Throttle and axisPID[PITCH]

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copterrichie
Posts: 2261
Joined: Sat Feb 19, 2011 8:30 pm

Throttle and axisPID[PITCH]

Post by copterrichie »

I do not know if this is a bug but it is driving me nuts. With the copter sitting perfectly level on my work bench and no motors running, if I increase the throttle to 1600+ in the GUI, the axisPID[PITCH] value goes from -30 to -126.

I added axisPID[PITCH] to debug[2] to the Mix table.

copterrichie
Posts: 2261
Joined: Sat Feb 19, 2011 8:30 pm

Re: Throttle and axisPID[PITCH]

Post by copterrichie »

I should also mention, this is when I have ANGLE mode enabled but I am sure it happens in HORIZON and ACRO modes as well.

copterrichie
Posts: 2261
Joined: Sat Feb 19, 2011 8:30 pm

Re: Throttle and axisPID[PITCH]

Post by copterrichie »

Although this is my VTOL, this problem has nothing to do with the Mixing table itself. It is the value placed into the axis[PITCH].

http://youtu.be/YNHPaYbOcNA

PatrikE
Posts: 1951
Joined: Tue Apr 12, 2011 6:35 pm
Location: Sweden
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Re: Throttle and axisPID[PITCH]

Post by PatrikE »

In Multiwii.ino

Code: Select all

  #define BREAKPOINT 1500
  // PITCH & ROLL only dynamic PID adjustemnt,  depending on throttle value
  if (rcData[THROTTLE]<BREAKPOINT) {
    prop2 = 100;
  } else {
    if (rcData[THROTTLE]<2000) {
      prop2 = 100 - (uint16_t)conf.dynThrPID*(rcData[THROTTLE]-BREAKPOINT)/(2000-BREAKPOINT);
    } else {
      prop2 = 100 - conf.dynThrPID;
    }
  }

It's dynamicly lowering the PID's when you use much throttle.
Great if you have oscilations when you pull full throttle runs.
Especially on airplanes.
Set TPA in Gui to zero and it should be disabled.

copterrichie
Posts: 2261
Joined: Sat Feb 19, 2011 8:30 pm

Re: Throttle and axisPID[PITCH]

Post by copterrichie »

Thank you, you hit the nail directly on the head. I just did a EEPROM clear and the problem appears to be fixed on the bench. Seems when going from one firmware version to another even if they are minor changes, the EEPROM should be cleared.

copterrichie
Posts: 2261
Joined: Sat Feb 19, 2011 8:30 pm

Re: Throttle and axisPID[PITCH]

Post by copterrichie »

Eureka, Hooray, Bingo!!! That Damn Pitching Problem is GONE!!!

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