MEMS Sensor in Accelerometer Experiment

Objective

The objective of this experiment is to understand how a MEMS (Micro-Electro-Mechanical Systems) accelerometer works by measuring and analyzing its output when subjected to different motions and tilts. The experiment will demonstrate how MEMS sensors detect changes in acceleration and translate them into electrical signals.

Materials Needed

• MEMS accelerometer (e.g., ADXL345 or MPU6050)
• Microcontroller (e.g., Arduino or ESP32)
• Connecting wires
• Breadboard
• Power supply (e.g., 3.3V or 5V depending on the accelerometer)
• Computer with Arduino IDE (or appropriate microcontroller programming environment)
• Oscilloscope or serial monitor (for data observation)

Theory

MEMS accelerometers are widely used sensors that measure acceleration forces in one, two, or three axes. These forces may be static, such as gravity, or dynamic, such as vibrations and movements. MEMS technology combines mechanical components and electrical circuits on a single silicon chip to create compact, high-precision sensors.

An accelerometer measures acceleration by detecting changes in capacitance caused by the movement of tiny mechanical structures inside the MEMS sensor. The output is typically an analog or digital signal proportional to the measured acceleration.

Steps

1. Set Up the Circuit

   Connect the MEMS accelerometer to the microcontroller. If using a digital accelerometer like the ADXL345 or MPU6050, connect the appropriate I2C or SPI communication pins. For example, in I2C mode:

   • Connect VCC to 3.3V or 5V power supply.
   • Connect GND to ground.
   • Connect SDA (data line) to the corresponding pin on the microcontroller (e.g., A4 on Arduino).
   • Connect SCL (clock line) to the corresponding pin on the microcontroller (e.g., A5 on Arduino).

   Ensure all connections are secure and the sensor is powered correctly.

2. Write and Upload the Code

   Use the Arduino IDE (or another microcontroller environment) to write the code to read data from the accelerometer. If using I2C communication, you can use libraries like Wire.h and sensor-specific libraries (e.g., Adafruit_MPU6050.h) for easy data acquisition.

                           
   #include 
   #include 
   #include 
   
   Adafruit_MPU6050 mpu;
   
   void setup() {
       Serial.begin(9600);
       if (!mpu.begin()) {
           Serial.println("Failed to find MPU6050 chip");
           while (1) {
               delay(10);
           }
       }
       mpu.setAccelerometerRange(MPU6050_RANGE_2_G);
   }
   
   void loop() {
       sensors_event_t a, g, temp;
       mpu.getEvent(&a, &g, &temp);
   
       Serial.print("Accel X: "); Serial.print(a.acceleration.x); Serial.print(" m/s^2, ");
       Serial.print("Accel Y: "); Serial.print(a.acceleration.y); Serial.print(" m/s^2, ");
       Serial.print("Accel Z: "); Serial.print(a.acceleration.z); Serial.print(" m/s^2");
       Serial.println();
       delay(500);
   }
                           
                       

   Upload the code to your microcontroller using the provided USB connection and open the serial monitor to view the accelerometer data.

3. Observe Accelerometer Output

   With the serial monitor open, move the accelerometer by tilting or shaking it in different directions. You should observe changes in the accelerometer readings on the serial monitor, showing acceleration values along the X, Y, and Z axes.

   The accelerometer will output near-zero values when stationary and aligned horizontally. When tilted, the sensor will measure the gravitational force along each axis, and when subjected to motion, dynamic acceleration forces will be captured.

4. Analyze Data

   Based on the observed values, analyze how the sensor responds to changes in position and movement. Try to relate the numerical output with the actual physical motion. You can also plot the data using tools like Excel or a real-time graphing tool to visualize the motion.

Example Data

When the accelerometer is held stationary and aligned horizontally, typical readings may look like this:

Accel X: 0.03 m/s^2, Accel Y: 0.00 m/s^2, Accel Z: 9.80 m/s^2
            

When the sensor is tilted to the side, or during shaking, the values on the X and Y axes will change, while the Z-axis value may fluctuate depending on the movement.

Conclusion

In this experiment, we successfully demonstrated the functionality of a MEMS accelerometer by measuring acceleration forces along three axes. We observed how the sensor responds to static and dynamic forces, including tilts and movements. MEMS accelerometers are useful in a wide range of applications, including motion detection, vibration sensing, and orientation tracking in smartphones and wearable devices.