Method for calibrating of machine units located in machine tools or robotic devices
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01C-017/38
G06F-019/00
G01P-021/00
출원번호
US-0378541
(2003-03-03)
우선권정보
DE-0009141 (2002-03-01)
발명자
/ 주소
Stengele, Gerald
출원인 / 주소
Siemens Aktiengesellschaft
대리인 / 주소
Feiereisen Henry M.
인용정보
피인용 횟수 :
1인용 특허 :
4
초록▼
In a method for calibrating machine units in machine tools and robotic devices that perform a parallel-kinematic motion in a motion space, the position of the machine unit relative to a reference system is determined from the totality of the positions of all drives operating in parallel of the machi
In a method for calibrating machine units in machine tools and robotic devices that perform a parallel-kinematic motion in a motion space, the position of the machine unit relative to a reference system is determined from the totality of the positions of all drives operating in parallel of the machine units, whereby each drive moves relative to the reference system a single drivetrain that is associated exclusively with the drive. The machine units can be calibrated using a robust and efficient iterative process that generates a kinematic transformation.
대표청구항▼
1. 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 o
1. 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 J k ,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, andf) updating the kinematic transformation {right arrow over (g)} stored in the controller with the updated machine parameters. 2. The method of claim 1, wherein the number K of measurements is selected so that the system of linear equations has a unique solution. 3. The method of claim 1, wherein the number K of measurements is greater than necessary to produce a system of linear equations with a unique solution and wherein the system of linear equations is solved approximately using a least-squares method. 4. The method of claim 3, wherein the parameter errors are computed by including historic statistical data of measurement values and estimated parameter errors with a minimal variance. 5. The method of claim 1, wherein new machine parameters are computed by associating a weight with the parameter errors. 6. The method of claim 1, wherein the linearization is performed about the machine parameters that form the basis of the kinematic transformation {right arrow over (g)} and are stored in the controller. 7. The method of claim 1, wherein the Jacobi matrix J k is calculated numerically using a difference quotient, making use of the kinematic transformation {right arrow over (g)} stored in the controller as well as the Cartesian desired positions of the machine unit, or of the indirect kinematic transformation {right arrow over (f)} with the actual positions of the drive. 8. The method of claim 1, and further repeating the steps a) through f) until the positioning error is smaller than a predetermined value, wherein during the subsequent repetition of steps a) through f) the positioning error is either newly measured or computed with a predictive method based on a modified transformation. 9. The method of claim 8, wherein the predetermined value is defined such that a subsequent error compensation using the method can be performed with a lesser number of support points than an error compensation performed without using the method. 10. The method of claim 9, wherein the errors are compensated in a Cartesian coordinate system. 11. The method of claim 9, wherein the errors are compensated in a coordinate system of the axes drives. 12. The method of claim 1, wherein for measuring the positioning error, a master workpiece with machining features is scanned. 13. The method of claim 12, wherein the master workpiece is a plate and the machining features are implemented as bores having a known position, a known diameter and a known depth. 14. The method of claim 1, wherein the positioning error is measured with a measuring device selected from the group consisting of stylus, laser interferometer and laser tracker.
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이 특허에 인용된 특허 (4)
Red Walter E. (Provo UT) Davies Brady R. (Orem UT) Wang Xuguang (Provo UT) Turner Edgar R. (Provo UT), Device and method for correction of robot inaccuracy.
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Wang Xuguang (Provo UT) Red Walter E. (Provo UT) Manley Peter H. (Alpine UT), Robot end-effector terminal control frame (TCF) calibration method and device.
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