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

• US 20040172171A1
• Filed: 01/14/2004
• Published: 09/02/2004
• Est. Priority Date: 01/18/2003
• Status: Active Grant

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Lengenfelder, Hans, Kerner, Norbert
• Granted Patent: US 7,031,799 B2
• Time in Patent Office: Days
• US Class Current: 700/280
• 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:

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

and

wherein a first deviation of an actual rpm from a nominal rpm 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.

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

a second integral component that corresponds to said integral component of said rpm 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 is applied to a summing station located downstream of said integral component.

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

a position regulator that generates a nominal rpm signal;

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

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

a position regulator that generates a nominal rpm signal;

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

6. The control structure in accordance with claim 4, further comprising a DT1 member within said damping element that receives said difference between said nominal rpm signal and said derived rpm signal.

7. The control structure in accordance with claim 5, further comprising a DT1 member within said damping element that receives said difference between said nominal rpm signal and said derived rpm signal.

8. The control structure in accordance with claim 6, wherein a signal from an output of said DT1 member is supplied to a PT2 member.

9. The control structure in accordance with claim 7, wherein a signal from an output of said DT1 member is supplied to a PT2 member.

10. The control structure in accordance with claim 6, wherein an output of said DT1 member is supplied via a PT1 member to a branch of said nominal rpm conducted on said integral component of said rpm regulator.

11. The control structure in accordance with claim 7, wherein an output of said DT1 member is supplied via a PT1 member to a branch of said nominal rpm conducted on said integral component of said rpm regulator.

12. The control structure in accordance with claim 8, wherein said output of said DT1 member is supplied via a PT1 member to a branch of said nominal rpm conducted on said integral component of said rpm regulator.

13. The control structure in accordance with claim 9, wherein said output of said DT1 member is supplied via a PT1 member to a branch of said nominal rpm conducted on said integral component of said rpm regulator.

14. The control structure in accordance with claim 8, wherein a damping time constant of said PT2 member corresponds to a resonance frequency to be damped.

15. The control structure in accordance with claim 9, wherein a damping time constant of said PT2 member corresponds to a resonance frequency to be damped.

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

17. The control structure in accordance with claim 2, wherein said nominal rpm is conducted over a reference model of a control track prior to said determining said second deviation with said actual rpm at said second summing point.

18. The control structure in accordance with claim 17, wherein said reference model of said control track is embodied as a PT2 element, which simulates said control track and acts in a counter-phase manner.