Vibration-damped machine and control method therefor

• US 6,296,093 B1
• Filed: 11/09/1998
• Issued: 10/02/2001
• Est. Priority Date: 11/09/1998
• Status: Expired due to Fees

• Current Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Original Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Inventors: Meyers, Andrew D., Norris, Mark A., Margolis, Donald L.
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): NGUYEN, XUAN LAN T
• Application Number:
  US09/188,654
• Time in Patent Office: 1,058 Days
• Field of Search: 267/136, 267/140.14, 267/140.15, 188/378, 188/379, 188/380, 901/16
• US Class Current: 188/378
• CPC Class Codes: B23Q 11/0032 Arrangements for preventing or isolating vibrations in parts of the machine B23B29/022, B23D47/005 take precedence; means for damping or suppressing vibrations, in general F16F
• CPC Class Codes: B25J 19/0091 Shock absorbers in general F16F
• CPC Class Codes: F16F 7/1005 characterised by active control of the mass
• 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: G05D 19/02 characterised by the use of electric means
• CPC Class Codes: Y10T 409/304312 with means to dampen vibration

Abstract

A vibration-damped machine and method including beam being capable of gross movements in space relative to a stationary frame, means including a motor for causing the beam'"'"'s gross movements; the gross movements tending to induce vibration into the beam, sensors for providing a signal representative of the induced beam vibration, an linear-acting inertial actuator mounted to the beam, and control means for receiving the signal and generating an output signal to actively drive the linear-acting inertial actuator at the appropriate phase, frequency and magnitude to damp induced beam vibrations. Embodiments of the vibration-damped machine are illustrated for a gantry robot, a horizontal machining center, an adhesive dispenser and a pivoting robot. The linear-acting inertial actuator is preferably controlled according to an inertial damping control method where the actuator is forced to behave as a damper attached to ground.

Claims

1. A vibration-damped machine, comprising:

a beam being capable of gross motion in space relative to a stationary frame,

a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration in said beam,

a work member mounted to said beam,

a sensor device for providing at least one signal representative of said induced vibration in said beam,

at least one linear-acting inertial actuator mounted to said beam, wherein said at least one linear-acting inertial actuator comprises a plurality of inertial actuators each having a primary vibration axis, wherein said primary vibration axis of each of said plurality of inertial actuators are substantially orthogonal; and

a controller for processing said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator in said at least one direction at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam.

2. A vibration-damped machine of claim 1 wherein said sensor device comprises first and second sensors whose outputs are subtracted to provide a differential signal representative of said induced vibration.

3. A vibration-damped machine of claim 2 wherein said differential signal is further processed to provide a signal representative of vibrational velocity of said beam at a location of said first sensor.

4. A vibration-damped machine, comprising:

a beam being capable of gross motion in space relative to a stationary frame,

a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration in said beam,

a work member mounted to said beam,

a sensor device for providing at least one signal representative of said induced vibration in said beam, wherein said sensor device comprises first and second sensors whose outputs are subtracted to provide a differential signal representative of said induced vibration;

at least one linear-acting inertial actuator mounted to said beam, and

a controller for processing said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator in said at least one direction at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam.

5. A vibration-damped machine of claim 4 wherein said differential signal is further processed to provide a signal representative of vibrational velocity of said beam at a location of said first sensor.

6. A vibration-damped machine, comprising:

a beam being capable of gross motion in space relative to a stationary frame,

a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration in said beam,

a work member mounted to said beam,

a sensor device for providing at least one signal representative of said induced vibration in said beam,

at least one linear-acting inertial actuator mounted to said beam,

a controller for processing said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator in said at least one direction at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam, and

wherein said at least one linear-acting inertial actuator is controlled responsive to a signal representative of a velocity differential between a first and a second signal derived from a first and second sensor.

7. A vibration-damped machine, comprising:

a beam being capable of gross motion in space relative to a stationary frame,

at least one intermediate frame member moveable with respect to said stationary frame, said beam being moveably mounted to said at least one intermediate frame member,

wherein said at least one intermediate frame member comprises a first intermediate frame member mounted for orthogonal movement relative to a second intermediate frame member, said first intermediate frame member being moveably mounted to said stationary frame and said beam being moveably mounted to said second intermediate frame member,

a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration in said beam,

a work member mounted to said beam,

a sensor device for providing at least one signal representative of said induced vibration in said beam,

at least one linear-acting inertial actuator mounted to said beam, and

a controller for processing said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator in said at least one direction at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam.

8. A vibration-damped machine of claim 7 wherein said first intermediate member moves in a first direction, said second intermediate member moves in a second direction orthogonal to said first direction, and said beam moves in a third direction orthogonal to both said first and second directions.

