What does the accelerometer do on a phone? Accelerometer in a tablet - what is it? A brief excursion into history

What is MEMS? This abbreviation hides the name “microelectromechanical systems”. They are miniature devices containing microelectronic and micromechanical components. The very name MEMS, frankly speaking, is not at all familiar to users. However, every day we use many devices based on these solutions. The most simple example microelectromechanical system can serve as an accelerometer, which is used in all modern smartphones, game consoles and hard drives. However, there are many other systems, the use of which is by no means limited to consumer electronics. MEMS-based solutions are used in the automotive industry, the military industry, and medicine.

History and architecture

First, a little history. By and large, 1954 can be considered the beginning of the development of MEMS. It was then that the piezoresistive effect of silicon and germanium was discovered, which formed the basis of the first pressure and acceleration sensors. 20 years later - in 1974 - the National Semiconductor company launched mass production of pressure sensors for the first time. And in the 1990s, the market for microelectromechanical systems grew significantly due to the introduction of various miniature sensors in automotive electronics.

MEMS systems are given the prefix “micro” due to their size. The components of such devices have sizes from 1 to 100 microns, and the dimensions ready-made systems vary from 20 µm to 1 mm.

MEMS sensor

In terms of architecture, a MEMS device consists of several interacting mechanical components and a microprocessor that processes the data received from these components. There is no standard for mechanical elements: their type can vary greatly depending on the purpose of a particular device.

Both traditional silicon and other materials, such as polymers, metals and ceramics, can be used as materials for the production of MEMS. Most often, mechanical systems are made of silicon. Its main advantages lie in its physical properties. Thus, silicon is very reliable - it can operate over trillions of operation cycles without breaking down. As for polymers, the good thing about this material is that it can be produced in large quantities and, most importantly, with a variety of various characteristics for specific tasks. Well, metals (gold, copper, aluminum), in turn, provide high reliability indicators, although they are inferior in the quality of their physical properties to silicon.

It is worth mentioning separately such materials as silicon, aluminum and titanium nitrides. Due to their properties, they are widely used in microelectromechanical systems with piezoelectric architecture.

When it comes to MEMS manufacturing technologies, several main approaches are used. These are volumetric micromachining, surface micromachining, LIGA technology (Litographie, Galvanoformung and Abformung - lithography, electroplating, forming) and deep reactive ion etching. Bulk processing is considered the most cost-effective method for producing MEMS. Its essence lies in the fact that unnecessary areas of material are removed from a silicon wafer by chemical etching, as a result of which only the necessary mechanisms remain on the wafer.

Result obtained using volumetric processing

Deep reactive ion etching almost completely replicates the bulk micromachining process, except that plasma etching is used instead of chemical etching to create mechanisms. The exact opposite of these two processes is the surface micromachining process, in which the necessary mechanisms are “grown” on a silicon wafer by successively depositing thin films. Finally, LIGA technology uses X-ray lithography techniques to create mechanisms that are significantly taller than they are wide.

In general, all MEMS can be divided into two broad categories: sensors and actuators. They differ in the principle of their operation. If the sensor's task is to transform physical influences into electrical signals, then the actuator does the exact opposite work, translating the signal into some action. The same accelerometer is a sensor, and an example of a device using actuators is a DLP projector (Digital Light Processing).

BenQ DLP projector uses actuators

Well, now we’ll talk about each device separately.

Accelerometers

The most common MEMS device is the accelerometer. As mentioned above, the scope of its use is extremely wide. It covers mobile phones, laptops, game consoles, and more serious devices, such as cars. The very purpose of the accelerometer is to measure apparent acceleration. In the case of mobile phones, it is used for many purposes. For example, to change the screen orientation. Or performing any functions when “shaking” the device. In addition, we should not forget about games - they are, perhaps, the main area of ​​application of accelerometers. Nowadays it is difficult to imagine an “advanced” toy that would not be controlled by tilting the phone. In short, the accelerometer has become an integral part of smartphones. By the way, for the first time it was installed in a mobile Nokia phone 5500. Thanks to the accelerometer, the phone could be used as a pedometer. Morning joggers were delighted! But, of course, only after Apple release iPhone accelerometers have reached the peak of popularity. And in general, interest in MEMS began to grow along with the development iOS platforms and Android.

