Link actuation device

Patent metadata

Field	Value
Publication number	US-9522469-B2
Application number	US-201314385931-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Mar 23, 2012
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

A link actuation device includes a distal end side link hub connected with a proximal end side link hub through three or more sets of link mechanisms for alteration in orientation. By means of an actuator provided in the two or more set of the link mechanism, the distal end orientation, which is the orientation of the distal end side link hub relative to the proximal end link hub, is changed arbitrarily. The operating device includes an orientation designating unit for designating the distal end orientation aimed at by means of a coordinate position on the orthogonal coordinate system by an artificial manipulation, an orientation acquiring unit for acquiring the distal end orientation that is expressed by an angular coordinate system through calculation, and an orientation information applying unit for applying information on the distal end orientation so acquired to a control device for controlling the actuator.

First claim

What is claimed is:

1. A link actuation device comprising:
a proximal end side link hub;
a distal end side link hub connected with the proximal end side link hub through three or more sets of link mechanisms;
an actuator;
a control device to control the actuator;
an operating device to operate the control device;
wherein each of the link mechanisms includes proximal side and distal side end link members, which are rotatably connected at one end with the proximal end side link hub and the distal end side link hub, respectively, and an intermediate link member having its opposite ends rotatably connected with the other ends of the proximal end side and distal side end link members;
further wherein a geometric model of each of the link mechanisms is a parallel link mechanism in which a proximal end side portion and a distal end side portion represent a symmetric shape relative to an intermediated portion of the intermediate link member,
further wherein the actuator is provided in two or more sets of link mechanisms of the three or more sets of the link mechanisms of the parallel link mechanism and is operable to arbitrarily change a distal end orientation, which is an orientation of the distal end side link hub relative to the proximal end side link hub,
further wherein the control device is operable to stipulate the distal end orientation in terms of a bending angle, which is a vertical angle in which a center axis of the distal end side link hub is inclined relative to a center axis of the proximal end side link hub, and an angle of traverse which is a horizontal angle in which the center axis of the distal end side link hub is inclined relative to the center axis of the proximal end side link hub,
further wherein the operating device comprises:
an orientation designating unit to designate the distal end orientation, which is aimed at a coordinate position of a two dimensional orthogonal coordinate system that intersects an extended axis of the center axis of the proximal end side link hub with a position of origin lying on the extended axis of the center axis;
an orientation acquiring unit to acquire from the coordinate position, designated by the orientation designating unit, the distal end orientation that is expressed by the bending angle and the angle of traverse by means of a calculation; and
an orientation information applying unit to apply information on the distal end orientation, which has been acquired by the orientation acquiring unit, to the control device.

2. The link actuation device as claimed in claim 1 , wherein the orientation acquiring unit makes use of a convergence calculation based on the least squares method as the calculation for acquiring the distal end orientation that is expressed by the bending angle and the angle of traverse.

3. The link actuation device as claimed in claim 1 , wherein, when the angle of rotation of the proximal side end link member relative to the proximal end side link hub is expressed by βn, the angle formed between a first connecting end shaft of the intermediate link member, rotatably connected with the proximal side end link member, and a second connecting end shaft of the intermediate link member rotatably connected with the distal side end link member is expressed by γ, the angle of separation in a circumferential direction of each proximal side end link member relative to the proximal side end link member forming a reference is expressed by δn, the bending angle is expressed by θ and the angle of traverse is expressed by φ, the control device executes an inverse transformation according to the formula
cos (θ/2)sin β n −sin(θ/2)sin(φ+δ n )cos β n +sin(γ/2)=0

to thereby determine the angle of rotation of the proximal side end link member in the distal end orientation, which is aimed at, and calculates a commanded operation amount of each of the actuators from a difference between the angle of rotation, which has been so determined, and the angle of rotation of each of the proximal side end link member in the current distal end orientation.

4. The link actuation device as claimed in claim 1 , wherein, when the angle of rotation of the proximal side end link member relative to the proximal end side link hub is expressed by βn, the angle formed between a first connecting end shaft of the intermediate link member, rotatably connected with the proximal side end link member, and a second connecting end shaft of the intermediate link member rotatably connected with the distal side end link member is expressed by γ, the angle of separation in a circumferential direction of each proximal side end link member relative to the proximal side end link member forming a reference is expressed by δn, the bending angle is expressed by θ and the angle of traverse is expressed by φ, the control device executes an inverse transformation according to the formula
cos (θ/2)sin β n −sin(θ/2)sin(φ+δ n )cos β n +sin (γ/2)=0

to thereby formulate a table descriptive of relations between the distal end orientation and the angle of rotation of each of the proximal side end link members, and, by use of the table, to determine the angle of rotation of the proximal side end link member in the distal end orientation, which is aimed at, and calculates a commanded operation amount of each of the actuators from a difference between the angle of rotation, which has been so determined, and the angle of rotation of each of the proximal side end link member in the current distal end orientation.

5. The link actuation device as claimed in claim 1 , wherein the orientation designating unit executes a designation of the coordinate position on the orthogonal coordinate system by means of a numerical value input.

6. The link actuation device as claimed in claim 5 , wherein the orientation designating unit executes a designation of the coordinate position on the orthogonal coordinate system by means of a numerical value input of an absolute coordinate relative to a predetermined reference or by means of a numerical value input of the difference between the current coordinate position and a coordinate position which is aimed at.

7. The link actuation device as claimed in claim 1 , wherein the orientation designating unit designates a coordinate position on the orthogonal coordinate system by means of an operating amount determined in dependence on an operating time or an operating number.

8. The link actuation device as claimed in claim 1 , further comprising:
a decelerating unit to transmit a driving force of the actuator to a corresponding link mechanism, the distal end side link hub being positioned below the proximal end side link hub; and
a lubricant recovery member, provided in the parallel link mechanism or the decelerating unit, to receive a lubricant falling downwardly from at least one of the parallel link mechanism and the decelerating unit.

9. The link actuation device as claimed in claim 8 , wherein the lubricant recovery member is a dish-like member comprising:
a plate shaped portion; and
a projecting portion projecting from an outer peripheral edge of the plate shaped portion in one direction intersecting a surface of the plate shaped portion, the projecting portion being arranged in the distal end side link hub so as to project towards the proximal end side link hub.

10. The link actuation device as claimed in claim 9 , wherein the projecting portion of the lubricant recovery member is inclined towards a center axis of the distal end side link hub.

11. The link actuation device as claimed in claim 10 , wherein when a vertical angle, in which the center axis of the distal end side link hub is inclined relative to a center axis of the proximal end side link

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Isobe Hiroshi
• Nishio Yukihiro
• Yamada Hiroyuki

Classifications

• B25J9/0048 Primary

  with kinematics chains of the type rotary-rotary-rotary · CPC title

• B25J9/1623

  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

• B25J9/12

  electric · CPC title

• B25J13/087

  for sensing other physical parameters, e.g. electrical or chemical properties · CPC title

• G05B2219/39476

  Orient hand relative to object · CPC title