Electric lawn mower with intelligent control

In an electric lawn mower for cutting lawns comprising:

• a frame supporting an operator station, a mower deck with at least one cutter blade rotated by an electric motor, at least two opposed wheels driven by associated reversible electric wheel-drive motors, and at least one stabilizing, undriven-swivel-wheel;
• a source of electrical power for said motors;
• operating controls for mower-operator actuation associated with said operator station for directing electrical power selectively to each of said wheel-drive motors;
• wherein said frame is hinged to a leading frame having at least one leading caster and having a mowing deck with leading and trailing edges, said leading edge hingedly suspended from said leading frame and said trailing edge supported by at least one wheel;
• and
• an electrical system interconnecting said source of power, said at least one mower deck motor, said operator controls and said wheel-drive motors,
• The improvement comprising:
• an intelligent control unit electrically interposed between each of said wheel-drive motors and said operator controls and an information sensing unit associated with each of said wheel-drive motors for providing informational input to said control units from said wheel-drive motors.

An intelligent control system for controlling the speed of an electrically powered lawn maintenance vehicle, the vehicle having a known weight and comprising:

• a source of electrical power;
• a drive subsystem comprising at least one motor drive unit and at least one electric wheel-motor for propulsion, a motor speed and direction current sensor, and at least one temperature sensor;
• a power distribution subsystem;
• and
• an operator control unit;
• the control system comprising:
• a microcontroller, programmed to sense motor speed and direction, operator commands from the operator control unit, and temperature of the drive subsystem components, and to generate pulse width modulated speed control signals;
• the microcontroller being programmed with tables of speed control values for generating corresponding pulse width speed control signals, and the motor drive unit being capable of supplying current to the at least one motor in accordance with the speed control signals,
• and the operator control unit, having a control handle operatively connected to a handle position sensor, the position sensor having a home position to indicate a desired STOP condition and at least two forward and two reverse speed positions, being capable of generating operator commands,
• the table of speed control values being selected in accordance with the dynamic operating characteristic of the electric motor and the weight of the vehicle,
• whereby safe and effective operation of said vehicle is achieved, conditions harmful to the drive subsystem are avoided and forces harmful to the lawn and to the operator are avoided by means for avoidance of sharp reversal of said wheel-motors and drive wheels when a wheel-motor sensor indicates presence of short circuit or drive current sufficient to cause harm, and operation over a safe temperature is avoided by means responsive to said temperature sensor.