Link actuating device

Patent metadata

Field	Value
Publication number	US-9249869-B2
Application number	US-201113878523-A
Country	US
Kind code	B2
Filing date	Oct 3, 2011
Priority date	Oct 14, 2010
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A link actuating device connects an output member to an input member through three or more link mechanisms for alteration in posture. Each of the link mechanisms includes end portion link members on input and output sides, and an intermediate link member. The link mechanisms are of such shapes that geometric models representing the link members by straight lines are such that input and output side portions are symmetrical to each other relative to an intermediate portion of each of the intermediate link members. Immobilizing mechanisms are provided in all of the link mechanisms to immobilize the output member in an arbitrary attitude relative to the input member. A structure body is provided to connect the input and output member to each other while being in contact with contacted portions formed in the input and output member.

First claim

What is claimed is:

1. A link actuating device to connect an output member to an input member through three or more set of link mechanisms for alteration in posture, each of the link mechanisms including:
end portion link members on an input side and an output side having one ends thereof rotatably connected respectively to the input member and the output member;
an intermediate link member to which the other ends of the respective end portion link members on the input side and the output side are rotatably connected;
immobilizing mechanisms to immobilize the output member in an arbitrary attitude relative to the input member are provided in all of the three or more link mechanisms, the immobilizing mechanisms each including an actuator connected directly or indirectly to the end portion link member on the input side, the actuators acting so as to restrain rotation of the end portion link member on the input side relative to the input member;
a structure body is provided to connect the input member and the output member to each other while being in contact with a contacted portion formed in the input member and a contacted portion formed in the output member; and
a controller that, when the immobilizing mechanisms immobilize the output member in an arbitrary attitude relative to the input member, controls the actuators so as to increase a contact force acting between the structure body and the contacted portions of the input member and the output member,
wherein a geometric model representing each of the link mechanisms by a straight line is such that an input side portion and an output side portion of each of the intermediate link members relative to an intermediate portion of each of the intermediate link members are symmetrical to each other.

2. The link actuating device as claimed in claim 1 , wherein when the immobilizing mechanism immobilizes the output member in an arbitrary attitude relative to the input member, the controller controls the actuators so as to drive the actuators in directions in which forces generated by the respective actuators interfere with each other.

3. The link actuating device as claimed in claim 1 , wherein when the attitude of the output member is altered relative to the input member, the controller controls two of the actuators such that operating positions of the two actuators approach predetermined control target positions, and controls at least one remaining actuator such that a torque generated by the at least one remaining actuator approaches a predetermined control target position.

4. The link actuating device as claimed in claim 1 , further comprising a force transmitting mechanism capable of transmitting forces between the respective actuators and the respective end portion link members on the input side,
wherein when the attitude of the output member is altered relative to the input member, the controller controls two of the actuators such that operating positions of the two actuators approach predetermined control target positions, and controls at least one remaining actuator such that a torque generated by the at least one remaining actuator approaches a predetermined control target position, or drives the at least one remaining actuator in a servo-off state where a feedback control function is off.

5. The link actuating device as claimed in claim 1 , wherein each of the actuators is a rotary actuator having a brake device that locks a rotation of a rotary shaft of the rotary actuator, and
when the output member is immobilized in an arbitrary attitude relative to the input member, the brake device is actuated.

6. The link actuating device as claimed in claim 1 , wherein the attitude of the output member relative to the input member is controlled by inverse-transforming a formula represented by cos(θ/2)sin βn−sin(θ/2)sin(φ+δn)cos βn+sin(γ/2)=0,
where an angle of rotation of the end portion link member on the input side relative to the input member is βn;
an angle between an axis of a connecting end of the intermediate link member, rotatably connected to the end portion link member on the input side, and an axis of a connecting end of the intermediate link member, rotatably connected to the end portion link members on the output side, is γ;
a space angle, in a circumferential direction, of each of the end portion link members on the input side relative to one of the end portion link members on the input side, which serves as a reference, is δn;
a vertical angle of an inclination of the output member relative to a center axis of the input member is θ; and
a horizontal angle of an inclination of the output member relative to the center axis of the input member is φ.

7. The link actuating device as claimed in claim 1 , wherein the structure body generates a force between the input member and the output member.

8. The link actuating device as claimed in claim 1 , wherein each of the input member and the output member has the same number of shaft portions as the number of the link mechanisms, the shaft portions protruding from an outer peripheral surface thereof,
the end portion link members on the input side and the output side of each of the link mechanisms are rotatably connected to the shaft portions, and
the contacted portions are arranged radially inwardly of the shaft portions.

9. The link actuating device as claimed in claim 1 , wherein the contacted portions of the input member and the output member have spherical shapes whose centers conform with link spherical surface centers of the respective link mechanisms, and the structure body has opposite ends provided with spherical contacting portions that are slidably fitted into the contacted portions.

10. The link actuating device as claimed in claim 1 , wherein the input member has a recessed portion that is conical and tapered on an end face thereof on the output member side, and the output member has a recessed portion that is conical and tapered on an end face thereof on the input member side, and
innermost portions of the recessed portions serve as the contacted portions.

11. The link actuating device as claimed in claim 10 , wherein a maximum bending angle of a bending angle, which is an angle between a center line of the input member and a center line of the output member, is θ max ; and
an angle between a generatrix of an inner peripheral surface of the recessed portion of the input member and the center line of the input member, and an angle between a generatrix of an inner peripheral surface of the recessed portion of the output member and the center line of the output member are both θ max /2.

12. The link actuating device as claimed in claim 1 , further comprising rotational angle detectors provided in two or more of the three or more link mechanisms to detect angles of rotation of the end portion link members on the input side.

13. The link actuating device as claimed in claim 12 , wherein the attitude of the output member relative to the input member is estimated by forward-transforming a formula represented by cos(θ/2)sin βn−sin(θ/2)sin(φ+δn)cos δn+sin(γ/2)=0,
where an angle of rotation of the end portion link member on the input side relative to the input member is βn;
an angle between an axis of a connecting end of the intermediate link member, rotatably connected to the end portion link member on the input side, and an axis of a connecting end of the intermediate link member, rotatably connected to the end portion link members on the output side, is γ;
a space angle, in a circumferential direction, of each of the end portion link members on the input side relative to one of the end portion link members on the input side, which serv

Assignees

• Isobe Hiroshi
• Nishio Yukihiro
• Nagano Yoshitaka
• Ntn Toyo Bearing Co Ltd

Inventors

• Isobe Hiroshi
• Nishio Yukihiro
• Nagano Yoshitaka

Classifications

• F16H21/54 Primary

  for conveying or interconverting oscillating or reciprocating motions · CPC title

• B25J9/0048

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

• B25J9/0078

  actuated by cables · CPC title

• Y10T74/18888

  Reciprocating to or from oscillating · CPC title

• B25J11/00

  Manipulators not otherwise provided for · CPC title