How to set weights of costs according to the time interval in MPC prediction horizon

User Questions
4

You’re Welcome!

You’re right about the first part of your text.

However parameter are defined as loose symbols in acados. You can define everything as a parameter (e.g. your reference y_{ref}) with casadi/acados => those symbolic parameters can then used in your system dynamics, cost function, constraints, etc.

One example:
You want to change the weights of your external cost function in every control cycle. So you do something like this:

w = cs.SX.sym(‘w’)
ocp.model.p = w
ocp.model.parameter_values = 1

cost_func = w * (y - y_ref) * (y - y_ref)
ocp.model.cost_expr_ext_cost = cost_func

#run mpc
…
#change weight
for n in range(0,N+1)
ocp_solver.set(n, ‘p’, w_{new})

I hope you get what I mean. Maybe @FreyJo can point you towards a good example :slight_smile: !
Best Luck with your implementation!
Thorben

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