initiating combustion to a crankshaft angle before top dead center that establishes the burn center at a predetermined crankshaft angle, the burn center being determined by monitoring the value of an indicator function PV.nu. during the combustion period.

Abstract: A microprocessor based fuel control for automotive vehicle engines samples the measured air flow rate at fixed intervals and calculates the air mass flow for a cylinder interval which varies with engine speed. A sensor on the engine detects cylinder position for the cylinder interval determination. An independent clock controls the air flow rate sampling periods. During each cylinder interval the air flow rate is integrated for each whole sampling period and is approximated for each partial period at the boundaries of the cylinder interval. The results are summed to obtain the mass air flow for the cylinder interval.

Abstract: A hierarchical brake controller is described having two control levels, a high level supervisory controller and a low local controller. The supervisory controller receives a vehicle deceleration rate command from the vehicle operator and determines a commanded brake line pressure value to establish the actual vehicle deceleration at the operator commanded rate. The supervisory controller then proportions the commanded brake line pressure between the front and rear brakes based on a determined proportioning factor. The local controller at each wheel functions to establish the respective commanded front or rear brake line pressure. In addition, the local controller for each of the rear brake limits the applied brake pressure in response to a sensed incipient wheel lockup condition to prevent lockup of the braked wheel. The local controller for a rear brake that is limiting brake pressure to prevent a lockup condition provides a maximum allowable rear brake pressure value to the supervisory controller.