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--- en:iot-open:hardware2:sensors_angle [2023/08/25 12:21] – external edit (Unknown date) 127.0.0.1
+++ 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.
-<figure label>
-{{ :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 label>
-{{ :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 label>
-{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:sch_apz_shemas_potentiometer.png?400 | 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 can be measured by the accelerometer:
   * moving forward/backwards,
   * moving left/right,
@@ Line 56: / 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 the axis is 1, 2 or 3 axes in the gyroscope. A gyroscope is commonly used with an accelerometer to precisely determine the device's orientation, position and velocity.
+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.
-An **accelerometer** measures the acceleration of the object. The sensor uses microelectromechanical system (MEMS) technology, where capacitive plates are attached to springs. When acceleration force is applied to the plates, the capacitance is changed; thus, it can be measured. Accelerometers can have 1 to 3 axis. The 3-axis accelerometer can detect the device's orientation, shake, tap, double tap, fall, tilt, motion, positioning, shock or vibration. Outputs of the sensor are usually digital interfaces like I2C or SPI. The accelerometer is often used with a gyroscope for precise measurement of the object's movement and orientation in space.
+An **accelerometer** measures the acceleration of the object. The sensor uses microelectromechanical system (MEMS) technology, where capacitive plates are attached to springs. When acceleration force is applied to the plates, the capacitance is changed; thus, it can be measured. Accelerometers can have 1 to 3 axes. The 3-axis accelerometer can detect the device's orientation, shake, tap, double tap, fall, tilt, motion, positioning, shock or vibration. Outputs of the sensor are usually digital interfaces like I2C or SPI. The accelerometer is often used with a gyroscope to measure the object's movement and orientation in space precisely.\\
-Accelerometers are used to measure objects' vibrations, including cars, industrial devices, and buildings, and to detect volcanic activity. In IoT applications, it can also be used for accurate motion detection for medical and home appliances, portable navigation devices, augmented reality, smartphones and tablets.
+Accelerometers measure objects' vibrations, including cars, industrial devices, and buildings, and detect volcanic activity. IoT applications can also be used for accurate motion detection for medical and home appliances, portable navigation devices, augmented reality, smartphones and tablets.
 A **magnetometer** is a sensor that can measure the device's orientation to the Earth's magnetic field. A magnetometer is used as a compass in outdoor navigation for mobile devices, robots, and quadcopters.
-There are different elements available that allow measuring linear accelerations, angular accelerations, and magnetic fields, all 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), MPU9250, and BNO055 (3-axes gyro, 3-axes accelerometer, 3-axes magnetometer). All of them can be programmed in an Arduino environment with the use of dedicated libraries. The latter automatically calculates additional information like gravity vector, and absolute orientation expressed as an Euler vector or as a quaternion.
+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 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.
-<todo>Take a photo of MPU6050.</todo>
+<figure imu6050>
-<figure label>
+{{ :en:iot-open:hardware2:20230925_114148_-_kopia.jpg?300 | IMU MPU6050 module}}
-{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:imu_mpu6050.jpg?200 | IMU MPU6050 module}}
 <caption>IMU MPU6050 module</caption>
 </figure>
-<todo>Take a photo of MPU9250.</todo>
+<figure imu9250>
-<figure label>
+{{ :en:iot-open:hardware2:20230925_114235_-_kopia.jpg?300 | IMU MPU9250 module}}
-{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:imu_mpu9250.jpg?200 | IMU MPU9250 module}}
 <caption>IMU MPU9250 module</caption>
 </figure>
-<figure label>
+<figure bno055>
 {{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:imu_c.jpg?200 | IMU BNO055 module}}
 <caption>IMU BNO055 module</caption>
 </figure>
-<figure label>
+<figure bno055_2>
 {{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:imu_sch_hd.jpg?400 | Arduino Uno and IMU BNO055 module schematics}}
 <caption>Arduino Uno and IMU BNO055 module schematics</caption>
@@ Line 100: / Line 55: @@
 void setup(void)
 {
-bno.setExtCrystalUse(true);
+  bno.setExtCrystalUse(true);
 }
 void loop(void)
 {
-//Read sensor data
+  //Read sensor data
-sensors_event_t event;
+  sensors_event_t event;
-bno.getEvent(&event);
+  bno.getEvent(&event);
-//Print X, Y And Z orientation
+  //Print X, Y And Z orientation
-Serial.print("X: ");
+  Serial.print("X: ");
-Serial.print(event.orientation.x, 4);
+  Serial.print(event.orientation.x, 4);
-Serial.print("\tY: ");
+  Serial.print("\tY: ");
-Serial.print(event.orientation.y, 4);
+  Serial.print(event.orientation.y, 4);
-Serial.print("\tZ: ");
+  Serial.print("\tZ: ");
-Serial.print(event.orientation.z, 4);
+  Serial.print(event.orientation.z, 4);
-Serial.println("");
+  Serial.println("");
-delay(100);
+  delay(100);
 }
 </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 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>