Nokia 5500 is the first phone with an accelerometer

Accelerometers are also available in various controllers game consoles, be it an ordinary gamepad or a slightly different device, for example, a PlayStation Move motion controller. By the way, the accelerometer is also used in the helmet announced recently virtual reality Sony Project Morpheus.

Of particular importance is the accelerometer used in laptops, or more precisely, in their hard drives. Everyone knows that hard drives are quite fragile devices, and in the case of laptops, the likelihood of them being damaged increases significantly. So, when a laptop falls, the accelerometer detects a sharp change in acceleration and gives a command to park the head hard drive, preventing both device damage and data loss.

Accelerometer InvenSense MPU-6500

By a similar principle, the accelerometer affects the operation of a car DVR. During sudden acceleration, braking and lane changes vehicle The video recording is marked with a special marker, which protects it from erasing and re-recording, which greatly facilitates further analysis of road accidents.

Overall, the largest and most promising market for accelerometers and other MEMS is the automotive industry. The fact is that, unlike the mobile and gaming devices, where accelerometers are used for entertainment purposes, in cars literally all safety systems are based on the operation of the accelerometer. With their help, the airbag deployment system, anti-lock braking system, stabilization system, adaptive cruise control, adaptive suspension, Traction Control system work - and this is far from full list! Considering that car manufacturers devote Special attention safety, the number of accelerometers and other MEMS applications will only increase.

Crash test of the Opel Vectra. In the 90s, airbags were often only an option

But despite the fact that the scope of use of the accelerometer is quite clearly defined, developers continue to think about what other purposes this device can be used for. For example, scientists from the National Institute of Geophysics and Volcanology of Italy, Antonio D'Alessandro and Giuseppe D'Anna, proposed using the accelerometer of a mobile phone as an earthquake sensor. Very interesting! The studies were conducted with an iPhone accelerometer, and the results were compared with readings from a full-fledged earthquake sensor from Kinemetrics. As it turned out, mobile gadget capable of detecting strong earthquakes measuring more than 5 on the Richter scale, but only if it is located near the epicenter of tremors. The results are not so impressive, but scientists are confident that the sensitivity of accelerometers will only increase, and in the future they will be able to detect less powerful earthquakes. The only question that remains is: why would a phone's accelerometer measure the strength of tremors when there are earthquake sensors? The thing is that scientists set as their goal the creation in the future of an entire network of smartphones in seismically active areas. In theory, during earthquakes, data from smartphones will be sent to an analytical center, which will make it possible to determine the areas most affected by the disaster and properly coordinate rescue operations. The idea is more than interesting and, most importantly, really in demand in some parts of the world, but now it is difficult to imagine how it will be implemented in practice.

Now let's talk about the design of the accelerometer itself. There are several types of devices depending on their architecture. The operation of the accelerometer can be based on the capacitor principle. The moving part of such a system is an ordinary weight, which moves depending on the tilt of the device. As it is displaced, the capacitance of the capacitor changes, namely, the voltage changes. Based on these data, it is possible to obtain the displacement of the weight, and at the same time the desired acceleration.

Accelerometer based on the capacitor principle. The photo shows capacitor plates, a fixed part (proof mass), and a spring.

The most common type of accelerometers are piezoelectric systems. Just like in capacitor accelerometers, they are based on a weight that exerts pressure on a piezoelectric crystal. Under pressure it produces electricity, which allows you to calculate the desired acceleration, knowing the parameters of the entire system.

There is another type of accelerometer, which is fundamentally different from capacitor and piezoelectric. Such accelerometers are called thermal. Their architecture involves the use of an air bubble. When accelerated, the bubble deviates from its initial position, and this is recorded by sensors. Knowing how much the bubble moved during movement, you can calculate the magnitude of the acceleration.

