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Comment: Adds additional info/clarity on Gemini in Ground Systems

Competition

2023-2024 Aerial Evolution of Canada Student Competition

Team

Waterloo Aerial Robotics Group

Technical Director

Anthony Luo

Version

Document Version

Status
colourGreen
titleV. 055058
updated on . See changelog at end for details.

On this page

Table of Contents
minLevel1
maxLevel5

...

Expand
titleMechanical Standards

List of mechanical-maintained standards:

Expand
titleElectrical Standards

List of electrical-maintained standards:

Expand
titleSoftware Standards

List of autonomy-maintained standards:

List of embedded flight software maintained standards:

...

Airframe

Part Function

Manufacturer

Part Name & Link

Qty

Notes

Propulsion

Part Function

Manufacturer

Part Name & Link

Qty

Notes

Propellers

T-Motor

MF2211

4 Indiv

2 CW

2 CCW

Expand
titleAlternatives

May be reasonable replaced with other props of similar size/pitch

Motors

T-Motor

Antigravity MN6007II

4 Indiv

See Motor Selection Subpage

ESC

Advanced Power Drives [APD]

120F3[X]v2

4

Expand
titleAlternatives

This can reasonably be replaced by any 12S capable ESC that is able to support BI-directional dshot and > 50A continuous

Power Distribution

Part Function

Manufacturer

Part Name & Link

Qty

Notes

Batteries

Turnigy

Heavy Duty 5000mAh 6s 60C LiPo Pack w/XT90

Heavy Duty 6200mAh 6s 60C LiPo Pack w/XT90

4

5000mAh (current batteries) to be supported until competition cycle testing.

6200mAh batteries to be used for competition.

PDB

Advanced Power Drives [APD]

PDB500[X]

1

Expand
titleAlternatives

Could reasonably be replaced with any 12S capable PDB, or with a wire harness.

Power Monitor

Holybro

Holybro PM02D High Voltage

1

BEC

Mateksys

BEC12s-Pro

1-2

Expand
titleOptional

The number of BEC uses depends on the number of subsystems that need voltage isolation which are present

Flight Control System

Part Function

Manufacturer

Part Name & Link

Qty

Notes

Autopilot

Holybro

Pixhawk 5/6x + SD Card (logging)

1

Expand
titleWhich one?

The autopilot standard gets revised every so often. The 6x is significantly improved from the 5x, and we recommend it for the competition drone.

Expand
titleOnboard Sensors

Note that the “Cube” standard has multiple internal sensors, some of which we may list externally for redundancy or performance reasons!

GPS

Holybro

Holybro M9/10N GPS

1 Prim

1 Sec

Expand
titleWhich one?

The M10 is newer & cheaper. We have a lot of M9’s but newer GPS’s are better.

Expand
titlePrimary vs Secondary

You’ll notice that you have an option for “Primary” and “Secondary” on the GPS’s. This refers to the wiring of the “Switch” on the gps and the termination of the GPS. With the pixhawk baseboard standard, most systems accept 1 primary GPS and 1 secondary GPS.

Unknown

Future RTK system

Expand
titleHow does RTK Help?

RTK gives more precision, which is always useful when we’re trying to have very precise position hold

Rangefinder 🔍

Benewake

TFMINI-S Micro LIDAR Module I2C

1+

Expand
titleSemi-Optional

Using a rangefinder is not strictly necessary for any flight mode but greatly improves the accuracy of auto-landing and stability of the drone when hovering close to ground level.

Expand
titleQuantity

Using (1) rangefinder is the minimum for the system to function, but it is possible to use multiple rangefinders to get better data or to offer horizontal or vertical object detection.

Expand
titleAlternatives

There are many different rangefinders available. Lidar typically reports least noise and is more accurate over a wider range of circumstances

Optical Flow Sensor (OFS) 🔍

CubePilot

HereFlow

1

Expand
titleSemi-Optional

The drone will fly in all modes without the OFS, but it greatly improves position hold at altitude.

