info
Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Accelerometer
24 views
Skip to first unread message
jsscs...@gmail.com
Nov 29, 2015, 1:03:23 PM11/29/15
to
Hi,
I am controlling a single axis DC motor to follow the elevation of the Sun using two light sensors. The motor moves 180 degrees in a day.
The control circuitry of the motor ( solar tracker) will be mounted on the moving solar panel mechanical assembly. I want to know the changing tilt / position.
I choose the following accelerometer to calculate the tilt from dimension engineering
https://www.dimensionengineering.com/datasheets/DE-ACCM3D.pdf
The accelerometer part number is ADXL335B. The accelerometer is 3 axis. It operates at 3.3V with sensitivity of 333mV/g. Its data sheet is as follows
http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL335.pdf
My questions are
1. How to choose the accelerometer for such an application?
2. Did I choose the right accelerometer? Can it follow 180 degrees? How should I proceed with the software?
jess
I am controlling a single axis DC motor to follow the elevation of the Sun using two light sensors. The motor moves 180 degrees in a day.
The control circuitry of the motor ( solar tracker) will be mounted on the moving solar panel mechanical assembly. I want to know the changing tilt / position.
I choose the following accelerometer to calculate the tilt from dimension engineering
https://www.dimensionengineering.com/datasheets/DE-ACCM3D.pdf
The accelerometer part number is ADXL335B. The accelerometer is 3 axis. It operates at 3.3V with sensitivity of 333mV/g. Its data sheet is as follows
http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL335.pdf
My questions are
1. How to choose the accelerometer for such an application?
2. Did I choose the right accelerometer? Can it follow 180 degrees? How should I proceed with the software?
jess
Jasen Betts
Nov 30, 2015, 12:34:16 AM11/30/15
to
On 2015-11-29, jsscs...@gmail.com <jsscs...@gmail.com> wrote:
> Hi,
>
> I am controlling a single axis DC motor to follow the elevation of the Sun using two light sensors. The motor moves 180 degrees in a day.
>
> The control circuitry of the motor ( solar tracker) will be mounted on the moving solar panel mechanical assembly. I want to know the changing tilt / position.
>
>
> I choose the following accelerometer to calculate the tilt from dimension engineering
>
> https://www.dimensionengineering.com/datasheets/DE-ACCM3D.pdf
>
> The accelerometer part number is ADXL335B. The accelerometer is 3 axis. It operates at 3.3V with sensitivity of 333mV/g. Its data sheet is as follows
>
> http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL335.pdf
>
>
> My questions are
>
> 1. How to choose the accelerometer for such an application?
it seems ok.
> Hi,
>
> I am controlling a single axis DC motor to follow the elevation of the Sun using two light sensors. The motor moves 180 degrees in a day.
>
> The control circuitry of the motor ( solar tracker) will be mounted on the moving solar panel mechanical assembly. I want to know the changing tilt / position.
>
>
> I choose the following accelerometer to calculate the tilt from dimension engineering
>
> https://www.dimensionengineering.com/datasheets/DE-ACCM3D.pdf
>
> The accelerometer part number is ADXL335B. The accelerometer is 3 axis. It operates at 3.3V with sensitivity of 333mV/g. Its data sheet is as follows
>
> http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL335.pdf
>
>
> My questions are
>
> 1. How to choose the accelerometer for such an application?
> 2. Did I choose the right accelerometer? Can it follow 180 degrees?
> How should I proceed with the software?
180 degrees is no probelem
atan2()
--
\_(ツ)_
jsscs...@gmail.com
Nov 30, 2015, 10:08:42 AM11/30/15
to
Hi,
The thing is that I measured single x axis tilt with respect to earth. The accelerometer was sitting flat on the table. I used arc sin to calculate the tilt. I used protractor to confirm the calculated tilt. It was ok.
Then I measured single y axis tilt and used arc sin and the result was good.
I get confused when I tried to measure the tilt with x and y axes. Someone advised me to measure the tilt using "arc tan" and with respect to z axis. How does this work?
I will mount the accelerometer on the box and the box will move with the panel from its resting position. There will be some values of x, y and z. I will subtract these values from the future values of the x, y and z and calculate the tilt or current position using arc tan.
I sound confused and horrible. Please help what direction should I take.
jess
The thing is that I measured single x axis tilt with respect to earth. The accelerometer was sitting flat on the table. I used arc sin to calculate the tilt. I used protractor to confirm the calculated tilt. It was ok.
Then I measured single y axis tilt and used arc sin and the result was good.
I get confused when I tried to measure the tilt with x and y axes. Someone advised me to measure the tilt using "arc tan" and with respect to z axis. How does this work?
I will mount the accelerometer on the box and the box will move with the panel from its resting position. There will be some values of x, y and z. I will subtract these values from the future values of the x, y and z and calculate the tilt or current position using arc tan.
I sound confused and horrible. Please help what direction should I take.
jess
Tim Wescott
Nov 30, 2015, 12:02:31 PM11/30/15
to
Each axis should respond to the acceleration due to gravity as cos
(theta), where theta is the angle of _that axis_ from vertical (so you
really have theta_x, theta_y, theta_z).
You ought to be able to work backwards from there, after coiling yourself
in much trigonometry. It's best to do the math yourself -- that way you
know that it applies to your situation, and you're not depending on
someone else's competence or assumptions.
--
www.wescottdesign.com
0 new messages