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, and existing evasive maneuvers may eventually fail and require repair.
Innovation Solution
Implementing path planning techniques using a predetermined terrain map to orient the mower for optimal traction and avoid obstacles by analyzing the terrain and deciding on forward or reverse travel directions, and using sensors to detect and avoid obstacles before contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If autonomous lawn mowers use differential drive systems to simplify the power train, then device complexity is reduced, but the mower loses traction on steep slopes and becomes stuck
Solution Approach 1:
The path planning system proactively identifies steep slopes from terrain data before the mower reaches them, and pre-calculates appropriate travel directions (uphill or downhill) to ensure optimal traction. This preliminary planning prevents the mower from encountering situations where it would lose traction, resolving the contradiction by maintaining reliability without adding mechanical complexity to the drive system.
2Reliability
If the mower takes evasive actions when already on a steep grade, then it may exit the problem area temporarily, but the surface wears down and subsequent evasive actions fail, causing the mower to become stuck
Solution Approach 1:
The system uses pre-acquired terrain maps to identify steep slopes before the mower encounters them, allowing it to plan a travel path that approaches and crosses these areas at optimal angles. This prevents the mower from needing to take reactive evasive actions that damage the turf, thereby maintaining reliability without causing harmful surface wear.
Solution Approach 2:
The terrain data, which could reveal problematic areas that might cause the mower to get stuck, is converted into a beneficial planning tool. By using this information proactively, the system transforms potential harm (getting stuck) into benefit (successful navigation), avoiding the need for damaging evasive maneuvers.
3Reliability
If the level detector senses steep grade to trigger evasive maneuvers, then the mower attempts to exit the problem area, but it may have already lost the ability to reverse or turn away from the boundary
Solution Approach 1:
The path planning system uses predetermined terrain maps to identify steep slopes before the mower reaches them, allowing advance planning of the approach angle and direction. This eliminates the need for reactive level detection and evasive maneuvers, providing sufficient time to execute smooth, controlled navigation through problem areas without losing traction or damaging the turf.
4Productivity
If the mower uses random travel pattern within a fixed property boundary, then it can cover the area without complex path planning, but obstacles impede its ability to effectively cover the work region
Solution Approach 1:
The system uses predetermined terrain maps that include obstacle locations to plan travel paths in advance. This allows the mower to navigate around obstacles efficiently without random trial-and-error movements, improving both productivity by reducing unnecessary travel and reliability by ensuring successful obstacle avoidance.
Data Source
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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.