Dual-mode model-based control of a process

A method 500 comprising: implementing model-based control of a process represented by a set of process variables (PVs) including a set of adjustable manipulated variables (MVs) and a set of controlled variables (CVs), dependent on one or more MVs; initiating a scan 505 to obtain a current set of CVs; prior to the scan ending, implementing a dual-mode of operation that includes selecting a current move plan for the set of MVs and a set of constraints for the PVs, including: using the current set of CVs as model inputs for the process model to generate an unconstrained solution and a constrained solution 507, including a series of bounded move plans that avoid violating any of the set of constraints. When the constrained solution is generated before the end of the scan period, a first move plan is selected from the constrained solution 515. When the constrained solution is not generated before the end of the scan period, a first move plan is selected from the unconstrained solution 520. The method further comprises implementing control of the process before the end of the scan period by setting the MVs to a set of values included in the current move plan by: transmitting a set of controller outputs to the field devices to cause the field devices to drive the set of MVs to the set of values.