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[Bug 1529592] [NEW] Accelerometer has an offset

To: touch-packages@xxxxxxxxxxxxxxxxxxx
From: Uranicus <1529592@xxxxxxxxxxxxxxxxxx>
Date: Mon, 28 Dec 2015 10:14:57 -0000
Reply-to: Bug 1529592 <1529592@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx

Public bug reported:

Summary:
The accelerometer data is in detail not correct. This is either a specific hardware bug of my phone, the Aquaris 4.5 or all Aquaris phones or this is a software bug in reading the accelerometer data of the sensor.

This might also be a root cause of bug:
https://bugs.launchpad.net/ubuntu/+source/unity8/+bug/1474225

My phone:

current build number: 28
device name: krillin
channel: ubuntu-touch/stable/bq-aquaris.en
last update: 2015-12-16 12:25:08
version version: 28
version ubuntu: 20151210
version tag: OTA-8.5
version device: 20150821-736d127
version custom: 20151111--36-46-vivid

Task 1:
I have attached a screenshot of the app "Level". I have placed the phone on a surface which is leveled quite well.
Expectation 1:
The app level shows that the surface is leveled and the red dot is in the middle.
Result 1:
The red dot shows an offset of about 0.5 - 1 degree to "bottom left". This might be caused by a not fully leveled surface.

Task 2:
I have turned the phone by 90°
Expectation 2:
The red dot moves by 90° in the direction I turn the phone.
Result 2:
The red dot stays in exactly the same position (in relation to the orientation of the phone): bottom left. This means that a second screen shot would show exactly the same picture eventhough I have turned the phone by 90°.

Task 3:
I used "Sensor Status" - Accelerometer and I made 5 screen shots where I placed the phone on the same leveled surface and rotated the phone to 0°, 90°, 180°, 270°, 360°.
Expectation3:
The calculation of the angles of the 5 screen shots should give 4 different angles differing each by approx. 90°.
Result3:

Results of the „Sensor Status“ Accelerometer of the BQ Aquaris 4.5 lying on a flat surface

angle of the phone x y calculated angle
0 -0,421 -0,277 -146,66

90 -0,43 -0,335 -142,08

180 -0,43 -0,316 -143,69

270 -0,44 -0,306 -145,18

0 -0,44 -0,296 -146,07

I have also attached the 5 screen shots and the Calc file with the
background how I came to these results.

This clearly shows that the accelerometer has an offset. This is either
a specific hardware bug of my phone, the Aquaris 4.5 or all Aquaris
phones or this is a software bug in reading the accelerometer data of
the sensor.

Uranicus

** Affects: unity8 (Ubuntu)
Importance: Undecided
Status: New

** Attachment added: "Bug Accelerometer.7z"
https://bugs.launchpad.net/bugs/1529592/+attachment/4541265/+files/Bug%20Accelerometer.7z

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https://bugs.launchpad.net/bugs/1529592

Title:
Accelerometer has an offset

Status in unity8 package in Ubuntu:
New

Bug description:
Summary:
The accelerometer data is in detail not correct. This is either a specific hardware bug of my phone, the Aquaris 4.5 or all Aquaris phones or this is a software bug in reading the accelerometer data of the sensor.