Abstract: A variable droop engine speed control system includes a proportional-integral-derivative (PID) engine speed controller as its central component. The PID controller includes the standard proportional, integral and derivative gains associated with the proportional, integral and derivative portions of the controller, and further includes a droop gain associated only with the integral portion. The PID transfer function has a pole associated strictly with the droop gain such that a full range of droop may be provided by varying only the droop gain.

Abstract: An engine speed control apparatus wherein the upper limit of engine speed can be set and then not be exceeded once a key-operated switch has been activated to an "off" position. The key can be removed from the switch so that the operator cannot exceed the maximum selected engine speed.

Abstract: The present invention relates to a governor device for an internal combustion engine where a portion of the engine output is taken off as driving force for vehicle mounted accessory equipment which requires constant speed rotation with changes in load. By controlling the intake air quantity passing through a bypass passage which bypasses a mixing device for mixing fuel and intake air at a predetermined ratio, controlling a sub-throttle valve provided in an intake passage in series with a main throttle valve, and controlling a supply quantity of auxiliary gas fuel so that a detected air-fuel ratio is constant, the engine output is increase/decrease controlled in spite of changes in load in accessory equipment, to give constant engine rotational speed and good operability of an auxiliary power take-off device.

Abstract: A constant speed running device controls a vehicle speed, which includes a running condition setting member for setting an aimed vehicle speed for at least one of the constant speed control, an acceleration condition and a deceleration condition. The device further includes control member to calculate controlled variables for controlling the vehicle speed in accordance with a deviation between the actual running speed detected by a vehicle speed sensor and the aimed vehicle speed. The running condition setting member sets the aimed vehicle speed to the actual running speed when a predetermined period of time elapses after at least one of operations of the acceleration condition and deceleration condition.

Abstract: A target torque is determined in a target torque determination device on the basis of an accelerator operation amount detected by an accelerator operation amount detector and power source output detected by a power source output detector. A target driving force is determined in a target driving-force determination device on the basis of driving force detected by a driving-force detector and the target torque. A target acceleration is determined in a target acceleration determination device on the basis of a travel resistance detected by a travel resistance detecting device and the target driving force. The operation of an actuator is controlled on the basis of an acceleration detected by an acceleration detecting device and the target acceleration. Thus, it is possible to provide a power source output control in accordance with the travel resistance, while simultaneously taking into consideration the current state of the power source and the responsiveness thereof.

Abstract: Internal combustion engine speed is controlled through a nested plurality of compensation loops each of which is dedicated to exclusively addressing engine control processes and the delays associated therewith. State observers provide predicted state values to the plurality for generation of desired state values at a subsequent cylinder event. Feedforward compensation is included to compensate for substantially constant engine loads of known magnitude while such loads are determined to be applied. Ignition timing advance compensation is favored for small speed errors or when rapid response is required, and engine inlet air rate compensation is favored for large speed errors or when slower response can be tolerated.

Abstract: Embodiments of engine speed control and methods of maintaining engine speed control and fuel injection so as to minimize hunting and improve exhaust emission control, particularly at low speeds. This is achieved by setting a fixed amount of fuel supplied to the engine per cycle, per cylinder when the engine speed is below a predetermined speed or a speed below a predetermined speed is called for. Engine speed control is maintained under the constant fuel position by controlling the spark advance in one embodiment. A manual spark advance and automatic spark advance are depicted.

Abstract: A vehicle speed control method and apparatus are provided which can ensure a smooth driving feeling even if an automotive vehicle has entered into an ascending sloped road during a constant speed control. The speed increasing control is stopped when the vehicle speed data obtained from the vehicle speed sensor is not greater than the memory vehicle speed, a deviation between the vehicle speed data and the memory vehicle speed is greater than a predetermined level and the acceleration at that time is greater than a predetermined level.

Abstract: An automatic engine speed hold control system (430) allows an engine (420) to quickly achieve a commanded engine speed and thereafter maintain a constant commanded engine speed regardless of changes in engine loading. An engine speed error signal (444) is computed as the difference between an operator commanded engine speed (440) and actual engine speed (434,436). The engine speed error signal (444) is scaled based on an engine speed error gain (448), and the scaled engine speed error (452) is then provided via an integral path (456) and a proportional path (454) to a summing junction (478) where it is summed with load anticipation trim signals (474,467) to provide a final trim signal (485).

