Diagnostic method for localizing technical faults in a motion system

Patent metadata

Field	Value
Publication number	US-12429863-B2
Application number	US-202418596859-A
Country	US
Kind code	B2
Filing date	Mar 6, 2024
Priority date	Mar 16, 2023
Publication date	Sep 30, 2025
Grant date	Sep 30, 2025

Abstract

A diagnostic method localizes technical faults in a motion system that includes a base adapted to receive a motion stage for equipment, a machine frame resting on the floor, dampers adapted to support the base, and an active isolation system arranged between the base and the machine frame. The active isolation system and the base form a mechanical system. The active isolation system includes actuators, adapted to impart six degree-of-freedom (DOF) motion to the base in a reference frame, and inertial sensors adapted to provide a six DOF measurement of the base's motion. The method includes: i) applying a control signal for actuating or contributing to the actuation of the actuators of the active isolation system to impart a motion to the base; ii) obtaining, with the inertial sensors, a six DOF measurement of the base's motion relative to a reference point; iii) creating a measured process sensitivity matrix of the mechanical system using the six DOF measurement; and iv) determining, based on the measured process sensitivity matrix, whether all the actuators and sensors of the active isolation system are working as expected and/or whether there is a pivot point impeding the movement of the base.

First claim

What is claimed is:

1. A diagnostic method for localizing technical faults in a motion system that includes a base adapted to receive a motion stage for equipment, a machine frame, dampers adapted to support the base, and an active isolation system arranged between the base and the machine frame, the active isolation system and the base forming a mechanical system, the active isolation system including actuators adapted to impart a six degree-of-freedom motion to the base in a reference frame and inertial sensors adapted to provide a six degree-of-freedom measurement of the motion of the base, comprising:
applying a control signal to actuate and/or contributing to actuation of the actuators of the active isolation system to impart a motion to the base;
obtaining, by the inertial sensors, a six degree-of-freedom measurement of the motion of the base relative to a reference point;
creating a measured process sensitivity matrix of the mechanical system based on the six degree-of-freedom measurement; and
determining, based on the measured process sensitivity matrix, whether all of the actuators and sensors of the active isolation system are working as expected and/or whether there is a pivot point impeding movement of the base.

2. The method according to claim 1 , further comprising identifying, for troubleshooting, at least one faulty actuator based on the process sensitivity matrix.

3. The method according to claim 1 , further comprising identifying, for troubleshooting, at least one faulty inertial sensor based on the process sensitivity matrix.

4. The method according to claim 1 , further comprising identifying, for troubleshooting, at least one faulty actuator and/or at least one faulty inertial sensor based on the process sensitivity matrix.

5. The method according to claim 1 , further comprising applying a control signal as a disturbance in each of the six DOF to actuate the corresponding actuators to move the base, the corresponding sensors measuring the motion of the base in all of the six degrees-of-freedom to create the measured process sensitivity matrix.

6. The method according to claim 5 , wherein the control signals are applied as a disturbance on each of the six degrees-of-freedom sequentially for actuating the corresponding actuators to move the base, the corresponding sensors measuring, for each sequential control signal, the motion of the base in all of the six degrees-of-freedom to create the measured process sensitivity matrix.

7. The method according to claim 5 , wherein the control signals are applied simultaneously as a disturbance on each of the six degrees-of-freedom to create the measured process sensitivity matrix, the control signals being of different frequencies to discriminate them from each other.

8. The method according to claim 1 , wherein the motion system includes a closed loop control system having a PID controller for each of the six degrees-of-freedom, an actuator force calculator adapted to compute a force reference of each actuator based on an output of a corresponding PID controller, and a sensor displacement calculator adapted to compute a displacement value in each of the six degrees-of-freedom based on an output of each inertial sensor output, the displacement value being subtracted from a desired motion value relative to the reference point and being fed to the corresponding PID controller to create a damping effect.

9. The method according to claim 8 , wherein in response to a faulty actuator and/or a faulty sensor, gains of the PID controllers are reduced to stabilize the active isolation system.

10. The method according to claim 8 , wherein in response to a faulty actuator, gains of the PID controllers are reduced to stabilize the active isolation system.

11. The method according to claim 8 , wherein in response to a faulty sensor, gains of the PID controllers are reduced to stabilize the active isolation system.

12. The method according to claim 1 , further comprising executing a least square algorithm based on a composite sinusoidal motion retrieved from at least one column of the measured process sensitivity matrix to determine a location of an unwanted pivot point in the active isolation system impeding or stopping the motion of the base.

13. The method according to claim 8 , further comprising:
generating a dynamic model of the motion system based on dimensions of the base and of the dampers and gains of PID controllers of the active isolation system;
simulating motion of the base for any possible failure of each actuator and each sensor and for any possible combination of two or more faulty actuators and sensors when at least one control signal is virtually applied as a disturbance on each of the six degrees-of-freedom;
creating and storing a library of virtual process sensitivity matrices of the active isolation system for each possible failure;
comparing the virtual process sensitivity matrices with the measured process sensitivity matrix; and
determining at least one faulty actuator and/or at least one faulty sensors based on the comparison.

14. The method according to claim 13 , wherein a neural network is used to identify at least one faulty actuator and/or at least one faulty sensor based on the comparison.

15. The method according to claim 14 , wherein the neural network is trained using the library of virtual process sensitivity matrices.

16. The method according to claim 1 , wherein the machine frame is adapted to rest on a floor.

17. The method according to claim 1 , wherein the machine frame rests on a floor.

18. The method according to claim 1 , wherein the equipment includes semiconductor processing equipment.

19. The method according to claim 1 , wherein the six degrees-of-freedom include three translational degrees-of-freedom along three orthogonal axes and three rotational degrees-of-freedom around the three orthogonal axes.

20. A non-transitory, computer-readable storage medium having stored thereon instructions, which, when executed by a processor that controls a motion system causes the processor to control the motion system to perform the method recited in claim 1 .

Assignees

• Etel Sa

Inventors

• Graf Basile Renaud
• Coleman Ralph

Classifications

• G05B2219/24065

  Real time diagnostics · CPC title

• G05B23/0221

  Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods · CPC title

• G01B11/002

  for measuring two or more coordinates · CPC title

• F16F2230/24

  Detecting or preventing malfunction, e.g. fail safe · CPC title

• F16F15/002

  characterised by the control method or circuitry (control of mechanical oscillations per se G05D19/00) · CPC title