Journal of Control Science and Engineering 2 (2015) 64-78 doi:10.17265/2328-2231/2015.02.002 Analytical/Numerical Modelling of Two Parallel Robots as Laser Calibration Instruments Controlled by Classical/Intelligent Schemes Ricardo Zavala-Yoe 1 , Ricardo A. Ramirez-Mendoza 1 , Daniel Chaparro-Altamirano 2 and Javier Ruiz-Garcia 1 1. Tecnologico de Monterrey, Escuela de Ingenieríay Ciencias, Calle del Puente 222, Ejidos de Huipulco 14380, Mexico City 2. Computer Science Department, Columbia University, New York, USA Abstract: Industrial metrology deals with measurements in production environment. It concerns calibration procedures as well as control of measurement processes. Measuring devices have been evolving from manual theodolites, electronic theodolites, robotic total stations, to a relatively new kind of laser-based systems known as laser trackers. Laser trackers are 3D coordinate measuring devices that accurately measure large (and relatively distant) objects by computing spatial coordinates of optical targets held against those objects. In addition, laser trackers are used to align truthfully large mechanical parts. However, such aligning can be done in moving parts, for instance during robot calibration in a welding line. In this case, serial robots are controlled in order to keep a prescribed trajectory to accomplish its task properly. Nevertheless, in spite of a good control algorithm design, as time goes by, deviations appear and a calibration process is necessary. It is well known that laser tracker systems are produced by very well established enterprises but their laser products may result expensive for some (small) industries. We offer two parallel robot-based laser tracker systems models whose implementation would result cheaper than sophisticated laser devices and takes advantage of the parallel robot bondages as accuracy and high payload. The types of parallel robots evaluated were 3-SPS-1-S and 6-PUS. Modelling of the parallel robots was done by analytical and numerical techniques. The latter includes classical and artificial intelligence-based algorithms. The control performance was evaluated between classical and intelligent controllers. Key words: Parallel robots, laser calibration, classical and al-controllers. 1. Introduction The laser tracker measures 3D coordinates by tracking a laser beam to a retro-reflective target held in contact with the object of interest. They determine three dimensional coordinates of a point by measuring two orthogonal angles (azimuth and elevation) and a distance to a corner cube reflector; typically a SMR (spherically mounted retro-reflector). These balls work as interface between the optical measurement from the tracker and moving system [1, 7]. In this work we propose to use a couple of parallel robots, a 3-SPS-1-S and a 6-PUS to implement a laser tracker in calibration mode for a serial robot in a welding line. In such a process, serial manipulators Corresponding author: Ricardo Zavala-Yoe, Ph.D., research fields: modeling, nonlinear control, robotics. E-mail: rzavalay@itesm.mx. need to be readjusted as time goes by. This readjustment is done by tracking of the serial robot position trajectory. Certain smooth path (a sinusoid for instance) is fed to the serial manipulator in order to be followed by a calibration device (the laser tracker). We propose to simulate this calibration process by coupling the dynamics of the arm with the parallel robots’ one. So, the serial manipulator will move following certain trajectory and the parallel robot in turn has to track this trajectory in order to determine if the serial robot is still calibrated. In order to accomplish this task, both parallel robots will be evaluated to determine which one tracks better the serial arm. In numerical simulations, we assume that an SMR is placed at the far end of the welding robot. Once that this robot starts moving following a reference signal D DAVID PUBLISHING