integration

[achay]

Dear Jeff,

i am new on this forum, and at first I would like to congratulate you for the brilliant job you have done about this device (6050) !

 

I am trying to understand the usage of the DMP and what you have done about it.

 

Tell me if I am wrong:

 

1)The DMP is and internal cpu inside the 6050

2) its instructions (code) reside in an volatile ram that has to be loaded after each power off

3) you have got this code but you don't know which instructions are really coded

4) by analysing the output you know what are the values given by the DMP

5) except some parameter you can't alter the computation done bu the DMP

 

My question is:

I would like to make some computation that needs fast integration of linear acceleration and rotation speed to get a kind of heading lock system

and position locking, this can be done by integration of these values with a fixed clock wich will give me linear and rotational displacement from

a given origin. Do you know if the DMP can do this or will be able to ? when reading the invensense pdf it seems they plan to.

 

Do you know why invensense seems so opaque about how can be programmed this DMP ?

 

 

Otherwise do you think an Arduino is fast enough to do the extra computation ?

 

Thanks for your answer.

 

 

 

 

 

 

 

 

 

 

 

 

[Jeff Rowberg]

Hi achay,

 

Thanks for your comments about the project! I am hopeful that it can continue to grow into a very useful community.

 

You are correct on all five points in your list. In short, we can make the DMP work to spit out quaternion data, but we don't know how it works. Displacement is hard to calculate accurately since it requires double integration of acceleration, and therefore is prone to a whole lot of error unless timing is very precise and the measurement error is low. Assuming the measurement data is accurate though, a rough estimate should be possible of both linear and rotational displacement. I believe a guy named Seb Madgwick was working this very problem using an Arduino, though I could have that wrong and I'm not sure if he's working with this particular sensor.

 

I'm not sure whether the DMP itself could be made to do this calculation for you, but I have no idea how to approach that goal. I figure InvenSense is opaque about it because it's a unique value-add feature for them, and opening it wide up would deprive them of some opportunities. (Of course, it would also open up many other opportunities, but that's apparently not their focus.)

[achay]

Hi Jeff,

Thanks for your answer.

 

What you depict about Invensense policy is exactly what I am affraid of.

 

So the next question is : there is another sensor that has this capability ?

if not, I am sure that some will soon build such one if we consider the wide developpment of this kind of application in a large variety of devices ( smartphone, robots, toys,...)

the need of low power consumption will guide to integrate these functions (and very more) on the same chip.

 

For now I will continue to fight with our slow and tiny Arduino to achieve some stabilisation and positioning job.

[Jeff Rowberg]

I'm not aware of any other sensors that have something like the DMP right on the chip. I believe there are some others which have raw 9-axis or even 10-axis (+altitude) sensors in them, but not the DMP. I could be wrong about this though.