Guidance system for automatic riveters

Abstract

An optical edge guidance system for automatic riveters. The guidance system utilizes a light source which directs light toward the material to be drilled/riveted, a video camera is also directed toward the portion of an object to be drilled/riveted and detects reflected source light from the material. The light from the source directed toward the material is angled about 10 to 15 degrees from the vertical. The material either is marked with a dark stripe or, for example, when the material cross-section is in the shape of a hat section, i.e. an aircraft longeron, a shadow is cast by the light striking the edge of the material and forms a dark area along the longitudinal centerline thereof. The edge of the dark stripe or shadow is detected by the video camera. The video signal from the camera is processed into a voltage equivalent of the video signal. A known reference voltage signal is established when the material positioned properly for drilling/riveting. If this reference voltage signal varies either plus or minus the drill/rivet head is repositioned until the reference voltage is again re-established. The drill/rivet head is moved by means of a servo motor drive controlled by the reference voltage signal which translates the head according to the amount of plus or minus voltage signal from the reference voltage until the exact reference voltage is again achieved for proper drilling/riveting head location.