Abstract: A system for guiding a vehicle along a pre-determined rectilinear path which comprises a vehicle having a laser fixed thereon so as to direct a laser beam along the direction of motion of the vehicle towards a target carrying beam reversing means positioned on the vehicle path so as to direct the beam back to the vehicle.

Abstract: A vehicle guidance system for a tractor has a horizontal scanning laser on the tractor and a target arranged to return the laser beam along its path. When returned laser light is detected, indicating alignment of the beam with the target, the angle of the beam relative to the tractor axis illustrates the steering correction required. The target has an array of beam reflecting elements patterned to define a target datum. Continuous low amplitude and relative high frequency scanning of the laser in a vertical direction provides a detector output which is indicative of the error between beam orientation and target datum.