Is gyroscope able to detect the phone position even when phone is not moving? - Page 1
Forum section: electronics / beginners

author: m4rtin
author_rank: Regular Contributor
timestamp: September 19, 2015, 04:04:15 pm
content: Is gyroscope in modern phones/tablets able to detect the phone position even when phone is not moving? I installedGyroscope Explorerto my Samsung Galaxy S5 and according to this it looks like gyroscope, unlike accelerometer, is able to detect the phone position regardless that phone is still.

author: zapta
author_rank: Super Contributor
timestamp: September 19, 2015, 04:41:21 pm
content: Quote from: m4rtin on September 19, 2015, 04:04:15 pmChances are you phone has both, and a magnetic compass. Look for Android apps that visualize sensors, for example GPS Status.

author: ejeffrey
author_rank: Super Contributor
timestamp: September 19, 2015, 05:08:25 pm
content: Gyroscopes in phones are actually rate gyros. They only detect rotation, not absolute orientation. Orientation is given by integration aka dead reckoning . I don't know how much the drift is. Normally you combine the gyro information with the accelerometer and magnetic compass to cancel the drift and provide an absolute reference.

author: LukeW
author_rank: Frequent Contributor
timestamp: September 19, 2015, 05:17:39 pm
content: The magnetometer and the accelerometer can also give you absolute orientation, roughly, assuming you're in Earth's magnetic field and away from any artificial magnets, and there is no acceleration present other than gravity.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 19, 2015, 06:01:59 pm
content: Well this all depends on the drift of the gyroscope.A ICBM missile might have a very expensive laser gyroscope that tells it where it is not, but your phone will probobly only be useable as a tracker for a short time without a signal before things get all screwey.

author: SeanB
author_rank: Super Contributor
timestamp: September 19, 2015, 06:32:54 pm
content: I know that the original Boeing 747 IMU gyros were developed to be good enough that they could track the rotation of the Earth around the sun, and if you averaged out the drift of a few units in a test bench you could start to detect the motion of the solar system around the Milky Way coming out of the noise.

author: zapta
author_rank: Super Contributor
timestamp: September 19, 2015, 07:07:17 pm
content: Quote from: sarepairman2 on September 19, 2015, 06:01:59 pmNot really, between the linear accelerometer, gravity and the magnetic compass you can get pretty good orientation.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 19, 2015, 07:12:02 pm
content: Quote from: SeanB on September 19, 2015, 06:32:54 pmi would like to know more

author: SeanB
author_rank: Super Contributor
timestamp: September 19, 2015, 07:22:51 pm
content: They were good enough that the IMU could handle the entire flight from London to Sydney in non stop ( full fuel load, reduced cargo load for the range without refuelling) flight with the error on most IMU units only being such that at stop on the demarcation point the error would be under 30m. Only with the later upgrading to GPS as a primary input to the flight systems did the accuracy improve over that. They got that using precision magnetic bearings and a He fill for the units to reduce frictional losses, along with having triple redundancy inside the IMU itself.

author: m4rtin
author_rank: Regular Contributor
timestamp: September 19, 2015, 07:25:22 pm
content: Quote from: ejeffrey on September 19, 2015, 05:08:25 pmI see. However, in short, gyro is not able to detect the phone position when phone is not moving? In addition, gyros in phones are some sophisticated IC's which mimic the operation of actual rotating gyro?

author: helius
author_rank: Super Contributor
timestamp: September 19, 2015, 07:45:13 pm
content: https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope#MEMS_gyroscopesThe gyro's drift is a time constant that limits the period over which it provides useful position data. With extremely low drift, the position data could be valid for a long time. With a high drift, the position is only valid over short intervals like seconds. The control algorithm uses additional inputs (like GPS or linear accelerometers) to update the baseline position for the gyro data.