Nonholonomic Robot Field Coverage With Minimum-Radius Lane Linking

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Solution Overview

Problem

Prior art algorithms fail to effectively handle non-holonomic robots with limited turning radius, leading to incomplete field coverage and incorrect path generation due to mislabeled cells and inability to link lanes, especially when transitioning between adjacent cells and navigating around obstacles.

Innovation Solution

The method generates a path for nonholonomic robots to cover a field by using lane linking, cell traversal, and lane wrapping algorithms, ensuring the robot follows a straight line as much as possible while avoiding obstacles and completing tasks efficiently, with the aid of sensors like GPS, RADAR, and LIDAR for navigation and obstacle detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If prior art algorithms are used for field coverage, then the robot can navigate the field, but the field coverage is incomplete and incorrect due to inability to handle nonholonomic constraints

Engineering Contradiction:
Improvefield coverage completenessVSAvoidhandling nonholonomic robot constraints
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The field is divided into discrete cells that can be individually processed and labeled. This segmentation allows the algorithm to systematically handle each cell's coverage requirements while respecting nonholonomic constraints, ensuring complete and correct field coverage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension of cell labeling that incorporates nonholonomic constraints into the path planning process. By adding this dimensional consideration to traditional field coverage algorithms, the system can generate valid paths for nonholonomic robots while maintaining complete coverage.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the robot follows straight lines to minimize turns, then coverage efficiency improves, but the robot cannot navigate around obstacles or follow complex boundary shapes

Engineering Contradiction:
Improvecoverage efficiencyVSAvoidobstacle avoidance capability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The path planning algorithm dynamically adjusts the robot's trajectory by introducing turn commands at appropriate locations while maintaining straight-line segments elsewhere. This dynamic path generation allows the robot to efficiently cover the field while adapting to obstacles and boundary constraints.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent uses intermediate cells as mediators to connect straight-line path segments. These intermediate cells provide the necessary turning space for nonholonomic robots to transition between parallel coverage lanes while avoiding obstacles and following boundary shapes.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If the robot makes tight turns to follow field boundaries and avoid obstacles, then path accuracy improves, but the robot violates minimum turning radius constraints

Engineering Contradiction:
Improvepath following accuracyVSAvoidconstraint satisfaction
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The algorithm incorporates curved transition paths with controlled curvature that respect the robot's minimum turning radius. Instead of sharp angular turns, the system generates smooth curved segments that allow the robot to follow field boundaries and avoid obstacles while maintaining reliable constraint satisfaction.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The path planning algorithm adjusts path geometry parameters (such as turn radius and transition curve length) to ensure they meet the robot's minimum turning radius constraints. By dynamically changing these parameters based on local environmental features, the system maintains both path accuracy and constraint satisfaction.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If the algorithm processes every cell individually to ensure complete coverage, then coverage completeness improves, but computational complexity and processing time increase

Engineering Contradiction:
Improvecoverage completenessVSAvoidalgorithm complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The algorithm merges adjacent cells that share similar coverage characteristics and constraint requirements into processing units. This merging reduces the total number of individual cell processing operations while maintaining complete coverage, thereby lowering computational complexity and processing time.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent develops a universal cell processing framework that handles multiple functions (coverage verification, constraint checking, path generation) in a single integrated algorithm. This multi-functional approach eliminates the need for separate processing steps for each function, reducing overall algorithmic complexity while ensuring complete and correct coverage.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS11029691B1Nonholonomic robot field coverage method
Publication Date: 2021.06.08 THE TORO COMPANY
  • US11029691B1 patent drawing
  • US11029691B1 patent drawing
  • US11029691B1 patent drawing

AI summary

A software product and methods determine a field coverage method for a nonholonomic robot to process a field using parallel lanes. A cellular decomposition algorithm divides the field into a plurality of cells, each having a plurality of parallel lanes. Permutations of lane processing orders are determined for each cell, based upon a minimum turning radius of the robot. A cell graph is generated to determine a shortest path for single-time processing each lane in each cell without violating the minimum turning radius of the robot. A step list defining movement of the nonholonomic robot along each lane in each cell of the shortest path through the cell graph is generated, and transits between the lanes, and laps around the field and any obstacles are added. A path program to control the nonholonomic robot to process the field is generated based upon the step list.