Hi everyone and the authors! I really appreciate your excellent work! However, i noticed the definition of "xdes":
xdes: Denotes the desired setpoint vector for the states.
It seems like that "xdes" can only be the setpoint for this moment tk. But in some cases the setpoints for the next several moments till tk+N are also already known (previewing). Can this previewing of "xdes" also take place in grampc?
And another question: what does "Nhor", "discretization points" exactly mean?
Nhor: Denotes the number of discretization points for the numerical integration.
When i correctly understand, the "numerical integration" is the integration of sysfct f(t,x,u). Shouldn't this take place for Thor/dt times in one MPC step?
I'm looking forward for an answer and thanks a lot in advance!
Best regards
Last edit: Tianyu Liao 2017-06-28
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Hello,
xdes denotes, a set point that is constant over the horizon. If you want to use variable values for the set point, for example, you must use pCost. Depending on the integration algorithm, you must find the right index in the pCost vector and may interpolate these values using the time value t. (e.g. in case of ruku45)
You have correctly understood the meaning of Nhor. Nhor can be set to Thor/dt, however, if your system is very stiff or not, it may be sensible to raise or to reduce the numer of discretization points.
Best regards
Last edit: Tobias Englert 2017-06-28
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi everyone and the authors! I really appreciate your excellent work! However, i noticed the definition of "xdes":
It seems like that "xdes" can only be the setpoint for this moment tk. But in some cases the setpoints for the next several moments till tk+N are also already known (previewing). Can this previewing of "xdes" also take place in grampc?
And another question: what does "Nhor", "discretization points" exactly mean?
When i correctly understand, the "numerical integration" is the integration of sysfct f(t,x,u). Shouldn't this take place for Thor/dt times in one MPC step?
I'm looking forward for an answer and thanks a lot in advance!
Best regards
Last edit: Tianyu Liao 2017-06-28
Hello,
xdes denotes, a set point that is constant over the horizon. If you want to use variable values for the set point, for example, you must use pCost. Depending on the integration algorithm, you must find the right index in the pCost vector and may interpolate these values using the time value t. (e.g. in case of ruku45)
You have correctly understood the meaning of Nhor. Nhor can be set to Thor/dt, however, if your system is very stiff or not, it may be sensible to raise or to reduce the numer of discretization points.
Best regards
Last edit: Tobias Englert 2017-06-28