Abstract: An automatic steering device is presented for controlling the direction of travel of an asphalt finisher during a paving operation. The device is provided with a laser generator (18) which projects a laser beam of a slit shape on a series of objects along the roadside which is selected to served as a reference line (A). An image recording device (17), a CCD camera, is disposed on the vehicle member (2), which records the projected laser light illuminating the objects and outputs a generated image (Ba) to a master controller (22). The master controller (22) determines the current deviation of the vehicle member (2) from the reference line (A) by the changes in the position of the generated image (Ba), and operates the automatic control device so as to steer the vehicle member (2) in the correct direction to permit the asphalt finisher to follow the reference line (A).

Abstract: Efficient paving operation requires that the levelling operation of asphalt be carried out accurately along a reference line which follows a given direction along a roadside. A simple and effective automatic control device for controlling the steering direction in conjunction with adjustments of the screed for an asphalt finisher (shortened to finisher) is presented. The control device automatically regulates the extension or retraction of the screeds on both sides of the finisher in reference to a visual display of the reference line following some objects along the roadside. The visual detection system of control is simple and economical and provides an accurate control over the direction of paving.