Drone and Rover System Debugging Guide

1. Purpose

This document explains how to debug the drone and rover system in the field. It focuses on the actual vehicle system:

Windows ground station
LQ3 communication network
Raspberry Pi 4B on rover
Pixhawk flight controller
ArduPilot / ArduCopter / ArduRover
MAVProxy or MAVLink bridge
Rover UDP motor agent
STM32 motor controller
GPS and EKF readiness
Camera video stream

Use this guide when a drone does not arm, a rover does not move, GPS is missing, MAVLink heartbeat is missing, or video/network is unstable.

2. System Architecture

Drone Path

Typical drone mission flow:
Heartbeat → GPS OK → EKF OK → GUIDED mode → Arm → Takeoff → Velocity forward command → Land

Rover Path

Rover Pixhawk: Used for heartbeat, GPS, and EKF readiness.
Rover motors: Not driven by Pixhawk. Command goes through Raspberry Pi UDP to STM32 motor controller.

Typical rover mission flow:
Pixhawk heartbeat → GPS OK → EKF OK → Rover agent UDP ping OK → Mission start sync → UDP move command → STM32 serial motor command → Stop command

3. Important IP Addresses and Ports

Common Network

Windows PC LQ3-side IP: 192.168.1.234
Mac debug IP: 192.168.1.10
Typical subnet: 192.168.1.0/24
Gateway: 192.168.1.1

Rover Examples

ROVER_1 Raspberry Pi IP: 192.168.1.101
ROVER_2 Raspberry Pi IP: 192.168.1.102
ROVER_3 Raspberry Pi IP: 192.168.1.103
Rover UDP motor port: 15000

MAVLink Ports

DRONE_1: UDP 14501, sysid 1
DRONE_2: UDP 14502, sysid 2
DRONE_3: UDP 14503, sysid 3

ROVER_1: UDP 14511, sysid 11
ROVER_2: UDP 14512, sysid 12
ROVER_3: UDP 14513, sysid 13

The UDP port and the vehicle SYSID must match the script configuration.

4. Field Debug Order

警告 Do not start with the full mission script. Test each layer first.

5. Power Checks

Drone

Flight battery connected
Pixhawk powered
GPS module LED active
Telemetry / LQ3 link powered
ESCs powered
Propellers removed for indoor tests
Propellers installed only for outdoor flight tests

Rover

Raspberry Pi powered
Pixhawk powered
STM32 motor controller powered
Motor battery connected
USB cable from Raspberry Pi to STM32 connected
USB cable from Raspberry Pi to Pixhawk connected if MAVProxy bridge is running on Pi
Rover wheels lifted for first motor test

6. Network Debugging

Check IP Address on Raspberry Pi

ip addr
hostname -I
ip route

Expected: eth0 has 192.168.1.xxx, default route uses eth0 if LQ3 is the main link.

If hostname -I is empty, the Pi has no active IP address.

Check Netplan

cat /etc/netplan/01-uav.yaml

network:
 version: 2
 ethernets:
 eth0:
 optional: true
 dhcp4: no
 addresses:
 - 192.168.1.102/24
 gateway4: 192.168.1.1
 nameservers:
 addresses: [8.8.8.8, 1.1.1.1]
 wifis:
 wlan0:
 optional: true
 dhcp4: no

sudo netplan generate
sudo netplan apply
ip addr
ip route

警告 Important:
• addresses must be indented correctly
• gateway4 should line up with addresses
• Do not put gateway4 inside the address list

Ping Test

# From Windows
ping 192.168.1.102

# From Raspberry Pi
ping -c 3 192.168.1.234

If ping fails: Check LQ3 power · Ethernet cable · IP address · Subnet · Windows firewall · Duplicate IP addresses

7. SSH Debugging

# From Windows
ssh ubuntu@192.168.1.102

# If password login is disabled
ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no ubuntu@192.168.1.102

# On Raspberry Pi
sudo vim /etc/ssh/sshd_config

Useful settings:
PasswordAuthentication yes
PubkeyAuthentication yes
KbdInteractiveAuthentication yes

sudo systemctl restart ssh

8. MAVLink Heartbeat Debugging

py -c "from pymavlink import mavutil; m=mavutil.mavlink_connection('udpin:0.0.0.0:14512'); print('waiting heartbeat'); m.wait_heartbeat(); print('sysid', m.target_system, 'compid', m.target_component)"

Expected: waiting heartbeat → sysid 12 compid 0

If no heartbeat: Confirm MAVProxy service · UDP output IP · Windows IP · Port · Pixhawk USB · Pixhawk powered · ArduPilot booted

9. MAVProxy Bridge Debugging

sudo systemctl status mavlink-router.service
sudo systemctl status mavproxy.service
journalctl -u mavlink-router.service -n 50 --no-pager

mavproxy.py \
 --master=/dev/serial/by-id/usb-ArduPilot_fmuv2_xxxxx-if00 \
 --baudrate=115200 \
 --out=udp:192.168.1.234:14512

ls -l /dev/serial/by-id/

Use stable USB paths. Do not rely on /dev/ttyACM0 or /dev/ttyACM1 if multiple USB devices are connected.

