Walk Power Mower Handle Grip Force Control

Solution Overview

Problem

Existing walk power mowers with bidirectional traction drive systems require significant up and down travel of the handle grip to control ground speed, complicating the design and user experience.

Innovation Solution

A handle grip system with a force sensor and control system that adjusts the ground speed of the mower based on the force applied by the operator, using a load cell and microcomputer-based motor controller to minimize perceivable motion and match walking pace seamlessly in both forward and reverse directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a slidable handle grip is used to control ground speed in bidirectional traction drive systems, then the ground speed can be matched to the operator's walking speed, but the handle grip requires significant up and down travel which complicates the design

Engineering Contradiction:

Improveground speed matchingVSAvoidhandle grip travel

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical slidable handle grip system with an electronic sensing and control system. A force sensor (load cell) mounted in the handle grip detects the operator's pushing or pulling force, and a microcomputer-based controller processes this signal to control the traction drive motor, thereby adjusting ground speed electronically rather than mechanically.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from physical displacement (handle grip travel distance) to applied force (operator input force). The force sensor measures the force applied by the operator on the handle grip, and this force parameter is used to control the ground speed, eliminating the need for large mechanical travel.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a slidable handle grip is used to control ground speed, then the operator can maneuver the mower, but the significant up and down travel required complicates the design and user experience

Engineering Contradiction:

Improvemower maneuverabilityVSAvoidhandle grip mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical slidable handle grip system with an electronic sensing and control system. A force sensor (load cell) mounted in the handle grip detects the operator's pushing or pulling force, and a microcomputer-based controller processes this signal to control the traction drive motor, thereby adjusting ground speed electronically rather than mechanically.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a force sensor (load cell) as an intermediary between the operator's manual input on the handle grip and the traction drive motor. This intermediary device converts the operator's mechanical force input into an electrical signal that the microcomputer controller can process to adjust motor speed, simplifying the overall system while maintaining ease of operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the handle grip is made fixed to eliminate travel, then the design is simplified, but the ability to control ground speed through handle grip motion is lost

Engineering Contradiction:

Improvehandle grip structureVSAvoidground speed control

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical slidable handle grip system with an electronic sensing and control system. A force sensor (load cell) mounted in the handle grip detects the operator's pushing or pulling force, and a microcomputer-based controller processes this signal to control the traction drive motor, thereby adjusting ground speed electronically rather than mechanically.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a force sensor (load cell) as an intermediary between the operator's manual input on the handle grip and the traction drive motor. This intermediary device converts the operator's mechanical force input into an electrical signal that the microcomputer controller can process to adjust motor speed, simplifying the overall system while maintaining ease of operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system allows for precise control of ground speed without noticeable handle grip motion, enhancing user experience and simplifying design by reducing the required handle grip travel to nearly imperceptible levels.

Implementation Method 1

A force sensor, e.g., a load cell, is mounted in the handle grip to detect forward force components applied to the handle grip by the operator

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12016267B2Walk power mower with ground speed responsive to force applied to a handle grip by the operator

Publication Date: 2024.06.25 THE TORO COMPANY

AI summary

A walk power mower comprises a housing having an upwardly and rearwardly extending handle that is gripped by an operator. A load cell is responsive to the force applied by the operator to the handle during a grass mowing operation. Input from the load cell is used by a control system to vary the ground speed of the mower in accordance with the sensed operator applied force through control of an electric traction drive motor.