Expand
titleAlternatives

ATM, there are multiple supported alternatives but please ensure they function at the same range

Compass 📉

Barometer 📉

Autonomy computer

NVIDIA

Connect Tech

Jetson TX2i with Quasar carrier

1

Jetson

Is not mounted on the drone.

Alternatively: Any computer that supports real time image inference at the required rate.

Raspberry Pi

Raspberry Pi Model 4b

1

Mounted on the drone.

Omnidirectional Lidar

Lightware

SF 45/B

RF + Peripherals (grouped because it’s small bits of things)

Part Function

Manufacturer

Part Name & Link

Qty

Notes

Control Link

HappyModel

EP1 TCXO Dual

1

1 ELRS Diversity RX Airside run in gemini mode.

Gemini PCB as an option in case higher telemetry power is needed.

WARG

ELRS Gemini

1

Telemetry Link

1

1 LTE Hat

RFD900x made available as an option in case of LTE failures. Not intended to be mounted on the primary system.

Abra Electronics

LTE Hat

RF Design

RFD900x

Video Transmitter

FlyWoo

VTX-1G3

1 FlyWoo

Mateksys

VTX 1G3SE

Expand
titleDISCONTINUED

Most 1.3GHz VTX’s are no longer available due to current political conflicts.

Foxeer

1.2G 5W (Enhanced) 4ch

FPV Cameras

Caddx

Baby Ratel 2

2 or 3

Number dep. on pilot pref. TBD

OSD

Holybro

Holybro Micro OSD V2

1

Expand
titleHARD TO FIND

Please be careful

Video Mux

Lumenier

3-Way Multi Camera Video Switcher Board

1

Lighting 🔍

-

-

NAVLights

-

-

Landing Lights

CV Camera

Hupuu

$200 CV Camera

1

$200 CV Camera

Groundside

Part Function

Manufacturer

Part Name & Link

Qty

Notes

Ground station computer

Lenovo

Thinkpad T490

1

Alternatively: Any computer that can run Mission Planner.

1.3G Video RX

FlyWoo

DRX-12A

1

Prefer this

ReadyMade RC

900-1.3 GHz Receiver w/Tuner

1

Available as a backup.

5.8G Video relay (TX)

AKK

TS832 5.8 GHz VTX

1

RC Control Link

WARG

ELRS Gemini

1

PREF GEMINI WHEN POSSIBLE

RadioMaster

RadioMaster Ranger FCC

1

RC Control Link Relay

HappyModel

EP2

1

see RF + Peripherals section later

Telemetry Link

WARG

ELRS Gemini

0

Used with flow control RC + MAVLink simultaneously. RC Priority. Backup to LTE.

RFDesign

RFD900x

0

Only used as a backup option.

Not to be mounted regularly.

❓

LTE Hotspot

1

No manufacturer

Telemetry Relay

Xbee

XBEE Pro 5.8

0

Backup

ELRS

ELRS Airport

2

Primary

FPV Goggles

-

Pilot Preference

RC Controller

RadioMaster

TX16s MkII ELRS Mode 2 HALL

2

Expand
titleModifications

The blue controller has an INTERNAL elrs rx hooked up to aux trainer so that wireless trainer may be used. pink → blue

Video Monitor

-

Generic 5.8 GHz Receiver

...

Min

Recc/Avg

Max

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

...

Pegasus is an X-frame configuration and motor arms attached directly to a straight aluminum block. Here are some of the key notes:

...

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

...

Panel
panelIconId26a1
panelIcon:zap:
panelIconText⚡
bgColor#FFFAE6

Electrical, please insert a schematic & layout diagram with motors, connectors, esc’s with breaks to the rest of the HV distribution system

...

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

Power Distribution

...

On Pegasus, “power distribution” refers to all elements that affect and interact with power before it is distributed to individual components. Typically, this includes:

...

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

...

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.

...

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

...

