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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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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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Our speed controllers often have through-hole solder pads and castellated pads. Refer to EE guidelines on how these should be soldered. The holes are not mounting holes, and the ESC’s are interfaced to the 30x30 mounting grid through the use of 3D-printed cases.

The 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

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

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This is done so that there is a common ground reference point (star topology). There exist solder pads in between the voltage pads for ground, signal, and telemetry on all APD esc’s and PDB’s. These should be used, with M1-4 connections on the PDB being taken to the pixhawk.

The 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

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.

Software Configuration

It is recommended to run the ESC’s using default firmware (BL_HELI, Bluejay, etc) at 48khz update loop. This offers the best blend of controllability and power efficiency.

Bidirectional dshot must be supported as this offers critical logging and flight performance data, as well as advanced filtering options for the autopilot. On Pegasus, it is recommended to run DShot 300, as 600 may introduce significant signal integrity issues, and DShot 150 may be too slow for accurate bidirectional data transfer.

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:

• Power distribution boards for ESC voltage

• 12v and 5v LV supply for peripherals

• Power monitoring & Power backups for the flight control system

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.

“High” Voltage

High 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.

<photo>

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>

Batteries & Harnessing

Pegasus officially supports 4, and 6 battery configurations. Physically 8 batteries will fit with a light enough payload.

<configuration image>

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

<Image / harnessing>

XT90 standard across the board, but the maximum peak current draw from all 4 motors is anticipated to be around 90Amps. Any individual motor will not draw more than 23 amps at a time, not including the path.

Errata

On certain long voltage runs, it may be necessary to “double up” on decoupling capacitors. <ee to fill in more>.

Low Voltage

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

• Jetson: 12v 4A

• Raspberry Pi + LTE: 12V 2A

• RFD900: 5V 1.5A

• Pixhawk: 5V 3A

• 800mW vtx: 12V 1A

• 5W vtx: 12V 5A?

• Gemini: ???

• I may be missing multiple items. EE leads please double check from prev. years and compare

Power Monitoring

We use powering monitoring from a Holybro PM02D HV module. This uses I2C to communicate with our autopilot, meaning that we don’t need to do analog voltage or current calibration.

This is used in isolation, with no backup. There is only 1.5A continuous draw available ee leads fact check me, and this power monitor will continue to update current and voltage measurements even after LDO failure.

LDO failure should be mitigated by providing the pixhawk with a BEC that is capable of up to 5A continuous draw. fact check me 5 or 3a.

Pixhawk Errata

Note that the pixhawk telemetry ports only support 0.5A current; with the exception being “Telem1” which supports up to 3A.

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.

Software Configuration

Sensors

Please refer to each sensors page under our operating manuals space in sysint.

Pegasus will use the following external sensors:

• Two M9 or M10 sensors, using GPS blending for position; or 2 RTK sensors being blended.

  • one of these will be the “primary” gps, and must have an accessible safety switch.

• 1 Optical flow sensor, facing downwards and aligned with the drone

• 1 Lidar rangefinder, facing downwards

Anni to make mounting requirements pages for all of these (see sysint space most likely).

Particular Mounting constraints

When using blended GPS sensors, these shall be placed as far apart as possible, with no wiring nearby and with the sensors elevated above the plane of the drone.

A word about calibration

It is not necessary to re-calibrate the compass every time you fly, but it is strongly recommended to do so if you have moved more than 40km from your original location as you may have different magnetic interference.

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

Frequency Distribution

Pegasus will support 2.4+900+433 interchangeable control links, as well as LTE+piggybacked telemetry, and dedicated 2.4 or 900 telemetry systems.

Pegasus will use 1.3 ghz as the primary airside video frequency.

Antenna placement

< EE TO ENTER MORE INFORMATION ABOUT RF STUFF >

Control Link

GEMINI GO BRR

Telemetry Link

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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