Can Drones Hover? Keeping a Drone in the Air Without a Pilot

Last updated July 20th, 2020
A drone hovering

One of the most exciting things about the movement of drones is the potential ability to hover on the same spot.

Believe it or not, the technology that makes that iconic drone hovering possible is no more than a few years old and is largely copied from your smartphone tech.

In this article, we’re not only going to understand how drones move and how they are able to hover, but we’re going to look at other forms of movement we have come to associate with unmanned aerial vehicles.

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How Do Drones Fly?

Drones are able to fly thanks to their rotors and a host of other components.

Gyroscope Stabilization

You know that smoothness and gracefulness you associate drone flight with and make them such a joy to control?

That’s thanks to gyroscope stabilization technology.

The gyroscope works to augment the drone’s flight capabilities. It is thanks to the gyroscope that a drone can hover, for example, and maintain steep angled turns.

To best understand the role of gyro stabilization in creating the flying experience you expect, it is important to take note that every drone is constantly being subjected to a host of forces coming from various directions.

These forces, like wind for example, affect the way the drone moves, making it very difficult to control a drone.

Integrated gyroscopes come to the rescue by almost instantly detecting changes in the position of a drone and compensating for it in such a way that it basically seems unaffected.

The gyroscope re-adjusts the drone’s position hundreds of times every second so that your drone calmly “hovers” in the same position.

It’s a balancing act for the ages, which is barely noticeable to the naked eye.

Modern gyroscopes are manufactured with components between 1 to 100 micrometers in size and often include sensors for multiple axes in a single package.

The gyroscope is embedded in the inertial measurement unit (IMU)

Inertial Measurement Unit (IMU)

The IMU operates by tracking the current rate of acceleration with he help of one or more accelerometers.

Because the IMU contains one or more gyroscopes, it is able to detect changes in the rotational features like pitch, roll, and yaw.

Some of the more advanced drones even have magnetometers included  in the IMU to help in calibration against orientation shift.

Processors onboard the IMU continuously calculate the drone’s present position. First they integrate the sensed acceleration, and they estimate the gravitational pull on the drone. This information is then used to calculate the present velocity of the drone. The IMU then uses the velocity of the drone to calculate the current present position of the drone.

In order to drift in any direction, the flight controller collects data from the IMU which pertains to present positioning and then sends the information to the motor electronic speed controllers (ESC).

The electronic speed controllers in turn coordinate with the motors to adjust the speed and thrust needed for the drone to fly in any required direction or hover on the same spot.

The inertial measurement unit is able to impact flight and hovering in this manner because it is embedded in the drone’s flight controllers.

Flight Controllers

Flight controllers are not just any piece of hardware. They can be characterized as the brain of the drone.

This part of the drone is made up of so many smaller components, all of which play essential roles in accomplishing the extraordinary stuff we have come to expect from drones.

The best examples are the gyroscope and IMU which all contribute in propelling the drone during flight, determining direction, and sensing orientation.

The flight controller also contains high-level software and mathematical programs that all work in unison with the hardware to fly and navigatethe drone with stability.

A few of the functions of the flight controller which need the IMU and gyroscope to be executed include:

  • Intelligent orientation controls
  • Signals the motor ESC’s on direction and thrust
  • Points of Interest flight mode
  • Auto return or home flight
  • Intelligent landing gear function
  • Very sensitive in-built damper IMU module
  • Multi-rotor fail protection
  • Banked turn module and cruise control features
  • In-built bluetooth module and mobile parameter adjustments support
  • High precision satellite receiver

Rotors and Vertical Motion

Rotors play a very important role in flying and hovering because the drone uses them for propulsion and control.

Think of them as fans, since they pretty much do the same thing. You should also never put your finger into spinning rotors for this very reason.

In order for a drone to lift vertically, it must produce a lift force that exceeds the forces dragging it down: gravity.

To accomplish this, the spinning rotors push air down. This air, in turn, pushes the drone upwards at the same time. Forces always happen in pairs, according to the laws of physics.

This controlling of the upward and downward force is the basic idea behind lift, and it is leveraged in some form in all vertical moving vehicles or aircrafts.

As you can imagine, the faster the rotors spin, the more air they push down and the greater the lift force. Likewise, the less air pushed down, the lower the lift force.

On the vertical plane, there are three main movements which a drone can do: hovering, climbing, and descending; and achieving all three entail manipulating the lift force of the drone as required.

To hover at the same height, the drone has to use the rotors to produce a lift force that is equal to the gravitational force pulling it down. Once this is achieved, the drone neither falls to the ground nor rises in the air. It hovers. And we wonder at the beauty of it.

In order to climb, the drone must use the rotors to produce a lift force that exceeds the drag forces weighing the drone down. This is what happens when you instruct the drone to climb with your remote control. The rotors spin faster and increase the lift force till they exceed the force of gravity, at this point the drone rises. The faster the rotors spin, the faster the drone rises.

In order to descend, the drone rotors have to produce a lift force that is less than the force of gravity. Once this is achieved, the drone will lower to the floor. The slower the rotors are, the faster the descent. In the case where the rotors stop entirely, the drone will drop like a rock.

Can Drones Hover In Place Automatically?

Most drones don’t have a hover button or anything like that.

In order to hover, you have to first get your drone up into the air. Once airborne, you have to gently throttle in order to maintain a steady height.

However, when you start to look at drones with GPS and similar, a number of these will have hovering functionality, along with a whole host of other advanced flight features.

As well as hovering in place automatically, you can set your drone to fly specific routes using Waypoint functionality, or you could even set it to lock onto a target (such as yourself) and orbit it in a 360-degree motion — without any need to touch the transmitter yourself.

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