How can I get intermediate values when solving ODE's?

[J_Winkler]

I'm building a VI to solve a vehicle dynamics problem, and am having trouble getting intermediate values when solving the ODE's. I need to get the vertical wheel speed, one of the parameters I'm solving for, at each time step of the ODE solution, to determine what shock coefficients are appropriate for the next time step. I also need the current time at each time step to know where the vehicle is in the world. Is there a way to do this using LabView's built in ODE solvers, or do I need to create my own? I appreciate any advice you can offer.

[Ankita A.]

Hi,

Most of the LabVIEW's built-in ODE solvers like Runga Kutta 4th order.vi return an array of values (called X values(solution))corresponding to each time step. Since you want to decide the ODE coefficients based on the previous time step data, you can give a "time end" value to your ODE solver such that the ODE solver runs for only one time step. To get the current time use Get Date/Time in seconds.vi. Once you have the current time and the solution of the ODE solver at the current time step, you can change the coefficients accordingly and feed them to the ODE solver and repeat the process (using a loop).

If none of these suggestions help, or if I�m not correctly understanding your issue, please reply with comments or answers to the discussion above and a
ny additional information that may help, and I�ll be happy to look further into it.

Regards,
Ankita A.
National Instruments