Development of a dynamic model for a constant tension winch

Developing an effective controller for a towing winch is very important to maintain constant towing rope tension between a submarine cable burying machine and a cable ship. A valve-controlled hydro-motor system for the towing winch is a highly nonlinear and time varying system due to the flow-pressure dynamics, oil leakage, oil temperature variation, etc. In this paper, we develop the dynamic model of the valve-controlled hydraulic winch by linearizing its nonlinear dynamics at an operating point. Both the simulation and experimental results demonstrate that the developed model describes the dynamic relationship between input control signals from the electronic proportional valve and pull forces generated by hydro-motor well. We used the model to evaluate and analyze the PID and FUZZY P+ID controllers for the constant tension winch that operates under sea waves with significant variations (peak-to-peak) from 1.5 to 2.5 meters.