Control structure for the active damping of low-frequency oscillations in numerically controlled machine tools

• US 7,031,799 B2
• Filed: 01/14/2004
• Issued: 04/18/2006
• Est. Priority Date: 01/18/2003
• Status: Active Grant

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Kerner, Norbert, Lengenfelder, Hans
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): Garland, Steven R.
• Application Number:
  US10/757,376
• Publication Number:
  US 20040172171A1
• Time in Patent Office: 825 Days
• Field of Search: 700/174, 700/280, 700/71, 700/35, 700/38, 700/41, 700/42, 700/54, 700/55, 700/170, 700/176, 700/188, 700/175, 409/141, 82/1, 82/11, 829/04, 318/611, 702/56, 340/680, 340/683
• US Class Current: 700/175
• CPC Class Codes: F16F 15/02 Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems F16F15/005 takes precedence ; layered products B32B; suppression of vibration in ships B63; relieving load on bearings, using magnetic means F16C39/06
• CPC Class Codes: G05B 13/021 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/42034 Pi regulator
• CPC Class Codes: G05B 2219/49048 Control of damping of vibration of machine base
• CPC Class Codes: G05B 5/01 electric

Abstract

A control structure for the active damping of low-frequency oscillations in numerically-controlled machine tools. The control structure includes an rpm regulator having a proportional component and an integral component. The control structure further includes an active damping element that forms a low-frequency correction signal, which is phase-shifted with respect to an interfering low-frequency oscillation and free of d.c. components, and a summing point that is upstream or downstream of the integral component and receives the low-frequency correction signal.

Claims

1. A control structure for the active damping of low-frequency oscillations in numerically-controlled machine tools, comprising:

a speed regulator for generating a nominal current based on a difference between a nominal speed and an actual speed, said speed regulator comprising;

a proportional component; and

an integral component;

an active damping element that forms a low-frequency correction signal, which is phase-shifted with respect to an interfering low-frequency oscillation and free of d.c. components; and

a summing point that is upstream or downstream of said integral component and receives said low-frequency correction signal.

2. The control structure in accordance with claim 1, further comprising:

a second integral component that corresponds to said integral component of said speed regulator, wherein said low frequency correction signal is applied to an input of said second integral component and said second integral component generates a signal at its output that is applied to a summing station located downstream of said integral component.

3. A control structure for the active damping of low-frequency oscillations in numerically-controlled machine tools, comprising:

a speed regulator comprising;

a proportional component; and

an integral component;

an active damping element that forms a low-frequency correction signal, which is phase-shifted with respect to an interfering low-frequency oscillation and free of d.c. components;

a summing point that is upstream or downstream of said integral component and receives said low-frequency correction signal; and

a second summing point that determines a second deviation of an actual speed from a nominal speed and said second deviation is directed to said proportional component; and

wherein a first deviation of said actual speed from said a nominal speed is determined at said summing point and is directed to said integral component, and said low-frequency correction signal is applied at said summing point upstream of said integral component.

4. The control structure in accordance with claim 3, further comprising:

a position regulator that generates a nominal speed signal;

a third summing point within said damping element that receives said nominal speed signal and a derived speed signal that is derived from a nominal position value, said third summing point generates said correction signal based on a difference of said nominal speed signal and said speed derived signal.

5. The control structure in accordance with claim 4, further comprising a first order delay time member within said damping element that receives said difference between said nominal speed signal and said derived speed signal.

6. The control structure in accordance with claim 5, wherein a signal from an output of said first order delay time member is supplied to a second order delay time member.

7. The control structure in accordance with claim 6, wherein said output of said first order delay time member is supplied via a delay member to a branch of said nominal speed conducted on said integral component of said speed regulator.

8. The control structure in accordance with claim 6, wherein a damping time constant of said second order delay time member corresponds to a resonance frequency to be damped.

9. The control structure in accordance with claim 5, wherein an output of said first order delay time member is supplied via a delay member to a branch of said nominal speed conducted on said integral component of said speed regulator.

10. The control structure in accordance with claim 4, wherein said difference between said nominal speed and said derived speed is multiplied by an amplification factor.

11. The control structure in accordance with claim 3, wherein said nominal speed is conducted over a reference model of a control track prior to said determining said second deviation with said actual speed at said second summing point.

12. The control structure in accordance with claim 11, wherein said reference model of said control track is embodied as a second order delay time element, which simulates said control track and acts in a counter-phase manner.

13. A control structure for the active damping of low-frequency oscillations in numerically-controlled machine tools, comprising:

a speed regulator comprising;

a proportional component; and

an integral component;

an active damping element that forms a low-frequency correction signal, which is phase-shifted with respect to an interfering low-frequency oscillation and free of d.c. components;

a summing point that is upstream or downstream of said integral component and receives said low-frequency correction signal;

a second integral component that corresponds to said integral component of said speed regulator, wherein said low frequency correction signal is applied to an input of said second integral component and said second integral component generates a signal at its output that is applied to a summing station located downstream of said integral component;

a position regulator that generates a nominal speed signal; and

a second summing point within said damping element that receives said nominal speed signal and a derived speed signal that is derived from a nominal position value, said second summing point generates said correction signal based on a difference of said nominal speed signal and said derived speed signal.

14. The control structure in accordance with claim 13, further comprising a first order delay time member within said damping element that receives said difference between said nominal speed signal and said derived speed signal.

15. The control structure in accordance with claim 14, wherein a signal from an output of said first order delay time member is supplied to a second order delay time member.

16. The control structure in accordance with claim 15, wherein said output of said first order delay time member is supplied via a delay member to a branch of said nominal speed conducted on said integral component of said speed regulator.

17. The control structure in accordance with claim 15, wherein a damping time constant of said second order delay time member corresponds to a resonance frequency to be damped.

18. The control structure in accordance with claim 14, wherein an output of said first order delay time member is supplied via a delay member to a branch of said nominal speed conducted on said integral component of said speed regulator.