Abstract: A speed control system maintains vehicle speed at a desired speed by controlling the engine throttle. The speed control system includes feedback from a quadratic control signal having an amplitude related to a square of the speed error signal and also having the speed error signal's sign. The speed control system also includes integral feedback control and proportional feedback control.

Abstract: An engine speed control apparatus employs a governor responsive to predetermined control input signals for controlling engine speed. An accelerator sensor produces an accelerator control input signal corresponding to the position of an accelerator. A mode selector selects one of a governor mode and a throttle mode, and produces one of a governor mode control input signal and a throttle mode control input signal corresponding to the mode selected. The governor is responsive to the governor mode control input signal for permitting the selection of an upper limit of engine speed within a predetermined range of speeds and thereafter for controlling the engine speed to maintain the engine at this upper limit when the accelerator control signal corresponds to a maximum accelerator position.

Abstract: An apparatus includes an inter-vehicle distance sensor for measuring a distance from a self vehicle to a vehicle traveling ahead, and a relative speed is calculated on the basis of the inter-vehicle distance data detected by the inter-vehicle distance sensor. When a variation of the relative speed is small, it is recognized that a vehicle is present ahead of the self vehicle. An acceleration/deceleration is obtained from a stored acceleration/deceleration basic map on the basis of a difference between the inter-vehicle distance and a target inter-vehicle distance, and the relative speed with the vehicle ahead, and an acceleration/deceleration correction coefficient is calculated from a correction map set with adjustment constants in correspondence with the measured inter-vehicle distance. An acceleration/deceleration is calculated by multiplying the acceleration/deceleration with the correction coefficient.

Abstract: An aromatic cruising speed controller for an automotive vehicle adjusts the throttle valve of the engine to perform the constant speed cruising control of the vehicle. A running resistance detector unit 18 calculates the running resistance R from the output torque T of the engine, the vehicle acceleration .alpha., and the engine set-up condition including the gear ratio G. During the transient period immediately after the cruising control is commenced or resumed, the torque T0 of the engine which is necessary for attaining the target vehicle speed V0 is determined from the running resistance R, the gear ratio G, and the target throttle position is determined on the basis of this torque T0. Under the steady state, on the other hand, the throttle position is controlled in accordance with the proportional plus integral control method, such that the deviation .DELTA.V of the vehicle speed V from the target vehicle speed V0 is reduced to zero.

Abstract: The modular, automatic idle down system is plugged in series between the 120 VAC output connector of a generator and the input plug of the load device. One prong of the load's input plug may be received directly in a load sensor, such as a Hall effect sensor. The self-contained modular unit is connectable to the mechanical or electronic governor of the generator's engine. The idling system provides two time delays which delay the idling down of the engine upon initial starting and when the load is removed from the generator. When the sensed load current falls below a threshold value, the idling system generates an output signal, after the predetermined time delays, to override the engine's mechanical or electronic governor. The speed-of the engine is thereby reduced from the governed speed to an idle speed.

Abstract: In a constant speed driving device in which an amount of control of a throttle actuator for driving a throttle valve is calculated by using a control constant so that an actual vehicle speed reaches an aimed vehicle speed, the control constant is changed according to parameters corresponding to the effective operation and non-effective operation of a pressure-charger. Thus, with the device, the constant speed driving operation is achieved suitably independently of the operating conditions of the pressure-charger.

Abstract: A speed control system electronically controls the engine throttle to maintain vehicle speed at a reference speed in response to a control signal. The control signal is generated by multiplying a speed error signal by a gain value. Such gain value is provided with a variable amplitude having a first linear relationship to the error signal which is increased to a second linear relationship having greater sensitivity when the error signal exceeds a preselected amplitude.

Abstract: A vehicle control apparatus comprises various sensors sensitive to vehicle operating parameters for producing signals having values sensed for the respective vehicle operating parameters. The vehicle control apparatus also comprises a transition detector. The transition detector includes a memory for storing threshold values specified for the respective vehicle operating parameters, and a comparator for comparing the sensed values with the respective threshold values in a predetermined sequence to sense a transition in one of the vehicle operating parameters when the value sensed for the one vehicle operating parameter is in a range defined by the threshold value specified for the one vehicle operating parameter. The transition detector is coupled to a control unit for controlling the automotive vehicle for the sensed transition.

