Application of optical range-sensors for guidance of industrial robots in the automobile industry

Sensory control of robots requires information about position and orientation of workpieces and other objects. Especially important fields of application in the automobile industry are concentrated in the chassis and final assembly, where three dimensional sensory data are crucial for robot control. Optical rangefinders represent a type of sensor providing particularly useful information about depth and surface orientation which vision can hardly supply. This paper presents a systmatic classification for optical range sensors according to task, sensor type and application strategy. The classification system is explained through four different examples arising from projects carried out at IPA in the domain of automobile applications. First we present a robot arm with a hand-mounted rangefinder, which performs a one dimensional scan in order to determine the opening angle of a car door. A three dimensional position measurement using an optical rangefinder mounted on a moving vehicle is a further step in terms of complexity. Combining several rangefinders in a parallel arrangement allows measurement of surface orientation. It is demonstrated with a modular tool-integrated sensor-system developed at IPA. Finally, the assembly of waterhoses with the help of a two dimensional laserscanner is presented.