8 replies to this topic

[liuwei05412]

hi,I am a graduate student.I am making AHRS and faces some problems.First, I want to know if this AHRS is used in room without GPS data,how the openpilot AHRS to work?Second,if the openpilot AHRS is used in room ,then Kalman filter state equation and measurement equation how to establish? third,if use component of gravity measured by Accelerometer Calculate angle,but Under the dynamic it can bring harmful acceleration,and how to eliminate?
That's all.Thank you.Waiting for your answer.

[peabody124]

When indoor we don't use a gps. The attitude is solved through two ways - applying a correction saying the velocity is zero (true on average) with a high variance so it's a weak bias and also using the mags which can provide a lot of information. Agreed about the physical acceleration confounding a read on gravity - that's why we don't look at the accels for down directly and in outdoor mode the gps is used to properly correct for that effect.

[liuwei05412]

peabody124, on 28 November 2010 - 06:03 PM, said:

When indoor we don't use a gps. The attitude is solved through two ways - applying a correction saying the velocity is zero (true on average) with a high variance so it's a weak bias and also using the mags which can provide a lot of information. Agreed about the physical acceleration confounding a read on gravity - that's why we don't look at the accels for down directly and in outdoor mode the gps is used to properly correct for that effect.

Thanks for your answers.First, I know that the mags can measure Heading,could it be said that mags can measure the Pitch and Roll,but you refer to that "using the mags which can provide a lot of information for measuring attitude ",so I want to know what "a lot of information" include other detailed information? Second, From the Openlilot source code about truck\flighe\AHRS,when I use the AHRS indoor,what the code need me to modify? That'a all,Thank you!

[peabody124]

Because the magenetic flux isn't just horizontal (or really even if it were) a 3D magnetic measurement can inform about roll, pitch and yaw. The INS algorithm used takes that into account and fuses it with the GPS information, baro, gyro's and accels. Dig through the forums and Dschin posted a writeup of the maths.

You don't need to modify the code to use indoor mode, it's just a setting in AHRSSettings.Algorithm.

[liuwei05412]

peabody124, on 29 November 2010 - 05:33 AM, said:

Because the magenetic flux isn't just horizontal (or really even if it were) a 3D magnetic measurement can inform about roll, pitch and yaw. The INS algorithm used takes that into account and fuses it with the GPS information, baro, gyro's and accels. Dig through the forums and Dschin posted a writeup of the maths.

You don't need to modify the code to use indoor mode, it's just a setting in AHRSSettings.Algorithm.

Oh, Thank you for your answer. And I want to buy a suit of the AHRS hardware,How can I get it?
First , I want to see the actual consequent of AHRS Module in the Openpilot project, could you give me a video URL links?
I see a AHRS Module video in (http://v.youku.com/v...gwOTM2Mjgw.html),Does the Openpilot AHRS have the consequent?
That's all,thank you.

[peabody124]

liuwei05412, on 01 December 2010 - 03:48 PM, said:

Oh, Thank you for your answer. And I want to buy a suit of the AHRS hardware,How can I get it?
First , I want to see the actual consequent of AHRS Module in the Openpilot project, could you give me a video URL links?
I see a AHRS Module video in (http://v.youku.com/v...gwOTM2Mjgw.html),Does the Openpilot AHRS have the consequent?
That's all,thank you.

I'm not really sure what you mean by consequence, but here is a video just showing the board working. The wiki has more information about it.

[liuwei05412]

peabody124, on 01 December 2010 - 03:58 PM, said:

I'm not really sure what you mean by consequence, but here is a video just showing the board working. The wiki has more information about it.

Oh, Thank you for your Video but I couldn't look it becouse the Web couldn't show the video
, and I don't know the reason.So could you send the Vidio by E-mail, and my E-mail is:
liuwei05412@163.com or 295705932@qq.com , That's all thank you.

[osnwt]

liuwei05412, on 02 December 2010 - 01:10 AM, said:

Oh, Thank you for your Video but I couldn't look it becouse the Web couldn't show the video, and I don't know the reason.

The reason is that some sites (namely, YouTube and Google, and maybe Vimeo as well) are not available in China.

[Brian Gou]

That's a bad news!

osnwt, on 03 December 2010 - 10:15 AM, said:

The reason is that some sites (namely, YouTube and Google, and maybe Vimeo as well) are not available in China.