This repository contains a ROS workspace for using stereo-visual navigation with ROS and ArduPilot.

The end result is the ability to use non-GPS navigation with ArduPilot, using a stereo camera.

Hardware:

• Stereo Camera. Global shutter preferred (such as https://www.arducam.com/product/arducam-1mp2-wide-angle-stereo-camera-for-raspberry-pi-jetson-nano-and-xavier-nx-dual-ov9281-monochrome-global-shutter-camera-module/)
• Nvidia Jetson Nano
• ArduPilot flight controller (connected to UART on Jetson 40-pin header)

Software:

• ROS Melodic
• VINS-GPU Lite
• MAVROS

The VINS_Lite_GPU (https://github.com/KopiSoftware/VINS_Lite_GPU) algorithm is used as a ROS module to take in stereo camera images and generate a pose in 3D space. This pose is sent to ArduPilot via MAVROS and the VISION_POSITION_ESTIMATE message. ArduPilot then uses these messages as a non-GPS navigation source.

Note the VINS_Lite_GPU used here is slightly modified from source - adding a odometry message compatible with MAVROS.

It is a "lighter" version of VINS-GPU (https://github.com/pjrambo/VINS-Fusion-gpu) which allows for better realtime performance on a Jetson Nano.

Follow the instructions at https://www.arducam.com/doc-old/camera-for-jetson-nano/multiple-cameras-on-the-jetson/how-to-use-stereo-camera-to-perform-location-with-visual-slam/#ftoc-heading-20, noting the following changes:

• Use git clone https://github.com/stephendade/Camarray_HAT.git repo in place of git clone -b ov9281_stereo https://github.com/ArduCAM/Camarray_HAT.git
• Use git clone https://github.com/stephendade/Nvidia_Jetson_ROS_SLAM_VINS.git repo in place of git clone https://github.com/ArduCAM/Nvidia_Jetson_ROS_SLAM_VINS.git
• Use this repository as your ROS workspace
• Install MAVROS via sudo apt install ros-melodic-mavros ros-melodic-mavros-extras
• Use systemctl stop nvgetty && systemctl disable nvgetty on the Jetson and reboot to disable the system console on the UART.

• If not using the ArduCAM OV9281 stereo camera, edit jetson.launch to suit your stereo camera setup
• Edit jetson.launch to point the to appropriate UART or UDP port for MAVROS.

Ardupilot will need the following parameters:

SCHED_LOOP_RATE  250 
VISO_DELAY_MS    150
VISO_ORIENT      0
VISO_POS_M_NSE   0.100000
VISO_POS_X       0.000000
VISO_POS_Y       0.000000
VISO_POS_Z       0.000000
VISO_SCALE       1.000000
VISO_TYPE        2
VISO_VEL_M_NSE   0.010000
VISO_YAW_M_NSE   0.100000

Use launch.sh to run the ROS instance. If using a remote ROS node (for viewing, debugging, etc) edit the IP addresses in launch.sh as required.

When connecting a ground station, ensure the streamrate is 20Hz. This is required for the VINS inertial message (/mavros/imu/data) input.