Collaborative robot

{
  "publication_number": "US10029369B1",
  "country": "US",
  "kind": "B1",
  "title": "Collaborative robot",
  "abstract": "A collaborative robot employs low ratio drives for three or more axes of movement, such as three primary axes. An arm assembly may be mounted to a support for movement along a vertical linear axis, and the arm assembly may include first and second arm links that are each rotatable about vertical axes, e.g., such that the arm links move in a horizontal plane. Low ratio drives may be used for movement along the vertical linear axis and the rotary axes for the first and second arm links. Feedforward and feedback control may be employed to control the movement of the arm assembly and arm links, and feedback torque components may be limited to 25% or less of the maximum drive torque.",
  "claims": [
    "1. A robot comprising: a base, a vertical support extending from the base along a vertical linear axis, an arm assembly supported by the vertical support and moveable relative to the vertical support along the vertical linear axis, an arm assembly drive arranged to move the arm assembly relative to the vertical support, the arm assembly drive including a motor and drive train arranged to move the arm assembly and having a drive ratio of less than 25:1, the arm assembly further comprising: a first arm link coupled to the vertical support and arranged to rotate relative to the base about a first rotary axis that is oriented in a vertical direction, a first link drive including a motor and drive train arranged to rotate the first arm link relative to the base about the first rotary axis and having a drive ratio of less than 25:1, a second arm link coupled to the first arm link and arranged to rotate relative to the first arm link about a second rotary axis that is oriented in the vertical direction, the second rotary axis being spaced from the first rotary axis, a second link drive including a motor and drive train arranged to rotate the second arm link relative to the first arm link about the second rotary axis and having a drive ratio of less than 25:1, and a third link coupled to the second arm link and arranged to rotate relative to the second arm link about a third rotary axis, and a controller constructed and arranged to provide control signals to the arm assembly drive and to the first and second link drives to move the arm assembly, the first arm link and the second arm link, wherein the control signals provided by the controller include feedforward torque components determined in real time using a dynamic model of the robot and that include at least one of acceleration, gravity, velocity and friction compensation torque components to drive at least the arm assembly, the first arm link and the second arm link, the control signals provided by the controller further including a feedback torque components and the controller comprising a control circuit that limits the feedback torque component of a control signal for the arm assembly drive or for the first and second link drives to less than 25% of a maximum motor torque for the respective drive.",
    "2. The robot of claim 1, wherein the controller is arranged to detect a collision of the robot with an object based on a magnitude of a feedback torque determined for at least one of the arm assembly drive and to the first and second link drives.",
    "3. The robot of claim 1, wherein the controller is arranged to detect a collision of the robot with an object if a magnitude of a feedback torque for at least one of the arm assembly drive and to the first and second link drives reaches the control circuit limit for the feedback torque component for a specified period of time.",
    "4. The robot of claim 1, wherein the control signals provided by the controller to the arm assembly drive and to the first and second link drives include a linearization compensation to compensate for non-linearities of a motor and drive train of a corresponding drive.",
    "5. The robot of claim 1, wherein the vertical support is arranged to pivot relative to the base about the first rotary axis, and the first link drive is arranged to pivot the vertical support relative to the base about the first rotary axis, and thereby rotate the first link relative to the base about the first rotary axis.",
    "6. The robot of claim 1, wherein the arm assembly includes a carriage that is attached to the vertical support and is arranged to move relative to the vertical support along the vertical linear axis, wherein the arm assembly drive is arranged to move the carriage relative to the vertical support along the vertical linear axis, wherein the first arm link is pivotally attached to the carriage and arranged to pivot relative to the carriage about the first rotary axis, and wherein the first link drive is arranged to rotate the first arm link relative to the carriage about the first rotary axis.",
    "7. The robot of claim 1, wherein the first arm link has a proximal end attached to the vertical support and a distal end attached to the second arm link, and the second arm link has a proximal end attached to the distal end of the first arm link and a distal end attached to the third link.",
    "8. The robot of claim 1, wherein the first and/or second link drives include belt drives between the motor and the first and second arm links, respectively.",
