Device and method for controlling link actuation device

Patent metadata

Field	Value
Publication number	US-10065310-B2
Application number	US-201615233409-A
Country	US
Kind code	B2
Filing date	Aug 10, 2016
Priority date	Feb 20, 2014
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

In this link actuation device, arms of a plurality of link mechanisms are driven to be rotated by actuators, whereby the posture of a distal end side link hub is changed. A divided section setter divides a trajectory on a work surface on which an end effector works, into a plurality of sections at pass points and sets the sections. An arm rotation speed calculator calculates a rotation speed at which each arm performs constant speed rotation in each section on the basis of: a time period of movement in the section which is determined from a target moving speed and the distance of the section; and a rotation-angular movement amount of the arm in the section. A posture change controller performs positioning control on each actuator so as to cause its corresponding arm to continuously rotate at the corresponding rotation speed without acceleration/deceleration.

First claim

What is claimed is:

1. A control device configured to control a link actuation device, the link actuation device including a proximal end side link hub, a distal end side link hub, and three or more link mechanisms which each connects the distal end side link hub to the proximal end side link hub such that a posture of the distal end side link hub can be changed relative to the proximal end side link hub, wherein each of the link mechanisms includes a proximal side end link member having one end rotatably connected to the proximal end side link hub, a distal side end link member having one end connected to the distal end side link hub, and an intermediate link member having opposite ends rotatably connected to other ends of the proximal side end link member and the distal side end link member, respectively, a geometric model of each of the link mechanisms showing rotation symmetry relative to a center line of the intermediate link member, two or more link mechanisms among the three or more link mechanisms are each provided with an actuator to changes the posture of the distal end side link hub relative to the proximal end side link hub by causing an arm, forming the proximal side end link member, to rotate, and the distal end side link hub has an end effector installed thereon, the control device comprising:
a divided section setter configured to divide, into a plurality of sections at one or more pass points, a trajectory from a start point to an end point along which the end effector moves, the trajectory being on a work surface on which the end effector works, the divided section setter being configured to set a position of each of the one or more pass points;
an arm rotation speed calculator configured to calculate a rotation speed at which each arm performs constant speed rotation in each section, on the basis of a time period of movement in the section which is determined from a distance of the section and a target moving speed which has been designated and is a constant speed, and a rotation-angular movement amount of the arm in the section; and
a posture change controller configured to set the rotation speed of the arm in the section to a value of the rotation speed calculated by the arm rotation speed calculator and to perform positioning control on the actuator corresponding to the arm so as to cause the arm to continuously rotate without acceleration/deceleration in the section.

2. The control device for the link actuation device as claimed in claim 1 , wherein the work surface on which the end effector works is a flat surface.

3. The control device for the link actuation device as claimed in claim 2 , wherein the arm rotation speed calculator calculates the rotation speed of the arm toward a point that is one of the start point, the end point and the one or more pass points, on the basis of:
a time period which is obtained from the target moving speed and a distance between arbitrary two points in a rectangular coordinate system representing the work surface; and
the rotation-angular movement amount of the arm between the two points.

4. The control device for the link actuation device as claimed in claim 1 , wherein the work surface on which the end effector works is a spherical surface.

5. The control device for the link actuation device as claimed in claim 4 , wherein the arm rotation speed calculator calculates the rotation speed of the arm toward a point that is one of the start point, the end point and the pass points, on the basis of:
a time period which is obtained from the target moving speed and a movement amount between arbitrary two points obtained through spherical trigonometry; and
the rotation-angular movement amount of the arm between the two points.

6. The control device for the link actuation device as claimed in claim 1 , further comprising a section correspondence setting information memory configured to, with respect to the position of the pass point corresponding to the section and the rotation speed of the arm in the section, store values calculated before actual use of the link actuation device,
wherein during the actual use, the posture change controller performs control by reading out the position of the pass point and the rotation speed of the arm which are stored in the section correspondence setting information memory.

7. A control method of a control device for controlling a link actuation device, the link actuation device including a proximal end side link hub, a distal end side link hub, and three or more link mechanisms which each connects the distal end side link hub to the proximal end side link hub such that a posture of the distal end side link hub can be changed relative to the proximal end side link hub, wherein each of the link mechanisms includes a proximal side end link member having one end rotatably connected to the proximal end side link hub, a distal side end link member having one end connected to the distal end side link hub, and an intermediate link member having opposite ends rotatably connected to other ends of the proximal side end link member and the distal side end link member, respectively, a geometric model of each of the link mechanisms showing rotation symmetry relative to a center line of the intermediate link member, two or more link mechanisms among the three or more link mechanisms are each provided with an actuator to change the posture of the distal end side link hub relative to the proximal end side link hub by causing an arm, forming the proximal side end link member, to rotate, and the distal end side link hub has an end effector installed thereon, the control method of the control device comprising:
dividing, into a plurality of sections at one or more pass points, a trajectory from a start point to an end point along which the end effector moves, the trajectory being on a work surface on which the end effector works;
calculating a rotation speed of each arm in each section, on the basis of a time period of movement in the section which is determined from a distance of the section and a designated target moving speed, and a rotation-angular movement amount of the arm in the section; and
setting the rotation speed of the arm in the section to a calculated value of the rotation speed, to perform positioning control on the actuator corresponding to the arm so as to cause the arm to continuously rotate without acceleration/deceleration in the section, thereby causing the end effector to operate at a substantially constant speed from the start point to the end point through the plurality of sections between a plurality of points on the work surface.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Sakata Seigo
• Nishio Yukihiro
• Isobe Hiroshi
• Yamada Hiroyuki

Classifications

• B25J9/1623 Primary

  Parallel manipulator, Stewart platform, links are attached to a common base and to a common platform, plate which is moved parallel to the base · CPC title

• F16H21/46

  with movements in three dimensions [3D] · CPC title

• B25J9/1651

  acceleration, rate control · CPC title