Gyroscopes

Another interesting sensor often used in conjunction with an accelerometer is a gyroscope. Its main purpose is to measure angular velocities relative to one or more axes. Actually, the combination of an accelerometer and a gyroscope allows you to track and record movement in three-dimensional space.

The first of mobile devices, possessing a gyroscope, became Apple iPhone 4, after which the presence of this MEMS became almost a mandatory requirement for any smartphone. Users were able to evaluate the functionality of the gyroscope in many mobile games, where instead of one of the two virtual joysticks a shot button appeared. Well, you already had to aim by positioning the smartphone in space, which became possible thanks to the presence of a gyroscope.

Gyroscope used in Apple iPhone 4

In addition to mobile devices, gyroscopes are present in controllers for PlayStation, Xbox and Wii game consoles, where they function together with accelerometers. These systems are also used in cameras for optical stabilization to obtain high-quality images.

The architecture of gyroscopes is in many ways similar to that of accelerometers. Many of these devices have a capacitor structure. This design, for example, is used in its products by STMicroelectronics. Their gyroscope is based on a mechanical element that works on the principle of a tuning fork and uses the Coriolis effect to convert angular velocity into movement of a sensitive structure. Let's explain this process a little.

Two moving masses are in constant motion, and in opposite directions, which are indicated in blue in the figure. When the angular velocity changes, the Coriolis force begins to act, designated yellow. In this case, the direction of the Coriolis force is perpendicular to the direction of mass movement. The Coriolis force causes a displacement of masses proportional to the magnitude of the angular velocity. Since the system has a capacitor structure, any displacement causes a change in electrical capacitance. And thus angular velocity converted to electrical parameter. It is also worth noting that thanks to the use of special tuning forks, STMicroelectronics gyroscopes are insensitive to random vibration. With such an undesirable effect on the moving masses, they will both shift in the same direction, thereby not changing the capacitance of the capacitor.

This is what a gyroscope chip made by STMicroelectronics looks like

Magnetometers and barometers

Another interesting microelectromechanical system is a magnetometer. It, like a regular magnetic compass, tracks the device’s orientation in space relative to the Earth’s magnetic poles. The information obtained is used mainly in mapping and navigation applications.

In addition to a magnetometer, a MEMS barometer is often used. The barometer first appeared in Samsung device Galaxy Nexus, released in 2011. Again, its functionality is no different from the traditional one - it measures atmospheric pressure in current location devices. At the same time, the barometer reduces the time it takes to connect to the GPS system. The very essence of the sensor’s operation is to compare the external atmospheric pressure in relation to the vacuum chamber inside the sensor itself. This allows you to determine the user's location with an accuracy of 50 cm in height and significantly expands the user's navigation capabilities, since it also allows you to determine the vertical location. For example, a mobile phone with a barometer will help determine your route on any floor shopping center what it can't cope with GPS system, indicating only the location on the plane.

Just a few years ago, we could not even imagine that there were games on smartphones where control was carried out by rotating the device itself! Nowadays there are a great many such games in online mobile app stores, but back then it seemed something incredible.

Want an example? This could be, say, various car races, which are controlled by tilting a smartphone or tablet in different sides, while the car turns. One of the most famous such games is Asphalt 8:

Attention, question! How is this possible? Answer: This is made possible thanks to the accelerometer.

What is an accelerometer and how does it work?

An accelerometer is a device that measures the projection of apparent acceleration (the difference between the true acceleration of an object and the gravitational acceleration). The accelerometer allows you to record even minor changes in acceleration depending on its position in space.

In a smartphone or tablet, the accelerometer is an extremely small part, often slightly larger than a match head. Despite this, he performs his actions as expected.

Where is the accelerometer used?

As mentioned above, the device is used in smartphones and tablets. Moreover, they began to install it relatively recently - along with the advent of iPhone smartphone, and after that it began to be installed in other mobile devices.

In addition, the accelerometer is used:

• In industrial aviation, where it is an integral part of navigation systems, as well as aircraft control.