10. GPS Debugging

py -c "from pymavlink import mavutil; m=mavutil.mavlink_connection('udpin:0.0.0.0:14512'); m.wait_heartbeat(); print('heartbeat', m.target_system); 
while True:
 msg=m.recv_match(type='GPS_RAW_INT', blocking=True, timeout=2)
 if msg:
 print('fix', msg.fix_type, 'sats', msg.satellites_visible, 'eph', msg.eph)"

Good GPS: fix_type >= 3 · sats >= 8 · HDOP low, preferably below 2.0

If GPS is not detected: Check GPS cable · GPS port · Baud rate · Serial protocol · GPS module power LED · Move outdoors · Wait several minutes for first lock

For Pixhawk 2.4.8, common GPS serial settings:
SERIAL3_PROTOCOL = GPS
SERIAL3_BAUD = 115200 or 38400
GPS_TYPE = Auto

If compass is detected but GPS is not, I2C compass works while UART GPS does not. Check GPS UART wires, port, baud, or GPS protocol.

11. EKF Debugging

The mission waits for EKF position by checking GLOBAL_POSITION_INT.

If GPS has fix but EKF is not ready: Wait longer outdoors · Check compass calibration · Accelerometer calibration · EKF origin · Vehicle not indoors · ArduPilot pre-arm warnings

In Mission Planner: Messages tab · Status tab · EKF flags · PreArm messages

12. Drone Debugging

Drone Heartbeat Test

py -c "from pymavlink import mavutil; m=mavutil.mavlink_connection('udpin:0.0.0.0:14503'); m.wait_heartbeat(); print('connected sysid', m.target_system)"

Drone Mode Test

master.set_mode_apm("GUIDED")
master.set_mode_apm("STABILIZE") # Indoor motor tests without props

Drone Arm Test

master.mav.command_long_send(
 master.target_system,
 master.target_component,
 mavutil.mavlink.MAV_CMD_COMPONENT_ARM_DISARM,
 0, 1, 0, 0, 0, 0, 0, 0
)

If drone does not arm: Pre-arm message · GPS if GUIDED · Safety switch · RC calibration · Accelerometer calibration · Compass calibration · Battery failsafe · Valid mode

Drone Forward Movement

distance = speed × time
Examples:
0.2 m/s × 30 sec = ~6 m
0.2 m/s × 50 sec = ~10 m
0.5 m/s × 20 sec = ~10 m

send_velocity(master, 0.2, 0, 0)

This is a body-frame velocity command, not a true GPS waypoint mission.

13. Rover Debugging

The rover has two independent systems:
Pixhawk: GPS / EKF / heartbeat
Raspberry Pi + STM32: Motor control
Both must work.

Rover Pixhawk Heartbeat

py -c "from pymavlink import mavutil; m=mavutil.mavlink_connection('udpin:0.0.0.0:14512'); m.wait_heartbeat(); print('rover sysid', m.target_system)"

Rover Agent Service

sudo systemctl status acker-rover.service
journalctl -u acker-rover.service -n 50 --no-pager

Rover Agent Manual Run

sudo systemctl stop acker-rover.service
python3 ~/acker_rover/rover_agent.py

[ROVER] Connecting STM32...
[ROVER] STM32 OK
[ROVER] STOP
[ROVER] UDP listening on 0.0.0.0:15000

Rover UDP Ping

py -c "import socket,json; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.settimeout(2); s.sendto(json.dumps(dict(cmd='ping')).encode(),('192.168.1.102',15000)); print(s.recvfrom(4096))"

Expected: {"ok": true, "status": "alive"}

Rover Move Test

py -c "import socket,json; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.settimeout(2); s.sendto(json.dumps(dict(cmd='move',x=200,z=0,duration=2)).encode(),('192.168.1.102',15000)); print(s.recvfrom(4096))"

py -c "import socket,json; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.settimeout(2); s.sendto(json.dumps(dict(cmd='stop')).encode(),('192.168.1.102',15000)); print(s.recvfrom(4096))"

If UDP reply says moving but wheels do not spin: STM32 USB path wrong · STM32 firmware stuck · Motor battery off · Motor controller needs reboot · Wrong serial command format · Wrong USB serial device

14. STM32 Serial Debugging

ls -l /dev/serial/by-id/

Expected motor controller path:
usb-1a86_USB_Single_Serial_xxxxx-if00
or usb-WCH.CN_USB_Single_Serial_xxxxx-if00

python3 -c 'import serial,time; ser=serial.Serial("/dev/serial/by-id/usb-1a86_USB_Single_Serial_5C2C061781-if00",115200,timeout=1); f=bytes.fromhex("7B 00 00 00 64 00 00 00 00 1F 7D"); s=bytes.fromhex("7B 00 00 00 00 00 00 00 00 7B 7D"); print("forward"); ser.write(f); ser.flush(); time.sleep(2); print("stop"); ser.write(s); ser.flush(); ser.close()'

