Learn how to Set Up Optical Move & Rangefinder Sensors in iNav – Place/Altitude Maintain for FPV Drones

Learn how to Set Up Optical Move & Rangefinder Sensors in iNav – Place/Altitude Maintain for FPV Drones

Flying an FPV drone in Place Maintain and Altitude Maintain modes could be considerably improved with the addition of Optical Move and Sonar (rangefinder) sensors. These sensors assist keep a secure hover by offering exact knowledge in regards to the drone’s place and altitude. On this tutorial, I’ll information you thru establishing these sensors in iNav.

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This information is predicated on the directions offered by the producer of the optical stream sensor I bought. These steps won’t work for different varieties of optical stream/sonar sensors.

Why Add a Rangefinder and Optical Move Sensor?

Including a rangefinder and optical stream sensor enhances your quadcopter’s stability and precision. The optical stream sensor works just like the sensor in a pc mouse, capturing pictures of the bottom to find out motion. The rangefinder (sonar) offers extra correct altitude measurements in comparison with a barometer, which is particularly helpful throughout touchdown, although the utmost efficient altitude is usually lower than a couple of meters.

Required Parts

You will want two issues:

  • Optical Move and Rangefinder Sensor
  • A drone with an iNav-compatible flight controller and a spare UART

Microair Mtf 01 Ranger Finder Optical Flow Sensor Module

I’m utilizing the MicroAir MTF-01, a rangefinder sensor with built-in Optical Move functionality. It’s an amazing module as a result of the connection and setup are very simple, and it helps iNav. You may get the MTF-01 right here:

I like to recommend getting the bundle that features the USB to TTL programmer, as you may want it to alter settings.

MTF-01 Specs:

  • Helps Ardupilot, PX4, and iNav
  • PMW3901 optical stream sensor
  • Excessive-performance TOF sensor
  • Output mode: UART
  • Output frequency: 100Hz
  • TOF Vary: 0.02-8m
  • Vary accuracy: 2%
  • Wavelength: 830-870nm
  • Resistance to ambient mild: 70K Lux illumination
  • Distance FOV: 6°
  • Optical stream FOV: 42°
  • Ambient mild demand of optical stream: >60Lux
  • Optical stream working distance: >80mm
  • Energy consumption: 500mW
  • Working voltage: 4.0- 5.5V
  • Module weight: 4.5g
  • Dimensions: 29 * 16.5 * 15mm

For the drone, I’m utilizing the GEPRC Cinebot25. I’m not snug testing place maintain indoors with any drones with out prop guards, so a small cinewhoop is an ideal alternative. See my evaluation of this drone right here: https://oscarliang.com/geprc-cinebot25/

Nevertheless, the GEPRC flight controller doesn’t help iNav (but), so I needed to swap it out with the Flywoo GN745 V3. Listed here are particulars about this FC and the way I changed it: https://oscarliang.com/flywoo-goku-gn745-aio-v3-fc/

New to iNav? Try my newbie tutorial on methods to arrange iNav on an FPV drone: https://oscarliang.com/setup-inav-fpv-drone/

Step 1: Configuring the Module

The MTF-01 module helps the next output protocols:

  • Microlink: a customized protocol which helps FMT
  • MSP: helps iNav
  • Mavlink_APM: Mavlink protocol for Ardupilot
  • Mavlink_PX4: Mavlink protocol for Pixhawk 4

My unit was set to Microlink by default, so I needed to change it to MSP protocol to work with iNav. You may simply change the output protocol of the MTF-01 utilizing the MicoAssistant software program, however you’ll need a USB to TTL programmer.

Obtain MicoAssistant software program: https://github.com/micoair/MTF-01_USER_MANUAL

Join the MTF-01 to your PC utilizing the USB to TTL module.

Microair Mtf 01 Ranger Finder Optical Flow Sensor Module Usb To Ttl Programmer

Open the MicoAssistant software program, choose the proper COM port within the higher proper nook, set the baud fee to 115200, and click on on the connection icon.

Microair Mtf 01 Ranger Finder Optical Flow Sensor Module Usb Microassistant Configure Connection

As soon as linked, click on on the Setup Menu (gear icon), choose the protocol you wish to use (on this case, MSP), after which click on the WRITE button.

Microair Mtf 01 Ranger Finder Optical Flow Sensor Module Usb Microassistant Configure Output Protocols Msp

Step 2: Wiring the Sensors

Join the 4 wires from the MicroAir MTF-01 sensor to any spare UART in your flight controller. I linked it to UART4 on my FC.

  • 5V to 5V
  • GND to GND
  • TX to RX
  • RX to TX

Observe: If the rangefinder and optical stream sensor don’t get powered through the USB cable, you may need to plug in a battery to energy these sensors.

