Autonomous Mower Path Planning for Slope Traction and Obstacle Avoidance

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Solution Overview

Problem

Autonomous lawn mowers with differential drive systems often lose traction on steep slopes, leading to becoming stuck, and struggle with obstacles, which reduces their effectiveness and can damage the turf.

Innovation Solution

Implementing path planning based on a predetermined terrain map to orient the machine for maintaining traction and avoid obstacles by analyzing the terrain and deciding on forward or reverse direction, and using sensors to detect and change course before contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If autonomous lawn mowers use differential drive systems to simplify the power train, then device complexity is reduced, but traction is lost on steep slopes causing the mower to become stuck

Engineering Contradiction:

Improvepower train complexityVSAvoidtraction on steep slopes

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The level detector senses steep grades in advance before the mower reaches them, triggering evasive maneuvers proactively. This preliminary detection and response prevents the mower from losing traction and becoming stuck on steep slopes, resolving the reliability issue while maintaining the simple differential drive system.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the level detector triggers evasive actions when sensing steep grades, then traction loss is prevented, but the mower may still become stuck when approaching boundaries at steep grades downhill

Engineering Contradiction:

Improvetraction maintenanceVSAvoidability to continue cutting grass

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The mower is designed to traverse steep downhill slopes in reverse rather than forward. By inverting the direction of travel on steep declines, the mower maintains better traction and control, preventing it from becoming stuck at boundaries while continuing to cut grass effectively.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If evasive actions are taken on steep grades to prevent getting stuck, then temporary recovery is achieved, but the turf surface is damaged and traction is further reduced

Engineering Contradiction:

Improvemower recovery from stuck conditionVSAvoidturf damage and surface wear

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The mower takes preliminary evasive actions when level detectors sense steep grades before significant damage occurs. By proactively reversing or rotating to exit problem areas early, the mower prevents the turf from being worn down and maintains surface integrity for future operations.

Inventive Principle:

Principle #9Preliminary anti-action

4Ease of operation

If autonomous mowers use random travel patterns within fixed boundaries, then coverage is simplified, but problem areas like steep slopes and obstacles cause the mower to become trapped

Engineering Contradiction:

Improvetravel pattern simplicityVSAvoidability to avoid trapped conditions

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The mower uses level detectors and obstacle sensors to provide feedback about terrain conditions. This feedback enables the mower to adjust its random travel pattern in real-time, avoiding steep slopes and obstacles that would cause it to become trapped, while maintaining the overall simplicity of random pattern operation.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11832553B2Autonomous grounds maintenance machines with path planning for trap and obstacle avoidance

Publication Date: 2023.12.05 THE TORO COMPANY

AI summary

Operating an autonomous grounds maintenance machine includes determining a travel path for the machine to reach a destination waypoint in a zone of a work region. The travel path is analyzed for problem areas based on a predetermined terrain map. Rotations of the machine may be planned even before the machine begins to travel down the path to proactively prevent the machine from becoming trapped.