If no movement: Reboot STM32 · Replug USB · Check power · Check correct /dev/serial/by-id · Check if another process is holding the serial port

sudo lsof /dev/ttyACM0

15. Camera Stream Debugging

lsusb
ls -l /dev/video*
python3 -c "import cv2; cap=cv2.VideoCapture('/dev/video0'); print('opened', cap.isOpened()); ret, frame=cap.read(); print('ret', ret, 'shape', None if frame is None else frame.shape); cap.release()"

Expected: opened True · ret True · shape (480, 640, 3)

python3 -m pip install --user flask opencv-python-headless
python3 capture_video.py

Open: http://PI_IP:8080/video

For LQ3 low bandwidth: WIDTH=128 · HEIGHT=96 · FPS=3 · JPEG_QUALITY=20

16. Emergency Stop

# Stop Rover Agent Mission
py -c "import socket,json; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.settimeout(2); s.sendto(json.dumps(dict(cmd='stop')).encode(),('192.168.1.102',15000)); print(s.recvfrom(4096))"

# Stop Rover Service
sudo systemctl stop acker-rover.service

# Disarm Drone by MAVLink
master.mav.command_long_send(... 0, 0, 0, 0, 0, 0, 0, 0)

# Kill Python mission
pkill -f mission_script_name.py

# Kill camera stream
pkill -SIGTERM -f capture_video.py

17. Common Problems and Fixes

Problem	Fix
MAVLink heartbeat missing	Check UDP port, Windows IP, Pixhawk USB, MAVProxy service, LQ3 link, firewall
SYSID mismatch	Change `expected_sysid` in script or `SYSID_THISMAV` parameter
GPS fix_type 1, sats 0	Move outdoors, wait longer, check antenna direction, GPS wiring
Compass detected but GPS not detected	Check GPS UART cable, serial port, baud rate, `SERIALx_PROTOCOL = GPS`
Rover UDP says moving but wheels don't move	Check STM32 power, motor battery, USB serial path, rover agent logs, reboot STM32
Ctrl+C does not stop script	Use STOP_EVENT, timeout loops, signal handler, disarm all MAVLink masters
Drone does not arm	Check pre-arm message: GPS, compass, accelerometer, safety switch, RC calibration, battery failsafe, mode
LQ3 video freezes	Reduce resolution, FPS, JPEG quality; use one high-resolution stream; use low-resolution thumbnails

通过 18. Pre-Mission Checklist

[ ] All vehicle batteries charged
[ ] Drone props installed only outdoors
[ ] Rover wheels clear
[ ] LQ3 connected
[ ] Windows has correct LQ3 IP
[ ] All Pixhawks powered
[ ] MAVProxy services running
[ ] MAVLink heartbeat confirmed
[ ] GPS fix confirmed
[ ] EKF/global position confirmed
[ ] Rover agents running
[ ] Rover UDP ping works
[ ] Rover move test works
[ ] Emergency stop tested

19. Recommended Debug Commands Summary

# Pi Network
ip addr; ip route; hostname -I; cat /etc/netplan/01-uav.yaml

# Pi USB Devices
lsusb; ls -l /dev/serial/by-id/; ls -l /dev/video*

# Pi Services
sudo systemctl status acker-rover.service
sudo systemctl status mavlink-router.service
journalctl -u acker-rover.service -n 50 --no-pager
journalctl -u mavlink-router.service -n 50 --no-pager

# Windows Ping
ping 192.168.1.102

# Windows MAVLink Heartbeat
py -c "from pymavlink import mavutil; m=mavutil.mavlink_connection('udpin:0.0.0.0:14512'); print('waiting'); m.wait_heartbeat(); print(m.target_system, m.target_component)"

# Windows Rover UDP Ping
py -c "import socket,json; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.settimeout(2); s.sendto(json.dumps(dict(cmd='ping')).encode(),('192.168.1.102',15000)); print(s.recvfrom(4096))"

# Windows Rover Move
py -c "import socket,json; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.settimeout(2); s.sendto(json.dumps(dict(cmd='move',x=200,z=0,duration=2)).encode(),('192.168.1.102',15000)); print(s.recvfrom(4096))"

20. Final Notes

The most important idea is to debug one layer at a time.

For drones, MAVLink controls the vehicle directly.

For rovers, MAVLink checks GPS/EKF, but Raspberry Pi UDP controls motors.

Because of this, a rover can have good GPS and still not move if the rover agent, STM32, motor battery, or serial path is not working.

Likewise, a rover can move manually but still fail a GPS mission if Pixhawk GPS or EKF is not ready.

平台：Windows · LQ3 · Raspberry Pi 4B · Pixhawk · ArduPilot · MAVLink
(c) 卓博泰科技 · Drone and Rover System Debugging Guide

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