Using non linear unconstrained optimizers

[tlin067]

Hi,

I am having an issue using the uncontrained optimization vi. I have used the template for the objective function provided but I can't seem to get it to work. My error message says "LabVIEW:  An input parameter is invalid. For example if the input is a path, the path might contain a character not allowed by the OS such as ? or @."

My application is to find an optimum set of quaternion parameters which describe a rotation between 2 vectors. The vector in this case contains six elements as there are 2 vectors (1 each from individual sensors). To begin with, the obj funciton should be equal to zero (no rotation) and I input the correct quaternion describing this into the optimizer (hence solution is already a minimum??).

But when I run it, the control within the obj function describing the quaterion parameters is NaN and not what I wire to the "Start" input.

Does anyone know what is going on and is able to help me?

Thanks very much,

Tom

(code is attached)

[Josh_B1]

Hi tlin067,

I am having so trouble running the code you sent. It appears I am missing Quaternion to Rotation Matrix.vi. Could you resend the code and make sure all the subvi's are included. 

Thanks,

Josh Brown

[tlin067]

HI Josh,

Thanks for the reply. That vi is part of the robotics toolbox. That may mean you are unable to help me?

Cheers,

Tom

[Josh_B1]

Hey Tom,

I am going to install the robotics toolbox and take another look at your code. I will get back to you when I have something.

Josh Brown

[Josh_B1]

Hey Tom,

So I installed the robotics kit and was able to recreate your error. I think I have figured out were it is actually happening. In your main vi open the Unconstrained Optimization. Then within this vi open Armijo rule stepsize reduction. Then within this open unco_function and gradient. Then open the call object fuction.vi. The error appears to taking place at the reference node within this vi. My computer was giving me the following error: call by reference node in NI_Gmath.lvlib:ucno_call objective funtion.vi:28. I believe this is the root of your problem so try to figure out what is going on with the reference node. I hope this helps.

Josh Brown