Abstract: The electronic governor has a fast response time by eliminating the return spring of prior art governors. Instead, a magnetic field generated either by permanent magnets or by a second actuator coil is used to oppose the force created by a first actuator coil. The current to the first actuator coil is pulse width modulated. If a second coil is used instead of permanent magnets, the current to the second coil may be either pulse width modulated or may be a constant DC signal. An actuator having a low inertia rotor and a stationary core is preferred to further reduce the response time.

Abstract: A constant-speed cruising control apparatus for vehicles, which comprises a reed switch for generating a vehicle speed signal, a set switch for setting the cruising speed, a memory circuit for storing and outputting a cruising speed signal, a first comparing circuit for comparing the cruising speed signal with the vehicle speed signal, an actuator for actuating a throttle valve according to a signal output from the first comparing circuit, a first computing circuit for calculating expectation value of vehicle speed change on basis of the signal output from the first comparing circuit, a second computing circuit for calculating change of the vehicle speed signal, a second comparing circuit for comparing signals output from the first and the second computing circuits, and a down-shift circuit for shifting an automatic transmission into lower gear on basis of a signal output from the second comparing circuit.

Abstract: A speed control system controls the engine throttle to maintain vehicle speed at a desired speed and increments the desired speed to a previous reference speed during resume mode of operation or other speed alteration mode of operation. A control signal is generated which is related to both the difference between actual vehicle speed and desired speed. The control signal is multiplied by a gain value generated with a first amplitude when the vehicle speed is within a preselected range from the reference speed, a second amplitude when the vehicle speed is within the preselected range, and a third amplitude when the vehicle speed is greater than a desired speed. An actuator controls the engine throttle in response to the product of the error signal times the gain value for asymptotically approaching the previous reference speed.

Abstract: A rotational speed control system for an internal combustion engine capable of preventing a dead time or dead section from occurring in controlling of a rotational speed of the engine. An integrating circuit is controlled by means of an output of a comparator for comparing a rotational speed detection signal with a target rotational speed setting signal, to thereby obtain an integral voltage which falls and rises when the rotational speed detection signal is above and below the target rotational speed setting signal, respectively. Comparison of the integral voltage with a sawtooth signal voltage leads to a pulse signal subjected to pulse width modulation. The pulse signal is fed to an actuator driving circuit to carry out on-off controlling of a drive current for the actuator. Connection of voltage limiting circuits to the integrating circuit causes a variation of the integral voltage to be limited within a range of amplitude of the integral voltage, to thereby eliminate the dead time or dead section.

Abstract: A self-tuning speed control system is disclosed. The gain of the system controller is tuned to provide optimal performance based upon a sensitivity point analysis and gradient optimization of a prescribed cost index.

Abstract: A microprocessor engine control for a diesel engine powered truck is provided with a grade-holder vehicle speed control by another algorithm that is effective to cause the engine operation to move from one horsepower vs. speed curve to another when the vehicle encounters a change in load, such as when the vehicle encounters a change in grade.

Abstract: A pro-active engine control system for a rotary engine having a governor generating a fuel command signal determined to maintain the actual engine speed at a setpoint speed. A fuel logic circuit converts the fuel command signal to a flow rate signal actuating a fuel delivery device to supply fuel to the engine at a rate required to maintain the speed of the engine at the setpoint speed. The fuel command signal is multiplied by a desired air-fuel ratio to generate an air command signal. An air logic circuit converts the air command signal to air rate signals activating an air delivery device to deliver air to the engine at a rate such that the ratio of air-to-fuel delivered to the engine has the desired air-fuel ratio.

Abstract: A constant-speed driving control device having an output abnormality detection means in a control unit which detects any output abnormality of command switches from the changed state of the switches.

Abstract: An engine speed control system for a working vehicle having an engine, and a propelling transmission and a power takeoff device driven by the engine. Engine speed is adjustable by an accelerator controlled by control signals outputted from a control unit. The control unit is connected to a clutch operation detecting switch for detecting an operative state of a power takeoff clutch for operating a power takeoff device and to a shift condition detecting switch for detecting a shift of the propelling transmission. The control unit outputs a control signal for rotating the engine at an idling speed when the propelling transmission is in neutral and the power takeoff clutch is disengaged, and a control signal for rotating the engine at a high rotating rate when the propelling transmission is in a drive transmitting position or the power takeoff clutch is engaged.

