Abstract: A cruise control sub-system is incorporated into an electronic throttle control system. The sub-system comprises a cruise control module that provides respective charge and discharge signals to a circuit for charging and discharging a capacitor. The voltage across the capacitor represents a cruise control signal and is supplied to a port of the electronic throttle control microprocessor. In the cruise control mode of operation, the microprocessor causes the throttle to be positioned by the cruise control signal. If the driver depresses the accelerator pedal to an extent that would command a throttle opening larger than that commanded by the cruise control signal, the microprocessor causes to throttle to be operated to the larger opening. When the cruise control mode of operation ceases, the throttle is controlled by the accelerator pedal alone. The microprocessor also performs testing of the cruise control sub-system and gives a fault indication if a fault is detected.

Abstract: Rather than having the two throttle position sensors connected directly to a common D.C. power supply, isoation circuits are connected between each sensor and the power supply so that a short in one sensor will be indicated to the ECU without adversely affecting the signal from the other sensor. The isolation circuits are simple RC circuits.

Abstract: A unipolar motor control system includes motor current regulation derived from monitoring battery voltage and motor temperature. The monitored battery voltage and motor temperature are inputs to a microprocessor control which has one or more look-up tables for developing an appropriate scaling factor that adjusts the voltage across the motor coils so that proper current magnitude is delivered to the motor.

Abstract: An accelerator pedal position signal is transmitted by wire to the electronic control unit which operates a unipolar stepper motor to position the throttle in correspondence with the position of the accelerator pedal. A circuit of the electronic control unit monitors the response of the throttle to the release of the accelerator pedal and to the operation of the brake pedal in such a manner that unless the throttle is at, or at least within a predetermining distance of, its idle position within a certain limited time after the commencement of concurrence of accelerator pedal release and brake pedal application, the engine is shut down.

Abstract: High resolution microstepping of an unipolar stepping motor 18 is accomplished by applying from a look-up table the values of the SINE and COSINE of a given angle to the control circuit of a unipolar stepping motor. The difference between the present position and the desired position is calculated and depending upon the magnitude of the difference, the degree of microstepping is determined from four steps per ninety electrical degrees of motor rotation to thirty-two steps. By such selection, the positioning of the output shaft of the motor 18 is smoothly and accurately accomplished.

Abstract: High resolution microstepping of an unipolar stepping motor is accomplished by applying from a look-up table the values of the SINE and COSINE of a given angle to the control circuit of a unipolar stepping motor. The difference between the present position and the desired position is calculated and depending upon the magnitude of the difference, the degree of microstepping is determined from four steps per ninety electrical degrees of motor rotation to thirty-two steps. By such selection, the positioning of the output shaft of the motor is smoothly and accurately accomplished.

Abstract: In a digital control system wherein control voltages are analog voltages, a method and control system for generating a variable output bit resolution from an N bit analog to digital converter utilizing a control circuit to control the input spread of the voltage references to the A/D converter. Depending on the binary value of the MSD position, the input reference voltage spread is controlled. If the binary value is zero, the input reference voltage spread is one-half the normal value and the resolution is N+1 bits and if the binary value is zero for both the MSD and MSD-1 positions, the input reference voltage spread is one-fourth the normal value and the resolution is N+2 bits and so on until the first binary one value is found after consecutive preceding binary zero values.