Abstract: A materials handling vehicle includes an operator platform from which an operator can drive the vehicle; a traction control system for advancing the vehicle across a floor surface; at least one sensor configured to detect the presence of an object located at a position proximate to the vehicle; and a controller communicably coupled to the at least one sensor and the traction control system. The controller is responsive to the output of the at least one sensor to stop or slow down the vehicle if an object is detected proximate to the vehicle and the vehicle is traveling in response to a remote travel request. However, the controller does not slow down or stop the vehicle if an object is proximate to the vehicle while the operator is driving the vehicle on the operator platform.

Abstract: A materials handling vehicle includes an operator platform from which an operator can drive the vehicle; a traction control system for advancing the vehicle across a floor surface; at least one sensor configured to detect the presence of an object located at a position proximate to the vehicle; and a controller communicably coupled to the at least one sensor and the traction control system. The controller is responsive to the output of the at least one sensor to stop or slow down the vehicle if an object is detected proximate to the vehicle and the vehicle is traveling in response to a remote travel request. However, the controller does not slow down or stop the vehicle if an object is proximate to the vehicle while the operator is driving the vehicle on the operator platform.

Abstract: A materials handling vehicle includes a power unit, a load handling assembly, at least one first obstacle detector, and at least one second obstacle detector. The at least one first obstacle detector is mounted at a first location on the power unit to detect an object located along a path of travel of the power unit beyond a non-detect zone of the at least one first obstacle detector. The at least one second obstacle detector is mounted at a second location on the power unit, spaced from the first location in a first direction, and is capable of detecting an object in the non-detect zone of the at least one first obstacle detector.

Abstract: A materials handling vehicle implements a steer maneuver to hug an object. A controller on the vehicle receives sensor data from at least one sensing device and detects that a selected object is in an environment proximate the vehicle using the received sensor data. The controller performs a steer maneuver by causing the vehicle to steer such that the vehicle is substantially maintained at a desired distance from the selected object as the vehicle travels on a desired heading.

Abstract: A materials handling vehicle automatically implements steer maneuvers when objects enter one or more zones proximate the vehicle, wherein the zones are monitored by a controller associated with the vehicle. The controller tracks objects in the zones via sensor data obtained from at least one obstacle sensor located on the vehicle and via dead reckoning. The objects are tracked by the controller until they are no longer in an environment proximate the vehicle. Different zones result in different steer maneuvers being implemented by the controller.

Abstract: A supplemental control system for a materials handling vehicle comprises a wearable control device, and a corresponding receiver on the materials handling vehicle. The wearable control device is donned by an operator interacting with the materials handling vehicle, and comprises a wireless transmitter to be worn on the wrist of the operator and a travel control communicably coupled to the wireless transmitter. Actuation of the travel control causes the wireless transmitter to transmit a first type signal designating a request to the vehicle. The receiver is supported by the vehicle for receiving transmissions from the wireless transmitter.

Abstract: A remote control device worn by an operator in combination with a materials handling vehicle includes a wireless transmitter and control structure in communication with the wireless transmitter. The control structure is actuated by the operator to cause the wireless transmitter to generate a travel request signal. The vehicle includes a traction control system, a receiver for receiving travel request signals from the wireless transmitter, at least one sensor, and a controller. The sensor(s) is configured to detect objects near the vehicle or to detect a person on a vehicle operating platform. The controller is configured to decide not to cause the traction control system to advance the vehicle in response to a travel request signal from the receiver if the status from one or more of the at least one sensor is indicative of the presence of either: an object near the vehicle; or a person on the platform.

Abstract: A materials handling vehicle implements a steer maneuver to hug an object. A controller on the vehicle receives sensor data from at least one sensing device and detects that a selected object is in an environment proximate the vehicle using the received sensor data. The controller performs a steer maneuver by causing the vehicle to steer such that the vehicle is substantially maintained at a desired distance from the selected object as the vehicle travels on a desired heading.

Abstract: A materials handling vehicle automatically implements steer maneuvers when objects enter one or more zones proximate the vehicle, wherein the zones are monitored by a controller associated with the vehicle. The controller tracks objects in the zones via sensor data obtained from at least one obstacle sensor located on the vehicle and via dead reckoning. The objects are tracked by the controller until they are no longer in an environment proximate the vehicle. Different zones result in different steer maneuvers being implemented by the controller.

Abstract: A materials handling vehicle automatically implements steer maneuvers when objects enter one or more zones proximate the vehicle, wherein the zones are monitored by a controller associated with the vehicle. The controller tracks objects in the zones via sensor data obtained from at least one obstacle sensor located on the vehicle and via dead reckoning. The objects are tracked by the controller until they are no longer in an environment proximate the vehicle. Different zones result in different steer maneuvers being implemented by the controller.

Abstract: A materials handling vehicle includes a power unit, a load handling assembly, at least one first obstacle detector, and at least one second obstacle detector. The at least one first obstacle detector is mounted at a first location on the power unit to detect an object located along a path of travel of the power unit beyond a non-detect zone of the at least one first obstacle detector. The at least one second obstacle detector is mounted at a second location on the power unit, spaced from the first location in a first direction, and is capable of detecting an object in the non-detect zone of the at least one first obstacle detector.