Abstract: A plurality of characteristic variables concerning the rotational speed are detected so as to be used for inference, and the plurality of characteristic variables are divided into a plurality of sets. Groups of rules each indicating the relationship between the characteristic variable corresponding to each set and an amount of gain adjustment, as well as the relationship between the magnitude of the characteristic variable corresponding to each set and the degree of adoption of the amount of gain adjustment, are stored. When it is determined that each of the characteristic variables cannot be controlled within a permissible range, the relationship between each of the characteristic variables of the groups of rules and the amount of gain adjustment is corrected in such a manner that the permissible range is broadened.

Abstract: An electronic governor is disclosed for power producing and power absorbing devices having a minimum number of component parts. Power for all of the electronic governor components is supplied by a small coil, thereby avoiding the need for an additional coil frame or other power source. In a preferred embodiment, power supply circuitry converts the alternating signal from the coil to a direct current signal to power the governor. A signal conditioner also provides a low state signal to a 555 timer to start the timing cycle. The length of the timing cycle, and thus the high state control signal output of the timer, is a function of the desired device speed. When the timer output is at a high state while at the same time the alternating signal from the coil is at its first polarity, one or more switches conduct to adjust an electromagnetic actuator. In one embodiment, the switches control a motor connected to an engine throttle and operated in a stepper mode.

Abstract: An apparatus for controlling the speed of a direct fuel injected, scavenged two stroke engine comprises engine speed sensing means for determining the speed of revolution of an engine and means for sensing the degree to which the throttle. A comparing device produces a signal corresponding to the difference between the engine speed sensed by the engine speed sensing means and a predetermined engine speed corresponding to the degree of throttle opening. An control device adjusts an engine running parameter based on this difference.

Abstract: A vehicle speed control system having speed altering modes such as acceleration and resume modes. When resuming speed control operation to attain a previously set desired speed, a lower reference ramp and upper reference ramp are generated in a preprogrammed manner. The lower reference ramp is selected as the reference speed when vehicle speed is below such ramp, and the upper reference ramp is selected as the reference speed when the vehicle speed is greater than such ramp. The vehicle speed is selected as the reference speed when it is within both reference ramps.

Abstract: A speed control system operable during the resume mode which initially turns the engine throttle to an initial throttle position computed as a function of vehicle speed. A reference ramp is then incremented towards the previously set or resume speed and the throttle controlled in response to a speed error between reference and vehicle speed. When incrementing of the reference speed is terminated, the engine throttle is turned to a recomputed throttle position based upon the previously set speed.

Abstract: An apparatus for controlling the speed of a direct fuel injected, scavenged, two-stroke engine comprises a first sensor for sensing the degree to which the throttle is open, means for sensing whether the intake air amount is in the air-excess range, means for sensing whether the degree to whcih the throttle is open has been substantially constant for a predetermined amount of time, a sensor for sensing the engine revolution speed, means for producing a desired engine revolution speed based on the degree to which the throttle is open, and means for producing a signal coresponding to the difference between the engine revolution speed and the desired engine speed, when the degree to which the throttle is open has been substantially constant for the predetermined amount of time. A control device adjusts an engine running parameter based on this difference, to reduce this difference.

Abstract: An override speed control mechanism for an internal combustion engine. The override speed control system comprises a speed control lever that is movable by an operator within an actuation range having a lower control limit and an upper control limit. A throttle control mechanism is connectable to the carburetor to actuate the throttle plate of the carburetor. A coupling lever is detachably coupled to the speed control lever and the throttle control mechanism. The throttle control mechanism is caused to move through its entire operating range in response to movement of the speed control lever through a predetermined partial portion of its actuation range. The effective range of the speed control lever corresponds to the operating range of the throttle control mechanism, and movement of the speed control lever between the lower override limit and the lower control limit, and between the upper override limit and the upper control limit is ineffective to further move the throttle control mechanism.

Abstract: A constant-speed regulating device for a vehicle comprising: a control circuit which receives information regarding the running velocity of the vehicle and produces an output signal as a result of calculations in which said information and control constants are used; a drive circuit which receives the output signal and produces an drive signal; and an actuator for opening and closing the throttle valve of the vehicle. The actuator is driven in accordance with the drive signal. The actuator comprises a stepping motor. The control circuit receives data regarding the type of the vehicle, the state of the engine, and the gear position, and comprises: a first memory means for storing the rotation angle of the stepping motor which is within or beyond one revolution; a means for modifying at least one of the control constants; and a second memory means for storing said control constants even when the main power is turned off.

