Multirotor UAS Payload Detection Using Hover Thrust Deviation
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Solution Overview
Problem
Unmanned aerial systems (UAS) face challenges in detecting unauthorized payloads, which can lead to unsafe flight characteristics, nefarious use, and invalid certification, as existing technologies lack effective methods to ensure compliance with certified configurations.
Innovation Solution
The UAS is equipped with sensors and a processor that monitor rotational speed and flight power to detect anomalous configurations, including unauthorized payloads, and can inhibit flight or cause landing if such conditions are detected, using a combination of strain gauge load cells, motor controllers, and environmental sensors to estimate thrust and compare it to expected values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UAS carries additional payload to increase functionality, then the payload capacity is improved, but the flight safety and certification compliance deteriorate
Solution Approach 1:
The system performs preliminary detection of payload weight before flight using strain gauge load cells integrated into the motor mounts. The flight controller compares measured weight against the certified weight manifest to prevent unsafe flights before they occur, rather than reacting during flight
Solution Approach 2:
The system continuously monitors motor current draw and compares it against expected values for the certified configuration. This feedback mechanism detects unauthorized payloads during flight by identifying deviations in power consumption patterns that correspond to unexpected weight additions
2Adaptability or versatility
If the UAS uses thrust margin to carry payload, then the payload capacity is improved, but the detection of unauthorized payloads becomes more difficult
Solution Approach 1:
The system changes the detection parameter from direct weight measurement alone to a multi-parameter approach including motor current draw, rotational speed, and strain gauge readings. By monitoring multiple parameters simultaneously, the system can detect unauthorized payloads even when they fall within the thrust margin capacity
Solution Approach 2:
The strain gauge load cells act as intermediary sensors that indirectly measure payload weight through the force transmitted through motor mounts. This intermediary measurement approach provides more accurate detection than direct weight sensing, especially for small payloads under 1% of UAS weight
3Reliability
If the UAS implements strict configuration verification, then the certification compliance is improved, but the ease of operation deteriorates
Solution Approach 1:
The system performs self-verification of its own configuration by automatically comparing measured weight and power consumption against the certified weight manifest stored in memory. This automated self-check eliminates the need for manual verification procedures while maintaining strict compliance
Solution Approach 2:
The system requires users to pre-register authorized payloads in the weight manifest before flight. This preliminary action simplifies operation by allowing quick takeoff clearance when the actual configuration matches the manifest, while still enforcing compliance through automated verification
Data Source
AI summary
A modular unmanned aerial system (UAS) can be configured to detect an anomalous UAS configuration or operating condition, and to notify the user or inhibit further operation of the UAS in response to such a detection. An indication of the actual rotational speed of the motor or of the flight power needed to hold the UAS in a hover state may be compared to a predicted value based upon the expected UAS configuration. A variance between the actual values and the predicted values may indicate that the UAS is in an unauthorized configuration, which may be due to an unauthorized payload. The UAS may be a modular system, and may take into account authorized and attached modules in predicting the thrust required to hold the UAS in a hover state.