Capacitive Rain Detection Through a Robotic Mower User Interface

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Solution Overview

Problem

Robotic garden tools face challenges in accurately detecting liquid, such as rain, without exposing sensors to the environment and ensuring easy installation during manufacturing.

Innovation Solution

Incorporating a capacitance sensor with a sensing surface on the interior of an indented portion of the user interface, which is designed to accumulate liquid and has a surface treatment for increased affinity, allowing for discreet and effective liquid detection while protecting the sensor from environmental exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the sensor is exposed to the environment for liquid detection, then liquid detection accuracy is improved, but the sensor becomes vulnerable to environmental damage

Engineering Contradiction:

Improveliquid detection accuracyVSAvoidsensor protection from environmental elements

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The user interface element (button or indicator) serves as an intermediary between the sensor and the environment. Liquid accumulates on the exterior surface of this interface element, and the sensor detects the liquid indirectly through capacitance changes in the interface element, rather than directly exposing the sensor to environmental liquid.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sensor is nested within the housing, with the user interface element positioned between the sensor and the external environment. This nested structure allows the sensor to be protected inside while still enabling liquid detection through the interface element that protrudes or interfaces with the external environment.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If the sensor is protected from environmental exposure, then sensor reliability is improved, but liquid detection capability deteriorates

Engineering Contradiction:

Improvesensor protection from environmental elementsVSAvoidliquid detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The user interface element acts as a mediator that transmits liquid presence information to the protected sensor. The interface element's capacitance changes in response to liquid accumulation, and these changes are detected by the sensor without requiring direct sensor exposure to liquid.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical/contact-based liquid detection with a capacitive sensing mechanism. The sensor detects electrical field changes caused by liquid accumulation on the interface element, eliminating the need for mechanical contact or direct exposure between the sensor and liquid.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a complex sensor mounting structure is used to protect the sensor, then sensor protection is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvesensor protectionVSAvoidinstallation ease during manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The sensor is integrated directly into the housing structure, and the user interface element is formed as part of the housing or seamlessly attached to it. This merging of components eliminates the need for separate mounting brackets, adhesives, or complex assembly steps, simplifying manufacturing while maintaining sensor protection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The housing serves multiple functions: it provides structural support, protects the sensor, and forms or supports the user interface element for liquid detection. This multi-functionality reduces the number of separate components needed, simplifying the manufacturing process while maintaining sensor protection capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables accurate and reliable liquid detection, protecting the sensor from environmental elements and facilitating easy installation, thereby enhancing the operational safety and reliability of robotic garden tools.

Implementation Method 1

The sensor may be configured to sense a capacitance level associated with at least a portion of the user interface

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The at least a portion of the user interface of the robotic garden tool may include includes a surface treated to increase an affinity of the surface to liquid to facilitate liquid accumulation on the surface

Methodology Applied

Scientific EffectSurface affinity (hydrophilic): Hydrophile

Data Source

PatentEP4356709A1Liquid detection sensor for a robotic garden tool

Publication Date: 2024.04.24 TECHTRONIC CORDLESS GP

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AI summary

Embodiments of the disclosure provide a method, device, and system for detecting liquid contacting a robotic garden tool. The robotic garden tool may include a housing, and a user interface forming part of an outer surface of the housing. The robotic garden tool may also include a sensor coupled to the user interface. The sensor may be configured to sense a capacitance level associated with at least a portion of the user interface. The robotic garden tool may also include an electronic processor coupled to the sensor and configured to control an operation of the robotic garden tool based on an output of the sensor.