Interpretation of Laser Measurements Produced by the Reconfigurable Inspection Machine Using the 'Virtual Ball' Method

摘要

Current laser probes enable rapid and accurate non contact measurements. However, this measurement technique has different characteristics than the broadly used contact probe Coordinate Measurement Machine (CMM). As a result of these differences, the measurements reported will differ between the two measurement methods. Several differences can be theoretically explained by the fact that the CMM ball stylus is typically larger than the laser spot size. This sets the ground for developing an interpretation between both measurements. Since contact probe measurements are regarded as the common practice, such an interpretation aids engineers, because it establishes a quantitive conversion method between the two different measurement techniques. Within this paper, an interpretation method is suggested for conversion of laser measured data into values that would have been reported by a contact probe. The method is referred to as the "virtual ball" method, since the interpretation method considers the CMM ball stylus radius. The method was implemented and used to interpret results obtained by the Reconfigurable Inspection Machine (RIM). The RIM was designed for rapidly measuring a part family of engine heads with an array of accurate laser sensors. The laser probes rapidly measure surface features on an engine head. These RIM measurements are then interpreted using the "virtual ball" method to imitate contact probe measurements.