Competition | 2023-2024 Aerial Evolution of Canada Student Competition | ||||||
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Team | Waterloo Aerial Robotics Group | ||||||
Technical Director | |||||||
Version | Document Version
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This is the top-level document for the 2023-2024 AEAC competition aircraft “Pegasus”. These documents describe the purpose, function, and decisions made relevant to the design and use of the remotely piloted aircraft. It has been divided into sub-sections (in no particular order) which hope to offer a global overview of the design and implementation of all systems, as well as how they interface with each other.If you are editing
Ultimately, this document , please do your best to add in the changes made into the changelog and ID the version that you are serves as a “reference manual” for Pegasus, and should contain necessary information for the usage and support/maintenance of Pegasus. Engineering decisions and background knowledge should be provided as references, external links, or as subpages. We want to know how this drone works, and not necessarily why that decision was made.
If you are editing this document, please do your best to add in the changes made into the changelog and ID the version that you are on.
BOM
This lists all of the components that constitute the configuration of a drone that we wish to fly at competition in May 2024. Some parts may be listed as “Optional” (🔍), in which case they will bethey are not strictly necessary for flight but may be useful in improving system performance.
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Min | Recc/Avg | Max | |
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Propeller Diameter (in) | 20 | 22 | 24 |
Battery Voltage (v) | 36 | - | 50.4 |
Takeoff Weight | 4.5 | < | 8 |
Thrust (kg) | ~16 | ||
Flight time (min) | 30 | TBD (40?) | |
Wind Lim. (kt) | < 20 | TBD (< 60) | |
Altitude (m) | < 120 | 200 | |
Horizontal Pos Accuracy (cm) | +/- 2 | +/-30 | +/- 200 |
Vertical Pos Accuracy (cm) | +/- 2 | +/- 15 | +/- 30 |
Usable Range (km) | 1 | 10 | inf w/LTE |
Airframe
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Pegasus is an X-frame configuration and motor arms attached directly to a straight aluminum block. Here are some of the key notes:
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Motors are mounted on 3d printed mounts with a <pattern> (insert a photo if you can).
Propulsion
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< insert schematic here >
Pegasus uses 4 T-Motor Antigravity MN6007II kv160 motors. These motors are designed to run on 12s voltage and are wired to APD 120F3[x] v2 ESCs. The ESC’s are significantly overspecced and are designed to allow for continuous operation in high ambient heat environments and minimal passive cooling, although this is not a recommended mode of operation.
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The motors mount to a 3d printed block which attaches to the ends of the arms. Multiple propeller mounting options are available!
Propellers
The 3.5mm male bullet connectors will exist on the motor leads, and these will plug into 3.5mm female bullet connectors on 3-phase wires which run through the carbon fiber arms.
Propellers
The current propellers are T-Motor MF2211 props. These do not follow typical propeller naming convention. They are 22” in diameter, but 8” in pitch (not 11). The 11 at the end of the name refers to the maximum thrust which the prop may provide.
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Our props come balanced from T-motor, and may need to be balanced if they acquire nicks, scratches, chips, or other deformities. See <prop balancing link> for more information.
Safety & Storage
Polymer-carbon propellers are suspect to shattering under load, even with tiny surface scratches or nicks. Unless absolutely necessary it is not recommended to fly in marked or scuffed propellers.
Props should be stored in a low humidity and cool environment to prevent damage and aging to the propellersT-Motor Polymer folding props require particular storage and upkeep.
Please refer to <general prop storage> for storage information, and please refer to T-Motor instructions on tuning the friction of the joints to ensure safe operation.
Electronic Speed Controllers
For the most part, the choice of electronic speed controllers is fairly relaxed as there are many commercial and off-the-shelf hobby components that may do the job. Keep in mind when choosing your speed controllers the software, protocols, and current/volage ratings that it may have.
Interfacing
Our speed controllers often have through-hole solder pads and castellated pads. Refer to EE guidelines on ESC’s will have 3.5mm female bullet connectors on 3-phase live side. This will attach to a short MT-30 extension, where the MT-30 on the block-side will be fe-male, while MT-30 on the arm-side will be male.
Our speed controllers often have through-hole solder pads and castellated pads. Refer to EE guidelines on how these should be soldered.