Abstract: A cruise control apparatus for a vehicle periodically adjusts the opening of a throttle valve based on the function K..epsilon.+G..alpha., wherein .epsilon. is the deviation of the vehicle speed from a target value, .alpha. is the vehicle acceleration, K is a constant, and G is a variable control coefficient. G increases with an increase in the length of time since a change in the sign of acceleration or the length of time since a change in the sign of the rate of change of acceleration.

Abstract: An automatic control including a memory is provided to be loaded with positional data for the automatic control of a cycle of motions of preferably a plurality of power members. The speed reading the data in and out is freely selectable. Accordingly programming a cycle of motions may be performed in a slow motion process, whereas the speed of reading out the data is selected such that an optimum operational speed is obtained. In addition to the automatic speed control a manual control is provided to interrupt the cycle motion of the automatic control to manually adjust the position or the power member. In returning to the automatic control the further cycle of motion is taken up again where it has been interrupted.

Abstract: An engine controlling system for a vehicle which is suitable for use with an automobile. When an accelerated/decelerated condition detecting means detects an inoperative condition of an acceleration/deceleration instructing means and develops a non-operation detection signal, a constant speed running designation signal is developed from a constant speed running designating means, and an aimed speed setting means sets a speed of the vehicle to be aimed when the vehicle should make constant speed running. Then, a constant speed running controlling means controls an engine output adjusting means in response to a running speed detection signal from a running speed detecting means so that the running speed of the vehicle may become equal to the aimed speed. The engine output adjusting means thus adjusts the output power of an engine carried on the vehicle. Consequently, the vehicle thereafter makes constant speed running at a speed equal to the aimed speed.

Abstract: A system and method for automatically controlling a vehicle speed to a desired cruise speed are disclosed in which in addition to a control unit and a throttle actuator through which an opening angle of an engine throttle valve is adjusted so that the vehicle speed detected by a vehicle speed sensor coincides with a target cruise speed set by a vehicle driver through a set switch, a vehicle speed determining circuit is provided for determining whether the vehicle speed detected by the vehicle speed sensor exceeds a lowest speed limit above which the cruse control by the control unit and throttle actuator becomes effective. When the vehicle speed is below the lowest speed limit, the power supply to the throttle actuator is interrupted so that the cruise control by means of the throttle actuator is cancelled.

Abstract: An automatic car-speed controller is provided with a car-speed sensor, a command switch, a car-speed memory, an actuator, a control circuit for controlling the actuator, and a prohibition circuit for preventing a driving motor of the actuator to rotate in the accelerating direction at the time of cancelling car-speed control or occurrence of some abnormality in the control circuit or the like, or a discrimination circuit for detecting whether a first limit switch is normal or not without driving a throttle in the opening direction.

Abstract: A car-speed control system is provided with a car-speed sensor, a command switch, an actuator having an electromagnetic clutch, an actuator-driving circuit, a clutch-driving circuit, a car-speed memory, a controller and a comparing circuit for comparing voltage level with reference voltage at the time of changing the electromagnetic clutch to its unexcited state and for changing the actuator-driving circuit to its non-driving state if the voltage level of the clutch-driving means is higher than the exciting voltage of the electromagnetic clutch.

Abstract: A method for operating a drive unit comprised of an internal combustion engine having a hydraulic aggregate group connected to it. The amount of fuel supplied to the engine in the upper idling speed range is limited by a proportionally acting speed regulator. The power consumption of the hydraulic aggregate group is reduced by a maximum load regulator when the engine is overloaded. Theretofore the hydraulic aggregate group is adjusted toward a lower power consumption after the engine speed drops below an arbitrarily rated RPM which is monitored by the maximum load regulator. In order to facilitate a variable power limitation without the use of a hydraulic power limiter, the working RPM of the maximum load regulation is set at an arbitrary value corresponding to a desired power output between the nominal speed of the engine and the upper idling speed of the engine.

Abstract: In a traction control system for motor vehicles, a lower limit for throttle opening degree command with respect to each gear position of transmission is set up, and when the transmission is shifted up, the throttle opening degree command is decreased down to the lower limit for throttle opening degree command corresponding to the gear position assumed through the shift-up operation.

