UAV Touchdown Detection via Dynamics-Based Support Estimation

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Solution Overview

Problem

Autonomous unmanned aerial vehicles (UAVs) face challenges in safely and accurately detecting touchdown on various surfaces without tactile force sensors, especially when encountering obstacles or changing landing conditions, which is critical for safe and gentle landing.

Innovation Solution

The technique combines information from onboard sensors, such as cameras and inertial measurement units, with a dynamics model to estimate external forces and torques acting on the UAV, enabling it to determine if it is sufficiently supported by a landing surface and adjust its propulsion system accordingly, without relying on tactile sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If tactile force sensors are used to detect touchdown, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvetouchdown detection accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces tactile force sensors with a computational approach that uses existing onboard sensors (accelerometers, gyroscopes, propeller torque sensors) combined with a dynamics model to estimate external forces and detect touchdown. This substitutes a mechanical sensing system with a computational estimation system, reducing hardware complexity while maintaining detection capability.

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

Solution Approach 2:

The patent introduces a dynamics model as an intermediary that processes data from existing sensors to infer touchdown conditions. Instead of directly measuring contact force, the system uses the dynamics model to estimate external forces based on propeller torque and motion data, acting as a computational mediator between raw sensor data and touchdown detection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple sensors are integrated to improve detection reliability, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvetouchdown detection reliabilityVSAvoidsensor integration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges data from multiple existing onboard sensors (accelerometers, gyroscopes, propeller torque sensors) into a unified touchdown detection algorithm. Instead of adding separate sensor systems, it combines information from already-present sensors through a dynamics model, achieving reliable detection without increasing overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent makes existing onboard sensors serve multiple functions: they continue to provide navigation and flight control data while also contributing to touchdown detection through the dynamics model. This multi-functional use of existing sensors improves reliability without requiring additional dedicated sensors for touchdown detection.

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

3Adaptability or versatility

If the UAV reduces thrust gradually to detect touchdown on moving surfaces, then adaptability is improved, but loss of time increases

Engineering Contradiction:
Improvelanding surface adaptabilityVSAvoidtouchdown detection time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements continuous feedback through the dynamics model that monitors estimated external forces in real-time during the thrust reduction phase. This feedback mechanism allows the system to quickly detect touchdown conditions and adjust, reducing the time penalty associated with gradual thrust reduction while maintaining adaptability to different surface conditions.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS11726498B2Aerial vehicle touchdown detection
Publication Date: 2023.08.15 SKYDIO INC
  • US11726498B2 patent drawing
  • US11726498B2 patent drawing
  • US11726498B2 patent drawing

AI summary

A technique is introduced for touchdown detection during autonomous landing by an aerial vehicle. In some embodiments, the introduced technique includes processing perception inputs with a dynamics model of the aerial vehicle to estimate the external forces and/or torques acting on the aerial vehicle. The estimated external forces and/or torques are continually monitored while the aerial vehicle is landing to determine when the aerial vehicle is sufficiently supported by a landing surface. In some embodiments, semantic information associated with objects in the environment is utilized to configure parameters associated with the touchdown detection process.