From af34182f1e0f8be1394adf5e99ce619d7382dc22 Mon Sep 17 00:00:00 2001 From: Jet Hughes Date: Thu, 30 Mar 2023 10:47:23 +1300 Subject: [PATCH] vault backup: 2023-03-30 10:47:23 --- content/notes/10-orientation-sensors.md | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/content/notes/10-orientation-sensors.md b/content/notes/10-orientation-sensors.md index b42dd5715..81a0c7851 100644 --- a/content/notes/10-orientation-sensors.md +++ b/content/notes/10-orientation-sensors.md @@ -49,11 +49,6 @@ Compass / Magnetometer - iPhone 4 magnetometer range: ±2mT - Pro tip: prolonged exposure to a fridge magnet decalibrates your phones’ magnetometer for at least a week ;-) ![field strength examples|300](https://i.imgur.com/00VV74x.png) -> [!INFO] -> doesn't directly measure north -> measure magentic fielf of earth and aligns with magenetic north -> earth field is very weak so we need sensitive magnetometer -> ![Error around metal/magnetic objects](https://i.imgur.com/YIJAcGS.png) @@ -66,6 +61,13 @@ Compass / Magnetometer - Local discontinuities in magnetic field - Ferromagnetic materials - Power sources +> [!INFO] +> doesn't directly measure north +> measure magentic fielf of earth and aligns with magenetic north +> earth field is very weak so we need sensitive magnetometer +> electronic from phone affect sensor but the error can be calibrated out +> balance between what is cheap and what is good enough +> only one degree on freedom (bearing to north) ![gryroscope|300](https://i.imgur.com/VnL5seY.png) Gyroscope @@ -73,13 +75,20 @@ Gyroscope - Precisely: orientation can be computed from the angular rate that is detected by the gyroscope, expressed in rad/s [deg/s] on 3 axis. - Traditional gyroscopes use the e!ect of angular momentum ![gyro deg of freedom|300](https://i.imgur.com/q1LjfPD.png) -![gyro electronic|300](https://i.imgur.com/5Ti80sO.png) +![gyro electronic plane,satellite|300](https://i.imgur.com/5Ti80sO.png) +> [!INFO] +> car, phone, game controller, etc +> measure orientation +> measure change of orientation using angular rate +> use the effect of angular momentum. when you spin something fast, it want to keep that rotation axis - MEMS (microelectromechanical system) gyro - Used in most smartphones or mobile/embedded devices - Use the displacement of vibrating proof mass to compute orientation (Coriolis effect) ![MEMS gyro|100](https://i.imgur.com/dzTVCpE.png) ![gyro chip](https://i.imgur.com/zVoQ3wM.png) +> [!INFO] +> works similar to spinning gyro but uses vibrations instead Problem: - The gyroscope gives us angular rate with a unit of rad/s [deg/s]