Method and apparatus for controlling vibration using accelerometer

{
  "publication_number": "US7751935B2",
  "country": "US",
  "kind": "B2",
  "title": "Method and apparatus for controlling vibration using accelerometer",
  "abstract": "A method of controlling vibration of a moving system having driving and driven units includes measuring an acceleration of the driven unit, generating a nominal acceleration by subtracting gravity from the measured acceleration, generating a control driving force according to the nominal acceleration, the driving force having a direction opposite to that of the measured acceleration, and applying the control driving force to the driven unit.",
  "claims": [
    "1. A method of controlling vibration of a moving system having driving unit and driven units, the method comprising: applying a driving force to a driven unit and ceasing application of the driving force to the driven unit; measuring an acceleration of the driven unit after the ceasing application of the driving force to the driven unit; generating a nominal acceleration by subtracting gravity from the measured acceleration; generating a control driving force based on the nominal acceleration, the driving force having a direction opposite to that of the nominal acceleration; and applying the control driving force to the driven unit.",
    "2. The method of claim 1, wherein generating of the nominal acceleration comprises: dividing the measured acceleration into horizontal and vertical components; generating a nominal vertical component by subtracting the gravity from the vertical component; and determining the horizontal component as a nominal horizontal component.",
    "3. The method of claim 2, wherein dividing of the measured acceleration is performed using a horizontal difference angle between the measured acceleration and a horizontal line.",
    "4. The method of claim 3, wherein dividing of the measured acceleration is performed according to following equations, A′v=A′ sin γ A′h=A′ cos γ where, A′ is the measured acceleration, A′v is the vertical component, A′h is the horizontal component, and γ is the horizontal difference angle.",
    "5. The method of claim 2, wherein generation of the nominal acceleration comprises converting a cylindrical or spherical coordinate system into a rectangular coordinate system when the measured acceleration is represented in the cylindrical or spherical coordinate system.",
    "6. The method of claim 1, wherein generating of the control driving force comprises: determining if the nominal acceleration is identical to a design acceleration of the moving system; and generating, when the nominal acceleration is not identical to the design acceleration of the moving system, the control driving force according to the nominal acceleration and mass of the driven unit.",
    "7. The method of claim 1, wherein generating of the control driving force comprises: determining if the nominal acceleration is in a predetermined range according to a desirable design acceleration of the moving system; and generating, when the nominal acceleration is not in the predetermined range, the control driving force according to the nominal acceleration and the mass of the driven unit.",
    "8. The method of claim 1, wherein the moving system is a joint moving system of a robot.",
    "9. A robot joint system controlled by the method of claim 1.",
    "10. An apparatus for controlling vibration of a driven unit moving by a driving force, comprising: means for applying a driving force to a driven unit and ceasing application of the driving force to the driven unit; an acceleration measuring unit for measuring an acceleration of the driven unit after the ceasing application of the driving force to the driven unit; a nominal acceleration generating unit for generating a nominal acceleration by eliminating the gravity from the measured acceleration; and a driving unit for generating a control driving force according to the nominal acceleration, the control driving force having a direction opposite to that of the nominal acceleration.",
    "11. The apparatus of claim 10, wherein the nominal acceleration generating unit generates nominal vertical components by dividing the measured acceleration into horizontal and vertical components and subtracting the gravity from the vertical component.",
    "12. The apparatus of claim 11, wherein the nominal accelerating generating unit divides the measured acceleration into the horizontal and vertical components using a horizontal difference angle between the measured acceleration and a horizontal line.",
    "13. The apparatus of claim 12, wherein the dividing the measured acceleration is performed according to following equations, A′v=A′ sin γ A′h=A′ cos γ where, A′ is the measured acceleration, A′v is the vertical component, A′h is the horizontal component, and γ is the horizontal difference angle.",
    "14. The apparatus of claim 11, further comprising a coordinate converting unit converting a cylindrical or spherical coordinate system into a rectangular coordinate system when the measured acceleration is represented in the cylindrical or spherical coordinate system.",
    "15. The apparatus of claim 11, wherein the driving unit generates a driving force according to if the nominal acceleration is identical to a design acceleration of the moving system.",
    "16. The apparatus of claim 15, wherein the driving unit generates, when the nominal acceleration is not identical to the design acceleration of the moving system, the control driving force according to the nominal acceleration and the mass of the driven unit.",
    "17. The apparatus of claim 11, wherein the driving unit does not generate the control driving force if the nominal acceleration is in a predetermined range according to a design acceleration of the moving system.",
    "18. The apparatus of claim 17, wherein the driving unit generates, when the nominal acceleration is not in the predetermined range, the control driving force according to the nominal acceleration and the mass of the driven unit.",
    "19. The apparatus of claim 11, wherein the moving system is a joint moving system of a robot.",
    "20. A joint driving system of a robot, comprising: a driving unit generating a driving force; a driven unit moving by the driving force; an acceleration measuring unit measuring an acceleration of the driven unit; after ceasing application of the driving force to the driven unit: and a nominal acceleration generating unit generating a nominal acceleration by eliminating gravity from the measured acceleration, wherein the driving unit generates the driving force by setting a control driving force generated according to the nominal acceleration to a design driving force.",
    "21. A record medium storing a program for performing the method of claim 1 in a computer, wherein the program supplies operating instructions to the computer."
  ],
  "description_excerpt": "Priority is claimed to Korean Patent Application No. 2004-8936, filed on Feb. 11, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.\n\n1. Field of the Invention\n\nThe present invention relates to a method and apparatus for controlling vibration using an accelerometer and, more particularly, to a method and apparatus for controlling in a moving system such as a robot.\n\n2. Description of the Related Art\n\nIn recent years, moving systems having a driving unit generating a torque (a driving force) and a driving unit driven by the torque transmitted from the driving unit have been used for many applications in robotics, automotive engineering, etc. Particularly, for a moving system relating to a vertical multi-joint robot, a position error caused by vibration is a major factor affecting the performance of the moving system. That is, when a driven unit of the multi-joint robot moves by a torque of a driving unit, an inertia force caused by the movement of the driven unit generates a vibration. Vibration causes the driven unit to be mis-positioned. Therefore, since multi-joint robots are widely used in applications that require an accurate position control, vibration control becomes very important.\n\nOne of the conventional methods for vibration control is to increase the stiffness of the moving system. For this, components of the moving system are formed of high stiffness materials or the connection structures between the components of the moving system are made rigid.",
  "cpc": [
    "B62D 57/032",
    "B25J 9/1638",
    "B25J 9/1651",
    "B43K 21/08",
    "B43K 24/06",
    "B43K 27/04"
  ],
  "ipc": [
    "B25J 13/00",
    "B25J 13/08",
    "B25J 19/02",
    "B25J 9/06",
    "G05D 19/02",
    "G06F 7/00"
  ],
  "assignees": [
    "Samsung Electronics Co Ltd"
  ],
  "inventors": [
    "Joo-Young Kwak",
    "Yong-kwun Lee",
    "Young Son",
    "Chang-hyun Roh"
  ],
  "filing_date": "2004-12-01",
  "publication_date": "2010-07-06",
  "grant_date": "2010-07-06",
  "priority_date": "2004-02-11",
  "application_number": "US-42604-A",
  "family_id": "34858696",
  "cited_by_count": 4,
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}