VOXL m500 User’s Guide (Work In Progress!)
This guide will walk you from taking the VOXL M500 out of the box and up into the air!
For technical details, see the datasheet.
Unmanned Aerial Systems (drones) are sophisticated, and can be dangerous. Please use caution when using this or any other drone. Do not fly in close proximity to people and wear proper eye protection. Obey local laws and regulations.
Table of contents
- Connecting qGroundControl over WiFi
- Sensor Calibration
- RC Radio Setup
- Preflight Checks
- First Flights
To follow this user guide, you’ll need the following:
- Spektrum Transmitter (e.g. SPM8000 or SPMR8000)
- LiPo 4S battery with XT60 connector
- Host computer with:
- QGroundControl 3.5.6+
- a terminal program
What’s in the Box
Included in the box are:
- VOXL M500
- 10” props
- USB-to-JST Cable (not used in this guide)
- Spare landing gear mounting screws
The following images give an overview of the vehicle components.
Connecting qGroundControl over WiFi
For setup and configuration of your M500 you must Remove the Propellers for safety.
Power on VOXL and Flight Core
Now power up the VOXL and Flight Core on the M500. This can be done by connecting a 5V Power Supply to the power module’s barrel jack. Or you can plug in a 4S battery:
To install a 4S battery, slide into the body as shown. There is a stop at the front of the vehicle that will prevent the battery from sliding too far forward. The battery should be pressed all the way in until it hits the stop for a consistent center of mass. Power on the vehicle by connecting the battery to the M500’s XT60 connector.
Connect to VOXL Access Point
From the factory, the vehicle will power up as a WiFi Access Point with a name like
VOXL:XX:XX:XX:XX:XX). You can connect to it with a password of
Once connected to the VOXL AP, you’ll get an IP address from VOXL via DHCP, locate the address, in my case it’s
More details can be found at the VOXL WiFi quickstart page.
SSH into VOXL
The VOXL’s IP address by default is
192.168.8.1. SSH into VOXL using the
root user with password
More details available at the VOXL SSH quickstart page.
VOXL needs to know the IP address of your computer running qGroundControl. This is set in the ‘qgc_ip’ field of the
/etc/modalai/voxl-vision-px4.conf file on VOXL. This will inform the
voxl-vision-px4 systemd service to send MAVLink data to our computer.
Run the following command and update the
qgc_ip field to match your computer’s IP.
yocto:/home/root# vi /etc/modalai/voxl-vision-px4.conf
i to enter edit mode, use arrow keys to navigate to the
qgc_ip field and edit there. To save, hit
:wq to write and quit.
If you put VOXL on your own WiFi or LTE network you will have to do the same procedure.
For more information on this config file and the options available see the VOXL Vision PX4 manual.
Restart the voxl-vision-px4 Service
To reset the
voxl-vision-px4 service and reload the configuration, run the following command:
yocto:/home/root# systemctl restart voxl-vision-px4
Note this will also reset the Visual Inertial Odometry (VIO) algorithm and reset VIO’s origin to wherever the drone is when you reset the service.
Confirm Connection with QGroundControl
After the previous step is completed, the vehicle should automatically connect to QGroundControl
VOXL-M500 flight sensors are delivered pre-calibrated from the factory. PX4 will warn you if your compass needs to be re-calibrated depending on your location and environmental conditions. If so, or if you’d like re-calibrate all sensors, follow the px4 sensor calibration precedure.
RC Radio Setup
Now you need to bind and calibrate your DSM RC radio through the qGroundControl interface.
Bind to Spektrum
Instructions on how to bind a Spektrum radio can be found here.
Now follow the on-screen instructions to calibrate the range and trims of your radio.
Confirm RC Settings
Obviously every user will want to use different flight modes and different switch assignments, but for getting started with VOXL and and Flight Core we suggest starting with something similar to this configuration and working from there.
