How does the Three-Axis Gyroscope and accelerometer help the iPhone locate

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In June 8 last year, the Great Apple company released the latest iPhone 4G, which has many hardware upgrades. For gamers, the largest "Three-Axis Gyroscope "!

The first time I heard that this "Three-Axis Gyroscope" was a time ago, I occasionally found that Apple players were testing the positioning function of the iPod Touch. For details, see "location offset problem of different mobile devices ".
It seems very novel-Because iPod touch can be positioned without GPS, I have studied it specially.

After research, we found that this three-axis gyroscope is also a great news for our location locating enthusiasts, because WiFi and the gyroscope and accelerometer can also achieve positioning, although positioning accuracy remains to be verified, I would like to share with you the Three-Axis Gyroscope and accelerometer knowledge I have collected for this iPhone!

Explain the gyroscope before all


According to the definition of Wiki, "gyroscope is a device used to measure the angle or maintain the direction, based on the Conservation Principle of angular momentum .」

The point of this sentence is the measurement angle or maintenance direction, which is why the iPhone 4 is equipped with such a device. Mechanical gyroscope-for example, the following-has a turntable in the middle to detect changes in the direction. The iPhone 4 uses a miniature, electronic Vibration Gyroscope, also known as a micro-electromechanical gyroscope.

This is what it looks like (). It looks like a secret part in the watch!

Dynamic Display of Three-Axis Gyroscope

Note that the center is a golden rotor with high-speed rotation. Due to inertia, it will not be affected by external forces and change its posture, any changes in the posture of the peripheral device can be detected to determine the angle from which the object rotates in all directions.

Let's put it in one sentence. When I was a child, I used to play the gyro. I know that at a certain speed, I can keep it in a vertical direction.

The biggest role of A Three-Axis Gyroscope is to "measure the angular velocity to identify the motion of an object, so it is also called a motion sensor". In other words, this will let our iPhone know where and where we are going (where they are or where they're going )!

The accelerometer is one of the basic measurement components of inertial navigation and inertial guidance systems. It is essentially an oscillating system installed inside the motion carrier and can be used to measure the Motion Acceleration of the carrier.

The working principle of MEMS accelerometer is that when the accelerometer works together with an external object (the acceleration of the object is the acceleration to be tested) to accelerate the motion, the mass block is moved in the opposite direction by the inertia force. The displacement of the mass block is limited by the spring and damper, and the acceleration of the outside world can be measured by the output voltage.

Working principle of Accelerometer

 

 

 

From the application of MEMS gyroscope, the gyroscope can measure the angular velocity moving along one or several axes and can complement the advantages of MEMS accelerometer, by combining the accelerometer and gyroscope sensors, designers can better track and capture the complete motion of three-dimensional space, it provides end users with a more on-site user experience, precise navigation systems, and other functions.

To accurately describe linear (linear motion) and rotating motion (movement with changing turns), the designers need to use both gyroscope and accelerometer.

• The pure gyroscope solution can be used for rotating detection that requires high resolution and rapid response;
• The simple use of accelerometer solution can be used for applications with fixed gravity reference coordinate system, linear or skewed motion, but the rotation motion is restricted within a certain range. However, acceleration and gyroscope are required when linear motion and rotating motion are simultaneously processed.

In addition, to enable the design and production of gyroscope to have high acceleration and low mechanical noise, or to correct the Rotation Error of the accelerometer, some manufacturers use magnetic meters to complete the sensor functions traditionally implemented by gyroscope, so as to complete the corresponding positioning, so that the gyroscope industry has a specialization. This shows that the hybrid gyroscope, accelerometer, or magnetic induction Sensor combination solution is becoming a trend in the application of MEMS gyroscope technology. If you only use the traditional accelerometer, the user can either get an output that is agile but noisy, or the output that is slow but pure, if the accelerometer is combined with the gyroscope, the output can be both pure and responsive.

An accelerometer is one of the basic measurement components of inertial navigation and inertial guidance systems. It is essentially an oscillating system installed inside the motion carrier and can be used to measure the Motion Acceleration of the carrier, by using known initial speeds such as GPS measurement, you can know the carrier's speed and position by integrating acceleration points. Therefore, the performance and accuracy of the accelerometer directly affect the accuracy of the navigation and guidance system.

Outdoor

• GPS-used to search for a satellite outside

Indoor

• The accelerometer is used to measure the acceleration. Combined with the initial speed provided by GPS, the distance between some velocity movements can be calculated.
• Gyroscope is used to measure the variation of turns or slopes of a device.

In an environment where GPS signals are blocked or disturbed and cannot be located, another method of navigation can be implemented through gyroscope and accelerometer, which can greatly improve the efficiency and accuracy of positioning navigation. After the iPhone is installed with a gyroscope and accelerometer, it will drive a large number of mobile phone manufacturers to follow up, which will effectively promote the further growth of the LBS service.

Related Knowledge:

MEMS

MEMS is the abbreviation of micro-electromechanical systems. MEMS is called micro-machinery in Japan and micro-systems in Europe. It can be made in batches, A micro-device or system integrating micro-mechanisms, micro-sensors, micro-actuators, and signal processing and control circuits until interfaces, communications, and power supply are integrated. MEMS is developed with the development of micro-machining technology and ultra-precision machining technology of semiconductor integrated circuits. At present, MEMS processing technology is also widely used in micro-stream control chip and synthetic biology fields, so as to integrate the chips of biochemistry and other laboratory technical processes.