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--- en:iot-open:hardware2:sensors_angle [2023/10/12 15:10] – ktokarz
+++ en:iot-open:hardware2:sensors_angle [2024/05/23 22:44] (current) – pczekalski
@@ Line 1: / Line 1: @@
-==== Angle & Orientation Sensors ====
+====== Angle & Orientation Sensors ======
+{{:en:iot-open:czapka_b.png?50| General audience classification icon }}{{:en:iot-open:czapka_e.png?50| General audience classification icon }}\\
+== The Inertial Measurement Unit (IMU) ==
-=== Potentiometer ===
+An IMU is an electronic device that consists of an accelerometer, gyroscope, and sometimes a magnetometer. The combination of these sensors returns the object's orientation in 3D space. IMU sensors can present the object's current position and movement, expressed with at most six values called the DOF (Degrees Of Freedom). Three values represent the linear movements that the accelerometer can measure:
-A potentiometer is a type of resistor, the resistance of which can be adjusted using a mechanical lever. The device consists of three terminals. The resistor between the first and the third terminal has a fixed value, but the second terminal is connected to the lever. Whenever the lever is turned, a slider of the resistor is moved; it changes the resistance between the second terminal and side terminals. Variable resistance causes the change of the voltage, which can be measured to determine the position of the lever. Thus, the potentiometer output is an analogue value.\\
-Potentiometers are commonly used as a control level, for example, a volume level for the sound and joystick position. They can also be used to determine the angle in feedback loops with motors, such as servo motors. The potentiometer symbol is present in figure {{ref>potentiometer1}}, a device in figure {{ref>potentiometer2}} and a connection to the Arduino board in figure {{ref>potentiometer3}}.
-<figure potentiometer1>
-{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:potentiometer_symbol_europe.png?100 | Symbol of a potentiometer}}
-<caption>A symbol of a potentiometer</caption>
-</figure>
-<figure potentiometer2>
-{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:potentiometer_c.jpg?200 | Potentiometer}}
-<caption>A potentiometer</caption>
-</figure>
-<figure potentiometer3>
-{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:sch_apz_shemas_potentiometer.png?300 | Arduino and potentiometer circuit}}
-<caption>Arduino and potentiometer circuit</caption>
-</figure>
-An example code:
-<code c>
-//Potentiometer sensor output is connected to the analogue A0 pin
-int potentioPin = A0;
-//The analogue reading from the potentiometer output
-int potentioReading;
-void setup(void) {
-  //Begin serial communication
-  Serial.begin(9600);
-  //Initialize the potentiometer analogue pin as an input
-  pinMode(potentioPin, INPUT);
-}
-void loop(void) {
-  //Read the analogue value of the potentiometer sensor
-  potentioReading = analogRead(potentioPin);
-  Serial.print("Potentiometer reading = "); //Print out
-  Serial.println(potentioReading);
-  delay(10);
-}
-</code>
-=== The Inertial Measurement Unit (IMU) ===
-An IMU is an electronic device consisting of an accelerometer, gyroscope and sometimes a magnetometer. The combination of these sensors returns the object's orientation in 3D space. IMU sensors can present the object's current position and movement, expressed with at most six values called the DOF (Degrees Of Freedom). Three values express the linear movements that the accelerometer can measure:
   * moving forward/backwards,
   * moving left/right,
@@ Line 55: / Line 12: @@
   * yaw left and right.
-A **gyroscope** is a sensor that measures the angular velocity. The sensor is made with microelectromechanical system (MEMS) technology and is integrated into the chip. The sensor output can be analogue or digital, using I2C or SPI interface. Gyroscope microchips can vary in the number of axes they can measure. The available number of axes is 1, 2 or 3 axes in the gyroscope. A gyroscope is commonly used with an accelerometer to determine the device's orientation, position and velocity precisely.
+A **gyroscope** is a sensor that measures the angular velocity. A microelectromechanical system (MEMS) technology integrates the sensor into the chip. The sensor output can be analogue or digital, using I2C or SPI interface. Gyroscope microchips can vary in the number of axes they can measure. The available number of axes is 1, 2 or 3 axes in the gyroscope. A gyroscope is commonly used with an accelerometer to determine the device's orientation, position and velocity precisely.
 Gyroscope sensors are used in aviation, navigation and motion control.
@@ Line 64: / Line 21: @@
 Different elements allow measuring linear accelerations, angular accelerations, and magnetic fields in three axes. There exist elements that combine two (called 6-axis or 6-DOF) or all (9-axis, 9-DOF) measurement units. Popular integrated circuits are MPU6050 (3-axes gyro + 3-axes accelerometer, figure {{ref>imu6050}}), MPU9250 (3-axes gyro + 3-axes accelerometer + 3-axes compass, figure {{ref>imu9250}}), and BNO055 (3-axes gyro + 3-axes accelerometer + 3-axes magnetometer, figure {{ref>bno055}}). All of them can be programmed in an Arduino environment using dedicated libraries.
-\\ The latter automatically calculates additional information like gravity vector and absolute orientation expressed as an Euler vector or as a quaternion. The sample connection circuit for the BNO055 sensor is present in figure {{ref>bno055_2}}.
+\\ The latter automatically calculates additional information like gravity vector and absolute orientation expressed as an Euler vector or a quaternion. The sample connection circuit for the BNO055 sensor is present in figure {{ref>bno055_2}}. Note, figure {{ref>bno055_2}} does not present pull-up resistors on the I2C bus as they are integrated into the development boards.
 <figure imu6050>
@@ Line 118: / Line 75: @@
 </code>
-<note important>Most MEMS devices present built-in inaccuracy. For this reason, gyros and accelerometers should be calibrated before use to calculate their so-called offset, an average error they present (in each axis separately). Later, this error is used to calculate a correction factor that is applied during regular operation. Sample MPU6050 library along with calibration code can be found in the Github repository ((https://github.com/ElectronicCats/mpu6050/tree/master)).</note>
+<note important>Most MEMS devices present built-in inaccuracy. For this reason, gyros and accelerometers should be calibrated before use to calculate their so-called offset, an average error they present (in each axis separately). Later, this error is used to calculate a correction factor applied during regular operation. Sample MPU6050 library along with calibration code can be found in the Github repository ((https://github.com/ElectronicCats/mpu6050/tree/master)).</note>
 <note important>Similar problem is present in the case of the magnetometers: the surrounding environment can impact readings; thus, they require calibration that can be achieved by recording the minimum and maximum values during rotation in every axis. This process is common when using a drone in a new location.</note>