Microair Mtf 01 Ranger Finder Optical Flow Sensor Module Wiring Diagram Flight Controller Fc Uart Tx Rx

Flywoo Goku Gn745 45a Aio V3 Fc Flight Controller Replace Geprc Cinebot25 Taker G4 Wiring Gps Optical Flow

Mount the sensor on the underside of the quad, guaranteeing there’s nothing obstructing the view of the sensors. Use touchdown gears to make sure there’s adequate clearance between the bottom and the sensors throughout takeoff, ideally a few centimeters or extra.

Microair Mtf 01 Ranger Finder Optical Flow Sensor Module Install Geprc Cinebot25 Fpv Drone Cinewhoop Bottom

Step 3: Configuring iNav

Earlier than continuing, take away the propellers out of your quadcopter for security. Join the battery after which join the flight controller to your pc.


Open iNav Configurator, go to the Ports tab, and configure the UART you wired up as MSP. Save and reboot.

Inav Configurator Ports Setup Ranger Finder Optical Flow Sensor Msp


Within the Configuration tab, discover the “Sensors & buses” part. For Rangefinder and Optical Move, set them to MSP. Save and reboot.

After rebooting, the “Move” and “Sonar” sensor icons on the highest of iNav Configurator ought to flip blue, indicating they’re working accurately. If these sensors don’t flip blue however crimson, test that the TX and RX wires are accurately linked and that the battery is powering the sensors.

Inav Configurator Configuration Setup Ranger Finder Optical Flow Sensor

CLI Settings

Inav Configurator Cli Setup Ranger Finder Optical Flow Sensor Pid

Copy and paste the next strains within the CLI (these are configurations instructed by the maker of MTF-01).

  • Lifeless Reckoning: by enabling iNav_allow_dead_reckoning within the CLI, it enhance efficiency throughout temporary GPS outages.
  • Most Top Setting: by setting the inav_max_surface_altitude within the CLI, it defines the utmost peak at which the rangefinder is efficient, in cm.
set nav_mc_vel_z_p = 150 set nav_mc_vel_z_i = 250 set nav_mc_vel_z_d= 25 set nav_mc_pos_xy_p = 80 set nav_mc_vel_xy_p = 50 set nav_mc_vel_xy_i = 40 set nav_mc_vel_xy_d = 60 set debug_mode = FLOW_RAW set inav_allow_dead_reckoning = ON set nav_max_terrain_follow_alt = 200 set inav_max_surface_altitude = 200 save


Within the Sensors tab, gently tilt the quad aspect to aspect and entrance to again. The waveform of Debug 0 ought to look just like Debug 2, whereas Debug 1 ought to look just like Debug 3.

Debug 0/1 represents the accelerometer readings, whereas 2/3 are from the optical stream sensor. This check verifies the orientation of the optical stream sensor. The amplitude won’t be the identical, but when they transfer in the wrong way, you may want to alter the configuration in MicroAssistant (or set align_opflow=cw180 in CLI).

Inav Configurator Debug Setup Ranger Finder Optical Flow Sensor


Maintain the drone round 50-60 cm above the bottom and carry out the optical stream sensor calibration in iNav Configurator. This includes gently tilting the quad aspect to aspect and entrance to again barely and gently for about 30 seconds with none horizontal actions. Hit save and reboot when carried out.

MTF-01 recommends a scale worth between 4 to six. For those who get a price outdoors this vary, repeat the calibration at a greater peak with extra regular palms.

Inav Configurator Calibration Setup Ranger Finder Optical Flow Sensor Scale


Assign a change that may allow ANGLE, NAV POSHOLD (place maintain), NAV ALTHOLD (altitude maintain), HEADING HOLD, and SURFACE on the identical time.

Inav Configurator Modes Setup Ranger Finder Optical Flow Sensor Altitude Position Hold

Step 4: Testing the Setup

  1. Arm the drone and carry it right into a hover. If it doesn’t arm because of the lack of GPS lock, bypass this by pushing the throttle/yaw stick with the underside proper whereas arming.
  2. Change to Place Maintain mode and observe the soundness.
  3. Change to Altitude Maintain mode and test the altitude stability.

Troubleshooting and Professional Ideas

    • Sensor Initialization Failure: Make sure the wiring is right and the sensors are powered.
    • Inaccurate Place Maintain: Alter the Optical Move scaler worth.
    • Altitude Drifting: Recheck the Rangefinder configuration and calibration.
    • Initialization Clearance: Guarantee there’s a minimum of a few centimeters of clearance between the sensor and the bottom when powering up the quadcopter to keep away from incorrect readings.


Including the MTF-01 rangefinder and optical stream sensor to your iNav FPV drone is an easy course of that considerably enhances the soundness and precision of your drone in Place Maintain and Altitude Maintain modes, in addition to touchdown accuracy. With these sensors, your quadcopter will carry out extra like a DJI digital camera drone, holding its place and altitude with higher precision. Comfortable flying!

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