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Accelerometers

Accelerometers, gyroscopes and inertial navigation systems (IMU) are small, multi-purpose sensor devices that appear in an increasing number of electronic devices in our daily environment, including in mobile phones, game consoles, toys, self-balancing robots, as well as in Motion Capture - the technology of human body movement analysis used not only in medicine. Accelerometers are mainly used to measure the linear acceleration of an object, gyroscopes to measure its angular velocity and orientation, and the IMU systems are an integrated combination of a gyro and accelerometer, providing the control system with all the necessary data about the movement and position of the object. The implementation of such measurement functions is also possible thanks to our Grove accelerometers and gyroscopes.

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Accelerometers - the direct measurement of linear acceleration

3-axis accelerometers measure linear acceleration in three axes (X, Y, Z). A uniaxial accelerometer allows you to measure acceleration in any indicated direction. This is used in missiles, homing missiles, trains, and other applications where the object moves in one specific direction. By knowing the acceleration, velocity and time, the measurement system can calculate the distance travelled by the object. Due to the nature of the influence of the Earth's gravitational field, the acceleration of the earth is constant but also measurable by accelerometers - this will be noticeable when you place the accelerometer with the housing perpendicular to the ground of the Earth, and the acceleration will then be measured only in one axis (e.g. Z, for the X-axis and Y will be zero), while when the accelerometer is deflected by an angle different than 90 �, the measured acceleration, although it will be constant, its value will be further co-created by the value for the Z-axis and the non-zero values ​​of the components for the X and Y axes.

Interfacing accelerometers with Arduino boards

On most of the accelerometer boards offered at our store, the output should be connected to the analogue input on the Arduino board. Grove modules require a 3.3V or 5.0V power supply. When choosing an accelerometer to suit your project's needs, you must consider the maximum value of linear acceleration that the accelerometer can measure. For example, for a small riding robot, an accelerometer with a maximum range of linear acceleration of 2 g (twice the acceleration of gravity) will be appropriate, and for a rocket model, an accelerometer with a range of 16 g will be appropriate. In addition to the accuracy of the measurement reading, which is determined by the bit resolution of the analogue-to-digital converter included in the structure of the microcontroller with which the accelerometer works, it is worth knowing that the larger the measuring range of the accelerometer, the greater the measurement accuracy. If you choose an accelerometer with a too-small measuring range for your project, then you may notoriously obtain information about the reading off-scale, which will make it impossible to correctly determine the acceleration of the object.

What other factors are worth paying attention to when buying an accelerometer?

When using accelerometers, gyroscopes or IMU systems, to achieve and maintain the required position of an object in space, other factors may affect the measurement results. The main problem is the sampling rate of the analogue-to-digital converter built into the microcontroller that receives the signal from the gyroscope through the analogue input. Due to the structure of the Sample & Hold system, the microcontroller "needs" a certain amount of time to measure and store the measurement result, some measurement data is lost during each holding cycle of the previously measured voltage signal. One of the most popular methods to partially compensate for this problem is the use of the Kalman filter. Another factor influencing the accuracy of the measurement is temperature changes, to which the sensors may be particularly sensitive, depending on the quality of the structure, including the term kinetics of the elements that the sensor is made of. Most MEMS sensor application notes describe the effect of temperature on the sensor output signal.