DESIGN AND APPLICATION OF AN IMAGE-PROCESSING-BASED FUZZY AUTOPILOT FOR SMALL-BOAT APPROACHING MANEUVERS

This paper presents an image-processing-based fuzzy autopilot scheme for accomplishing small-boat approaching maneuvers in a harbor environment. In the proposed approach, two canvas targets are arranged in cascade on the quayside to form a leading line. The targets are detected by a charge coupled device (CCD) camera mounted on the bow of the boat, and their geometric centers are computed by a Hue- and Saturation-based image-processing scheme. The autopilot system calculates the current heading deviation and tracking deviation angles of the boat by analyzing the displacements of the target centers relative to the CCD center line. These angles are then supplied to a fuzzy-logic-based control system to determine the rudder commands required to bring the boat back on course. During the approaching maneuver, the autopilot system estimates the distance between the boat and the quayside using a simple trigonometric relationship, and at a certain pre-defined distance, automatically switches the steering control system from an approach mode to a berthing control mode. The experimental results obtained using a small FRP boat confirm the ability of the autopilot system to accomplish the approaching maneuver and show that the estimated value of the boat-to-quayside distance deviates by approximately 10 similar to 20% from the exact value.