Abstract: A materials handling vehicle automatically applies a steer correction maneuver if an object is detected in a steer bumper zone in front of the vehicle. A controller detects whether an object is in front of the materials handling vehicle and automatically determines whether a steer correction maneuver should be to the right or left of the traveling direction of the materials handling vehicle. The materials handling vehicle automatically steer corrects the vehicle, e.g., at a determined steer angle that is opposite the direction to the detected position of the object, and accumulates the distance traveled by vehicle while steer correction is being performed. The vehicle then automatically counter steers the vehicle, e.g., by a determined steer amount, in the opposite direction as the steer correction for a percentage of accumulated steer distance traveled. After performing the counter steer maneuver, the vehicle may, for example, resume a substantially straight heading.

Abstract: A materials handling vehicle automatically implements steer maneuvers when objects enter one or more zones proximate the vehicle, wherein the zones are monitored by a controller associated with the vehicle. The controller tracks objects in the zones via sensor data obtained from at least one obstacle sensor located on the vehicle and via dead reckoning. The objects are tracked by the controller until they are no longer in an environment proximate the vehicle. Different zones result in different steer maneuvers being implemented by the controller.

Abstract: A supplemental control system for a materials handling vehicle comprises a wearable control device, and a corresponding receiver on the materials handling vehicle. The wearable control device is donned by an operator interacting with the materials handling vehicle, and comprises a wireless transmitter to be worn on the wrist of the operator and a travel control communicably coupled to the wireless transmitter. Actuation of the travel control causes the wireless transmitter to transmit a first type signal designating a request to the vehicle. The receiver is supported by the vehicle for receiving transmissions from the wireless transmitter.

Abstract: A materials handling vehicle automatically applies a steer correction maneuver if an object is detected in a steer bumper zone in front of the vehicle. A controller detects whether an object is in front of the materials handling vehicle and automatically determines whether a steer correction maneuver should be to the right or left of the traveling direction of the materials handling vehicle. The materials handling vehicle automatically steer corrects the vehicle, e.g., at a determined steer angle that is opposite the direction to the detected position of the object, and accumulates the distance traveled by vehicle while steer correction is being performed. The vehicle then automatically counter steers the vehicle, e.g., by a determined steer amount, in the opposite direction as the steer correction for a percentage of accumulated steer distance traveled. After performing the counter steer maneuver, the vehicle may, for example, resume a substantially straight heading.

Abstract: A lift truck control system which utilizes a distributed control network including at least a display module, a distribution module, a traction module, a brake module and a steering module. The display and steering modules each are configurable by software which controls the module and the various drivers in each module. In the preferred embodiment, the display module includes flash memory which stores application software and can be rewritten so that the performance characteristics of the modules are software configurable. The display module is connectable to a programmable cartridge which includes nonvolatile flash memory that carries application software for the display and steering modules. When connected, the cartridge downloads the particular application software which is written over the stored software in flash memory for the display and steering modules.

Abstract: A lift truck control system which utilizes a distributed control network including at least a display module, a distribution module, a traction module, a brake module and a steering module. The display and steering modules each are configurable by software which controls the module and the various drivers in each module. In the preferred embodiment, the display module includes flash memory which stores application software and can be rewritten so that the performance characteristics of the modules are software configurable. The display module is connectable to a programmable cartridge which includes nonvolatile flash memory that carries application software for the display and steering modules. When connected, the cartridge downloads the particular application software which is written over the stored software in flash memory for the display and steering modules.

Abstract: A circuit is provided for detecting phase error between two signals by producing a phase error signal having a series of pulses wherein the widths of the pulses are representative of the phase error and producing a polarity signal representative of the polarity of the phase error. The phase error signal and polarity signal are used to produce a count representing the magnitude and polarity of the phase error for each of the pulses in the phase error signal. This count is converted to an analog signal which is compared to a pair of reference level signals to produce an output signal representative of the acceptability of the phase error corresponding to each of the pulses in the phase error signal.

Abstract: A pulse width modulated waveform measurement circuit is provided with a detector for detecting logic level transitions in a pulse width modulated waveform during a measurement interval, a counter for counting clock pulses, and a gate circuit for enabling the counter during a time period corresponding to the width of a preselected pulse in the pulse width modulated waveform. A comparison circuit is provided for comparing the output count from the counter with a predetermined count and for comparing the number of logic level transitions detected during the measurement interval with a predetermined number to obtain an indication of the operational status of the pulse width modulated waveform. In an alternative embodiment, the gate circuit enables the counter during time periods corresponding to the widths of successive pulses in the pulse width modulated waveform.

Abstract: A method for testing an inverter drive logic switching pattern signal combines six pulse width modulated switching signal pairs into six intermediate signals and further combines these six intermediate signals to produce three composite signals. The three composite signals are used to produce a test signal which is monitored to detect a failure in at least one of the pulse width modulated switching signals. Individual pairs of the intermediate signals can be further combined to produce three additional test signals which are used to detect a failure in a particular one of the pulse width modulated signals. These three additional test signals can be further combined to produce a fifth test signal which can be analyzed to detect an abnormal polarity in the pulse width modulated switching signals. Both the above test method and circuits which perform that method are disclosed.