**quadcopter frame****：**quadcopter frame KIT FDHI412 quadcopter frame is a long flight time four axis carbon fiber drone Frame , The arm of FDHI412 is pluggable, both the cover and arms can be locked with the quick locking hooks. Due to its detachable arm the FDHI412 drone Frame is also easy to carry.FDHI412 can be applied in many fields like aerial photography, emergency rescue, reconnaissance mission, power line inspection, remote sensing survey and mapping etc.

**Propellers:** All four propellers must provide lift, and at the same time, the spin of the propellers must be offset, so forward and reverse propellers are required, that is, the diagonal propellers rotate in the same direction, and the same direction. Adjacent paddles rotate in opposite directions, so do the opposite.

Proportional control: Amplify the error input by the controller according to a certain proportion

Integral control: However, the system in the steady state will also have a certain error. In order to eliminate the error in the steady state, the error in the steady state is integrated over time. The integral term will tend to 0 as the time increases, so the integral decreases. Steady-state error

Differential control: predicts the trend of the error change according to the change rate (differential) of the input error signal, avoids the lag characteristic of the controlled object, and realizes advanced control

Parameter adjustment: Constantly adjust the proportional coefficient, integration time and derivative time of the PID controller according to the characteristics of the controlled process

The four-axis rotor is divided into "+" and "x" type. The "+" type flight control board is in front of the rotor, and the "x" type flight control board is in front of the angle bisector. The following figure shows the flight principle of the “x” quadrotor.

Pitch: Rotate around the y-axis, low forward and high climb, 1,2 speed decreases, 3,4 speed increases, pitch is negative

Roll: Rotate around the x axis, the speed of 2,3 increases, the speed of 1,4 decreases, the body rolls right, and the roll value is positive

Yaw: Rotate around the z-axis, assuming 2,4 clockwise, 1,3 counterclockwise, when the speed of 2,4 increases and the speed of 1,3 decreases, the nose is yaw to the right, and the yaw value is positive

Vertical: adjust the throttle size, the speed of the four rotors will increase or decrease at the same time

Pitch: When the positive semi-axis is above the horizontal plane of the coordinate origin (look up), the pitch is positive, otherwise it is negative

Roll: The body rolls to the right as positive, otherwise it is negative

Yaw: right yaw of the nose is positive, otherwise it is negative

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Email: export at dronefromchina.com

Add: NO. 9 Dayu Road PiDu distric, ChengDu 611730, China