INAV for tracked rovers

INAV 2.5 introduced rover and boat support. However, INAV setup on tracked vehicles like tanks or with differential steering was never really working like expected. Turning was possible but only in forward or backward movement – throttle had to be not-idle. And that meant that turning in place was not an option.

Luckily, the INAV Programming framework can be used to build a fully functional tracked vehicle/differential steering mixer. Here is a short tutorial on how to do it.

You will need:

  • INAV compatible flight controller
  • INAV 2.5.2 or newer
  • tracked or other differential steering vehicle with two bi-directional ESC

Outputs Tab

Enable Reversible Motors Mode

INAV on tracked vehicles - Outputs

Programming tab

INAV on tracked vehicles - Programming

  1. Setup Is Armed conditions in LC#0
  2. Setup Not Is Armed condition in LC#1
  3. Map Throttle RC channel to -500:500 range in LC#2
  4. Set it in GVAR#0 to be used in the mixer in LC#3

Mixer tab

INAV on tracked vehicles - Mixer

  1. You have to connect motor ESC to servo outputs, not motor outputs
  2. Servo#0 will be the left motor
  3. Servo #1 will be the right motor
  4. For each servo configure:
    1. If LC#1 evaluates true (not armed) set the constant value of 1460 (default neutral)
    2. If LC#0 evaluates true (armed) mix GVAR#0 as throttle input and Stabilized Yaw as a rudder input

Summary

That's all. With the mixer above, when armed, differential steering will be possible even without throttle forward/backward. The vehicle will be able to turn in place.

The shortcoming is that with such a mixer, INAV is not capable of controlling the throttle during RTH and the driver has to keep the throttle open for the vehicle to drive manually. This will change in INAV 2.6. Luckily, INAV will be able to control yaw, so it will steer home!

2 thoughts to “INAV for tracked rovers”

  1. Fantastic illustration of the potential of the mixer. I knew yaw disarm was possible from a vehicle where the yaw was driven by a dedicated motor and was surprised to see is spin like crazy when disarmed, but this is a really nice and succinct was to setup a rover without messing around with complex setup on the transmitter side.

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.