Dynamic Positioning

Snapshot of the front panel of the simulator:

Mathematical model

The mathematical model constituting the basis of the simulator is described on the tab named Math model on the simulator.

PID tuning

PID tuning with Skogestadís SIMC rules assuming the PID controller is on parallel form, i.e. PID = P + I + D:

Kc = 2/(Kii*Tc^2)

Ti = 4*Tc

Td = Tc

where Tc [s] is the closed loop time constant specified by the user, Kii = 1/m is the double integrator gain, and m [kg] is mass of the ship. For the controller tuning, it is assumed that the ship model is a double integrator:

m*x'' = Fp

where x [m] is the ship position, and Fp [N] is the control variable (the propeller force). This is the ship model at the critical operating point, where damping environmental forces by wind and water are neglected.

Feedforward control

The control system includes feedforward from the position reference, and from disturbances, i.e. the environmental forces by wind and water. Feedforward control can be activated with a switch.

[SimView] [TechTeach]

Updated 31 August 2023. Developed by Finn Haugen. E-mail: finn@techteach.no.