9. A vibration-damped machine of claim 7 wherein said sensor device comprises first and second sensors whose outputs are subtracted to provide a differential signal representative of said induced vibration.

10. A vibration-damped machine of claim 9 wherein said differential signal is further processed to provide a signal representative of vibrational velocity of said beam at a location of said first sensor.

11. A vibration-damped machine, comprising:

(a) a beam being capable of gross motion in space relative to a stationary frame,

(b) means including a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration in said beam,

(c) a work member mounted to said beam,

(d) sensor means for providing at least one signal representative of said induced vibration in said beam,

(e) at least one linear-acting inertial actuator mounted to said beam, and

(f) control means for processing said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator in said at least one direction at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam, the control means is configured to generate said at least one output signal based on an inertial damping control equation and wherein said at least one output signal actively drives said linear-acting inertial actuator to behave as though said linear-acting inertial actuator were a damper attached to ground.

12. A vibration-damped machine, comprising:

(a) a stationary frame,

(b) a first intermediate frame member moveable relative to said stationary frame member in a first direction,

(c) a second intermediate frame member moveable relative to said first intermediate frame member in a second direction substantially orthogonal to said first direction,

(d) a beam mounted for movement relative to said second intermediate frame member in a third direction substantially orthogonal to both said first and said second directions,

(e) means including a motor for causing said movements in said first, second, and third directions, said movements tending to induce vibration within said beam,

(f) a work member mounted to said beam,

(g) sensor means for providing at least one signal representative of said induced vibration in said beam,

(h) at least one linear-acting inertial actuator mounted to said beam, and

(i) control means for receiving said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam.

13. A vibration-damped machine, comprising:

(a) a beam being capable of gross motion in space relative to a stationary frame,

(b) means including a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration within said beam,

(c) a work member mounted to said beam,

(d) sensor means for providing a signal representative of said induced vibration in said beam, said sensor means comprising a first acceleration sensor generating a first signal, a second acceleration sensor generating a second signal, said first and said second signal being subtracted to provide a differential acceleration signal and wherein said differential acceleration signal is integrated to provide a differential velocity signal,

(e) at least one linear-acting inertial actuator mounted to said beam, and

(f) control means for processing said differential velocity signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam.

14. A method for damping vibration in a flexible structure being capable of gross motion in space relative to a stationary frame wherein means for causing said gross motion of said flexible structure in at least one direction induces vibration in said flexible structure, the method comprising the steps of:

(a) providing a signal representative of said induced vibration,

(b) mounting an inertial actuator to said flexible structure at an attachment point,

(c) processing said signal representative of said induced vibration according to an inertial damping control law and generating an output signal, and

(d) actively vibrating said inertial actuator according to said output signal, said output signal actively driving said inertial actuator to behave as a damper connected between ground and said attachment point thereby damping said induced vibration.

15. A method for damping vibration in a flexible structure, comprising:

(a) providing a signal representative of induced vibration in said flexible structure,

(b) mounting an inertial actuator to said flexible structure at an attachment point,

(c) processing said signal representative of induced vibration according to an inertial damping control law to generate an output signal, said output signal actively driving said inertial actuator to behave as a damper connected between ground and said attachment point, and

(d) actively vibrating said inertial actuator according to said output signal thereby damping said induced vibration.

16. A vibration-damped machine, comprising:

(a) a beam being capable of gross motion in space relative to a stationary frame,

(b) means including a motor for causing said gross motion of said beam in at least one direction, said gross motion tending to induce vibration in said beam,

(c) a work member mounted to said beam,

(d) sensor means for providing at least one signal representative of said induced vibration in said beam,

(e) at least one linear-acting inertial actuator mounted to said beam, and

(f) control means for processing said at least one signal and generating at least one output signal to actively drive said at least one linear-acting inertial actuator in said at least one direction at the appropriate phase, frequency and magnitude to damp said induced vibration of said beam, wherein said control means is configured to generate said at least one output signal based on an inertial damping control equation and wherein said inertial damping control equation comprises;

$\frac{F_a<br><br>\left(s\right)}{V_s<br><br>\left(s\right)}=\frac{\left(b_d-b_a\right)<br><br>s^2+\left(\frac{b_a<br><br>b_d}{m_a}-k_a\right)<br><br>s+\left(\frac{k_a<br><br>b_d}{m_a}\right)}{s^2}$

where;

m_a is a mass of a tuning mass of said at least one linear-acting inertial actuator,

k_a is a combined stiffness of springs supporting said tuning mass,

b_a is a damping coefficient of said tuning mass,

b_d is a desired damping coefficient of said beam,

F_a is a force acting on said tuning mass produced by energizing coils,

s is a LaPlace frequency domain variable, and

V_s is a velocity of said beam.