Vision Drone Complete Guide

This is a complete guide about building and operating the vision drone from scrach.

Frame and Hardware Assembly

ESC Assembly

Prepare the following items:

Solder the capacitor, power cable into the ESCs. Pay attention to the front and back of the ESC.

Prepare the following items:

Solder the power cable.

Install the ESC into the frame with M2.5*20 screw. Pay attention to the front and back of the ESC.

Install arms.

Install motors.

Solder motor wire to ESC.

Pix32 Preparation

Before assembly: Upload custom firmware to Pix32. Calibrate the Acc, Gyro and compass.

Insert the nut into the Pix32 stands. Set iron to 200 degrees

Prepare the following items:

Due different motor ordering with 4 in 1 ESC and PX4, we need to remap the channel.

ESC wiring table:

ESC	Pix32
CUR	I
NC	NC
4	4
3	2
2	1
1	3
+	V
-	G

Solder it: Do not reference to the image, use the wiring table

Install the pix32 support with M2*12:

Connect the cable:

Install into the frame:

Battery stands and Xavier Assembly

Install the battery stands, replace bottom M3 strew with M3*16:

Install Xavier support:

Install Xavier:

Install WiFi module:

Install Xavier module:

The steps are same for assembling Jetson Orin instead of Xavier. Just use the A603 carrier board instead of the carrier board A203 used for Xavier.

PX4 Configuration Guide

For the purpose of checking the motors and calibrating the sensors, flash the default PX4 firmware using QGC on the Pix32 V6.

Setup Dshot and test motors

Make sure the propellers are removed for this setup and throughout testing the motors.
set SYS_USE_IO to IO_PWM_DISABLE
set DSHOT_CONFIG to DShot600
Verify motor order using Mavlink console dshot beep1 -m [Motor number]
Verify motor spinning direction
Use the following command to reverse motor dshot reverse -m [Motor number], dshot save -m [Motor number]
Motors can be checked individually inside the /Vehicle Setup/Motors tab inside the QGC.

Flashing the custom PX4-Autopilot-Quad

First clone the PX4-Autopilot-Quad

Run the following commands to make sure that px4 build will recognize the tags:

$ git clone git@github.com:dev10110/PX4-Autopilot-Quad.git
$ cd /PX4-Autopilot-Quad
$ git submodule update --init --recursive
$ git remote add upstream https://github.com/PX4/PX4-Autopilot.git
$ git fetch upstream --tags

Then build and run the docker using the following commands.

$ docker compose build
$ docker compose up -d
$ docker exec -it <container-name> bash

Make the px4 version using the following command inside the docker in /home/px4
```
$ make px4_fmu-v6c_dasc
```
Flash the px4_fmu-v6c_dasc using the QGC.

PX4 Parameter (old version 1.13)

Set MAV_SYS_ID to be a different value from other Drone (match number with name of drone)
Set Hold and Offboard for COM_RCL_EXCEPT
in EKF2_AID_MASK: Check GPS, vision position fusion, and vision yaw fusion if outdoor, and only vision position fusion and vision yaw fusion if indoor
- NOTE: Code for vision position fusion is different whether or note use GPS is checked
Set EKF2_HGT_MODE to GPS if doing outdoor testing and Vision if doing indoor testing
Set EKF2_GPS_P_NOISE to 0.2 m
Set EKF2_GPS_V_NOISE to 0.15 m/s
set MAV_0_RATE to 0 B/s (i.e. unlimited data sending rate)
set COM_RC_IN_MODE set to joystick only
set MAV_0_RADIO_CTL to disable
set SER_TEL1_BAUD to 115200 8N1
set RTPS_CONFIG to TELEM 2
set SER_TEL2_BAUD to 921600 (might need to reboot vehicle to see this option)

PX4 Parameter (new v1.14)

