Thrust Scaling for Coaxial setups

ArduCopter Copter 3.5
1

Good Day All

I have recently made the transition from DJI to arducopter for a large X8.

The AC is flying very well after the autotune, very have e made the switch.

The only function that I am missing is the abliity to scale the output of the top vs bottom motors…

On the DJI I could access a custom motor mix table and set the output of the top motors 10% less than the bottom motors.

this resulted in both sets of motors being roughly the same temperature after landing from a long flight.

I remember long ago there was a parameter to scale top and bottom motors but I cant seem to find anything now?

Is there a way to to access the “motor Mix Table” for arducopter?

Regards

2

Couldn’t you do this by manually adjusting each servo’s min/max pwm? If that works how I’m imagining, then you could also still have the ability to command 100% throttle for emergency situations using this method, instead of always being handicapped 5-7%.

3

You always can add your own frame type or just use thrust_compensation_callback to adjust your motor thrusts accordingly. I know it involves programing…

4

HI Keith

Thanks for the reply. If we were to adjust the top motors Max PWM down 10 percent then would it scale the output over the entire range, or just reduce the max signal that the ESC would see? Not sure if this solution will work, as I understand it?

5

Hi Andras

Yes it seems the only way to do this is compile some custom code.

Thanks for your input.

Regards

6

The only way to do this with Ardupilot is manually by making the top props 10% bigger, the bottom motors 10% higher KV and or the ptich 10% different.

7

yes correct, so that you would still have access to 100% throttle if needed unlike the method you are seeking… as you increase throttle, individual motor throttle will eventually match… i don’t see why you couldn’t get similar results to true mixing at part throttle