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If you are editing this document, please do your best to add in the changes made into remember to update the changelog and modify the version ID the version that you are on(found in the table at the top of the page).

This document will be considered controlled following from October 1st onwards. Any changes after that point must follow the formal RFC process. Ping Anthony Luo for more details.

Supporting Document

🗂 References and documentation

Anchor
arch24_refs arch24_refs

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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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Most components will run ~ 20-30 degrees hotter than ambient, and will thermal limit around 80 degrees celcius. This means that on an average “warm” day, our components have around 20-30 degrees of headroom. Think about how much hotter a cabin may cause components to be, especially if black carbon fiber and in the air (exposed, not under shade).

Propulsion

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Anti-spark XT90s need to be used for our battery connections. Anti-Spark Connector Standards

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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DShot is only available on FMU out as of 4.4.0, but will be available (tentatively), on certain I/O FMU Outputs in the future.

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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All PWM outputs will be attached to the I/O pins.

USB

• Usb port will be connected to the RPI for LTE Telemetry

Telem 1,2,3

• Telem1 will be reserved for the RFD900RFD900x (should it be needed)

  • Telem1 is the only port that is rated for 1.5A

• Telem2 will be connected to the LTE systemLightware SF45B

• Telem3 will be connected to ELRS Gemini

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• Diversity RX / Gemini RX (EP1 TCXO Dual)

GPS 1, 2

• GPS1 - GPS1 (front)

• GPS2 - GPS2 (back)

I2C

• I2C will be sent to the lidarrangefinder (downwards facing)

CAN1, 2

• CAN1 will be connected to the OFS

• CAN2 will be reserved for CAN interface boards (should they be required)

Serial/UART 4

• Reserved for Omnidirectional rangefinderfurther comms w/the rpi if necessary

Power 1, 2

• Power1 will be connected to the Holybro PM02D

• Power2 will be connected to a BEC

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Ground station is at the cruise scope, for multiple waypoints, and is responsible for guiding the drone along the most efficient waypoint to waypoint path. Control is handled by the pathing system and Mission Planner running on the ground station computer.

Pathing

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 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 Choice

2.4ghz antennas will be regular dipoles, potentially folded dipoles. Refer to and 5.8 video systems shall be supported. The primary distribution:

• 900mhz RFD900x or ELRS Airport - Backup telemetry. Not mounted typically but possible addition in case of poor LTE coverage.

• 2.4 ghz ELRS Gemini control link - Primary control link, carrying MAVLink info air->ground as well as typical control link ground->air

• 1.3 ghz video link - Primary pilot video link

• LTE Telemetry + Video streaming - Primary telemetry link, primary computer vision video link.

Antenna 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.

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< EE TO ENTER MORE INFORMATION ABOUT RF STUFF >

Control Link

GEMINI GO BRR

Telemetry Link

Telemetry will be provided through LTE, with ELRS gemini allowing MAVLink packets to be piggy-backed The airside control link will be an ELRS Diversity (true diversity) receiver wired into a telemetry port on the autopilot. This receiver will be flashed with gemini firmware, and paired with WARG’s gemini transmitters on the groundside.

The groundside control link will involve a TX16 paired with a small EP1 or EP2 receiver, which will be wired directly to the gemini transmitter. The EP2 receiver baud rate will be modified to match the gemini spec?

Telemetry Link

Telemetry will be provided through LTE, with ELRS gemini allowing MAVLink packets to be piggy-backed in between regular RC link packets. This gives us a second redundant option in case the LTE system loses power or is otherwise unusable, at least temporarily and for long enough to recover the drone.

Video System

1.3 go brrr. System unchanged from previous year: 1 forward facing camera There are no current plans to forrward MAVLink out from the TX16 - yappu scripts may be run in order to assert basic RTL functionality in the event of a lost LTE link.

Video System

There will be at least 1 forward facing and 1 downward facing camera. There may be a third camera installed at the pilots discretion.

The entire pilot video system uses Analog video, including:

• 2 Caddx baby Ratel 2 cameras (or cameras of similar size)

• 1 PWM-based video mux

• 1 OSD using ardupilot telemetry

• 1 1.3ghz video transmitter, either 5W or 800mW depending on application.

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The video transmitter will generate a lot of heat, and consideration must be made such that there is adequate thermal capacity (i.e: heatsink) on the video transmitter, and there must be passive airflow over the VTX while in flight. This may be achieved through the use of NACA ducts, large surface area heatsinks, or open-air componentsbut comes with a heat sink. The video transmitter will also mount to a standard 30x30 pattern (fpv standard).

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ok thank you for listening

Change Log

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