There are a number of external devices on the drone. Autonomy is largely responsible for additional compute, while Electrical is largely responsible for RF

...

It is possible to use other digital video transmission systems should the LTE system latency (~ 100ms) be too high. See Digital Video Transmission Systems - SysInt - WARG (atlassian.net) for more info.

Open Questions

PIKACHU OBLIGATORY PIKACHU

...

ok thank you for listening

...

Ground Systems

Our ground systems will consist of 2 primary tracking towers (Control + Video links), and one potential backup tower for Telemetry link.

All tracking antennas will consist of the same control scheme, using an arduino, neo m.8 gps, and bmx160 IMU. They will receive forwarded communication from the ground station computer, and will operate autonomously.

...

Control Link

Control will feature a small relay to allow for a fully wireless tracking antenna. Wireless SBUS trainer will be provided to the groundside TX16s, meaning that there are the following links:

TX16 (secondary) → EP2 (inside controller primary)

TX16 (primary) EP2 -(wired)-> Serial port 1

TX16(primary) → EP2 (tracking antenna)

EP2 (tracking antenna) -(wired)-> Gemini (tracking antenna)

Gemini → Diversity RX (airside)

Diversity RX -(wired)-> Autopilot

Gemini

The Gemini is supplied with 5V power from the tracking antenna PCB. The Gemini antennas that will transmit to the drone are clipped directly onto the two red TX modules on the PCB. It is directly wired to the TX16 controller to receive the command data over UART.

Note

Do not power the Gemini PCB without the Gemini antennas connected to the TX modules. Doing so can result in the TX modules becoming damaged.

The Gemini board draws an absolute maximum of 2.26A. During typical operation with both transmitters working it should draw somewhere around 1.2A ~ 1.5A.

A wiring diagram of the Gemini board in standard operation is shown below.

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An RGB LED on the PCB display’s the Gemini’s current status. The different statuses are described in the following table (taken from ELRS Wiki).

LED Indication

Status

Rainbow fade effect

Starting up

Green heartbeat

Web update mode enabled

Blue heartbeat

Bluetooth joystick enabled

Red flashing on/off every 100ms

Radio chip not detected

Orange flash every second

No handset connection

Solid single colour

Connected to receiver, colour indicates packet rate

Fading single colour

No connection to receiver, colour indicates packet rate

The Gemini PCB runs ExpressLRS code from the ELRS GitHub. Updating the code to a different version can be done over WiFi or USB. For details, see ELRS Gemini TX - Programming the Gemini TX.

Video will be run on 1.3. A diversity (!!!) video receiver will be connected to an omnidirectional antenna as well as a patch antenna. The output will be wired to a 5.8GHz video transmitter, which will re-broadcast the analog video signal to further groundside devices (goggles, displays, etc).

Open Questions

PIKACHU OBLIGATORY PIKACHU

...

ok thank you for listening

Change Log

Expand
titlev. 058 --- 2024-02-14 --- Farris Matar

  • Listed additional info on the Gemini PCB, including:

    • Info on powering the PCB (nom. voltage + current consumption)

    • A wiring diagram showing how the PCB connects to other parts of the system during standard operation

    • Definitions for the RGB status LED

    • Link to guide for programming the Gemini PCB

Expand
titlev. 057 --- 2023-01-24 --- Anthony Luo

  • added clarity for groundside systems, including diagram that Hardy Yu made!

Expand
titlev. 055 ---- 2023-01-23 --- Anthony Luo ---

  • Added RFC Section

  • Updated BOM

    • Batteries - 6200 mAh turnigy batteries

    • Control link relay clarity

    • Video System clarity

  • Updated pixhawk wiring

    • Added USB section for clarity

    • Updated telem 2 from LTE → Lightware SF45B

    • Updated Telem 3 from WARG Gemini → ELRS Diversity RX

  • Frequency distribution

    • added primary frequency distribution information.

  • Control link

    • added explanation of air/ground links.

...