Snapdragon Navigator

Table of contents

  1. Overview
  2. Installation
  3. Configuration

Overview

ModalAI maintains a fork of Snapdragon Navigator to support VOXL hardware.

Installation

1) Make sure you have an account at developer.modalai.com

2) Down the snav-modalai IPK package from https://developer.modalai.com/asset

3) Make sure the VOXL factory and software bundles are installed.

4) Push the snav-modalai IPK package to VOXL.

me@mylaptop:~$ adb shell mkdir -p /home/root/ipk/
me@mylaptop:~$ adb push snav-modalai_1.3.0_8x96.ipk /home/root/ipk/

6) Log into VOXL via ADB or SSH. Remove the ModalAI Vision lib (it conflicts) before installing SNAV.

me@mylaptop:~$ adb shell
/ $ bash # adb starts an sh shell, start a bash shell manually
yocto:# opkg remove modalai-vl
yocto:# opkg install ~/ipk/snav-modalai_1.3.0_8x96.ipk

Configuration

1) While still logged into VOXL, run the configuration script. You will be prompted by the first question:

/home/root$ bash /etc/snav/configure_snav.sh

Which camera channel is the tracking camera connected to?
0 for DFT-only configuration
1 for stereo configuration
2 for TOF configuration

The wide-angle tracking camera will enumerate as camera ID 0, 1, or 2 depending on what other cameras are connected. This not NOT the physical port the camera is connected to, this is the camera ID that it is enumerated as in software. The 3 most common configurations and their corresponding camera ID are listed in the command prompt and repeated above for reference.

If you are using another configuration refer to the Camera Configuration page. You can always check the cameras before this step with the camera-test app built into the VOXL image or with the voxl-cam-ros node. You can also go back later and change the camera channel used by the ModalAI Vision Lib by updating the “override_cam_id” value in /etc/snav/camera.downward.xml

2) Next you will be prompted with the second question:

Which physical configuration is this for?

1) 200_quad_2S_pack          3) voxlcam_upright_tracking_cam
2) 230_quad_3S_pack          4) voxlcam_upside_down_tracking_cam

This configures the position of the IMU relative to the wide-angle tracking camera for the Visual Inertial Odometry function. Most use cases will fall into these 3 options. For custom use cases refer to the camera imu coordindate frames page. This also sets up the orientation of the IMU relative to the drone and flight control parameters such as if it’s using a 2S or 3S lipo.

3) Now we need to calibrate the IMU. Set up your VOXL in whichever orientation you will consider roll/pitch to be zero. Ideally this will be done with VOXL mounted to the quadcotper/robot and sitting still with no vibration or human contact. For VOXLCam this orientation should be with VOXLCam upright and looking forward with no tilt. For a red tray mount this is with the tray level.

the next step is static IMU calibration
Make sure the quadcopter or VOXLCAM is flat/upright (roll/pitch=0)
be patient, this will take 20-30 seconds
PRESS ENTER to start static IMU calibration

This process will take 20-30 seconds, be patient. You can ignore any systemctl warnings that show up. When it’s done you should see:

[100] Static accel calibration was completed successfully
Restarting SNAV

DONE