- “Flap Gyro” switch left of Spektrum Logo
- Channel 6
- Up position: Manual Flight Mode
- Middle Position: Position Flight Mode
- Down Position: Offboard Flight mode
- Channel 6
- “Aux2 Gov” switch right of Spektrum Logo
- Channel 7
- Up position: Motor Kill Switch Engaged
- Down Position: Motor Kill Switch Disengaged (required to fly)
- Channel 7
Since we have a manual kill switch on the radio there is no need for the “safety switch” on the Pixhawk GPS module as so it is disabled in our params file in favor of the kill switch.
If you have a Spektrum DX8 radio with a clean acro-mode model you can accomplish the above channel mapping by loading the following config file
Still confirm the mapping in qGroundControl before flight!
Now disconnect the 5V power supply or battery you used during the configuration steps. Move the M500 to a safe location where you wish to fly and connect a battery for flight while the M500 is on the ground.
The position and direction VOXL powers up in will dictate the origin and orientation of the Visual Inertial Odometry (VIO) coordinate frame, also known as LOCAL_POSITION_NED in PX4 terminology. VOXL will correct for any tilt due to non-level ground.
Lift the vehicle and move it around, verify that the attitude reported in QGroundControl GUI looks and responds correctly. Try not to cover the tracking camera during this process.
VIO Data Validation
In QGroundControl, go to
Widgets > MAVLink Inspector. Find the
LOCAL_POSITION_NED node in the list, and validate the data as follows.
The local coordinate frame in PX4 is right-handed, with X pointing forward out the drone, Y pointing to the right, and Z-axis down in units of meters. This is also known as FRD frame (forward, right, down).
It should show roughly “0 0 0” if you placed the M500 back down where it powered up. The origin and orientation is initialized when the voxl-vision-px4 service starts. You can re-initialize by restarting the service as described before if you want to move to a new flight location.
- Lift the vehicle straight up a meter, validating that the Z measurement gets more negative, roughly 1 meter
- Walk forward 1 meter, validating that the X measurement gets more positive, roughly 1 meter
- Walk to your right 1 meter, validating that the Y measurement gets more positive, roughly 1 meter
- Place the vehicle back in the takeoff position, and validate that you are back to roughly “0 0 0
Arming Vehicle Without Props
With the propellers off arm the vehicle.
- Set killswitch to off (“Aux2 Gov” switch down)
- Left stick hold down and to the right
Validate the motor rotation is as expected and the vehicle responds to throttling up momentarily.
Disarm the vehicle:
- Left stick hold down and to the left
Correct rotation direction of motors:
Install the propellers following this orientation. Each motor shaft has a white or black top to indicate which propeller goes where. Note that the clockwise spinning propellers are reverse threaded to prevent loosening during flight.
Ensure you tighten the propellers down tightly by hand or they may spin off when engaging the kill switch.
First Flight (Manual Mode)
You should be comfortable flying before proceeding!
Arm the vehicle, now safely fly in manual mode! No instructions here, you should know what you are doing if you’re flying!
Land and disarm.
Second Flight (Position Mode)
The following will have you take off and fly in position flight mode. You should be comfortable flying before proceeding!
Check the VIO data by again looking at
Widgets > MAVLink Inspectorand ensure the
LOCAL_POSITION_NEDX Y and Z values look consistent with where the vehicle has landed.
On your RC Radio flip to position mode. If using the DX8 config described before, that will be accomplished by moving ghe flap_gyro switch to the middle position.
Validate that QGroundControl recognizes you are in
Arm the vehicle
To take off, move the throttle to 50% or the “hover” position then slowly increase throttle above %50 until the M500 takes off. Note that full throttle will raise the vehicle rapidly at 3 m/s (no throttle will drop at 1 m/s)
Having the sticks at ‘center’ position will hold the vehicle in place. Once the feedback controller settles, you should be able to leave the throttle stick in the middle position, and the M500 will hold still with no user input.
Land and disarm the vehicle