An event-based, robot-served flexible manufacturing cell modeller

Abstract

The development is described of a flexible manufacturing cell (FMC) programming and simulation system called FMCPS, which generates robot programs for a 6-DOF industrial robot. The development of FMCPS is based on an FMC that is being developed at UMIST. The cell consists of a Fanuc 600 ARCmate industrial robot, a Takisawa MAC V3 CNC machining centre and an MHP MT-50 CNC turning centre. The software has been developed on a SUN 4/110 workstation running under the UNIX operating system, using three-dimensional SUNCORE interactive graphics and SUNVIEW window systems. An event-oriented robot-programming method is used in the FMCPS. This method divides the robot tasks into different events. The user needs to define the points of the robot gripper route and the corresponding data for each event. The Cartesian coordinates of the points in the robot gripper paths are then transformed to the six robot joint angles by a variant inverse kinematics iteration method. These robot joint angles are used in the simulation model which generates robot programs suitable for the Fanuc robot. A three-dimensional, wire-frame-based graphical model is used for simulation. The user can observe the simultaneous animation of the robot movement, and display machine tool paths in separate graphics windows on the screen simultaneously. The various activities in the cell are simulated in pseudo-parallel mode by taking advantage of the multi-tasking and piping features of UNIX. At the end of a simulation exercise, the user is provided with the facility to obtain a performance report for the FMC which gives information on total operation time and on robot and machine utilisation, in addition to the robot program.