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--- projects:robots:michael_wrona_notes [2024/04/29 02:46] – created jhagstrand
+++ projects:robots:michael_wrona_notes [2024/04/29 03:42] (current) – [Michael Wrona notes] jhagstrand
@@ Line 1: / Line 1: @@
 ====== Michael Wrona notes ======
+youtube name: MicWro Engr
+Note that these videos contain theory learned from Michael's reading. \\
+He does not have any demonstrable hardware or software.
+==== Intro to Inertial Measurement Units (IMU) ====
+\https://youtu.be/LjeFZetmfYc?si=fNag0weh7Y1BTe6-
 Inertial Reference Frame \\
 Earth-Centered Inertial Frame, ECI Frame \\
-IMU
+IMU = accelerometer + gyroscope + (optional) magnetometer
-gyroscope
-measures angular rotation rate in radians per second or degrees per second
-bias and drift
-bias
+===gyroscope===
-when the sensor is stationary, the rate measurement is non-zero.
-this means that the bias the measurements are off-center.
-drift
+measures angular rotation rate in radians per second or degrees per second \\
-when we calculate the angles of the current orientation, by looking at the rate measurements,
+has bias and drift \\
-the bias in those measurements lead to drift in the current position angles.
-gyro bias causes gyro drift
+bias \\
+when the sensor is stationary, the measurement is non-zero.\\
+this means that the measurements are off-center. \\
-Ways to eliminate bias and drift:
+drift \\
-  * Extended Kalman Filter
+when we calculate the angles of the current orientation,
+by looking at the measurements over time,
+the bias in those measurements leads to drift in the current position angles.
+summary: gyro bias causes gyro drift
+how to eliminate bias and drift: Extended Kalman Filter
+=== accelerometer ===
-accelerometer
 measures linear acceleration in 3 axes: x,y,z
@@ Line 29: / Line 40: @@
 measured acceleration = linear and gravity - coriolis + centripetal
-coriolis and centripetal accleration depends on earth's rotation, velocity, and position
+coriolis and centripetal acceleration depend on earth's rotation, velocity, and position \\
-and are fine measurements relevant only to high-precision sensors.
+These are fine measurements relevant only to high-precision sensors.
-by looking at acceleration due to gravity, we can estimate roll and pitch
+by looking at acceleration due to gravity, we can estimate roll and pitch \\
-roll, phi, φ
+roll, phi, φ \\
 pitch, theta, θ
-integrate acceleration to velocity
+integrate acceleration to velocity \\
-integrate velocity to position
+integrate velocity to position \\
-accelerometer also has bias which leads to drift in velocity and position
+accelerometer also has bias which leads to drift in velocity and position \\
+Extended Kalman Filter can be used to eliminate bias \\
-Extended Kalman Filter can be used to eliminate bias
-accelerometer also has noise, due to vibration
+accelerometer also has noise, due to vibration \\
 Low-pass filter can be used to eliminate noise.
 Note: do NOT use a low-pass filter on gyroscope readings
+IMU grade and accuracy
 ^ IMU grade      ^ acc bias   ^ gyr bias ^
 | unit           | g          | degr/hr  |
 | Marine & space | 1E-5       | .001     |
-| Aviation       | 3E=5       | .01      |
+| Aviation       | 3E-5       | .01      |
 | Tactical       | .001 - .01 | 1-100    |
 | Automotive     |  >.01      | >100     |