Study On Laser Guided Measurement Robot System And Its Applications

Laser tracker system (LTS) is one of the latest portable large size coordinate measuring machines (CMMs). It measures 3D coordinates with laser beam by following a spherical mounted retro-reflector (SMR) with the advantages of broad range, high speed and high accuracy. However, the current inspecting task of LTS is performed manually to move SMR along the different positions on the surface of a given parts and measured with complex courses, low efficiency and the trial-and-error approach, which causes the deformation of the measured parts and seriously affects the measurement accuracy. In order to perform LTS more efficiently and automatically, a new laser guided measurement theory of"Laser Beam Moving and SMR Tracking"is studied based on the traditional method of"SMR Moving and Laser Beam Tracking". A miniature wheel-armed laser guided measurement robot (LGMR) system is developed based on this theory which can make LGMR move on the complex surface of measured parts. Also the LGMR can directly use the digital model of measured objects to control the laser beam and measuring robot. Therefore the measurement of given parts is performed automatically and effectively. The innovations of this dissertation are shown as following:1. A new laser guided measurement theory of"Laser Beam Moving and SMR Tracking"is proposed. On this basis, the laser guided measurement robot technology and the implemental method are researched.2. A miniature wheel-armed LGMR system is developed which can move on the complex surface of given parts. The LGMR system combines the merits of wheeled mechanism and armed mechanism; and possesses many advantages, such as less weight, small volume, simply structure and quick response. The LGMR can changes the measuring modes according different characteristics of parts. It moves on the measured surface with high speed and stable position by using wheeled system, and realizes strongcrosa-barrier ability by using armed mechanism. The kinematics modes of LGMR are already established.3. A fastly and highly integrated control system of LGMR is designed, which integrates visual system, wireless communication module, position control module, motor drive module, and so on. The software of LGMR is design based on C++, which possesses many advantages, such as compatible graphics, high-level language and assembly language. The position principle and method of LGMR is given based on vision system and photoelectric encoder.4. A novel screen data catching and sending system is developed. With this technology, it realizes the better real-time data communication between LGMR and LTS without considering the internal work of LTS.5. The adaptive measuring algorithm of LGMR is proposed based on the characteristics of CAD model and the given measured points of free-surface. The transformation relationship of coordinate system among CAD model, LGMR and LTS is established. The motion planning and tracking control method of LGMR moving on the parts surface is developed, and the automatically and efficiently measurement technology is developed. With the proposed methods, the digital model of measured object can be used to control LGMR and LTS and to generate automated scanning process under automaticity and accuracy constraints.Finally, The Faro SI laser tracker and Hexagon Globle9128 coordinate measuring machine (CMM) are used to test the performance of LGMR. The experimental results show that the measuring accuracy of LGMR is 0.05 mm+0.01 mm/m, and the LGMR can track laser beam automatically and effectively when LGMR measures on the surfaces of given parts. Therefore, two functions of laser tracking measurement and laser guided measurement are realized: (1) The LGMR can automatically track laser beam and move to the accurate position of given parts reliaby. (2) The LGMR can directly use the digital model to measure the objects automatically and efficiently.