This document describes an experimental study of yaw and pitch control in quadcopters. It discusses how quadcopters use independent variation of rotor speeds to control pitch, roll, and yaw. Yaw control is achieved by varying the net torque on the quadcopter by increasing the thrust of rotors spinning in one direction compared to the other. Pitch control is achieved by varying the net center of thrust. The document provides equations for calculating torque and describes how adjusting rotor thrusts can cause the quadcopter to yaw or rotate in different directions.

1. ASSIGMENT - 7
Name of the Experiment: EXPERIMENTAL STUDY
OF YAW AND PITCH CONTROL IN QUAD COPTER
Theory:
Quadcopters generally have two rotors spinning
clockwise (CW) and two counter clockwise (CCW). Flight
control is provided by independent variation of the speed
and hence lift and torque of each rotor. Pitch and roll are
controlled by varying the net centre of thrust, with yaw
controlled by varying the net torque.
Methodology :
Yaw, Pitch and Roll control: -

2. Yaw Control to Rotate Your Quadcopter
Once at a comfortable hover, push the left stick in either
direction. This will rotate the
quadcopter in place. Rotate it 360 degrees. Then push
the left stick in the opposite direction
and rotate it 360 degrees the other way.
The yaw controller reads the commands received from
the RC transmitter as angular velocities
to improve the movement of the system and avoid
oversensitivity with yaw movement. Thus,
on the controller input there is an integrator which
translates the angular velocity into an
angular set-point. Additionally, in yaw control, the
discontinuities of the system in 360° and -

3. 360° must be taken into account and corrected to avoid
misbehaviour of the system.
Understanding Torque
Let's first talk about centre of Gravity, have you ever
tried to balance an object on the tip of
your finger? That's a centre of gravity! Fun Fact: Your
centre of gravity is your belly button!
The quads are, predictably, near its centre. Torque (τ) is a
twisting force, you use it when you
do things like turn a door-knob handle, use a wrench, or
pedal a bicycle. Now, the torque
produced by a force equals the magnitude of the force
(F) times the radius (r), or distance from
the centre of gravity.
Τ = F∗r
Back to Yaw
So, what does torque have to do with the yaw of the
quadcopter? Well, it turns out, a heck of a lot!
Remember how the motors on our quadcopter spin?
Note that the force is drawn at the centre of the
propeller. In this example we're using the

4. average distance and force to simplify calculations. Feel
encouraged to follow along and use
calculus concepts (representing the force as a continuous
amount), the math still works out.
Calculating the net maximum torque in this diagram can
be done using the following equation:
τ=F(r1) − F(r2) = F(r1 − r2)
Were,
• r1 is the bottom (larger) radius, and
• r2 is the top (smaller) radius. The key takeaway here is
for each propeller despite the
forces being equal, the radii are not and because of that,
• τ is a positive value.
What we end up with is a small amount of torque being
created by each of the two active
motors, these two amounts are in the same direction,
and can be added together.
The combination of these two torques is sufficient to
cause the quadcopter to yaw (twist) in the air.

5. Fig. 2: quadrotor adjusts its yaw by applying more thrust to
rotors rotating in one direction.
A quadrotor yaws in the anticlockwise direction by
applying more thrust to the two clockwise
rotors than the two anticlockwise rotors. A conservation
of angular momentum causes the
quadrotor to rotate as desired. In this diagram, the
thickness of the arrows indicates the relative
amount of thrust applied.
Summary: -
In this experiment Yaw and Pitch control have been
studied.