Abstract: Information related to the rotary angular position of a steerable wheel portion of an electric vehicle is required for proper control of the vehicle and especially for differential control of the driven wheels of the vehicle. Available rotary position encoders are expensive, prone to damage in an industrial environment, and sensitive to misalignment between the encoder components. The instant apparatus provides a simple and durable rotary position encoder having a plurality of sensors positioned on a first mounting member and a plurality of sensible members positioned on a second mounting member. The apparatus is digital in design and the particular location and arrangement of the sensors and sensible members advantageously compensates for overtravel and misalignment of the encoder components.

Abstract: Power assisted steering systems are commonly used on industrial vehicles such as industrial lift trucks. Advantageously, the output of such systems should be responsive to vehicle speed and the systems should be energy efficient. The subject power steering control system includes processor means for receiving a steering demand signal and a speed control signal, producing a high fluid flow rate signal in response to receiving the steering demand signal and to the speed control signal representing a vehicle speed less than or equal to a predetermined vehicle speed, producing a low fluid flow rate signal in response to receiving the steering demand signal and to the speed control signal representing a vehicle speed greater than the predetermined speed, and producing an idle fluid flow rate signal in response to failing to receive the steering demand signal.

Abstract: Apparatus is provided for controlling increases in the speed of a motor, including a transducer coupled to an accelerator pedal, that generates digital numbers representing motor speed commands, a data processor for receiving the speed commands, generating motor speed limit signals in response to the digital numbers and delivering the limit signals to a controllable circuit for supplying power to the motor. The limit signals are delivered in response to time and the magnitude of the speed commands.

Abstract: A control system (28) is provided for controlling the supply of power to a motor (12) having an armature (34) and a plugging diode (38) connected across the armature (34), including a circuit (14) for producing direction command signals, a circuit (98) for generating digital motor power command signals, a circuit (16) for sensing a plugging condition and generating a plug signal, a microprocessor (46) for generating one of a plurality of pulse trains during typical plugging conditions and for automatically overriding the generation of the one pulse train and generating other of the plurality of pulse trains during special plugging conditions. By automatically providing the override feature during the special plugging conditions, the disadvantage of manual override in prior control systems is obviated.

Abstract: The invention pertains to an apparatus (10) for diagnosing and displaying the condition of various components in an electro-mechanical vehicle or other system. The apparatus (10) includes command signal producing devices (12), control signal receiving devices (14), and means (16) for delivering control signals to the receiving devices (14) in response to receiving the produced command signals. The means (16) includes means (128) for receiving diagnostic command signals and displaying a predetermined diagnostic code in response to receiving a predetermined command signal. Both in-service and out-of-service diagnostics are provided for and a minimum of equipment external to the apparatus (10) is required, thus making the system both efficient and low in cost.

Abstract: The invention pertains to a control system (46) for controlling the supply of power to a motor (12) to produce plugging electrical braking and current limit control, including a circuit (60) for controlling the direction of energization of the motor (12), a circuit (88) for generating digital numbers representing command motor speeds, a circuit (14) for generating a data signal representing a plugging condition, a programmable data processor (18) for generating pulse trains in dependence on the plugging condition, and a power transistor element (40) for coupling power to the motor (12) in response to the pulse trains. By using state-of-the-art digital, integrated circuit and software technology, prior, essentially linear or discrete component technology, which is relatively unreliable, expensive and slow, need not be used.

Abstract: Apparatus (10) is provided for controlling current through a motor (12), including a circuit (14) for generating motor speed command data, a circuit (26) for generating a control signal in response to a maximum value of current through the motor (12), a programmable data processor (72) for generating pulse trains in response to the command data, and a controllable supplying circuit (18) for coupling and decoupling power to the motor (12) in response to the pulse trains and for decoupling power to the motor (12) in response to the control signal independent of the pulse trains. By decoupling power from the motor (12) independent of the control produced by the data processor (72), the current limit is achieved even if the data processor (72) malfunctions, contrary to prior apparatus.

Abstract: Apparatus (10) for monitors and protects a plurality of contactor coils (14A-E) and coil drivers (16A-E) from damage owing to short circuits, and prevents the concurrent energization of more than a preselected number of the coils (14A-E). Included is a monitor (84) for sensing the total current flowing through the plurality of coils (14A-E) and supplying a variable current signal in response to a magnitude of the sensed total current, and a control (85) for receiving the variable current signal and controlling the energization of the coils (14A-E) in response to the magnitude of the current signal. By monitoring and controlling the energization of the plurality of coils (14A-E) damage due to excessive current flow through the coils (14A-E) is avoided and the number of concurrently energized coils (14A-E) is limited to the preselected number.

Abstract: An apparatus (10) for controlling the supply of power from a power source (12) to a motor (14,14'). The apparatus (10) has a controllable switch (20,20') for coupling power to the motor (14,14') responsive to a pulse train, a circuit (22,22') for converting the voltage applied to the motor (14,14') to a logic signal, a line contactor (26) for connecting and disconnecting the power source (12) to and from the motor (14,14'), and a microprocessor (60) for generating the pulse train and controlling the line contactor (26) to disconnect and connect the power source (12) from and to the motor (14,14') in response to the presence and absence of the logic signal, respectively. By sensing short circuits and discontinuing the supply of power in response to the short circuit, a runaway motor speed condition can be avoided, and by using a microprocessor, the present invention is highly reliable, fast, durable, and cost-effective.

Abstract: An apparatus (10) is provided for controllably operating at least one solenoid coil (12) in a battery operated system. The mean voltage applied to the coil (12) is controlled in response to at least the battery voltage, facilitating the use of various battery voltages with a single voltage coil (12). The apparatus (10) is readily adapted for controlling multiple coils (12) and is digital in design.

Abstract: The invention pertains to a control circuit (10) for controlling the speed of a pair of motors (12,14), including a pair of switching elements (68,74) coupling power to the motors (12,14), a pair of controllable circuits (64,74) for driving the switching elements (68, 74), a circuit (36) for generating digital numbers representing the same command speed for each of the motors (12,14), a circuit (38) for generating digital numbers representing differential command speeds for the motors (12,14), and a data processor (56) for controlling the pair of controllable circuits (64,74) in response to the digital numbers. By utilizing digital and integrated circuit technology, prior, essentially linear, control apparatus, which are relatively unreliable, expensive and slow, need not be used.

Abstract: A measurement circuit which is rendered insensitive to temperature and other environmental quantities comprising first and second electrically identical sensor elements (10, 12) which are alternately connected through multiplexed gates (G1, G2) into the tank circuit of an oscillator (14) to generate first and second signal frequencies f.sub.1 and f.sub.2. The first frequency f.sub.1 varies in the same sense with both temperature and the measured signal quantity but the second signal f.sub.2 varies in one sense with temperature and in the opposite sense with the measured signal quantity. A logic circuit (18) is provided for generating an output signal proportional to the ratio of f.sub.1 and f.sub.2. The ratio of the two signals is achieved by frequency dividing f.sub.1 and using the result as a variable length gating signal for f.sub.2. A non-multiplexed system using matched oscillators is also disclosed.

Abstract: A compensated measurement system utilizing dual sensing elements (10, 12) and a single variable frequency oscillator (14). A common operative association between the sensing elements (10, 12) and the oscillator (14) is achieved by multiplexing. Temperature and supply voltage variations are compensated by generating an output (f.sub.0) which is proportional to the ratio of the two generated frequencies (f.sub.1, F.sub.2).