An Investigation of a Type of Affine Nonlinear Ship Fuel Oil Viscosity and Temperature Control System

In this paper, based on the working processes and principles of a ship's fuel oil viscosity and temperature control system and the related theories in thermodynamics, a multi-input coupled nonlinear heat transfer model is established, in which the inlet and outlet temperatures of the heavy oil heater are used as the state variables, while the opening degrees of the regulating valve of the mixed oil tank and the steam flow regulating valve of the heater are used as the control inputs. In order to solve the state equation, a sliding mode variable structure controller should be solved using a decoupling control and a type of dual-input affine nonlinear control. Then, using the MATLAB simulation software platform, both the inlet and outlet temperatures of the heavy oil heater are controlled by means of a proportion-integration-differentiation (PID) control and sliding-mode variable-structure control respectively. The comparison results fully demonstrate a number of superiorities of the sliding-mode variable-structure controller; these mainly include a small overshoot, rapid response and strong anti-interference performance.