Gyroscope: all you need to know

Gyroscope module

Many electronic projects need an element of governance, and that happens by having a giroscope or gyroscope. This element can also detect movement or rotation of the device, and help generate a reaction to that movement. For example, if it’s a controller, it could make it turn in the direction the user wants to handle some element or a video game.

The applications of a gyroscope, as you can imagine, are many, like the one integrated in smartphones to be able to know when the screen has been turned and perform some control action on the operating system, to drive vehicles or video game characters, etc. It is also integrated in some laptops to determine that the equipment has been dropped so that the hard disk (HDD) can be turned off in time to prevent the head from hitting the rotating disk and breaking, etc.

They can also be used for orientation systems, to know where a device is going. This is useful for both autonomous robots, and other systems that need to orientate themselves properly with or without user intervention. The drones also have this type of elements installed, and even the virtual reality glasses, augmented reality or mixed, to be able to adapt the image that is seen according to the movement of the user .

Also in the military industry it has had many applications, such as being able to guide the first rockets and missiles that could be directed to a target better thanks to these gyroscopes. In addition, this coupled with modern satellite systems such as GPS, can have very high accuracies.

As you can see, applications are many, and surely you, as a maker, have more in your head for your future DIY project…

A little bit of history

Gyro effect

The sense of orientation has been necessary since many years ago, especially with navigation. The first systems were based on a spinning top, like the 18th-century one by British architect John Serson. With it, he intended to give another use to the spinning top to be able to locate the horizon in the open sea when the visibility was reduced or null.

Little by little the orientation devices evolved until the first gyroscope as such would not arrive until 1852, with Foucault’s invention. It emerged as the product of an experiment to demonstrate the rotation of the Earth. An element with a pendulum that could show that rotation in a simple way.

Little by little, mechanical devices evolved with the proliferation of the aeronautical industry, and military, for torpedoes and missiles. It is necessary to emphasize in this sense the giroscope of Sperry Corp, for the military industry and that was transformed into one of the first directional and modern concepts.

After that, they would start to improve, reduce in size, increase in precision until reaching the current electronic and miniaturized systems thanks to technologies such as MEMS. We already saw something of this in the article of the MPU6050 of this blog.

How does a gyroscope work?

MEMS gyro

The gyroscope or gyro is based on the gyro effect. This is a phenomenon that occurs when a device consisting of a disc mounted on a horizontal axis, around which the disc rotates freely at high speed. If an observer holds the axis of the bottom with the left hand and the axis of the front with the right hand, when lowering the right hand and raising the left one, he will feel a very peculiar behavior.

What the observer will feel is that the gyro pushes his right hand and pulls his left hand. That’s what’s known as the gyro effect. I don’t know if you have ever held in your hand a mechanical hard disk (HDD) with high rotation speeds (7200 RPM), when it is running, but you will surely notice that it has some inertia when you move it, something like this is what I am talking about here…

Well, that phenomenon is used by conventional gyroscopes to be able to tell when a movement occurs. Although the current integrated microelectronic devices in technological devices, referred to in this article, are sophisticated elements that capture the angular displacement per unit of time or how fast a body rotates around its axis, using a different effect.

They get very good accuracies thanks to the MEMS with a known effect this one sees as Coriolis. In this case, it was discovered by the French Gaspard-Gustave Coriolis in 1836. The effect observes in a rotating reference system when a body is in motion with respect to that reference system. It consists of a relative acceleration of the body in that system of rotation. This acceleration will always be perpendicular to the axis of rotation of the system and the speed of the body.

The object in this case undergoes an acceleration from the point of view of the rotating observer, as if there were an unrealistic force on the object that accelerates it. It is a Coriolis force of the inertial or fictitious type, thanks to which it is possible to measure the angular velocity, integrating the angular velocity with respect to time, the angular displacement, or simply to know if an object has moved .

Specifically, in a MEMS-type sensor, you have a small chip inside which a gyroscope has been implemented with a size ranging from 1 to 100 micrometers, that is, even smaller than a human hair. This device is sufficient so that when it is rotated, a small resonance mass moves with the changes in angular velocity, producing very low current electrical signals that will be read and interpreted by the control circuitry.

Characteristics to observe in a gyroscope

chip gyro

Some of the features you should consider when choosing a gyroscope for your project are

  • Range: maximum angular velocity you will be able to measure should not exceed the maximum range of the gyro you choose. However, you should also have the best possible sensitivity, and this is achieved by making the gyro range not much greater than you need.
  • Interface: not too much of a problem, since 95% of gyroscopes on the market have an analog output, although there are some with a digital interface of the SPI or I2C bus type.
  • Number of axes: as in accelerometers, this is very important. They usually do not have as many axes available as in the case of accelerometers, but the more the better. Currently, some 3-axis have started to appear, which is a very good thing. But most models have 1 or 2 axes, which should be enough for most projects. For 3-axis models you should check the information in the model to know which axis measures the roll, because the other two can also measure the pitch and roll of an object, while another one measures the pitch and yaw.
  • Consumption: another important feature, since if your project depends on a battery you must choose one that consumes little energy. Usually it is not too much, the average consumption is usuallyd about 100 micro amps. Some more advanced ones will have a power suspension function when not in use.
  • Extras: some may have some extras, such as accelerometer sensors, temperature meters, etc., in the same module.

Also, if you buy modules, they will have the chip and a PCB with some extras that will facilitate their integration with Arduino, for example, providing connection and power pins, etc.

Gyroscopes you can buy

There are several gyroscope that you can buy such as the MPU6050 which also includes an accelerometer. We already described it in another article, but besides that, there are others that you can easily integrate into your electronic projects along with Arduino.

  • You can buy a gyroscope like the STMicroelectronics LPY503AL. It is one of the most popular, and you can read its datasheet here.
  • You can also use the inertial sensor like the , and , plus the MPU6050…

Its connection and integration with Arduino will depend on each model and manufacturer. But it is not complicated. You can check their datasheets and pinout to know how to manage them. The question is how they work to know how to calculate the angular displacement and that your code in Arduino IDE interprets it and generates an action accordingly…

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