Android Question device displacement

Emerito · Feb 8, 2021

Using the sensors of the mobile I see its possible movements in the three axes x, y, z. But suppose that the mobile is in a car and the axles do not coincide with the axles of the car. By looking at the new sensor readings, can you tell the front and side lean of the car from the initial readings?

When the axes of the two coincide, for example, assuming that the mobile is embedded in the dashboard of the vehicle, the readings are direct (the new ones minus the old ones), but, logically, when they do not coincide, they are not.

Could you help me? What plans would they have to make?

Greetings.

Hamied Abou Hulaikah · Feb 8, 2021

logically:
car movement = value changed = coincide
no car movement = no value changed = no coincide

Sorry, I don't understand your exact question!

agraham · Feb 8, 2021

Emerito said:
By looking at the new sensor readings, can you tell the front and side lean of the car from the initial readings?

No. The readings will always be relative to the mobile, so without an external reference there is no way to correct the readings.

Emerito · Feb 8, 2021

Perdón por mi mal ingles.

Quiero medir la inclinación frontal y la inclinación lateral del vehículo, en base a la lectura de los sensores del móvil cuando el móvil no está ubicado coincidiendo sus ejes x, y, z con los del vehículo.

Cuando estos ejes coinciden (ocurre con un clinómetro físico incrustado en el salpicadero del vehículo), las lecturas de los sensores del móvil dan las dos inclinaciones, pero si el móvil se sitúa sobre un soporte cuyos ejes no coinciden con los de el vehículo, eso no es así.

No sé si me explico con suficiente claridad, también depende del traductor.

Saludos.

Emerito · Feb 8, 2021

At the beginning, I read the sensors and consider that this reading corresponds to the vehicle in a horizontal position on both axes, longitudinal and transverse. I scroll and read again, it will give me other readings. I think they can relate, but I don't know how.

agraham · Feb 8, 2021

Emerito said:
I think they can relate

Either the mobile has moved relative to the car and the car was static, or the car has moved and the mobile stayed static relative to the car. You can't tell the difference without an external reference.

Emerito · Feb 8, 2021

agraham said:
Either the mobile has moved relative to the car and the car was static, or the car has moved and the mobile stayed static relative to the car. You can't tell the difference without an external reference.

the car has moved and the mobile stayed static relative to the car.
So I try to relate the axes of the vehicle and the mobile. I put the vehicle in a horizontal position and read the sensors of the mobile. When I move the vehicle, I read again. Can't these two readings be related, since the relative position between the mobile and the vehicle remains the same?

Cableguy · Feb 8, 2021

As a starting point, you may consider "normal" movent of the car as being; going forward, forward turning Right, forward turning left and the same movements regarding reverse.
A car cannot produce a sideways movement without going either forward or backwards. At least not as a "normal" movement.
So you can maybe take this into account to determine the phones position relative to the car and also take into account "gravity" acceleration to determine if the phone is back-flat, front-flat, on the side etc...

agraham · Feb 8, 2021

As long as the mobile is fixed relative to the car then yes, the mobile movements reflect the car movements. But your original post implies that this is not necessarily the case.

Cableguy · Feb 8, 2021

Yes, of course. One has to assume the relative position of the phone to the car is fixed!

udg · Feb 8, 2021

I may be wrong, but my understanding of the initial post is: once I place my mobile in a given slot in my car, can I use mobile's sensors to follow the vehicle movements even if the two (mobile and car) have different axes references?
I would reply affirmatively since it should lead to a fixed transformation set of rules (the one that considers how the mobile reference systm relates to the car's one).

Emerito · Feb 8, 2021

udg said:
Puede que me equivoque, pero mi comprensión de la publicación inicial es: una vez que coloco mi móvil en una ranura determinada de mi coche, ¿puedo utilizar los sensores del móvil para seguir los movimientos del vehículo incluso si los dos (móvil y coche) tienen referencias de ejes diferentes? ?
Yo respondería afirmativamente, ya que debería conducir a un conjunto de reglas de transformación fijo (el que considera cómo el sistema de referencia móvil se relaciona con el del automóvil).
[/CITAR]
Despite my terrible English, you have perfectly understood the question.
But I don't know how to do it.

Cableguy · Feb 8, 2021

If the device position is known beforehand then it won't be that complicated since you will already known which phone axis correspond to the car's.

Emerito · Feb 8, 2021

Cableguy said:
Si la posición del dispositivo se conoce de antemano, no será tan complicado, ya que ya sabrá qué eje del teléfono corresponde al del automóvil.

Yes, the position is known and does not change. But I don't know how to relate the axes of the phone to the car.
I suppose there will be a trigonometric relationship, but what I am sure is not a direct axis-to-axis relationship.

Emerito · Feb 8, 2021

[QUOTE = "Emerito, publicación: 798105, miembro: 84497"]
Sí, la posición es conocida y no cambia. Pero no sé cómo relacionar los ejes del teléfono con el automóvil.
Supongo que habrá una relación trigonométrica, pero lo que estoy seguro no es una relación directa de eje a eje.
[/CITAR]

Hamied Abou Hulaikah · Feb 9, 2021

According to inclinometer app programming, we should assume the car horizontal position is the constant/reference axles for your app, when car tile in any axis you should add/deduce the new values from the constant/reference values.

Emerito · Feb 9, 2021

Yes. Something similar to that inclinometer that shows is what I want to do with the mobile, but I do not know how to relate the readings of the sensors when the vehicle has moved. As I said, if the device is perfectly aligned, the sensor readings directly give us the front and side inclination of the vehicle, but when it is not, the readings will have to be corrected and I don't know how to do it.

When you talk about the programming of the inclinometer application, is there something published in that regard?

Greetings.

Cableguy · Feb 9, 2021

Emerito said:
As I said, if the device is perfectly aligned, the sensor readings directly give us the front and side inclination of the vehicle, but when it is not, the readings will have to be corrected and I don't know how to do it

What's keeping you of creating a "setup" activity and prompt the end user to:
Place the car in an (as perfect as possible) perfectly flat parking area.
Chose/define the emplacement of the mobile inside the car.

This way you can determine your reference values.

Emerito · Feb 9, 2021

Cableguy said:
What's keeping you of creating a "setup" activity and prompt the end user to:
Place the car in an (as perfect as possible) perfectly flat parking area.
Chose/define the emplacement of the mobile inside the car.

This way you can determine your reference values.

I am doing so. But I don't know how to relate the two readings. I am going to develop a small code of how I am doing it and that does not give correct results.

Cableguy · Feb 9, 2021

Don't forget the sensor is both accelerometer and inclinometer, so the acceleration values are related to hearth gravity... I think...

Android Question device displacement

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