Automatic spreader-container alignment system using infrared structured lights.

This paper presents a computer-vision system to assist reach stackers to automatically align the spreader with the target container. By analyzing infrared lines on the top of the container, the proposed system is able to calculate the relative position between the spreader and the container. The invisible structured lights are equipped in this system to enable all-weather operation, which can avoid environmental factors such as shadows and differences in climate. Additionally, the lateral inclination of the spreader is taken into consideration to offer a more accurate alignment than other competing systems. Estimation errors are reduced through approaches including power series and linear regression. The accuracy can be controlled within 2 cm or 2 deg, which meets the requirements of reach stackers' operation.