    "9. The robot of claim 1, wherein the first and second link drives have a drive ratio of 1:1.",
    "10. The robot of claim 1, further comprising a third link drive including a motor and drive train arranged to rotate the third arm link relative to the second arm link about the third rotary axis, wherein the first, second, and third link drives have a drive ratio of 1:1.",
    "11. The robot of claim 1, wherein the second link drive is in or near the vertical support, and drives the second arm link via a belt.",
    "12. The robot of claim 1, wherein the first link drive is located coaxially with the first rotary axis, or the second link drive is located coaxially with the second rotary axis.",
    "13. The robot of claim 1, wherein the third rotary axis is parallel to a longitudinal axis of the second arm link.",
    "14. The robot of claim 1, wherein the third link includes one or more components arranged to rotate relative to the second arm link about a fourth rotary axis and a fifth rotary axis, where the fourth rotary axis is perpendicular to the third rotary axis, and the fifth rotary axis is perpendicular to the fourth rotary axis.",
    "15. The robot of claim 14, wherein the fourth rotary axis intersects the third rotary axis, and the fifth rotary axis intersects the fourth rotary axis.",
    "16. A robot comprising: a base, a vertical support extending from the base along a vertical linear axis, an arm assembly supported by the vertical support and moveable relative to the vertical support along the vertical linear axis, an arm assembly drive arranged to move the arm assembly relative to the vertical support, the arm assembly drive including a motor and drive train arranged to move the arm assembly and having a drive ratio of less than 25:1, the arm assembly further comprising: a first arm link coupled to the vertical support and arranged to rotate relative to the base about a first rotary axis that is oriented in a vertical direction, a first link drive including a motor and drive train arranged to rotate the first arm link relative to the base about the first rotary axis and having a drive ratio of less than 25:1, a second arm link coupled to the first arm link and arranged to rotate relative to the first arm link about a second rotary axis that is oriented in the vertical direction, the second rotary axis being spaced from the first rotary axis, a second link drive including a motor and drive train arranged to rotate the second arm link relative to the first arm link about the second rotary axis and having a drive ratio of less than 25:1, and a third link coupled to the second arm link and arranged to rotate relative to the second arm link about a third rotary axis, and a controller constructed and arranged to provide control signals to the arm assembly drive and to the first and second link drives to move the arm assembly, the first arm link and the second arm link, wherein the control signals provided by the controller to the arm assembly drive and to the first and second link drives include a linearization compensation to compensate for non-linearities of a motor and drive train of a corresponding drive.",
    "17. The robot of claim 16, wherein the first and second link drives have a drive ratio of 1:1."
  ],
  "description_excerpt": "Until recently all industrial robots installed in factories were separated from people by safety barriers and interlocks to prevent the robots from colliding with a human and possibly causing injury. Large robots can carry payloads of hundreds of kilograms and are therefore potentially very dangerous due to the masses involved. However, even small assembly robots, which often operate at high tool speeds of 7-10 meters per second, have enough energy to seriously injure humans though their payloads are typically 3 kg or less.\n\nRecently there has been growing interest in allowing robots to work safely next to people in the same working volume without the need for expensive and cumbersome safety screens. This class of robots is referred to in the industry as “Collaborative Robots.”\n\nIn 2016, an ISO standard ISO_TS 15066 2016 “Robots and Robotic Devices - Collaborative Robots,” was published listing safe levels for collision forces that would not cause injury to people. Collision force is determined by the robot's and the payload's kinetic energy, the stopping distance and commanded motor torque. The stopping distance is determined by the kinetic energy, the compliance (stiffness) of the part of the human body that is struck, the compliance of the robot structure that strikes the person, and whether the collision occurs in free space or traps a part of the body against a rigid surface. The safe stopping distance can typically vary from a few millimeters to a few centimeters, depending on these factors.",
  "cpc": [
    "B25J 9/1676",
    "B25J 13/085",
    "B25J 9/042",
    "B25J 9/104",
    "B25J 9/12",
    "G05B 2219/40201",
    "G05B 2219/40202"
  ],
  "ipc": [
    "B25J 13/08",
    "B25J 9/10",
    "B25J 9/12",
    "B25J 9/16",
    "G05B 19/04",
    "G05B 19/18"
  ],
  "assignees": [
    "Precise Automation Inc"
  ],
  "inventors": [
    "Brian Carlisle",
    "Bruce Shimano"
  ],
  "filing_date": "2017-08-22",
  "publication_date": "2018-07-24",
  "grant_date": "2018-07-24",
  "priority_date": "2017-06-09",
  "application_number": "US-201715682632-A",
  "family_id": "62874212",
  "cited_by_count": 30,
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}