Table of contents
ModalAI maintains a fork of Snapdragon Navigator to support VOXL hardware.
1) Make sure you have an account at developer.modalai.com
2) Down the Qualcomm Machine Vision and SNAV IPK packages from https://developer.modalai.com/asset
3) Download the Qualcomm Community License File (snapdragon-flight-license.bin) from https://developer.qualcomm.com/software/machine-vision-sdk/tools
You will need to create an account with developer.qualcomm.com and wait 1-2 days for this file to be emailed to you. This page offers downloads for the Machine Vision IPK package as well, however at time of writing these links are outdated. The version made available at developer.modalai.com is what is used and tested internally at ModalAI.
4) Push the Qualcomm Community License file to the voxl board. This command will do it via ADB:
adb shell mkdir -p /opt/qcom-licenses/ adb push snapdragon-flight-license.bin /opt/qcom-licenses/
5) Push the Machine Vision and SNAV ipks to VOXL
adb shell mkdir -p /home/root/ipk/ adb push mv_1.2.8_8x96.ipk /home/root/ipk/ adb push snav_1.3.0_8x96.ipk /home/root/ipk/
6) Log into VOXL via ADB or SSH to install these packages.
james@silverstone:~/git/documentation$ adb shell / $ bash # adb starts an sh shell, start a bash shell manually /home/root$ opkg install ipk/mv_1.2.8_8x96.ipk /home/root$ opkg install ipk/modalai-vl_0.0.1_8x96.ipk
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:
 Static accel calibration was completed successfully Restarting SNAV DONE
Copyright (c) 2019 ModalAI Inc.