Work Machine U-Turn Control to Prevent Lawn Peeling

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Solution Overview

Problem

Existing work machines, such as lawn mowers, experience issues with U-turns that cause lawn peeling and uncomfortable rides due to backward movements or multiple counter-rotation turns.

Innovation Solution

A work machine equipped with an automatic turn execution unit that performs a gentle turn followed by a counter-rotation turn, using independent wheel control to adjust rotation speeds and distances, preventing lawn peeling and uncomfortable rides.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a sharp turn is made to complete a U-turn faster, then the turn time is reduced, but the lawn may be peeled off

Engineering Contradiction:

Improveturn timeVSAvoidlawn peeling

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The U-turn operation is divided into multiple sequential phases: initial gentle turn, intermediate positioning, and final counter-rotation turn. This segmentation allows each phase to be optimized independently - the gentle turn protects the lawn while the counter-rotation turn achieves efficient repositioning, resolving the contradiction between turn speed and lawn protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Before executing the final counter-rotation turn, the system performs preliminary gentle turning and positioning actions. This preliminary action prepares the work machine in an optimal position and orientation, enabling the subsequent counter-rotation turn to be executed efficiently without causing lawn damage, thus balancing turn time reduction with lawn protection.

Inventive Principle:

Principle #10Preliminary action

2Shape

If backward movement is performed during U-turn, then the turn radius is reduced, but the ride becomes uncomfortable

Engineering Contradiction:

Improveturn radiusVSAvoidride comfort

Core Design Contradiction:

ShapeVSEase of operation

Solution Approach 1:

Instead of moving backward during the turn as in conventional approaches, the system inverts the sequence by performing forward gentle turning followed by a forward counter-rotation turn. This inversion eliminates backward movement entirely, maintaining ride comfort while achieving the necessary turn radius through controlled forward motion and differential wheel rotation.

Inventive Principle:

Principle #13The other way round (Inversion)

3Shape

If multiple counter-rotation turns are performed to make a U-turn, then the turn radius is reduced, but the turn time increases and ride becomes uncomfortable

Engineering Contradiction:

Improveturn radiusVSAvoidturn time

Core Design Contradiction:

ShapeVSLoss of time

Solution Approach 1:

The system maintains continuous forward motion throughout the U-turn operation, avoiding stops and reversals. The gentle turn and counter-rotation turn are executed as continuous rotational movements without interrupting forward progression, thereby reducing total turn time and maintaining ride comfort while achieving the required turn radius.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS12550803B2Work machine

Publication Date: 2026.02.17 HONDA MOTOR CO LTD

AI summary

A work machine includes: a pair of drive wheels that is either front wheels or rear wheels; a pair of non-driving wheels that is the other of the front wheels and the rear wheels; a work device disposed between the front wheels and the rear wheels; a machine body; and a control device including an automatic turn-execution unit configured to execute an automatic turn in a U shape. The automatic-turn execution unit is configured to execute: a gentle turn operation in which the work machine makes a gentle turn; and a counter-rotation turn operation in which the work machine makes a counter-rotation turn after the gentle turn operation.