Set MAV_SYS_ID to be a different value from other Drone (match number with name of drone). This number matches the number in the name px4_#. The current custom firmware PX4-Autopilot-Quad requires the robot name to be in the format px4_#. Here # is the MAV_SYS_ID.
Set Hold and Offboard for COM_RCL_EXCEPT
Set EKF2_EV_CTRL to 15 (check all boxes)
Set ‘EKF2_EVP_NOISE’ and ‘EKF2_EVA_NOISE’ to lowest possible values
Set EKF2_HGT_MODE to GPS if doing outdoor testing and Vision if doing indoor testing
Set EKF2_GPS_P_NOISE to 0.2 m
Set EKF2_GPS_V_NOISE to 0.15 m/s
set MAV_0_CONFIG to TELEM1 so that mavlink communicates using TELEM1.
set MAV_0_RATE to 0 B/s (i.e. unlimited data sending rate)
set COM_RC_IN_MODE set to joystick only
set MAV_0_RADIO_CTL to disable
set SER_TEL1_BAUD to 115200 8N1
set XRCE_DDS_CONFIG to TELEM2 (reboot after this)
set XRCE_DDS_DOM_ID to the ROS_DOMAIN_ID you are using.
set SER_TEL2_BAUD to 921600 (might need to reboot vehicle to see this option)
set EKF2_MAG_TYPE to None (disables mag, requires reboot)
make sure MAV_1_CONFIG, MAV_2_CONFIG etc are false, or atleast not using TELEM2 (which we have dedicated to the XRCE connection).

QuadControl Parameters(Updated 06/19/2024)

Set QUAD_ESC_NONLIN to 0.525
Set QUAD_IXX to 0.002 kgm^2
Set QUAD_IYY to 0.002 kgm^2
Set QUAD_IZZ to 0.003 kgm^2
Set QUAD_KOMEGA to 0.120 kOmega
Set QUAD_KRt o 0.900 kR
Set QUAD_KTHRUST to 1.370 (N / (kilo-rad/s)^2)
Set QUAD_KTORQUE to 0.190 (Nm / (kilo-rad/s)^2)
Set QUAD_KV to 4.0 kv
Set QUAD_KX to 7.0 kx
Set QUAD_OMEGA_MAX to 2.520 krad/s
Set QUAD_M to
- 0.680 kg if not using realsense
- 0.870 kg if using realsense D455
- Update this based on the mass of your quadrotor
Set all the motor positions
- if not using Realsense (i.e., the CG is pretty much at the exact center location)
  - QUAD_ROT1_POSX: 0.070
  - QUAD_ROT1_POSY: 0.085
  - QUAD_ROT2_POSX: -0.070
  - QUAD_ROT2_POSY: -0.085
  - QUAD_ROT3_POSX: 0.070
  - QUAD_ROT3_POSY: -0.085
  - QUAD_ROT4_POSX: -0.070
  - QUAD_ROT4_POSY: 0.085
- if using Realsense D455: (shifts the CG in the +x direction by 6.1 mm)
  - QUAD_ROT1_POSX: 0.064
  - QUAD_ROT1_POSY: 0.085
  - QUAD_ROT2_POSX: -0.076
  - QUAD_ROT2_POSY: -0.085
  - QUAD_ROT3_POSX: 0.064
  - QUAD_ROT3_POSY: -0.085
  - QUAD_ROT4_POSX: -0.076
  - QUAD_ROT4_POSY: 0.085

Setting up Orin or Xavier

First, use the SDK manager to flash the Orin
Connect the Orin with the carrier board to the host computer using the USB A-to-micro cable. Also, power the Orin carrier board using the power supply instead of the battery.
At this point, you might encounter the following scenarios:
- The SDK manager successfully detects the board. In this case, proceed to next step.
- The SDK manager does not detect the board. In this case, you need to force the Orin into recovery mode. For the Orin carrier board A603, recovery mode can be initiated by shorting 3 and 4 in W7. Please refer to the picture and this document for more details: A603 Documentation. If using Xavier with the carrier board A203, recovery mode can be initiated by shorting 6 and GND (1,2,3,4). A203 Documentation
[TODO: Add picture]
In the target components, select Jetson Linux only. You don’t need to select Jetson Runtime Components as we will mostly be working inside the Docker container. Accept the terms and continue.
In the SETUP PROCESS:
- Choose Automatic Setup in the Recovery mode setup.
- Keep the default IP address.
- If this is the first time, then enter username: ubuntu and password: hello123. We keep this consistent across all modules.
- If this is not the first time the Orin is being flashed, then enter the current username and password, and make sure the new username and password match the details given above. You can provide a new username and password by unchecking the Use current username/password box.
- Select the Storage Device as NVMe. This is becasue we are flashing on the SSD.
The flash can fail due to a bad Orin, carrier board, or SSD. Make sure to check each component.
After booting up the Orin, change the hostname permanently to orin# such that username@hostname = ubuntu@orin#. The number # should be selected after checking all numbers on the active orin modules. Follow these commands to change the hostname permanently:
```
$ hostname
$ sudo hostnamectl set-hostname NEW_HOSTNAME
```
Reboot and check if the hostanme has been set successfully.
In order to SSH into the orin remotely, set the first line of /etc/hosts to
```
127.0.0.1 $HOSTNAME
```
To SSH into the Orin remotely, use following commands:
```
$ ssh ubuntu@orin#.local
$ password: hello123
```
Then run the flash.sh inside the Orin once it is ready. The flash file can be found here. Consider removing sudo apt-get upgrade as it has previously deleted Kernel. The flash file can be executed using following commands
```
$ chmod +x path/to/flash.sh
$ ./flash.sh
```

