Indoor GPS Metrology System with 3D Probe for Precision Applications

There is an increasing demand from industry for intelligent reverse engineering solutions. The requirement is to be able to perform reverse engineering, to create CAD models, or to compare prototypes with CAD models. A reverse engineering solution that can be used for 6 degrees of freedom pose measurement in a large area is desired. With this application in mind, we have developed a ‘3D Probe’ solution. The 3D Probe is a portable measurement tool equipped with three receivers in optimum locations and a ball probe tip. The operator holds the 3D Probe in his hand and moves the probe tip over an object surface. Then, the X, Y and Z coordinates of the probe tip are measured in real time with high accuracy. Different probe tips of all sizes and shapes can be used on the probe to have access to all areas of the objects. The buttons on the probe allow the operator to start and stop the scanning process. The indicators on the probe give information concerning visibility and scanning mode. The 3D Probe is specifically designed for intelligent scanning using recently available indoor Global Positioning System (GPS) technology. A battery-operated transmitter uses laser and infrared light to create one-way position information, the relative azimuth and elevation from the transmitter to the receiver. The receiver contains photodiodes and senses the transmitted laser and infrared light signals. With the addition of a second transmitter of known location and orientation, users can calculate the position of the receiver in the base coordinate system. Adding more transmitters increases the accuracy of the system. The signal is transferred through a wireless network connection providing mobility to the operator. This paper describes the indoor GPS metrology system and the 3D Probe designed for reverse engineering and calibration. The concept of the 3D Probe is presented with the description of its design, components, and calibration process. The general concept and kinematics of the metrology system are described. The metrology system is applied to various engineering problems such as reverse engineering of standardized interface connection, actuator metrology, and robot metrology. Experimental results of standardized interface tests are presented along with procedures for actuator and robot metrology.