## Step 3: Some Extra Information Before We Proceed

From both sensor we can measure the angle but using two distinct technique.

To measure the angle using the gyro we have to integrate the signal.
But why we have to do this?
Because the gyro give us the angular rate, so a simple way to get the angle is have the angular rate multiplied by the time [angle = angle + w * dt]

To measure the angle using an accelerometer we have to sense the gravity in each axis of the accelerometer, what it means, the projection of the gravity acceleration on each direction of the sensor give us an idea about the angle. [angle_accel = arctg( Ay / sqrt( Ax^2 + Az^2 ) )]

So why we gonna use two sensor instead one?
To take the advantage of both sensor properties. If you look at the graphic the gyro data continuous increase, this is called drift and the accelerometer data change a lot at a small time.

And how to merge both signal?
We will use a technique called complementary filter. I don't know the exact theory behind this, but it works fine. There are some information at the internet, just google it if you need more information. This link has a lot of information and can be useful.

filtered_angle = HPF*( filtered_angle + w* dt) + LPF*(angle_accel); where HPF + LPF = 1

The values of HPF and LPF can be found at this link, on the filter.pdf file. Thanks you guys from "The DIY Segway".
Just for test purpose we gonna set this values like this, HPF = 0.98 and LPF = 0.02.

<p>this is nesessery encoder motor needed for self balancing robot</p>
<p>ok</p>
<p>Hello, First of all great work and thank you very much for sharing the knowledge. </p><p>I need to know a couple of things.</p><p>1. Are the angle measurements accurate. Does a 45 degree change show 45 degrees approxiamtely.</p><p>2. Up to what value of angle the device measure ? Is it capable of handling more than 90 degree angles</p>
<p>I made an equivalent tool in python that print real time data from ADXL345 accelerometer.</p><p><a href="https://github.com/mba7/SerialPort-RealTime-Data-Plotter" rel="nofollow">https://github.com/mba7/SerialPort-RealTime-Data-P...</a></p><p>may be it will be helpful for someone</p>
<p>is this possible to use only accelerometer for angle measurement.</p>
<p>It is possible to use only the accelerometer but the result may not to be so good.</p><p>It is recommended use both sensors.</p>
Nunchuck controller are use for what?? How can I use this, to combine with my pyranometer tracker?
Nunchuck controller has an internal integrated accelerometer.<br><br>You can use it for a variety of things, depend what are you doing or your need.
Desculpe-me, &eacute; que estou construindo um bicoptero e estou com um problema no equlibrio de todo o sistema, estudando seu codigo: angle_for_instructable.pde<br>N&atilde;o vi nenhuma linha para a execu&ccedil;&atilde;o dos motores que vc usou no seu rob&ocirc;.<br>estes comandos est&atilde;o em um outro arquivo a parte?<br>Obrigado pela aten&ccedil;&atilde;o.
The code link does not link to a .rar but to a .tmp file. Is the code link available somewhere else? <br> <br>Thanks, <br> <br>Jim
i need to build a human body sensor using an accelerometer and a gyroscope........and i am gonna use labVIEW as software for analysis.....can you please help me with the microcontroller part........should i go with lpc2138???<br><br>thanks
Is there any information about how that formula is derived, because I hate using things i dont fully understand
Read this instructable first, there is a plenty of information.<br><br>https://www.instructables.com/id/Accelerometer-Gyro-Tutorial/<br><br>Any doubt feel free to ask.
I mean the one to calculate the angle using accelerometers.
Sorry If i bother you but where can I buy the gyroscope device you used in your realization?
I bought this gyro at eBay. But is no longer available.
Thanks for the explanation. I&nbsp;was waiting for someone to do this.
Thanks, I'll need this for my next project.<br /> <br /> Justin<br />
Nice, xD<br />
When I try to download the .rar, all I get is a .tmp file. I have tried 3 different browsers, how does this work?
Try just renaming from .tmp to .rar