Motors and props of the quadcopter are mounted to spin in specific directions so that the software can control the roll, pitch, and yaw of the copter. The Aeroquad software we used allows for a number of different configurations, and as many as eight motors! The flight configuration that matched our quadcopter was the Quad X configuration, pictured here. Motors are labeled sequentially in a clockwise direction starting from the front left motor. To control the copter yaw (spin around the z-axis), motors 1 and 3 spin the copter counterclockwise , while motors 2 and 4 spin the copter clockwise. Individually, motors 1 and 3 should spin clockwise with a clockwise prop, and motors 2 and 4 should spin counterclockwise with a counterclockwise prop. To easily recognition the quadcopter’s logical orientation, we marked the front of our quadcopter with a long piece of masking tape. For more information about the copter orientation, Aeroquad’s website explains the quadcopter coordinate system.
The motor’s ESCs also need to be wired to the correct Arduino pins. The ESC signal wires for motors 1, 2, 3, and 4 should be connected to Arduino Uno pins 3, 9, 10, and 11 respectively by default. We used different pin numbers for reasons explained on the motor speed control page. Furthermore, we physically attached the props to the motors by using magneto wire for reasons explained on the troubleshooting page.
Before flight testing, we needed to ensure the motors were spinning in the correct direction and that props were attached correctly (airflow moves downwards), otherwise the quadcopter will spin out of control! The Aeroquad configurator software can spin the motors one at a time to test that each motor/prop is oriented properly. To do this, connect the quadcopter to a laptop running the Aeroquad configurator (NB: the Aeroquad software must already be installed in the copter). Once connected, power on the copter by attaching the battery. Using the “motor commands” information display in the Aeroquad Configurator, each motor can be powered on and tested individually.
If a motor is not spinning in the correct direction, it can be reversed by powering off the copter and switching any two of the three wires connecting the motor to the ESC. If the motor is spinning in the correct direction, but airflow is moving upwards instead of towards the ground, then the opposite prop should be attached.