Senior Project - Quadcopter with Rotating Arms

In summary, the conversation discusses the torque required to rotate an arm with a propeller attached to it for a senior project. The gyroscopic force of the spinning propeller and the counter rotation of the propellers on the quadcopter's yaw are potential challenges. The equation for calculating the torque is discussed, but there may not be enough data available. The effect of tilting the propellers on the quadcopter's pitch and the possibility of using mixers to counteract it is also mentioned.
  • #1
meshein
1
0
Hello,

I am working on a senior project right now and I need some assistance with determining the torque required to rotate an arm with a propeller attached to it.

upload_2017-4-20_0-40-34.png


Any of the 4 arms can be rotated to control the direction of travel. The idea is the control system will have a consistent set point at all times. There are two things that theoretically could be a problem. The first is the gyroscopic force of the spinning propeller. This will potentially create a procession of drifting the arm rotationally in one direction. Additionally, there will probably be a very large resistance to changing the angle. This is a very light weight propeller, but it spins are a very high speed and I want to double check that the servos I am using are going to be powerful enough to overcome the torques that are generated by the propellers. In symbolic variable form, what equation would I need to generate to get these values? I don't quite know where to start.

The second issue at hand is the effect of counter rotation on the yaw of the quadcopter. Each opposite propeller spins the same direction, and each adjacent propeller spins the opposite direction. When moving diagonally (lets say to 45 degrees to the right of forward), two propellers will be horizontal and appear like the photo above and two propellers will be angled at about 45 degrees from horizontal pointed in the direction of travel. See photo below.

upload_2017-4-20_0-54-16.png


The concern here is that the counter rotation of the propellers is used to prevent and control the change of yaw of the quadcopter. When the two propellers spinning in the opposite direction go out of plane, will there be a large effect on this yaw? I don't quite know how to calculate this. I suspect the mass of the quadcopter and the mass of the propellers are important. I do know that the quadcopter controls the yaw through its PID. I am just concerned that this out of plane rotation will not be compensated quick enough by the PID response and cause a rotational drift.

Thank you for any help you may be able to provide. Other than trial and error testing, I would like to get a theoretical calculation.
 
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  • #2
Yes the motor and prop could act as a gyro. Look up the torque required to precess a gyro or similar. As I recall its something like..

T = ωsLR
where
T is the torque
ωs is the swiveling rate (rads/sec)
LR is the angular momentum of the gyro

However I suspect you might not have enough data to do the calculations? If you already have the copter it might be easier to measure the torque required to tilt the rotor? Spring balance?

Tilting the props as shown in your second picture will cause the body of the copter to pitch due to Newtons third law. If you have individual control over the speed of each rotor it should be possible to use mixers to counter act that effect.
 

Related to Senior Project - Quadcopter with Rotating Arms

1) What is a quadcopter with rotating arms?

A quadcopter with rotating arms is a type of drone that has four arms attached to its center, each with its own motor and propeller. The arms are able to rotate, allowing the drone to move and change direction in the air.

2) What is the purpose of a quadcopter with rotating arms?

A quadcopter with rotating arms can be used for various purposes such as aerial photography, surveillance, delivery, and recreational activities. It is also commonly used for research and scientific experiments.

3) How does a quadcopter with rotating arms work?

The quadcopter with rotating arms is controlled by a flight controller, which receives input from the pilot and adjusts the speed of each motor accordingly. By changing the speed of the motors, the drone is able to move, hover, and change direction in the air.

4) What are the main components of a quadcopter with rotating arms?

The main components of a quadcopter with rotating arms include the frame, motors, propellers, electronic speed controllers (ESCs), flight controller, battery, and remote controller. Other optional components may include a camera, GPS, and sensors for stability and navigation.

5) Are there any safety precautions to consider when operating a quadcopter with rotating arms?

Yes, it is important to follow all safety guidelines and regulations when operating a quadcopter with rotating arms. This may include registering the drone with the appropriate authorities, flying in designated areas, and being aware of any potential hazards in the surrounding area. It is also important to regularly maintain and inspect the drone to ensure its safe operation.

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