Contact sensors for a mobile robot

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Solution Overview

Problem

Existing mobile robots rely on mechanical switches for bumper contact detection, which provide limited information about obstacle interactions, such as force location, magnitude, and duration, and are not sensitive enough to avoid complex obstacles effectively.

Innovation Solution

The use of capacitive, inductive, or Hall effect sensors mounted on a bumper with movable and stationary plates, generating electrical signals proportional to displacement, allowing for the detection of force attributes like location, magnitude, and duration, enabling more nuanced obstacle interaction and navigation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mechanical switches are used for bumper contact detection, then the device complexity is reduced, but the measurement precision and information quality about obstacle interactions deteriorate

Engineering Contradiction:
Improvedetection precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical switches with capacitive, inductive, or Hall effect sensors that provide continuous analog signals proportional to bumper displacement. This substitution enables precise measurement of force location, magnitude, and duration while maintaining relatively simple device architecture through the use of standard sensor components.

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

2Reliability

If mechanical switches are used for bumper contact detection, then the device complexity is reduced, but the ability to detect and respond to obstacles effectively deteriorates

Engineering Contradiction:
Improveobstacle detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces binary mechanical switch outputs with continuous analog signals from capacitive, inductive, or Hall effect sensors. This enables the robot to detect obstacle characteristics such as force magnitude and duration, improving reliability in obstacle detection and response while keeping the device structure relatively simple.

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

Solution Approach 2:

The patent implements feedback by using sensor signals to modify robot behavior in response to detected obstacles. The continuous measurement data allows the control system to adjust navigation decisions dynamically based on the magnitude and duration of forces detected, enhancing obstacle response capability.

Inventive Principle:
Principle #23Feedback

3Loss of information

If binary indication from mechanical switches is used, then the information processing complexity is reduced, but the loss of information about force attributes increases

Engineering Contradiction:
Improveinformation qualityVSAvoiddevice complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent replaces binary mechanical switch indications with continuous analog signals that preserve information about force location, magnitude, and duration. This substitution minimizes information loss while maintaining manageable device complexity through the use of standard sensor and processing components.

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

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

This sensor system enhances the robot's ability to detect and respond to obstacles with high sensitivity, reducing the likelihood of getting stuck and improving navigation by providing detailed force data for adjusted behaviors.

Implementation Method 1

each sensor may be a capacitive sensor having one plate movably mounted so that the plate moves along with the bumper relative to the chassis, and another plate mounted so that it is stationary relative to the chassis. Movement of one plate relative to another, due to the movement of the bumper, causes the capacitive sensor to output an electrical signal having a magnitude or value proportional to the distance between the plates.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

The sensor may be an inductive sensor that outputs an electrical signal in response to movement of the bumper.

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 3

The sensor may be a Hall effect sensor that outputs an electrical signal in response to movement of the bumper.

Methodology Applied
Scientific EffectHall Effect: Hall Effect

Data Source

PatentEP3366183B1Contact sensors for a mobile robot
Publication Date: 2019.10.02 IROBOT CORP
  • EP3366183B1 patent drawingFigure 1
  • EP3366183B1 patent drawingFigure 2
  • EP3366183B1 patent drawingFigure 3~4

AI summary

A robot includes a body and a bumper. The body is movable relative to a surface and includes a first portion of a sensor. The bumper is mounted on the body and movable relative to the body and includes a backing and a second portion of the sensor. The backing is movable relative to the body in response to a force applied to the bumper. The second portion of the sensor is attached to the backing and movable with the backing relative to the first portion of the sensor in response to a force applied to the bumper. The sensor is configured to output an electrical signal in response to a movement of the backing. The electrical signal is proportional to an amount of displacement of the second portion relative to the first portion.