• In industrial vibration diagnostics it is a vibration transducer that measures vibration acceleration in systems non-destructive testing and protection.

• In control systems hard drives to activate the damage protection mechanism. When accelerating (for example, when falling hard disk), the system “parks” the hard drive heads, thereby preventing damage to them, as well as data corruption.

• In video recorders. Here the accelerometer allows you to distinguish important events: sudden acceleration or braking, collision, etc.

• In game consoles, or to be precise - in control devices game consoles. The joystick may not even have buttons and is controlled by turning it in space, shaking it, etc.

Why do you need an accelerometer in a smartphone?

Currently, the accelerometer is used in smartphones and tablets both for the needs of the operating system and for running some applications, including games.

As for the operating system, thanks to the accelerometer, the screen on the device rotates when we turn it over.

Games were mentioned a little higher. In addition to racing, the accelerometer is actively used in casual games and even shooters.

In short, the accelerometer is an extremely important component of modern mobile technology, as you just verified.

Thanks to the development of technological progress, people have the opportunity to use a fairly large set of tools, while carrying only one smartphone. However, there is a small detail without which the use of this device would not be so convenient - the accelerometer. What is it and why is it so important?

The main function of this device is to measure the acceleration of ground vehicles, aircraft, rockets and other equipment. It first appeared at the end of the 19th century. The device was installed on trains and cars to be able to track the speed at which they were moving.

The scale displayed all possible and maximum valid values for a specific type of transport. This structure made it possible to prevent exceeding the speed limit and prevent engine destruction. But this assistant also had one drawback. What is this? The accelerometer was extremely bulky. So subsequently the design changed all the time.

The first such devices came to Russia as part of Ford and Mercedes-Benz cars. They also went along with steam locomotives made in Germany. There was just one problem. The problem was that these accelerometers could not withstand cold climates. Therefore, Russian transport engineering enterprises had to develop their own models.

Varieties

There are the following types of accelerometers:

• Capacitive. Monitors the change in capacitance between static and dynamic states.
• Piezoelectric. The device works due to the effect of the same name (depending on the pressure on the crystals, an electric potential appears).
• Piezoresistive. Measures electrical resistance depending on the applied mechanical pressure.
• Hall effect device. Measures changes in voltage that occur due to changes in the magnetic field around the device itself.
• Magnetic resistor. Detects changes in the magnetic field. Unlike the previous one, it measures resistance.
• Heat transfer device. Depending on the acceleration, it measures changes in heat transfer.

New time

In the photo above you can see mobile app, simulating an accelerometer.

The modern structure of accelerometers makes it possible to connect them with on-board computer in cars, trains, planes and rockets. Thus, an absolute integral system is obtained. Its main task is to analyze the measurement of the acceleration indicator. Subsequently, the computer gives the appropriate command to adjust the work, and the speed of movement increases or decreases.

On this moment The use of the accelerometer sensor has expanded beyond the transportation industry. This device also began to be installed in mobile phones, but in a slightly different form. It is the modern variation of the reduced device that will be discussed further.

Mobile industry

It has already been said above that an accelerometer is a device that allows you to measure and regulate changes in vehicle speed. However, today it can also be found in cell phones.

First device

The first mobile device to receive an accelerometer was the Nokia 5500. small body it was not possible to use the device in its original form. Because of this, it was decided to use a miniature chip. There was an inert mass inside it. A reasonable question arises: what function did the first accelerometer in a phone perform? What was it? The same thing that is extremely popular now in various fitness bracelets and other devices is a pedometer.

How it works

The general operating algorithm is not too different from the original device. The chip was embedded according to the principle of a fixed structure with attached conductors. The inert mass located inside, undergoing acceleration, changes its location in space. Thanks to this shift, the device receives data about all location changes. The conductors extending from the device were located between the contacts that took meter readings.

Due to the extremely small size of all chip parts, production of parts is carried out without human intervention - only automated conveyors.

