There are a number of different types of movements that take place when a drone are in flight.
The majority of these movements are defined as roll, pitch, and yaw.
But what exactly are they, anyway? And how are drones able to do them?
We wanted to put together the biggest guide on roll, pitch and yaw in the drone space…so here it is.
What is Roll, Pitch & Yaw?
Roll, pitch, and yaw all describe different types of flight for an aircraft. Unlike in a car or a boat, aircrafts are able to move through three dimensions of space. Cars and boats can only move through two.
This makes aircraft movement much more complex and dynamic than that of other forms of aircraft.
Apart from forward and backward movement, aircrafts like drones can perform other basic movements through three-dimensional space, and these are described as roll, pitch, and yaw.
To understand what these movements look like, imagine you watching a giant screen that has an image of an approaching airplane.
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The Differences Between Roll, Pitch & Yaw
What is Roll?
Roll is not quite what it sounds like it might be in drone flying. Whilst it might suggest that it means a horizontal flip — like a barrel roll — roll actually refers to the horizontal movement of a drone; left and right.
With the way that drone physics works, the drone will tilt slightly in the direction that it needs to fly. This tilt is roll.
What is Pitch?
This is movement forwards and backwards. Pitch will tilt a drone’s nose upwards or downwards depending on which way you want it to go.
What is Yaw?
This is a movement that is clockwise or anti-clockwise around the aircraft’s center axis — a rotation. Imagine placing your drone on the floor and then sticking a metal pole right through the middle of it into the ground. Your drone wouldn’t be able to move anywhere, but it could spin on the pole. It could yaw.
Yaw is analogous to turning left or right in a boat.
Oh, you didn’t ask about throttle? Well, we’re going to tell you anyway! Throttle is the vertical movement of a drone — you throttle in order to take flight from the ground, and gently reduce throttle in order to lower it.
How to Yaw, Pitch & Roll On A Drone Controller
To yaw, you simply need to push your controller’s left stick left or right. This is arguably the easiest drone flying lesson to master because you’re not affecting it’s flight — only the direction it’s facing.
Performing pitch movements and rolls are also easy and require you to do the simplest commands with your remote controller, but they take a little more practice to master.
To pitch — remember, that’s to move forwards or backwards — you push your right stick in the direction you wish to go.
To roll, use the same right stick as you would for pitching, but simply move it left or right.
You should ideally be using a drone with ‘headless’ mode, which most drones these days have, which means you don’t need to worry about which way your drone’s nose is facing. Instead, you can simply manouver the drone based on the direction you’re facing.
To throttle, press the left stick forwards. To decrease height, press it backwards.
So there you have the basics. Throttle and yaw are handled with the left stick of a drone controller, whereas pitch and roll are handled with the right.
For those of you that have ever played PlayStation or Xbox games, you’ll probably be used to moving your character around with your left joystick. Getting used to moving your drone around with the right stick therefore requires a bit of practise — but you can do it!
Other terms that you might need to know are rudder, which simply means controlling yaw with your left stick, aileron, which means controlling roll, and elevator, which means controlling pitch.
The Science: How Roll, Pitch & Yaw Works in Drones
Quadcopters operate under the influence of four rotors which we are going to name Rotor 1, Rotor 2, Rotor 3, and Rotor 4.
Assume that Rotor 1 and Rotor 3 rotate in a clockwise direction, while Rotor 2 and Rotor 4 rotate in a counter-clockwise manner.
Clockwise and counter-clockwise movement of the quadcopter’s rotors means that the net angular velocity of the system is zero.
And this in turn means that, despite the fact your rotors are spinning in alternate directions, the drone will not continually rotate but fly steadily in the air as required.
Now, assume that with your drone’s transmitter — another word for controller — you input instructions for your drone to roll to the right.
When performing a roll to the right, the motors that control the rotors on the right side of the drone — Rotor 2 and Rotor 3 in our example — will have their rotation speed or revolutions per minute decreased ever so slightly.
At the same time, the motors that control the rotors on the left side of the quadcopter — Rotor 1 and Rotor 4 — will have their rotation speed or revolutions per minute increased accordingly.
This does not cause the drone to lose any altitude, because the total thrust acting on the system remains the same and thus maintains the height of the drone in spite of drag forces like gravity.
The drone also does not spin out of control because one rotor on the right side spins in a clockwise manner, while the other spins in a counter-clockwise manner. The same happens for the rotors on the left side.
This maintains the net angular momentum at zero, thus keeping the drone steady rather than having it spinning out of control.
The higher rotation speed on the left side causes increased thrust on this side of the quadcopter, resulting in this side rising higher. The reverse happens on the right side. The reduced rotational speed means the drone dips on that side due to reduced thrust in that section.
Put simply: in order to move right, the drone’s left-hand rotors must actually do more work.
What you see from the ground is a drone banking on the right side along its longitudinal axis.
Rolls in which the left side is lifted higher than the right side are known as positive rolls in aviation circles. Moving left — where the right side is higher and it’s rotors are working harder — is known as a negative roll.
The science behind pitch is identical to that of roll, except the rotors that work in tandem with each other are switched.
Instead of our left-hand rotors working hard together to go right, or our right-hand rotors spinning faster to go left, they split and team up — one left and one right, to become front and back rotors.
In order to pitch forwards, the back rotors will spin faster and the front rotors will spin more slowly. The opposite occurs to pitch backwards.
Again, the total thrust remains the same and therefore the drone can maintain a steady height, even if it’s altering the direction in which it’s flying.
Thrust can be considered a push force. In an aircraft, it is the force that moves it through the air. In your drone it is what pushes your drone in any direction — forward, backward, and upwards.
To generate thrust in an aircraft, there is usually interplay between engines and a propulsion system.
In addition to this, torque is any force that causes rotation. You even generate torque when you do mundane tasks like twisting a door knob, pushing a bicycle pedal, and using a wrench to tighten a screw.
A spinning rotor is therefore powered by torque force. That’s why it spins. The magnitude of the torque equals the magnitude of the force causing it.
Just so your knowledge is complete you should take note that additional forces act on the drone apart from the torque and thrust. These are known as drag forces, and they act downwards (gravity) and in opposite directions (friction) to whatever direction the drone is moving.
The angular momentum of a drone — how quickly it rotates, or even if it rotates at all — depends on how fast the rotors of the device spin.
In the case of a quadcopter, where two sets of rotors are spinning in the opposite direction, the angular momentum of the system (aka the drone) is zero. Until you decide to yaw.
So long as there is no external torque applied to the device, which could be as simple as a gust of wind in a real scenario, the total angular momentum of the drone will remain constant at zero.
In this state, the drone remains facing one direction, turning neither left nor right, and not spinning on its center of gravity.
Should that change — e.g. the angular velocity becomes greater than zero — then the drone will yaw in the direction of which the dominant force is being applied.
Clockwise rotors have a positive angular momentum and counter-clockwise rotors have a negative angular momentum.
In order to yaw in a clockwise direction, your drone with simply speed up its clockwise-spinning rotors and slow down its anti-clockwise rotors.
Again, because the overall thrust hasn’t changed, the drone is able to hover in the air even whilst it’s spinning.