Debugging Solver Status == 1

Jannis · August 16, 2024, 10:22am

Hi all,

I have formulated an MPC with ACADOS. When using the generated s-function in Simulink I receive the solver status = 1. This means that there is some kind of ACADOS_Failure. I looked at this post which describes a similar error (Error status 1, what can I do to investigate this problem?), but it was not helpful to me.

I think it has something to do with my problem formulation, but I have used the same formulation in a different toolbox and it worked. Yesterday I tried many things to solve the issue, but I was not successful.

Can someone maybe give me some advice how to debug this issue.

If it is helpful, i can send my problem formulation, the main script for generating the s-function and the simulink model.

Thanks for the help

Jannis

kaethe · August 16, 2024, 1:13pm

Hi Jannis,

the forum post you are referring to is a bit outdated. Solver status 1 means that there have been NaNs detected.

github.com

acados/acados/blob/0d51bfa6180dc5ac2249747e732d64df31be4872/acados/utils/types.h#L77


      
          
          
          typedef int (*casadi_function_t)(const double** arg, double** res, int* iw, double* w, void* mem);
          
          
          
          // enum of return values
          enum return_values
          {
              ACADOS_SUCCESS,
              ACADOS_NAN_DETECTED,
              ACADOS_MAXITER,
              ACADOS_MINSTEP,
              ACADOS_QP_FAILURE,
              ACADOS_READY,
              ACADOS_UNBOUNDED,
          };
          
          
          /// Types of the cost function.
          typedef enum

Typically, NaNs results from a division by zero/a logarithm of a negative number/etc. Please check your problem functions, i.e. all CasADi functions defining your cost/dynamics/constraints.

Best, Katrin

kaethe · August 16, 2024, 1:15pm

And does this problem arise also in MATLAB or only in Simulink? If it is only Simulink, you might want to check the initialization.

Jannis · August 18, 2024, 3:20pm

Hi Katrin,

thanks for your response. I checked the casadi functions and I was able to solve the problem. It had something to do with too tight constraints and a missing integrator in the process mdel.

Thanks, Jannis