Research And Development Of3D Laser Scanning Measurement System

Coordinate Measurement Machine （CMM） is an intelligent measuringequipment of high precision, which integrates the application of precise mechanism，electronics，optics，control and computer technology. As an important tool ofmeasuring object’s space coordinate，CMM is widely used in science research andadvanced manufacturing technology. With the development of the sensor technologyand the laser technology, laser displacement sensors appeared，which can achievelong-distance and non-contact measurement with high speed, high accuracy and greatmeasuring range. Moreover, in electro-optical countermeasure environment，laserdisplacement sensor also works well. Nowadays，laser displacement sensor is widelyused in non-contact Coordinate Measurement Machine to measure distances. Thiskind of CMM is able to measure objects with complex curved-surface accurately,which works better than conventional contact CMM in such conditions. To measureobjects with complex curved-surface accurately, this paper researches and develops athree-dimensional Measurement System Based on Laser Scanning. It was found bytests that the motion precision of the measurement system’s each axis is within5μm.The main research contents and methods are as follows:1、Research, Development and Application of CMM based on laser scanningResearch, development and application of laser measurement technology andCoordinate Measurement Machine are introduced respectively, and the application ofthe laser measurement technology on Coordinate Measurement Machine is discussed.2、Design of system Platform and system overall StructurePersonal computer is selected as the hardware platform of the measurementsystem, and Windows XP Professional operating system is selected as the softwareplatform. The architecture of CNC system is "PC+Motion Control Board". Upper computer software, device drivers and hardware platforms, which together composethe overall structure of the measurement system, are analysed. Gantry gatemechanical structure is designed using Pro/E software, and the work principle of themeasurement system is introduced. The calculating formulas which are used tocompute the point’s three-dimensional coordinates are derived.3、Design and Analysis of the hardware of the Measurement SystemThe hardware components of the three-dimensional Measurement System areanalysed and chosen. The hardware system is mainly composed of precisionpositioning stage, servo driver, Numerical Display turret, laser displacement sensor,grating displacement sensor and limit switch. A fixture for laser displacement sensoris designed using Pro/E software. To control the laser displacement sensor，a controlsoftware is developed by using VB6.0development tool.4、Design of the hardware of the control systemCombined with functions of the motion control board and job requirements，control scheme for the three-dimensional Measurement System is analysed anddetermined. Four groups of controlling circuits are designed. A PCB(Printed CircuitBoard) is designed by use of Protel99SE software. The whole controlling circuit isintegrated by using the designed electrical control cabinet.5、Software Development and Experiments of the Measurement SystemSoftware execution graph is designed, software key modules and key libraryfunctions are analysed, and pulse equivalent is calculated. A motion control softwareis developed by using VC++development tool. Through testing on Y axis and Z axis,the performance of the measurement system is researched. The calculated motionaccuracy arrives at the anticipated goal. The three-dimensional Measurement Systemcan satisfy different measurement requirements.At prsent，the3D Laser Scanning Measurement System is used to measure thethickness of Hydroxyapatite(HA) coatings on titanium alloy substrate.