Abstract: A vehicle traction control system includes both driven wheel brake control and engine torque output control for limiting acceleration wheel slip. A boundary condition is identified where engine torque output control alone can be used without braking to regulate the acceleration wheel slip to any desired value. When the traction control system determines that the boundary condition is not exceeded such that engine torque output control alone is capable of preventing an excessive slip condition, only engine torque is controlled to limit wheel slip. However, when the system determines the boundary condition is such that engine torque output control alone will not prevent an excessive slip condition, the brakes of the slipping wheel is then additionally controlled to limit acceleration wheel spin.

Abstract: Mass air flow into an internal combustion engine is measured as a function of throttle opening. The mass air flow rate is expressed as an idle offset constant and the product of gain and effective air intake area which is a function of throttle position. During idle, the idle offset term is updated in response to an exhaust oxygen sensor feedback and during part throttle operation the gain is similarly updated to achieve stoichiometry. For subsonic air flow the mass air flow is further modified as a function of the ratio of manifold pressure to the pressure upstream of the throttle. At the same time the manifold dilution is controlled via an EGR valve to a predetermined schedule.

Abstract: A traction control system for limiting the slip of a driven wheel determines an excessive spinning condition of the wheel in response to an excess driving torque applied from the vehicle engine. If the vehicle speed is less than a predetermined value, a braking force is applied to the wheel that is a predetermined function of the spin ratio of the wheel and when the vehicle speed is greater than the predetermined value, a braking force is applied to the wheel that is a predetermined function of the difference between the driven wheel speed and the vehicle speed.

Abstract: A method is described for determining the cylinder mass of air available for combustion in a crankcase scavenged, two-cycle engine, based upon the Ideal Gas Law relationship and indications of pressure, volume, and temperature of air in the crankcase chamber, at predetermined points in the engine operating cycle. This is achieved by first determining the mass of air trapped and compressed in a crankcase chamber, and thereafter, determining the residual air mass remaining in the crankcase after the transfer of air to the associated combustion chamber. Then, the actual air mass transferred to the combustion chamber is determined as a function of the difference between the trapped and residual air masses. Engine trapping efficiency can be used to correct for air leakage from the combustion chamber prior to cylinder exhaust port closure.

Abstract: A rear wheel speed reference utilized in an anti-lock brake controller as the basis for controlling the rear wheel brakes of a vehicle controlled by a common control signal is established based on the road surface condition. When the vehicle is being braked on a split coefficient of friction surface, the rear wheel speed reference is established at the wheel speed which is the lowest between the two wheels. This provides braking in accord with a select low mode of operation. However, when the two rear wheels are being braked on a uniform surface, the rear wheel speeds are processed such that an average of the two wheel speeds is provided as the rear wheel speed reference for establishing the braking control signal for the rear wheels.

Abstract: The mass of air available for combustion within a cylinder of a crankcase scavenged two-stroke engine is obtained by estimating the mass of air trapped within a crankcase chamber, prior to its transfer to the associated cylinder combustion chamber. The estimate for air mass is derived from the product of pressure of the air in the crankcase chamber and the crankcase chamber volume at a selected engine cycle position during that portion of the engine cycle when the air is trapped and undergoes compression within the crankcase chamber divided by a factor containing the trapped air temperature at the selected engine cycle position.

Abstract: A process for maximizing the instruction processing efficiency of a digital computer for the purpose of calculating rotational speed wherein the calculation of speed is based upon speed signals generated by a tachometer. By (1) counting the quantity of the speed signals received during a fixed sampling period, and (2) recording the occurrence time of these speed signals only as necessary for the calculation of rotational speed, the invention improves over known methods in that it does not record the occurrence time of all speed signals, but rather records the occurrence time of only those speed signals necessary for the calculation. The invention accomplishes this by (a) anticipating when the speed signals necessary for the speed calculation will be generated (and subsequently received by the digital computer) and (b) recording the occurrence times only when it is anticipated that these necessary edges will be received by the digital computer.

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: An image processing method operates on an image from a ccd camera viewing a roadway scene in front of a vehicle to detect lane markers and determine the relationship of the vehicle to the lane. Obstacles in the lane near the vehicle are detected and a warning is given to the driver. The method uses template matching techniques or a Hough algorithm to detect the lane markers or road edges.

