  Co-simulation is widely used in the industry due to the emergence of modular
dynamical models made up of interconnected, black-boxed systems. Several
co-simulation algorithms have been developed, each with different properties
and different levels of accuracy and robustness. Among them, the most accurate
and reliable ones are the iterative ones, although they have a main drawback in
common: the involved systems are required to be capable of rollback. The latter
denotes the ability of a system to integrate over a co-simulation time step
that has already been simulated. Non-rollback-capable system can only go
forward in time and every integrated step is definitive. In practice, the
industrial modelling and simulation platforms rarely produce rollback-capable
systems. This paper proposes a solution that slightly changes the co-simulation
methodology and that enables to use iterative co-simulation methods on a
modular model which contains non-rollback-capable systems in case the latter
represent ordinary differential equations. The idea is to replace such a system
by a simplified version, which is used to estimate the results of the
integrations instead of integrating the real system. Once the co-simulation
method's surrogate iterations on these estimators predict the convergence on
the co-simulation step, the non-rollback-capable systems genuinely integrate
the step using the estimated solution on the other systems before moving
forward, transforming the iterative co-simulation method into a non-iterative
one.