It is worth noting that the accelerometer in a smartphone is a part that allows you to save important data. For example, when the device is in flight (falling or being thrown over), the device detects this state and issues a command to block the most fragile parts responsible for recording data. For example, this happens with the recording head of a laptop hard drive.

However, in modern gadgets You can find not only an accelerometer, but also a gyroscope.

What is a gyroscope?

In the photo above you can see a rotary gyroscope. This is a device that responds to changes in the angle of inclination relative to the Earth's surface. The simplest example is a spinning top. It was invented in 1817. Its advantage was the ability to work in fairly bad conditions, such as:

• low level of visibility;
• presence of electromagnetic interference;
• surface shaking and many others.

Varieties

At the moment, there are two main categories of these devices.

By degree of freedom:

• two-degree;
• three-degree.

Based on the operating principle:

• optic;
• mechanical.

First appearance in the mobile industry

The very first representative of this field to receive a gyroscopic sensor was a smartphone from Apple- iPhone 4. This feature allowed you to change the orientation of the phone from portrait to landscape, depending on its position in space.

This innovation was extremely popular among buyers, and therefore other mobile device manufacturers quickly picked up the idea and began installation of this element V own phones. It is worth noting that all subsequent iPhone models included this function on a mandatory basis.

However, devices on Android platform do not always have a gyroscopic sensor. Therefore, before purchasing a device with this operating system, it is worth inquiring about the presence of a gyroscope in the device. It can be done:

• by finding a list of characteristics on the Internet;
• ask a consultant at the store.

The first is preferable, since consultants are not always aware of the features of a particular smartphone model.

How to determine the presence of a gyroscopic sensor in a device?

As mentioned above, you can familiarize yourself with the characteristics of the phone on the website of the manufacturer or store that sells it. Most often, the presence of this element is required.

Another option is to check on a 360-degree video. If, when viewing it, there is a function to rotate the image in any valid direction, then the sensor is present.

And the last option is checking with the application AnTuTu Benchmark. It conducts full diagnostics smartphone and necessarily indicates the presence of this component.

Calibrate your phone's accelerometer

The presence of such an element in a modern smartphone is extremely important. It allows the device to perform a number of extremely important functions:

• display rotation;
• performing actions when shaking the screen;
• ensuring the operation of the pedometer;
• demonstration of the present position in space.

Below is an example of how to calibrate the Xiaomi accelerometer. This instruction Suitable for both mobile devices of this manufacturer and many other smartphones on the Android platform. It is quite simple and does not require a lot of time and knowledge about working with phone functions. To start screen calibration, you must perform the following sequence of actions:

• select the “settings” menu;
• go to the “display” item;
• Click on the “accelerometer calibration” function. Next, she herself will configure the correct display of the image on the screen in various positions.

Results

Despite the fact that the accelerometer and gyroscope appeared as devices for use in the field of mechanical engineering, today no smartphone can be considered complete if these components are missing. The above functions make its use as comfortable as possible. Therefore, before purchasing a phone, be sure to check their availability among the list of its main characteristics.

Accelerometer - what is it and why is it needed?

Our life consists of everyday little things that in one way or another affect our well-being, mood and productivity. I didn’t get enough sleep - my head hurts; I drank coffee to improve the situation and cheer up - but I became irritable. I really want to foresee everything, but I just can’t. Moreover, everyone around, as usual, gives advice: gluten in bread - don’t go near it, it will kill you; A chocolate bar in your pocket is a direct path to tooth loss. We collect the most popular questions about health, nutrition, diseases and give answers to them that will allow you to better understand what is good for your health.

The popularity of smartphones today is simply off the charts: it is very convenient to always have a microcomputer with a variety of useful functions, is not it? Much more convenient than carrying a laptop with you - you can’t put the latter in your pocket and you won’t be able to take it out unnoticed under your desk if the lesson turns out to be too boring... However, all phones have the same drawback - the screen is too small when compared with a computer or even a tablet and netbook. Because of this, surfing websites, using a reader and some applications is not so convenient... it would be if modern smartphones were not equipped with accelerometers.

