Building the UAVs

Component List

Part	Quantity
MatekSys H743-SLIM v3	1
Flywoo GOKU ESC (4in1 32bit 3-6S)	1
T-Motor F1404 KV3800	4
GEMFAN Hurricane 3016-3	4
VIFLY ShortSaver 2	1
MatekSys M10Q GPS	1
MatekSys mR900-30	1
MatekSys Optical FLow 3901-L0X	1

Design Files

Carbon Fibre Machining Companies

The base frame of the UAV is machined from a Carbon Fibre sheet. Unless you want to do this yourself, we recommend using one of the following companies for manufacturing the frames:

• CNC Madness (Canada) — Good price and quality, great if you are not in a rush
• Carbon Fibre Tubes (UK) — More expensive than CNC Madness, but they are located in Fareham and registered as a supplier with the university so better for quick turnarounds

Altering the frame design

If you need to change the design of the frame, maybe to accommodate different components, you are strongly encouraged to 3D print a prototype before ordering the frame. This will help you identify any potential issues with the design before investing significant time and money into having the frames manufactured. Please contact Toby Godfrey (t.godfrey ~at~ soton.ac.uk) with your updated designs so we can add them to these resources.

Assembly

Nylon Locking Nuts

Nylon Locking Nuts (A.K.A. Nylocks) are not infinite use. Once they have been tightened through the nylon ring several times, the the locking ring can be damaged and performance will degrade. Before tightening the bolt, ensure you will not need to remove that component many times again. It may be a good idea to leave all of the locking nuts off until the end of assembly.

1. Pass the M3x16 countersunk bolts from the bottom of the frame through the 4 larger countersunk holes and use an M3 nut to lock the bolt in place. Ensure the bolt is seated in the countersink bore on the underside of the frame. Place the flight controller (with the rubber grommets) onto the bolts and then use 4 M3 Nylock nuts to tightly lock the flight controller in place. Make sure the arrow on the board is on the top and facing forwards.
2. Attach the cable between the flight controller and the ESC, then pass the M2x14 countersunk bolts through the smaller 4 holes in the middle of the frame. Then use an M2 nut to lock those bolts to the frame. Place the ESC (with the rubber grommets) onto the bolts and then use 4 M2 Nylocks to secure the ESC in place.
3. Pass 4 M2x8 bolts through the 4 motor mount holes on one arm. Place the motor on top and thread the bolts into the motors. Repeat for the other 3 motors.
4. Place the radio module and the GNSS module into their respective mounts, and place them either side of the rear mounting arm. Pass one M3x14 bolt through each hole, and use an M3 Nylock to secure each bolt and keep the mounts flush against the frame.
5. Place the optical flow board on the underside of the mount between the front motors. Use M3x12 bolts and M3 Nylocks to secure the sensor to the frame. Ensure the arrow on the board is facing forwards.
6. Align the battery cage below the frame and use 4 M3 bolts through the mounting holes. The bolt length will depend on whether standoffs or Nylock nuts are used. Attach the relevant 'nut' on the other side of the bolt and ensure the battery cage does not move.

Wiring

ESC

On ESC	On FC	Notes
V	VBat	Power
G	G	Ground
1	S1	Motor 1 signal
2	S2	Motor 2 signal
3	S3	Motor 3 signal
4	S4	Motor 4 signal
C	Curr	Current sensor (optional)
T	RX8	Telemetry (optional)

GPS

On GPS	On FC
G	G
DA	DA1
CL	CL1
TX	RX2
RX	TX2
5V	4V5

mLRS Radio

On Radio	On FC
G	G
V	4V5
TX1	RX6
RX1	TX6

Optical Flow Sensor

Warning

This is so far untested

On OFS	On FC
G	G
5V	5V
TX	RX4
RX	TX4

ArduPilot Setup

Flashing ArduPilot

Updating Existing ArduPilot

If the flight controller has already been flashed with ArduPilot, it can be updated through QGroundControl using the ardupilot.hex file.

1. Download the ardupilot_with_bl.hex from https://firmware.ardupilot.org/Copter/stable/MatekH743-bdshot/
2. Open STM32CubeProgrammer to flash the flight controller
3. Plug the flight controller in via USB while holding down the DFU button
4. Change the mode in the top right drop-down to USB
5. Click on the Erasing & Programming tab on the left side
6. Click Full Chip Erase on the right side of the pane
7. Check Run after programming and browse to the downloaded firmware file
8. Click Start Programming

Setup

Accelerometer Calibration

• Open QGroundControl and navigate to Vehicle Setup > Sensors.
• Select Accelerometer and follow the on-screen instructions.
• Perform a six-point calibration (front, back, left, right, up, down) on a level, non-magnetic surface.

Compass Calibration

• Go to Vehicle Setup > Sensors > Compass.
• Calibrate in an area with minimal magnetic interference.
• Use Compass Learn if interference issues are encountered.

Motor Setup

• Set MOT_PWM_TYPE to 4 (DShot600) for the Goku 4-in-1 ESC.
• Use the Motor Test feature in QGroundControl to verify each motor spins correctly.
• The motors must be in the correct order as in the table below. Update the SERVOx_FUNCTION parameters (where x is the ESC port number) so the motors are labelled correctly.

Motor Number	Position	Motor Test Slider Label
1	Front Right	A
2	Rear Left	C
3	Front Left	D
4	Rear Right	B

Battery Setup

• Set BATT_MONITOR to 4 for analog voltage and current monitoring.
• Set BATT_CAPACITY to the mAh rating of the battery
• Set BATT_LOW_VOLT to 14.2 (3.55 V/cell)
• Set BATT_CRT_VOLT to 13.2 (3.3 V/cell)
• Set BATT_LOW_MAH to 400 (20% remaining)
• Set BATT_CRT_MAH to 200 (10% remaining)
• Set BATT_FS_LOW_ACT to 4 (SmartRTL or RTL)
• Set BATT_FS_CRT_ACT to 1 (Land)

GPS Setup

• Go to Vehicle Setup > Sensors > GPS.
• Set GPS_TYPE to 1 (NMEA) or 5 (u-blox) depending on the GPS protocol.
• Set SERIAL1_PROTOCOL to 5 (u-blox) or 1 (NMEA) for the GPS UART.
• Set SERIAL1_BAUD to 115 (115200 baud).

Radio Setup

• TODO

Optical Flow Sensor

• TODO

mLRS Radio Over USB

To use the radio over USB to connect to a groundstation it must be reflashed with the SikTelem version of the firmware. Use the mLRS web flasher (on Chrome or Edge): (https://olliw.eu/mlrsflasher)[https://olliw.eu/mlrsflasher].

Tuning

• Use the Autotune feature in ArduPilot for PID tuning.
• Adjust ATC_RAT_RLL_P, ATC_RAT_PIT_P, and ATC_RAT_YAW_P for stability.

Expansion Plates

Calibration