foreword
Most ESCs have a deadband at the bottom of their range. This page outlines how to test the size of the range, then set the spin and minimum throttle values appropriately when disarmed .
Although not required, advanced users may wish to proceed to the next step by measuring and adjusting the motor thrust curve ( motor thrust curve ).
！Note
Please complete the ESC calibration before setting the motor range .
1 Measurement dead zone
- Remove the propeller from the aircraft;
- Connect the lithium polymer battery;
- Connect the autopilot with the mission planner using a USB debug cable or telemetry ;
- Open the mission planner's initial settings >> optional hardware >> motor test page;
- Increment the " Throttle % " field and press each " Test Motor " button to determine the desired percentage of each motor rotation. If all the ESCs are from the same manufacturer, they will likely all have similar deadbands, but a difference of 1%~2% or two is very common. Pick the highest percentage of all motors - we'll use this percentage below.
2 Set MOT_SPIN_ARM and minimum throttle
By default, when the copter is unlocked but not flying, the motors will spin at a slightly slower speed than normal. This speed can be configured with the MOT_SPIN_ARM parameter (see MOT_SPIN_ARMED for older versions ). Once the vehicle starts flying, we want to make sure that we never output a value that causes the motors to stop spinning. This lower limit can be configured with the MOT_SPIN_MIN parameter.
- Set the MOT_SPIN_ARM parameter to (the percentage found above + 2% ) / 100 . In other words, if you find that the dead zone of the ESC is 7% , set MOT_SPIN_ARM to 0.09 (ie (7+2)/100 );
- Set the MOT_SPIN_MIN parameter to be at least 0.03 higher than MOT_SPIN_ARM . That is, if MOT_SPIN_ARM is 0.09 , set MOT_SPIN_MIN to 0.12 .
！Note
Setting MOT_SPIN_MIN higher than recommended above is acceptable if we want to account for voltage drop from the battery , but setting it too high will reduce the low speed range of the motor and thus reduce control, which can be significant, Especially on high powered rotorcraft with low hover throttle.
！Note
The MOT_SPIN_MAX parameter, taking into account the very top end of the ESC/motor range, usually does not generate extra thrust. By default, this value is 0.95 (i.e. the first 5% of the range produces no extra thrust).
！Note
If using ESC tach telemetry, the TKOFF_RPM_MIN parameter can be set slightly lower than the MOT_SPIN_ARM parameter to prevent takeoff attempts without one or more motors spinning, and subsequent takeoff flips.