Abstract: The invention features an electronic feedback circuit for varying the steering ratio of a motorized material handling vehicle in response to the vehicular speed. The lock-to-lock turn of the steering wheel or column is electronically adjusted in order to modify the steering response (i.e., steering angle) of the steer/drive wheel with respect to an increase in speed of the vehicle. The steering ratio can be a straight-line function of vehicular speed.

Abstract: A unique steer/drive control system is featured for steering a material handling vehicle by the use of directly coupled traction and steering motors. The steering motor is fabricated as a hollow shaft dc motor, whose inner ring represents the rotor, and whose outer ring represents the stator. The stator is connected to a frame of the vehicle carrying the steering and drive wheel. The rotor is integrally connected to the traction motor that drives the steering and drive wheel. A hand operated steering mechanism rotationally guides the vehicle. A steering angle sensor determines the difference between actual and desired heading of the steering and drive wheel. The steer/drive system utilizes the sensed difference, and generates a signal for controlling the heading of the steering and drive wheel.

Abstract: The present invention features a material handling vehicle identification system. The material handling vehicle has a universal system processor for controlling the vehicle speed, acceleration, direction and motion of a plurality of different vehicles. A semiconductor memory device is permanently affixed to the chassis of the vehicle during the manufacturing process. This memory device contains a unique identification tag. The identification tag is remotely disposed from, but operatively connected to the system processor. The identification tag includes data for uniquely identifying the material handling vehicle. The system processor can control the performance of the vehicle as a function of the data in the identification tag, whereby the system processor becomes customized to operate consistant only with the vehicle in which it is installed.

Abstract: A system for controlling separately excited shunt-wound dc motors, where control is achieved through microprocessor-based independent PWM control of a chopper (armature) and an H-bridge (field). Connected to the armature is an armature voltage amplifier for varying the applied armature voltage. A field voltage amplifier is also provided for determining the direction of motor rotation and varying the voltage applied to the field winding. A first sensor is connected to the motor armature in order to determine the motor rotational speed. A second sensor is connected to the armature circuit in order to determine the armature current. A third sensor is connected to the field circuit in order to determine the field current. A decoupling controller uses the motor speed and armature current information, and adjusts the armature voltage and the field voltage. An optimal controller uses the motor speed, field current and armature current information, and adjusts the armature voltage and the field voltage.

Abstract: A system for optimizing control of separately excited shunt-wound dc motors, where optimization is achieved through microprocessor-based independent PWM control of a chopper (armature) and an H-bridge (field). Connected to the armature is an armature voltage amplifier for varying the applied armature voltage. A field voltage amplifier is also provided for determining the direction of motor rotation and varying the voltage applied to the field winding. A first sensor is connected to the motor armature in order to determine the motor rotational speed. A second sensor is connected to the armature circuit in order to determine the armature current. A third sensor is connected to the field circuit in order to determine the field current. A decoupling controller uses the motor speed and armature current information, and adjusts the armature voltage and the field voltage.

Abstract: A travel speed limiting control system for lift trucks, particularly of the "orderpicker" type, having an extendible mast, is disclosed. The truck travel speed which the operator can command is limited by factors including load weight, load elevation, heading angle and direction of truck travel (forward or reverse) . Optionally, other factors may be involved, such as lateral tilt and load moment. An algorithm including the desired input factors is continually processed by an on-board microcomputer to provide an instantaneous speed limit signal. In addition to its normal operating mode, the microcomputer is also arranged to operate in a "learn" mode, whereby it runs through the ranges of various input signals and develops a set of stored values which indicate the allowable ranges of the inputs, as well as offset or bias values which compensate for manufacturing tolerances occurring in the components of the system.