Robotic Mower Height Calibration via Screw Feedback

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Robotic mowers face challenges in accurately adjusting and maintaining cutting height due to component slippage and electrical fluctuations, which can impact the precision of cutting height adjustments in varying operating conditions.

Innovation Solution

A robotic mower system featuring a height adjustment assembly with a motor bracket supported by a rotatable height adjustment screw, controlled by a height adjustment motor, and a calibration system that monitors the screw's rotation using a sensor to determine the cutting height, allowing for precise adjustments based on received information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a height adjustment motor and screw system is used to adjust cutting height, then the cutting height can be adjusted automatically, but component slippage and electrical fluctuations cause imprecision in height positioning

Engineering Contradiction:
Improveautomatic height adjustmentVSAvoidcutting height precision
Core Design Contradiction:
Extent of automationVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where a sensor detects the actual position of the height adjustment screw and sends this information back to the control circuitry. The control circuitry compares the actual position with the target position and makes corrections by adjusting the height adjustment motor, thereby compensating for slippage and electrical fluctuations to maintain precise cutting height positioning.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces pure mechanical height adjustment mechanisms with an electromechanical system that uses a height adjustment motor driven by control circuitry. This substitution allows for more precise control through electrical signals and enables the integration of feedback mechanisms and calibration systems that can compensate for mechanical slippage and electrical variations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the height adjustment screw rotates freely to adjust motor bracket height, then height adjustment is flexible, but slippage occurs reducing adjustment accuracy

Engineering Contradiction:
Improveheight adjustment flexibilityVSAvoidheight adjustment accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces manual mechanical rotation of the height adjustment screw with an automated electromechanical system. The height adjustment motor, controlled by control circuitry, rotates the screw with precise control over torque and position, eliminating the slippage that occurs with manual operation while maintaining flexibility through programmable adjustment.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-calibration and self-adjustment through the feedback mechanism. The sensor continuously monitors the screw position, and the control circuitry automatically compensates for any deviations or slippage without requiring manual intervention, thereby maintaining both flexibility and precision.

Inventive Principle:
Principle #25Self-service

3Extent of automation

If electrical signals control the height adjustment motor, then automated control is achieved, but electrical fluctuations cause positioning errors

Engineering Contradiction:
Improveelectrical control of height adjustmentVSAvoidpositioning reliability
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The feedback mechanism continuously monitors the actual position of the height adjustment screw and communicates this information to the control circuitry. When electrical fluctuations cause positioning errors, the feedback system detects the deviation from the target position and triggers corrective action by adjusting the motor, thereby maintaining reliable positioning despite electrical variations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary calibration to establish accurate reference positions for the height adjustment screw. By pre-calibrating the relationship between motor rotations and screw positions, the system creates a baseline that helps compensate for subsequent electrical fluctuations, improving positioning reliability.

Inventive Principle:
Principle #10Preliminary action

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 enables accurate and reliable control of cutting height, ensuring consistent mowing performance across different terrains and conditions by using a calibration system to monitor and adjust the height adjustment screw's rotation, thereby improving the operator's ability to set and maintain desired cutting heights.

Implementation Method 1

a height adjustment sensor that detects a rotation position of the height adjustment screw

Methodology Applied
Scientific EffectSensor detection:

Implementation Method 2

a height adjustment motor configured to adjust a position of the motor bracket by rotation of a height adjustment screw

Methodology Applied
Scientific EffectElectromagnetic conversion:

Data Source

PatentEP4173465A1Calibration of cutting height for a robotic mower
Publication Date: 2023.05.03 HUSQVARNA AB
  • EP4173465A1 patent drawingFigure 1
  • EP4173465A1 patent drawingFigure 2A~2B
  • EP4173465A1 patent drawingFigure 3

AI summary

A robotic mower comprises a chassis; a cutting motor driving at least one cutting blade; and a height adjustment assembly including a height adjustment motor (140) configured to adjust a height of a motor bracket (100) via rotation of a height adjustment screw (136) driven by the height adjustment motor (140), the motor bracket (100) providing structural support for the cutting motor at an adjustable level relative to the chassis.