Abstract: A vehicle speed control system comprises a vehicle speed controller (14) and an auxiliary engine speed controller (17) which keeps to the engine speed set by the first controller (14) and which controls the amount of fuel and/or air supplied to the vehicle engine. A comparator (13) compares actual and desired vehicle speed signals and is connected to the first controller (14), which produces a desired engine speed signal which is compared (16) with the actual engine speed signal from a sensor (21).

Abstract: A system and method for automatically controlling a vehicle speed to a desired cruise speed are disclosed in which a vehicle speed sensor which output an analog quantity corresponding to a current vehicle speed is provided, a vehicle speed determining circuit which derives the current vehicle speed on the basis of the analog quantity derived from the vehicle speed sensor and determines whether the derived current vehicle speed is below a predetermined speed above which the cruise speed control run is appropriate is furthermore provided independently of a control unit of the system. When the vehicle speed determining circuit outputs a determination signal indicating that the current vehicle speed is below the predetermined speed and the control unit outputs a predetermined control command signal, a power supply line connected to a throttle valve actuator is, at first, interrupted. Then, the power supply to the control unit is interrupted.

Abstract: An improved fail-safe device for a motor vehicle speed governor of the type having a control system to switch a supply of power to an actuator ON and OFF for the control of the traveling speed of a motor vehicle to keep a constant speed. A latch is connected to power supply control circuit which controls the power supply to an actuator. The actuator actuates a throttle valve in an intake manifold of an engine for providing constant speed travel by turning the throttle valve ON and OFF in accordance with an output of the latch. The latch is set with a command signal and reset with a cancel signal or a reset signal. The resetting of the latch is executed if an absence of a watch dog signal is detected or a change of output generating status of the latch is detected under certain conditions. The state of the latch can be maintained if the conduction of a switching circuit for the actuator is detected regardless of a command signal to start up the constant speed traveling.

Abstract: An engine speed controlling apparatus for an internal combustion engine for controlling the engine speed of an internal combustion engine which has a mechanism for governing the engine speed and in which a manipulated variable of the governing mechanism and torque are in non-linear relationships. Although a real manipulated variable and the torque are in non-linear relationships, a virtual manipulated variable in which an actual engine speed becomes a targeted engine speed is calculated assuming those relationships as being linear. The virtual manipulated variable is converted to the real manipulated variable by using the actual non-linear relationships between the real manipulated variable and the torque, and the governor is controlled on the basis of the converted real manipulated variable.

Abstract: The present invention provides a drive engagement control and speed governor system for a vehicle which is capable of adapting a prior art system, known as a DEC/G system, to different types of vehicles. To accomplish this, the invention provides a valve system having fluid pressure delivery as a function of the magnitude of the control signal fed by an electronic control system. According to this invention, the electronic control system transmits a control signal to the valve system which is only sufficient to eliminate the spinning of a drive wheel on such vehicle or to eliminate exceeding of a predetermined maximum speed by an operator of such vehicle.

Abstract: An automatic car-speed controller is provided with a car-speed sensor, a command switch, a car-speed memory, an actuator, a driving motor, an abnormality detector for detecting an abnormality in an electromagnetic clutch of the actuator by detecting the time required for returning a throttle to the fully closed position from the position at which the electromagnetic clutch is released, and a control system for making the actuator inoperative when the abnormality detector detects an abnormality in the electromagnetic clutch.

Abstract: A nonlinear feedback control method and apparatus for an internal combustion engine in which a model of the engine is formulated, and load torque is estimated as a variable representing the operating state of the engine. Deviations of the engine from the engine model are formulated as disturbances. Other variables which cannot be measured are determined by making experiments and using tables. Based on the estimated load torque, the formulated deviations and other formulated variables, precise feedback control is executed for the engine, which varies in its operating conditions so that the rotation speed of the engine is adjusted to a target rotation speed by controlling a throttle opening. The estimated load torque is a physically significant control quantity which is easy to manipulate, and which can also be used for various controls such as an ignition timing control and a fuel injection control.

Abstract: A throttle controller for an internal combustion engine employs a stepper motor to move the throttle valve and provides a controller to permit the use of the stepper motor. The stepper motor requires no return spring or position sensor and hence offer weight and cost advantages. The throttle position is deduced by means of an up-down counter tracking movement of the stepper motor during throttle control. The controller includes an integration means to accommodate the unknown starting throttle position. A fuel cutoff solenoid is activated in the event of over-speed or power loss. An engine speed signal for the controller is produced by a variable reluctance sensor providing a signal to a slope detector circuit to eliminate the influence of external magnetic fields.