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\uD83D\uDCDA Relevant data
This follows from the discussion during the 2023-09-24 Conops Brief for the 2024 AEAC Student UAS competition brief.
\uD83D\uDCD8 Background
Our end-goal is to provide safety for the drone and it’s payload when landing in a LZ-C, which is a BVLOS landing zone with overhangs and obstacles.
Existing support
Ardupilot has native support for both object detection, as well as multiple lidar sensors. Using information synthesized from up to 10 sectors (8 around, 1 top, 1 bottom), and known INS parameters, the vehicle is able to stop at a predetermined distance from the fence regardless of the speed of the vehicle. This service is provided in all guided flight modes, as well as altitude hold.
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Multiple kinds of rangefinders are supported within ardupilot, which can be found within copter documentation: Rangefinders (landing page) — Copter documentation (ardupilot.org).
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\uD83C\uDF08 360 vs Unidirectional
360 | Unidirectional | |
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Description | Using a 360 degree lidar, it is possible to obtain distance and object avoidance on all sides. | Using a series of omnidirectional rangefinders, it is possible to maintain object avoidance on as many sides as sensors are used |
Pros and cons |
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360 object avoidance. Fairly simple configuration and setup
Cost (~ 500 CAD)🚨 Omnidirectional Sensor Options
Buy link / datasheet |
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Product Page | RPlidar A2 - SLAMTEC Global Network Lidar Sensor RPlidar A2 cheap lidar scanner | TeraRanger Tower Evo | Solid state LiDAR system | Anti-collision (terabee.com) | |||||||||||||||||||||||
Coverage (degs) | 360 | 350/320 | 360 | 360 | 120 | ||||||||||||||||||||
Cost (CAD) | 800 | 450 | 220 | 1000 | 180 | ||||||||||||||||||||
Weight (grams) | 256 | 59 | 190 | 135 | 28g | ||||||||||||||||||||
Max range (m) | 100 | 50 | 16 | 60/8 | 8 | ||||||||||||||||||||
Min range (m) | 0.2 | 0.2 | 0.2 | 0.5/0.75 | 0.2 | ||||||||||||||||||||
VSupply | 12v, 5v | 5v | 5v | 12-24v | 5v | ||||||||||||||||||||
Interfaces (not all may be supported by Ardupilot) | Serial UART | Serial UART, I2C | Serial UART | Serial UART | Serial UART | ||||||||||||||||||||
OK in direct sunlight? (Per manu recc:) | Y | Y | N | Y | N | ||||||||||||||||||||
Weatherproof? | No | No | No | ? | No |
❗ Unidirectional Sensor Options
Since the list is incredibly exhaustive, I have pre-selected sensors which meet the minimum range (~ 8m) and cost requirements (< 100 per part).
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It is worth noting that all unidirectional sensors will need to use a periph can node, which is around 4 grams per board and costs ~20 CAD. |
\uD83C\uDF1F Recommendations
Pending review, the recommended solution is to use 3 Benewake TF-Mini-S series sensors or 1 Lightware SF45-B Sensor. Should the need present itself, the SF45-B may be augmented by downwards and upwards facing rangefinders. The following considerations should be reviewed:
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The unidirectional system would total to around 180, while the omnidirectional system would be a flat price of around 450 cad. Both costs are still significantly lower than other alternatives, with the possibility of using superior sensors unidirectionally, or more sensors unidirectionally, to compensate for the relatively worse performance of the TF-Mini-S.
✅ Outcome
For 360 | For Uni |
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Anni
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🗒️ Changelog
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