Quadrotor


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A quadrotor, also called a quadrotor helicopter or quadrocopter, is a multicopter that is lifted and propelled by only four rotors. Quadrotors are classified as rotorcraft, as opposed to fixed-wing aircraft, because their lift is derived from four rotors. Unlike most helicopters, quadrotors use fixed-pitch blades, whose rotor pitch does not vary as the blades rotate; control of vehicle motion is achieved by varying the relative speed of each rotor to change the thrust and torque produced by each.
There are two generations of quadrotor designs. The first generation quadrotors were designed to carry one or more passengers. These vehicles were among the first successful heavier-than-air vertical take off and landing (VTOL) vehicles. However, early prototypes suffered from poor performance,and latter prototypes required too much pilot work load, due to poor stability augmentation.
The more recent generation of quadrotors are commonly designed to be unmanned aerial vehicles (UAVs). These vehicles use an electroniccontrol system and electronic sensors to stabilize the aircraft. With their small size and agile maneuverability, these quadrotors can be flown indoors as well as outdoors.


Flight Control


Each rotor produces both a thrust and torque about its center of rotation, as well as a drag force opposite to the vehicle's direction of flight. If all rotors are spinning at the same angular velocity, with rotors one and three rotating clockwise and rotors two and four counterclockwise, the net aerodynamic torque, and hence the angular acceleration about the yaw axis is exactly zero, which implies that the yaw stabilizing rotor of conventional helicopters is not needed. Yaw is induced by mismatching the balance in aerodynamic torques (i.e., by offsetting the cumulative thrust commands between the counter-rotating blade pairs).
Angular accelerations about the pitch and roll axes can be caused separately without impacting the yaw axis. Each pair of blades rotating in the same direction controls one axis, either roll or pitch, and increasing thrust for one rotor while decreasing thrust for the other will maintain the torque balance needed for yaw stability and induce a net torque about the roll or pitch axes. This way, fixed rotor blades can be made to maneuver the quad rotor vehicle in all dimensions. Translational acceleration is achieved by maintaining a non-zero pitch or roll angle.



Preparing the transmitter:

Create a new model memory and make sure that all mixes are disabled, all trims are neutral
and that all End Point Adjustments (EPA) and D/R’s are set to 100%
If you have a computer-radio you can chose either airplane or helicopter mode. It doesn’treally matter. The helicopter mode will have the advantage of setting a custom throttle curve
for those who doesn’t like a linear response on the throttle. If you use the helicopter mode
make sure that the swash is set to; two servos 90°.
Arming and disarmed the flight-controller:
The flight-controller has a built in safety feature which disables the throttle stick. This is a
great feature that probably will save your platform or face at least once.
The Control board will on power up be in the “locked”/disarmed position. The LED on the board
indicates if the board is armed or not.
LED off = “locked”/disarmed, LED on = Armed.
To arm the board move the throttle/rudder stick down to the right corner and hold it there
for about 5 seconds. The LED will turn on indicating that the board is armed and ready. To
unarm/lock the board again move the throttle/rudder stick down in the left corner for 5
seconds.
1. Check if the throttle stick

This is to ensure that the throttle stick is moving the right direction and have enough trow
to initialize the flight-controller.
Never perform this step with the props mounted!
- Turn on the transmitter and then the flight-controller
- Move the throttle/rudder stick to the down-right corner
- The LED should turn on, if it doesn’t:
- Try adding a bit of “down” trim on the throttle channel
- Try increasing the EPA on the throttle channel
- Try reversing the throttle channel

2. Calibrating the throttle range on the ESC’s

This is to ensure that all the ESC’s have the same throttle range end points. This step only
needs to be performed once. Fail to do this calibration can result in an uncontrollable
platform. If you ever install new ESC’s this step needs to be performed again.
Never perform this step with the props mounted!
- Make sure that the flight-controller is turned off
- Turn the Yaw pot to the MIN position
- Turn on the transmitter
- Move the throttle stick to top (full)
- Turn on the flight-controller
- Wait until the ESC's beeps twice after the initial beeps. (Plush and SS ESC's)
- Swiftly move the throttle stick fully down (closed). The ESC’s beeps
- Power off the flight-controller
- Restore the yaw pot to around 50%

3. Checking the direction of the transmitter channels

This step is to ensure that the sticks actually perform the action in the way that they are
supposed to.
Never perform this step with the props mounted!
- Turn on the transmitter and then the flight-controller
- Arm the controller. (Move the throttle stick to the down-right corner)
- Start the motors by raising the throttle (around 1/4 or so)
- Move the Pitch (Elevator) stick on the transmitter forward. The back motor should speed
up. If it doesn’t, reverse the channel in your transmitter.
- Move the Roll (Aileron) stick to the left. The right motor should speed. If it doesn’t,
reverse the channel in your transmitter.
- Move the Yaw (Rudder) stick to the left. The front and back motor should speed up. If it
doesn’t, reverse the channel in your transmitter.