ESC calibration

Most models of PWM based ESC need to be calibrated to ensure that all the ESCs respond to the same input with the same speed. To calibrate them they need to receive maximum PWM input when initially powered on, then receive minimum PWM input when they have beeped to indicate that the maximum has registered.

The method for calibrating the ESCs on an ArduPilot QuadPlane depends on what version of the firmware you have loaded. The old method is used on versions prior to the 3.6.0 release. The new method is used on 3.6.0 and later.

Warning

You must remove all propellers from your vehicle before doing any ESC calibration. Calibrating with propellers installed is dangerous.

ESC Calibration Procedure (3.6.0 and later)

This process uses the Q_ESC_CAL parameter to enable ESC calibration in QSTABILIZE mode. There are two modes of operation available:

  1. with Q_ESC_CAL=1 the output to the motors will come directly from the throttle stick in QSTABILIZE mode when the vehicle is armed
  2. with Q_ESC_CAL=2 the output to the motors will be full throttle when the motors are armed

The process when using Q_ESC_CAL=1 is

  1. remove your propellers for safety
  2. power up just the flight board and not your motors. If you don’t have the ability to isolate power to the ESCs when on battery power then power up your flight board on USB power
  3. set the Q_ESC_CAL parameter to 1
  4. change to QSTABILIZE mode
  5. set the safety switch off to activate the outputs
  6. arm your aircraft. The PWM output on all quad motors will now be controlled by your throttle stick
  7. move the throttle stick to maximum
  8. add power to your ESCs by connecting the battery
  9. wait for the ESCs to beep to indicate they have registered the maximum PWM
  10. lower the throttle stick to zero and disarm your aircraft
  11. you should hear a beep from your ESCs to indicate they have registered the throttle range

The process when using Q_ESC_CAL=2 is

  1. remove your propellers for safety
  2. power up just the flight board and not your motors. If you don’t have the ability to isolate power to the ESCs when on battery power then power up your flight board on USB power
  3. set the Q_ESC_CAL parameter to 2
  4. change to QSTABILIZE mode
  5. set the safety switch off to activate the outputs
  6. arm your aircraft. The PWM output on all quad motors will now be at maximum
  7. add power to your ESCs by connecting the battery
  8. wait for the ESCs to beep to indicate they have registered the maximum PWM
  9. disarm your aircraft
  10. you should hear a beep from your ESCs to indicate they have registered the throttle range

Note that using Q_ESC_CAL=1 can be useful for testing your motors response. This is the only mode when you are able to directly control the throttle level on all your motors at once. While in this mode you can use a laser tachometer to test your motor speeds at different throttle levels if you have one.

Old ESC Calibration Procedure (3.5.3 and earlier)

  1. remove your propellers for safety
  2. power up just the flight board and not your motors. If you don’t have the ability to isolate power to the ESCs when on battery power then power up your flight board on USB power
  3. set both the parameters Q_M_SPIN_ARMED and Q_THR_MID to 1000. This sets the PWM output when armed at zero throttle to full power
  4. set the safety switch off to activate the outputs
  5. arm your aircraft. The PWM output on all quad motors will now climb to maximum.
  6. add power to your ESCs by connecting the battery
  7. wait for the ESCs to beep to indicate they have registered the maximum PWM
  8. disarm your aircraft. The ESCs should beep again indicating they have registered minimum PWM

Now set the Q_M_SPIN_ARMED and Q_THR_MID parameters back to the correct values. A value of 50 for Q_M_SPIN_ARMED is a reasonable starting point. For Q_THR_MID a value of between 500 and 600 is good depending on the power of your motors