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Permalink Reply by Himanshu Agrawal on September 19, 2012 at 6:35am

Hey ....can u give me the correct code for the arduimu v3 ....

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Permalink Reply by Alain Spineux on September 20, 2012 at 1:14am

This is the line I wrote in first post :

MPU6000_SPI_write(MPUREG_ACCEL_CONFIG,0x08);            // Accel scale 4g (4096LSB/g)

attached is the code I use.

Regards

 

Attachments:

• MPU6000.ino, 4 KB
• MPU6000.h, 2 KB

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Permalink Reply by Himanshu Agrawal on September 25, 2012 at 2:31am

Thanks Alain for the reply ...i am currently using the following code for arduimu v3 ....

http://code.google.com/p/ardu-imu/downloads/detail?name=ArduIMU_1.9...

..i think it is similar to one u r using .....

the problem i face are :

accelerometer doesn't provide good values when moving at faster speed .....

and when i turn my board by 90 degrees ..heading does not change by 90 degrees ..any solution to above issues...??

to convert acc to dist i used the logic -  sqrt((.125*.125*square(ax) +(.125*.125*square(ay)+(.125*.125*square(az)) ... .125 is sampling time....

i.e net diatance =sqrt(dx(2)+dy(2)+dz(2))

dx= .125*.125*ax and so on ....is my method correct ?

and repeating the same for entire set of readings and adding them .....

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Permalink Reply by Alain Spineux on September 25, 2012 at 1:12pm

In my original post, I just say that the spec of the MPU60*0 in the ArduIMU board looks to the documentation and the spec of another MPU60*0 board. 

ArduIMU_1.9 code is working fine with the ArduIMU board ! 

Now, about your equations : 

The definition of speed and acc are :

speed = variation of the distance versus time 

acceleration  = variation of the speed versus time

the opposite require to make some integral calculation

speed=integral of the acc by the time + original speed 

distance = integral of the speed + original position

if acc is a constant or if the period is short :

(1) speed = acc *  delta_time + s0

(2) distance = speed * delta_time + d0

because this is integral calculation you cannot replace speed of (2) by speed of (1) 

double integral of the constant acc is  : (acc*t^2)/2 + v0*t + d0

Then  your equation would be better like this :

sqrt(square(0.5*.125*.125*ax)+square(0.5*.125*.125*ay)+square(0.5*.125*.125*az))

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Permalink Reply by Himanshu Agrawal on September 25, 2012 at 10:32pm

Thanks Alian ,

what u told i implemented it in the attached file ...column N denotes the same ...and column O denotes the corresponding total distance .

Also what i want to ask is that do you get change in heading of about 90 degrees by turning the board by 90 degrees..? also Heading should remain constant when we move in a straight line but it changes practically ..... Heading is calculated by Tan-1(-MY/Mx) (magnetometer readings) if we neglect roll and pitch effects....

Attachments:

• rtn100.xlsx, 41 KB

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Permalink Reply by Alain Spineux on September 26, 2012 at 1:45am

Sorry I have not the time to throubleshot your program or data.

My ArduIMU 3 is working well with ArduIMU_1_9 or with my own software.

Be carefull they is lot of trap when working in 3D. Data are not always what you expect and sometime you see the oposit of what you are expecting. 

Here the force is always in the opposite direction of the move.

An yes my magnetometer is working fine and as expected and show a rotation when I turn of 90°

Regards

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Permalink Reply by Himanshu Agrawal on September 26, 2012 at 2:42am

ok ..no problem ...thanks once again ...:)

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Permalink Reply by Himanshu Agrawal on October 4, 2012 at 11:20pm

HI ..i got fine yaw values when i switched off the magnetometer with expected turn ...but problem is that there is a yaw drift ...any idea how to solve it ...?

What does 1g/4g range actually means..?

Also i want to take readings from GPS only periodically and switch it off for remaining time ...what changes do i need to incorporate in my code..?

Thanks in advance

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