Abstract: A method and apparatus for improving the output torque response of a crankase scavenged, two-stroke engine to a change in throttle position by adjusting the conventional timing of cylinder fuel injection as a function of the position of the throttle and the time rate of change in the throttle position. Preferably, throttle position is measured with a potentiometer connected to the engine air intake throttle, and then filtered with a filter having a first order lag characteristic. Injection timing is advanced based upon a first predetermined schedule as a function of the measured throttle position. The difference between the measured and filtered throttle positions represents an indication of the time rate of change of throttle position and is employed to advance or retard timing in accordance with the second predetermined schedule, depending upon whether the difference is positive or negative, respectively.

Abstract: A method and apparatus 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. 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 method and apparatus for controlling the idling rotational speed of a direct fuel injected, crankcase scavenged, two-stroke engine are disclosed. This is accomplished by regulating the timing of engine fuel injection within the rotational cycle of the engine. If the engine idling speed is outside a predetermined range of speeds, containing a target idling speed, the timing of fuel injection is advanced within the rotational cycle of the engine to increse idling speed, or retarded to decrease idling speed. The value by which fuel injection timing is advanced or retarded is determined by the difference between the actual idling speed and the target idling speed. The target idling speed is made a function of engine operation temperature to assure that a cold engine will idle properly when first started. After fuel injection timing is changed, a predetermined period of time is waited before repeating the idle control steps, to allow engine speed to stabilize.

Abstract: A system provides for controlling various vehicle functions by use of a free-running counter that drives the address lines of a random access memory which are shared with a control microprocessor. The counter represents a clock which directly maps addresses in the RAM to discrete moments in time. Each bit at each RAM memory location describes an on or off control command of a particular function. The microprocessor sets selected bits corresponding to the control function in two address locations corresponding to the on and off points in time so as to enable the generation of a pulse of exact direction for control.

Abstract: The ratio air and fuel mixture delivered to the fueled cylinders of an engine of a vehicle is controlled while selective cylinders of the engine are unfueled to reduce engine torque output to inhibit excessive wheel spin during vehicle acceleration. The air/fuel ratio of the mixture delivered to the fueled cylinders is increased as cylinders are selectively unfueled to reduce engine torque output and power enrichment to the fueled cylinders is inhibited when any cylinders are unfueled to reduce engine torque output for traction control and for a time period after all cylinders are again fueled.

Abstract: A method for preventing excessive spin to the driven wheels of a vehicle by determining the value of slip where the wheel/road tractive force is maximized for the particular coefficient friction road operating surface. The reaction torque, as translated through the differential, is considered and wheel control is therefore optimized based upon individual wheel acceleration characteristics and cross-differential torque transfer.

Abstract: When an excessive acceleration spin condition is detected in one or both of the driven wheels of a vehicle, braking pressure is applied to one or both wheel brakes to quickly take control of the respective excessive spin condition. A value representing the total engine torque being absorbed by both driven wheel brakes above a predetermined low value is determined from which a desired engine torque reduction amount is determined. The actual engine torque output value is determined and reduced by the desired engine torque reduction amount resulting in a desired value of engine torque output. The engine torque output is then decreased to the desired engine torque output.

Abstract: An engine control system is disclosed for reducing the hydrocarbon content in exhaust gas from a crankcase scavenged, two-stroke engine in the operating range near idle, with light operator induced engine loading. As operator demand for engine output power is increased, the control system increases the fuel per cylinder delivered to the engine, while restricting the supplied mass of air per cylinder to a value less than or equal to that flowing at unloaded engine idle.

Abstract: Misfire is detected in an internal combustion engine during its starting mode by analyzing the engine speed profile. Average speed is determined for 60.degree. increments of crankshaft rotation. If an increment midway between top dead center positions has a higher speed than the previous increment and a higher speed than cranking speed, combustion occurred, otherwise a misfire occurred. When misfires are detected for a particular cylinder the calculated fuel allotment for that cylinder is reduced in accordance with the number of consecutive misfires for that cylinder.

Abstract: A method for determining barometric pressure uses a manifold pressure sensor for measuring the manifold absolute pressure. A pressure drop between the atomosphere and the intake manifold is determined by utilizing stored lookup tables based on measured values of throttle angle and engine speed. Barometric pressure is then determined by summing the manifold absolute pressure and the pressure drop.

Abstract: A brake control system is described that prevents a wheel lockup condition by identifying the brake pressure that produces the maximum possible braking effort during each brake pressure application period and applying a predetermined fraction of the identified pressure after an incipient wheel lockup condition is sensed. The predetermined fraction provides for adaptive adjustment of the brake pressure if the identified brake pressure is in error until a pressure is applied that produces substantially the maximum possible braking effort.