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There are thru-holes on the ESC’s. These are not mounting holes. |
The ESC cases may be made of any material, but general guidelines are that they should be made of non-conductive and thermally resistant materials. 3D-printed TPU is often a good choice.
Heatsinks + Cases
The ESC cases must allow for the removal and replacement of ESC’s with only the disconnection of 3.5mm and xt60 connectors, and with no disruption to other parts of the drone. (I.e. ESC only replacement must be possible).
Heatsinks + Cases
ESC’s generate a lot of heat, and are prone to foreign objects shorting terminals or interfering with operation. ESC’s should be mounted in a way such that the possibility of foreign objects are minimized when in regular operations, and heatsinks shall be added as necessary to prevent thermal limiting or runaway.
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Telemetry wires shall be connected to a uart port, in the case of a bidirectional dshot failure. This is significantly slower than bidirectional dshot but offers us a failsafe and backup.
Power Distribution
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On Pegasus, “power distribution” refers to all elements that affect and interact with power before it is distributed to individual components. Typically, this includes:
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All power on pegasus runs to a common source (the PDB), with the exception of the pixhawk system power delivery which will be provided by the power monitor + BEC backup.
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Battery Voltage
< Insert schematic here >
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EE to fill in with more information |
High Battery voltage is around 50 volts for pegasus. All high voltage systems follow <EE to insert spec here>.
Interfacing
There exists 30x30mm mounting holes on the PDB. These may be used directly on the 30x30mm mounting holes on the drone. Electrical isolation must be provided between the contacts of the PDB and the carbon fiber, as voltage may arc across the carbon fiber starting (at worst) fires.
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A case shall be provided for the PDB that covers the terminals, but leaves sections exposed such that it is possible to attach wires to the LV and motor busses.
<EE to attach photo>
XT90’s will be used between battery and PDB
XT60’s will be used between PDB and ESC
Batteries & Harnessing
Pegasus officially supports 4, and 6 battery configurations. Physically 8 batteries will fit with a light enough payload.<configuration image>
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These batteries are cross-connected from each other, meaning that the only difference between a 4 and 6 battery connection is the NC of one pair. These should be labelled or colour coded
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On certain long voltage runs, it may be necessary to “double up” on decoupling capacitors. <ee to fill in more>.
Low Voltage
< Insert schematic here >
Low voltage systems on Pegasus run at either 5 or 12v. Below are the voltage and current draws of each (potential) Noteworthy peripheral. Please refer to individual documentation for more information
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The pixhawk also supports two concurrent power monitors. We are using 1 power monitor and 1 BEC with NC’s on the remaining pins for better redundancy under thermal limit.
Flight Control System
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Pegasus will operate using an ardupilot software stack. As of Fall 2023 Pegasus runs software revision 4.4.0, as this brings necessary changes for digital power monitoring and bidirectional dshot.
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Accelerometer calibration does not need to be done more than the first time you did setup, or if there is significant concern about the health of the system.
RF + Peripherals
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There are a number of external devices on the drone. Autonomy is largely responsible for additional compute, while Electrical is largely responsible for RF
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Pegasus will use 1.3 ghz as the primary airside video frequency.
Antenna
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Choice
2.4ghz antennas will be regular dipoles, potentially folded dipoles. Refer to https://docs.google.com/spreadsheets/d/1G2Ue9xrBFwbJbkzpw3Gx3-eZ3x3dWSVjVrP4fPepvcg/edit#gid=0 for the best selection.
1.3ghz antennas will be circularly polarized antennas provided by TrueRC. Airside antennas will be Singularity 1280’s.
900 MHz antennas tbd
433 MHz antennas tbd.
Antenna Placement
< EE TO ENTER MORE INFORMATION ABOUT RF STUFF >
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GEMINI GO BRRR LTE GO BRRR
Video Link
1.3 go brrr. System unchanged from previous year: 1 forward facing camera and 1 downward facing camera
PIKACHU OBLIGATORY PIKACHU
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ok thank you for listening
Change Log
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brrr. System unchanged from previous year: 1 forward facing camera and 1 downward facing camera
PIKACHU OBLIGATORY PIKACHU
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ok thank you for listening
Change Log
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