Generate a new SSH key for github (Link). Or follow these commands and then copy the key from the last command to the github account

git config --global user.email "your_email.com"
git config --global user.name "username"
ssh-keygen -t ed25519 -C "your_email.com"
eval "$(ssh-agent -s)"
cat ~/.ssh/id_ed25519.pub

Clone the px4-jumpstart repository and build the docker file.

$ git clone https://github.com/dasc-lab/rover_px4_ros2_jumpstart.git
$ cd rover_px4_ros2_jumpstart
$ docker compose build

The docker-compose.yaml can be changed accordingly if required. At a minimum, it should contain the following:

version: "3"
services:
  ros:
    build: .
    privileged: true
    tty: true
    network_mode: "host"
    volumes:
       - ./colcon_ws:/home/colcon_ws
       - /tmp/.X11-unix:/tmp/.X11-unix
       - $HOME/.Xauthority:/home/admin/.Xauthority:rw 
    environment:
      - DISPLAY=$DISPLAY
      - FASTRTPS_DEFAULT_PROFILES_FILE=/home/colcon_ws/rtps_udp_profile.xml
      - ROS_DOMAIN_ID=4

Configure some ROS2 settings: Tuning the DDS settings at a system kernel level can help avoid missed messages. See https://docs.ros.org/en/humble/How-To-Guides/DDS-tuning.html for more details. The main thing to do is to create/append to the file /etc/sysctl.d/local.conf with the following lines:
```
net.ipv4.ipfrag_time=3 # 3s (default = 30s)
net.ipv4.ipfrag_high_thresh=134217728 # 128MB (default = 4MB)
```
By changing this file (instead of using the cli to set the parameter) the parameters persist between reboots. These settings should also be available in the docker container.
For Orin Only: The Seeed Studio A603 carrier board for the NVIDIA Orin NX has an issue with the kernel drivers for usbserial. Essentially, instead of using the usbserial.ko for the board which are modified by Seeed, the default usbserial.ko is used. This causes the FTDI driver to not work as expected. The solution is to move the usbserial.ko file which causes the new file from Seeed Studio to be used.

$ cd /lib/modules/5.10.120-tegra/kernel/drivers/usb/serial/
$ sudo mv usbserial.ko usbserial.ko.bk

Use dmesg | grep tty to check if the tty/UAB0 and tty/USB1 are successfully detected.
Configure the colcon_ws/src/all_launch/config/mavlink-router.conf file. The Address should match the ip address of your computer running the QGC. The ip address can be checked by running ifconfig

[UartEndpoint alpha]
Device = /dev/ttyUSB0
Baud = 115200

[UdpEndpoint alpha]
Mode = Normal
Address = <host_computer_ip> 
Port = 14550

Configure the /colcon_ws/src/all_launch/launch/px4.launch.py such that the microXRCE_bridge uses /dev/ttyUSB1 and the robot_name = "px4_#, where the # matches the MAV_SYS_ID in the QGC parameters.
Once the files are configuresd, build the rover_px4_ros2_jumpstart

$ docker compose up -d
$ docker exec -it <Container-name> bash
$ cd /root/colcon_ws
$ colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=Release

First flight

Make sure that the drone is properly tethered.
To avoid any crashes, start with a quarter of the original quadrotor mass, i.e., QUAD_M/4. This will provide less thrust than required for the drone to lift. Slowly increase the mass to the correct value once the motors are confirmed to be working fine.
Consider using the px4 Flight Review to debug.

On Orin

Run the docker and launch the px4.launch.py

$ docker compose up -d
$ docker exec -it <Container-name> bash
$ ros2 launch all_launch px4.launch.py

On ground station

Run the docker and launch the gs.launch.py

$ git clone git@github.com:dasc-lab/rover_groundstation_ros2_jumpstart.git
$ cd rover_groundstation_ros2_jumpstart
$ docker compose build
$ docker compose up -d
$ docker exec -it <Container-name> bash
$ ros2 launch ground_station_launch gs.launch.py