MPC Predictive Control of Electropneumatic Position Valves with Grip
Valve Stiction, Nonlinear Predictive Control, Constraints, Compensation.
This work presents the implementation of a system that deals with static friction (stiction)
in electropneumatic control valves, one of the most common nonlinearities that causes
problems such as limit cycles and consequently wear of the valve and its moving
parts, as well as losses in production and maintenance costs. This system is composed
of a non-linear predictive controller with adjustable constraints and an online database
for estimation of the stiction parameters. The predictive controller uses constraints on
the valve speed during its excursion, as well as constraints on the control signal to bring
the valve to the desired position and slip it when necessary. The strategy adopted also
showed robustness, being able to cope with changes in the spring and stiction parameters,
which caused mismatch between the valve model and the present controller model, the
that should cause loss of performance or even instability.