Steer-by-Wire with Force-Feedback for Marine Crafts

The objective of this master's thesis was to implement and test a Steer-by-Wire (SBW) system with Force-Feedback on Combat-Boat 90 (CB90) designed by Dockstavarvet and the Swedish Defence Materiel Administration (FMV). The CB90 uses waterjets at its stern to propel itself, to control the boat a hydraulic steering system is currently used. A SBW system, as the name suggests, uses wires to send electrical signals to actuators, as opposed to a hydraulic system where turning the steering wheel, which is connected to the orbitrol, causes the waterjet nozzles to move. A SBW system allows for a reduced weight as it eliminates the need for a mechanical link between the manual control unit and actuators. It also gives the opportunity to tune how the steering should behave, increasing steering feel and safety. However, when removing the mechanical connection between the steering wheel and the hydraulic system, you also remove the feedback felt when steering, which can cause pilot-induced oscillations. However, with an external brake connected to the steering wheel this feedback can be replicated. In this project two different Electromagnetic particle brakes were tested and evaluated. The goal of this project was to see whether a SBW system with Force-Feedback could replicate, or improve, the steering feel compared to the current hydraulic system. Multiple steering ratio curves, which could alter how much the boat turns when turning the steering wheel, were designed and tested. Three brake curves were also designed, which altered how much and when the brake should be activated when the steering wheel turned faster than the waterjet nozzles. Other features such as a center-click were also implemented and tested to increase steering feel. To test the SBW system three experienced combat boat pilots from Dockstavarvet and one previous member of the Swedish Amphibious Corps were asked to evaluate the steering feel with the SBW rig. The tests were done during high and low velocities, testing how it felt during fast turns as well as checking the course stability. The results after testing the system on the CB90 was that all combat boat pilots confirmed that the SBW system could replicate the steering feel of the hydraulic system. One of the pilots even preferred the SBW system. The final result was a Steer-by-Wire rig with Force-Feedback that could replicate the steering feel of the hydraulic system.