From 93520e1ff959b0ba8fa89ee3b756b2476fc8a51a Mon Sep 17 00:00:00 2001
From: Jet Hughes <jethughes0@gmail.com>
Date: Tue, 4 Apr 2023 12:12:34 +1200
Subject: [PATCH] vault backup: 2023-04-04 12:12:34

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+---
+title: "11-orientation sensors-2"
+tags: 
+- lecture
+- info305
+---
+
+> [!INFO] we need sensors to that computing can be ubiquitous. from this we can think of completey new interfaces
+
+> [!INFO] gyroscope
+> say a phone is rotating by 5 degree per seconds. usualy want to know absolute angle.  this is the integral over time, we know what the angular rate is and the time. 
+> problem: cannot take perfectly continuous integral. they do more than 100 measurements per second. gryoscope data changes faster than samplling frequency. this is called drift/bias, as the error accumulates. 
+> when the sensor is stationary, it still measures a small value, which is inherent in accuracy. so the sensor thinks it is moving when it is not. the bell curve of inaccurate measurements is not centred. 
+
+Advanced sensing
+- Current situation: 
+	- Many different sensors with different characteristics 
+		- Precise but slow, noisy but fast, drift biased,… 
+		- We cannot measure everything… 
+- Can we combine sensors for model more complex states? 
+- Can we filter sensor measurements to improve the data quality?
+
+Sensor Fusion
+- The idea: 
+	- Combine (fuse) sensor to achieve better results 
+	- Better Location (When signal ist lost, not enough satellites, ..) 
+	- Better Orientation (Less drift (gyroscope), less error prone (compass), ..)
+
+Sensor Fusion
+- Example for Orientation 
+	- Combine strength of several integrated sensors 
+	- Avoids gyro drift and noisy orientation 
+		- http://www.thousand-thoughts.com/2012/03/android-sensor-fusion-tutorial/ 
+	- Gyroscope output is applied only for orientation changes in short time intervals (high-pass filtering) 
+	- Accelerometer/Magnetometer is used as support information over long periods of time for absolute orientation (low pass filtering)
+![sensor fusion](https://i.imgur.com/vO3rjBd.png)
+
+![sensor fusion signal filters](https://i.imgur.com/oYSFNvi.png)
+
+Dead Reckoning
+- 
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 - [x] [[08-proximity sensors]]
 - [x] [[09-location-sensors-3]]
 - [x] [[10-orientation-sensors]] 
+- [ ] [[11-orientation sensors-2]]
 # Info
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