Research Article
Towards Online Model Predictive Control on a Programmable Logic Controller: Practical Considerations
Algorithm 1
Steps to compute the inputs of the experimental set-up.
| Offline: Calculate H’, G1 and G2 | | Online: Start PLC or PAC | | Store all precomputed matrices in working memory, together with the reference for | | inputs and output | | while CPU is running do | | if 1 second passed since last call then | | Scale the temperatures | | Calculate current state | | Calculate g, and | | case Hildreth algorithm | | Calculate the unconstrained inputs of the process. | | if unconstrained inputs violate constraints then | | while maximum numbers of iterations is not reached and solution not | | found do | | Solve one iteration of the QP | | end | | if maximum numbers of iterations is reached then | | Use unconstrained solution with inputs violating the constraint | | limited to the constraint | | end | | end | | endsw | | case qpOASES | | while maximum numbers of iterations is not reached and solution not | | found do | | Solve one iteration of the QP | | end | | if maximum numbers of iterations is reached then | | Use last sub-optimal solution | | end | | endsw | | case CVXGEN | | while maximum numbers of iterations is not reached and solution not | | found do | | Solve one iteration of the QP | | end | | if maximum numbers of iterations is reached then | | Use unconstrained solution with inputs violating the constraint limited | | to the constraint | | end | | endsw | | Apply the inputs to the system | | end | | end |
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