Accelerometer on a phone - what is it?

An accelerometer is a built-in device that automatically changes the screen orientation from portrait to landscape and vice versa when you rotate or shake the device. It is worth explaining with an example. You stood and read something from the display. We got tired, decided to rest and lay down on the sofa. Since lying on your side is healthier than lying on your back, you assume the fetal position - and find that the contents of the screen “lay on its side” with you. No matter what position you hold the phone in, the lines on the display will be parallel to the ground.

Since the architecture of most Internet sites is designed for viewing from computer monitors, it is more convenient to read them from a phone. horizontal orientation – the line becomes wider. You don't need to make the font tiny to fit the entire column on the screen. It’s also more convenient to type messages: the keyboard buttons are getting larger. And when you need to use your smartphone how regular phone, that is, to call someone - just flip it vertically, and the accelerometer will align screen objects to a vertical orientation. Long live automation - it allows us to save time without performing unnecessary manual actions!

Accelerometer in a tablet - what is it?

What an accelerometer is in a tablet is not worth explaining at length, since it is not much different from the telephone analogue. Because this device Invented for viewing Internet sites, photo albums and movies, as well as for killing time with video games, automatically expanding the image on its screen by turning the body is simply necessary. The convenience of this function was appreciated by everyone who was lucky enough to use first an old tablet, then a new one. Almost all new models are equipped with accelerometers: their presence or absence has little effect on the final price of the device, which is why tablets without accelerometers have simply become unclaimed.

Majority modern smartphones equipped with an accelerometer. However, not everyone knows what it is and why an accelerometer is installed in a phone.

An accelerometer or G-sensor is a sensor that determines the angle of inclination electronic device in relation to the earth's surface. Based on sensor data software understands the position of the smartphone and rotates the image on the display. In other words, it is the accelerometer that helps automatically rotate the screen landscape orientation when turning the phone.

This sensor also records the acceleration of the device’s movement in space, simultaneously comparing three spatial coordinates. We can say that the sensor measures the difference between the projections of absolute and gravitational acceleration.

Today, accelerometers are installed in many smartphones. After all, it is this sensor that makes it possible to use applications such as a pedometer, or change the position of the screen automatically taking into account the position of the gadget itself. Within the game, the G-sensor allows control without buttons.

Why do you need a G-sensor in a smartphone?

As we said above, in mobile phones New generation accelerometers are used very often. This sensor allows you to install and use various applications. If there is no sensor in the smartphone, it functionality are significantly reduced.

The accelerometer in a smartphone allows you to use:

1. Pedometers or other similar services. Thanks to the ability to measure the position of the device in space, as well as its acceleration, the sensor provides correct operation pedometer. This indispensable assistant for fans of jogging or walking. There is no need to buy a separate fitness tracker because you can install an app on your phone and use it for specific purposes.

2. Games. Thanks to the G-sensor, the gaming process becomes a real pleasure, because the sensor instantly reacts to minimal changes in the position of the phone. You can abandon the classic console control system, since you can adjust the position by changing the position of the phone in space.

3. User-friendly interface. When you change the position of the smartphone, the sensor will immediately rotate the device interface to the desired position. Operation of the device is as convenient and comfortable as possible. Auto-rotate the screen is especially convenient when watching videos or movies.

How is the G-sensor calibrated?

Calibration is a list of operations to determine the relationship between the values ​​of certain quantities obtained using an accelerometer or any other measuring device and reference values. The resulting difference allows you to calibrate the device. Why calibrate? It's simple. Only fine tuning of the sensor guarantees its correct operation, which in turn will ensure the correct operation of applications and individual device functions.

Calibration is performed using special applications, which can be downloaded on the Internet. Install the appropriate application on your phone. Then place the device on a perfectly flat surface. If it has any protruding elements, it is better to remove it while calibrating the sensor.

Now go to the applications menu and find the “G-sensor calibration” tab. After some time, the application will display a message on the smartphone screen indicating that the sensor is fully calibrated.