Patent ID: 6785624
Filing Date: 2004-08-31
Classification: B25J,G05B

Abstract:
A method for calibrating machine units disposed in machine tools and robotic devices and moved by a parallel kinematic in a motion space, the machine units including between two and six drives that can be controlled independently of each other, directly or via force transmitting and guide means or articulated joints that operate on a moved machine unit, a controller for setting desired positions and/or desired trajectories in a Cartesian coordinate system and for converting the Cartesian desired positions and desired trajectories into desired positions and/or desired trajectories of the two to six drives through a kinematic transformation {right arrow over (g)}, depending of a finite set of invariant machine parameters, measurement and control devices for controlling the two to six drives to their desired positions and/or desired trajectories, with a device for measuring a deviation of an actual position from the position set by the controller, the method comprising the steps ofa) determining on a number of K positions in the motion space of the moved machine unit the deviation of the actual position from the position set by the controller, b) linearizing for each position k of the K positions the nonlinear relationship between parameters errors and positioning errors by way of a Jacobi matrix Jk, c) forming a system of linear equations between parameters errors and positioning errors from the K linearized relationships, d) computing the parameter error by at least approximately solving the system of linear equations, e) computing new machine parameters from the machine parameters used in the transformation {right arrow over (g)} with the computed parameter errors, and f) updating the kinematic transformation {right arrow over (g)} stored in the controller with the updated machine parameters.