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Advanced User Guide

Actuator Allocation and Motor Testing

QGC's Actuators Setup is used to configure the number of motors, airframe geometry, output channels, motor rotation directions, and control allocation relationships. Incorrect c…

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QGC's Actuators Setup is used to configure the number of motors, airframe geometry, output channels, motor rotation directions, and control allocation relationships. Incorrect configuration will affect attitude control, and incorrect output mapping may cause the aircraft to roll over during takeoff.

Danger:

Before starting the configuration, remove all propellers, clear the area around the motors, and prepare a power source that can be disconnected immediately. After completing the control allocation configuration, perform ground verification first. Do not install the propellers and proceed directly to a test flight.

Prerequisites

  1. The correct airframe type has been selected in the current PX4 firmware.
  2. The ESCs, motors, and FlyCore-FC output interfaces have been connected.
  3. All propellers have been removed.
  4. The aircraft has been securely restrained, and the battery power supply and emergency-stop provisions meet the test requirements.
  5. The current parameters have been exported and backed up.

Actuators Setup

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Configure the following in sequence according to the actual airframe:

  1. Select the actual number of motors, such as for a quadcopter, hexacopter, or octocopter.
  2. Enter the geometric position of each motor relative to the aircraft's center of gravity.
  3. Confirm whether each motor rotates clockwise or counterclockwise.
  4. Map the logical motor numbers to the actual FlyCore-FC output channels.
  5. Save the configuration and restart the flight controller, then read back the control allocation settings.
  6. Use actuator testing to verify each motor's number, position, and rotation direction individually.

Motor Geometry

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The coordinate origin is the aircraft's center of gravity, not the flight controller's mounting position. Motor positions are measured in meters:

Field Meaning Positive Direction
Position X Fore-aft position relative to the center of gravity Toward the nose
Position Y Left-right position relative to the center of gravity Toward the right side of the airframe
Position Z Vertical position relative to the center of gravity Downward

After entering the values, verify that the number of motors matches the actual airframe, the coordinates match the physical layout, and all coordinates use the same metric unit of meters.

Output Mapping and Propeller-Free Testing

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  1. On QGC's Actuators page, locate the output assignment area and map the logical motors to the actual output channels.
  2. In the Actuator Testing area, enable Enable Sliders.
  3. Gently move each motor slider, testing only one motor at a time.
  4. Verify that the motor that actually rotates matches the motor number shown in QGC.
  5. Verify that each motor's rotation direction meets the airframe requirements.

QGC propeller-free motor test

Acceptance Criteria and Risks

  • Each motor number corresponds to its physical position, output channel, and rotation direction;
  • No abnormal vibration, desynchronization, or communication alarms occur during motor testing;
  • DShot ESCs can use the direction-setting function currently provided by PX4/QGC; for standard PWM ESCs, disconnect power and swap any two phase wires between the motor and ESC to reverse the rotation direction;
  • Proceed to subsequent testing with propellers only after all motor numbers and rotation directions are correct and the test results have been recorded.

For the PWM pin sequence, see Appendix: FlyCore-FC Interfaces and Pin Definitions. For interface functions and actuator power requirements, see FlyCore Interface Description and FlyCore Electrical Integration Guide.