Tennant Company

John Peter Haeg

Robert Erko

Richard F Milun

Terry B Schwartz

Bruce Phillip Bushey

Robert J Erko

A control system for a linear actuator having an electric motor drawing a variable current level during operation. The control system includes a current level sensor for determining an operational current level of the linear actuator and a controller for generating a drive signal and a force request signal representative of a desired current level of the linear actuator. The drive signal remains constant during a predetermined time interval of the controller. The control system further includes a current limiting component for receiving the force request signal, the current level of the linear actuator and the drive signal. The current limiting component minimizes the current level of the electric motor in response to a comparison between the force request signal and the desired current level within a time interval substantially smaller than the predetermined time interval of the controller.

Linear actuator control structure

A control system for controlling the work output delivered to a floor surface by a work tool associated with a floor maintenance machine, such as a burnisher, is provided. In one embodiment, a voltage regulator regulates the voltage provided to the motor assembly that drives the work tool. A current sensor monitors the motor current drawn by the motor assembly and provides a signal representative thereof to a controller. The controller also receives as an input a work selector signal representative of a desired level of work output. Based on the work selector signal and the sensed motor current, the controller provides a control signal to an actuator. In response to the control signal, the actuator raises or lowers the work tool relative to the floor as need to control the work output delivered to the floor. In another embodiment, the voltage regulator is omitted, and the controller is configured to generate the control signal based on the product of the motor current and the voltage provided to the motor assembly.

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Minneapolis, MN, United States of America

John Peter Haeg