# Why Do Quadcopter Control Equations for Roll and Pitch Exclude Aerodynamic Drag?

• Benyoucef Rayane
In summary, the conversation is about quadcopters and how to control their movements. The speaker is confused about the effect of changing the velocity of the motors on the angular velocity and thrust generated. They also mention a book they are referencing and ask two questions about the equations for roll and pitch movements and the difference in signs between them. They apologize for any typos in their post.
Benyoucef Rayane
Hey, everyone, I have a question regarding quadcopters, when the set of the arms is of configuration X, to roll we increase the velocity of the two motors on the left/right and decrease the other motors on right/left, the question is when doing so the total angular velocity is zero that means the moment of each thrust generated will be canceled out, this whole thing is confusing, I know I 'm wrong somewhere, Please any explication!

Last edited by a moderator:
Benyoucef Rayane said:
this whole thing is confusing
So is your post. Try separate sentences, precise description of the different situations and a clear question.

sorry, there is a typo, it is not the rolling movement actually it is yawing, so my questions are: considering the figure taken from the book " Quad Rotorcraft Control. Vision-Based Hovering and Navigation", you can find it in this link https://www.researchgate.net/publication/278745381_Quad_Rotorcraft_Control_Vision-Based_Hovering_and_Navigation
1. why the roll and pitch equations, unlike yaw equation, don't take into account the aerodynamic drag
2.since the thrust is always up and the vector from the center of mass to the applied force (Thrust) is the same whether in pitch or roll rotation, so why the negative and positive signs are different in pitch and roll equations

## What is the concept of "the total moment when rolling"?

The total moment when rolling refers to the combination of rotational and translational motion that occurs when an object rolls along a surface. It takes into account the object's mass, shape, and surface it is rolling on.

## How is the total moment when rolling calculated?

The total moment when rolling is calculated by multiplying the mass of the object by its velocity and the radius of the rolling surface. This can be represented by the equation M = mvr, where M is the total moment, m is the mass, v is the velocity, and r is the radius.

## What factors affect the total moment when rolling?

The total moment when rolling is affected by several factors, including the object's mass, shape, and surface it is rolling on. Additionally, the object's initial velocity and any external forces acting on it can also affect the total moment.

## Can the total moment when rolling be negative?

Yes, the total moment when rolling can be negative. This occurs when the object is rolling in the opposite direction of its initial rotational motion. In this case, the rotational motion is acting in the opposite direction of the translational motion, resulting in a negative total moment.

## Why is understanding the total moment when rolling important?

Understanding the total moment when rolling is important because it helps us understand the overall motion of an object and how different factors can affect it. This knowledge is crucial in fields such as engineering, physics, and sports, where rolling objects are common and their motion needs to be accurately predicted.

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