Dynamic system control method

• US 8,144,417 B2
• Filed: 09/23/2008
• Issued: 03/27/2012
• Est. Priority Date: 03/04/1999
• Status: Expired due to Fees

• Current Assignee: Convolve Incorporated
• Original Assignee: Convolve Incorporated
• Inventors: Singer, Neil, Tanquary, Mark, Pasch, Kenneth
• Primary Examiner(s): Wong, K.
• Application Number:
  US12/236,269
• Publication Number:
  US 20090190248A1
• Time in Patent Office: 1,281 Days
• Field of Search: None
• US Class Current: 360/75
• CPC Class Codes: G11B 5/5556 with track following after a "seek"

Abstract

Techniques are provided herein for reducing vibrations in various modes of a dynamic system. One such technique comprises incorporating vibration limiting and sensitivity constraints into a partial fraction expansion equation model of the system so as to reduce vibrations to specific levels. Another technique comprises shaping a command determined using the partial fraction expansion equation model to produce a desired output. The entire command may be shaped or only selected portions thereof which produce vibrations. Another technique involves commanding in current to produce saturation in voltage. By doing this it is possible to command voltage switches. The times at which the switches occur can be set to reduce system vibrations. Other techniques are also provided. These include varying transient portions at the beginning, middle and/or end of a move and using Posicast inputs, among others.

Claims

1. A method of using a position-velocity relationship to control a dynamic system, the method comprising the steps of:

comparing a preset destination position of a component of the dynamic system to a measured position of the component in order to generate a position variable for the system;

determining a velocity command for the system using the position-velocity relationship and the position variable;

shaping a feed forward path of a control loop after the position-velocity relationship in order to generate a shaped command;

inverse shaping a signal in a feedback path of the control loop; and

controlling the system based on the shaped command, wherein the shaping and inverse shaping steps reduce unwanted dynamics in the dynamic system.

2. The method according to claim 1, wherein the component comprises a head of a data storage device;

and

wherein the controlling step controls the head to move among various tracks of a data storage medium in the data storage device.

3. The method according to claim 1, wherein the shaping step and the inverse shaping step reduce unwanted acoustics or vibrations resulting from movement of the component.

15. The method according to claim 1, wherein the position-velocity relationship is provided in the form of a table, paramaterized curves, or a function.

4. A method of generating a trajectory for inclusion in a position-velocity relationship which is used to control a dynamic system, the method comprising the steps of:

generating a trajectory for the dynamic system, the trajectory defining system velocity in terms of system position and one or more additional variables;

storing the trajectory in a position-velocity relationship having N (N>

2) dimensions; and

controlling the dynamic system in accordance with the trajectory stored in the position-velocity relationship.

5. The method according to claim 4, wherein the method controls a component of the dynamic system, the component comprising a head of a data storage device;

and

wherein the controlling step controls the head to move among various tracks of a data storage medium in the data storage device.

6. The method according to claim 5, wherein one of the variables comprises a desired movement distance of the component.

7. The method according to claim 5, wherein the trajectory is generated in real-time based on a partial fraction expansion that defines behavior of the dynamic system.

16. The method according to claim 4, wherein the position-velocity relationship is provided in the form of a table, paramaterized curves, or a function.

8. A data storage device which uses a position-velocity relationship to control movement of a component of the data storage device, the data storage device comprising:

a memory which stores the position-velocity relationship and computer-executable instructions; and

a processor which executes the instructions stored in the memory so as

(i) to compare a preset destination position of the component to a measured position of the component in order to generate a position variable for the component;

(ii) to determine a velocity command for the component using the position-velocity relationship, the processor determining the velocity command based on the position-velocity relationship;

(iii) to shape a feed forward path of a control loop after the position-velocity relationship in order to generate a shaped command to reduce unwanted dynamics resulting from movement of the component;

(iv) to inverse shape a signal in a feedback path of the control loop; and

(v) to control the component to move based on the shaped command.

9. The data storage device according to claim 8, wherein the component comprises a head of the data storage device;

and

wherein the processor controls the head to move among various tracks of a data recording medium in the data storage device.

10. The method according to claim 8, wherein the shaping and inverse shaping performed by the processor reduce unwanted acoustics or vibrations resulting from movement of the component.

17. The apparatus according to claim 8, wherein the position-velocity relationship is provided in the form of a table, paramaterized curves, or a function.

11. An apparatus which generates a trajectory for inclusion in a position-velocity relationship that is used to control a dynamic system, the apparatus comprising:

a memory which stores computer-executable instructions and a position-velocity relationship having N (N>

2) dimensions; and

a processor which executes the instructions stored in the memory so as (i) to generate a trajectory for the system, the trajectory defining system velocity in terms of system position in one or more additional variables, (ii) to store the trajectory in the position-velocity relationship, and (iii) to control the system in accordance with the trajectory stored in the position-velocity relationship.

12. The apparatus according to claim 11, wherein the apparatus controls a component of the dynamic system, the component comprising a head of a data storage device;

and

wherein the processor controls the head to move among various tracks of a data storage medium in the data storage device.

13. The apparatus according to claim 12, wherein one of the variables comprises a desired movement distance of the component.

14. The apparatus according to claim 12, wherein the processor generates the trajectory in real-time based on a partial fraction expansion that defines behavior of the dynamic system.

18. The apparatus according to claim 11, wherein, the position-velocity relationship having N (N>

2) dimensions is provided in the form of a table, paramaterized curves, or a function.