Multirotor Drone Peripheral Protection with Strain Sensors

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Solution Overview

Problem

Existing multirotor drones face challenges in navigating through spaces with reduced visibility and many obstacles due to the complexity and sensitivity of existing obstacle detection systems, which can be hindered by environmental conditions like fog, smoke, or rain.

Innovation Solution

A multirotor drone equipped with a continuous peripheral protection system that includes deformation sensors to detect collisions and adjust rotor control setpoints based on impact positions, allowing autonomous navigation and obstacle avoidance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If light-based detection systems (cameras, laser) are used to detect obstacles, then the drone can detect obstacles and modify trajectory, but the system becomes complex and has large mass

Engineering Contradiction:
Improveobstacle detection capabilityVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex optical detection systems (cameras, laser range finders) with a simple mechanical deformation detection system. Strain gauges are attached to the protective cage to detect mechanical deformations caused by obstacle contacts, substituting sophisticated optical-mechanical systems with a straightforward mechanical sensing approach.

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

Solution Approach 2:

The patent extracts only the essential detection function from complex optical systems. Instead of using entire camera or laser systems, it isolates the detection capability to simple strain gauge measurements on the protective cage, removing unnecessary complexity while retaining obstacle detection functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If light-based detection systems (cameras, laser) are used to detect obstacles, then the drone can detect obstacles, but the system has large mass

Engineering Contradiction:
Improveobstacle detection capabilityVSAvoiddetection system mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces heavy optical detection systems with lightweight strain gauges. The strain gauges are minimal mechanical components that can be directly attached to the protective cage, dramatically reducing the mass of the detection system while maintaining obstacle detection capability through deformation sensing.

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

Solution Approach 2:

The patent discards the heavy optical components (cameras, laser beams, processors) and recovers only the essential detection function through simple strain measurements. This selective discarding of mass- intensive components while retaining detection functionality achieves lightweight design.

Inventive Principle:
Principle #34Discarding and recovering

3Reliability

If light-based detection systems (cameras, laser) are used to detect obstacles, then the drone can detect obstacles, but performance is significantly limited by environmental conditions such as fog, smoke or rain

Engineering Contradiction:
Improveobstacle detection capabilityVSAvoidsensitivity to environmental conditions
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces optical detection systems that are highly sensitive to environmental conditions (fog, smoke, rain) with a mechanical deformation detection system. Strain gauges on the protective cage detect physical contacts regardless of visibility conditions, eliminating sensitivity to atmospheric interference that plagues light-based systems.

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

Solution Approach 2:

The patent converts the harmful effect of environmental conditions (fog, smoke, rain) into a benefit by using a detection method that is inherently insensitive to these factors. The mechanical strain gauge system thrives in conditions where optical systems fail, turning the challenging environment into an operating regime where the mechanical system excels.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 drone effectively navigates in environments with reduced visibility by accurately detecting collisions and modifying its trajectory to avoid obstacles, enhancing its ability to perform missions like searching for people in challenging conditions.

Implementation Method 1

the peripheral continuous protection comprising a peripheral outer wall able to deform elastically under the effect of a reaction force exerted by the obstacle on the peripheral outer wall during the collision

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The at least two deformation sensors can for example be formed by extensometers with resistant wires generally designated by strain gauges. These sensors are advantageously attached by bonding to the peripheral outer wall and then make it possible to translate the deformation or more precisely measurements of the normal stress in bending of the peripheral outer wall by variations in electrical resistance at their terminals.

Methodology Applied
Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentEP3854685B1Multirotor drone provided with a peripheral protection and method for controlling such a multirotor drone
Publication Date: 2022.07.13 EUROCOPTER FRANCE SA
  • EP3854685B1 patent drawingFigure 1~2
  • EP3854685B1 patent drawingFigure 3~5
  • EP3854685B1 patent drawingFigure 6~8

AI summary

The present invention relates to a multirotor drone (1) comprising a carrier frame (2), at least two propulsion and/or lift rotors (4, 14, 24, 34) and a continuous peripheral protection (5) laterally protecting said at least two rotors (4, 14, 24, 34) during a collision of said drone (1) with an obstacle arranged laterally with respect to an elevation direction Z, said continuous peripheral protection (5) comprising a peripheral outer wall (6) capable of elastically deforming under the effect of a reaction force F exerted by said obstacle on said peripheral outer wall (6) during said collision.According to the invention, such a drone (1) comprises at least two strain sensors (7, 17, 27, 37) arranged at the level of said peripheral outer wall (6), each strain sensor (7, 17, 27, 37) being capable of performing measurements varying according to a deformation of said peripheral outer wall (6), a processing unit (8) connected to said at least two strain sensors (7, 17, 27, 37) and a control element (9) for generating control instructions for said at least two rotors (4, 14, 24, 34).