US 11,298,814 B2 · Link actuating device having a proximal-end-side link hub, a distal-end-side link hub, and three or more link mechanisms

Abstract

A link actuation device includes a proximal-end-side link hub, a distal-end-side link hub, three or more link mechanisms each coupling the link hubs such that a posture of the distal-end-side link hub can be changed relative to the proximal-end-side link hub. Each link mechanism includes a proximal-side end link member, a proximal-side intermediate link member, a distal-side intermediate link member, and a distal-side end link member. Actuators for arbitrarily changing the posture and a distance from the distal-end-side link hub to the proximal-end-side link hub are provided to three or more link mechanisms of the three or more link mechanisms. A control unit calculates a rotation angle of the proximal-side end link member according to a targeted posture of the distal-end-side link hub and a targeted distance between the centers of the spherical links, and controls the respective actuators so as to attain the calculated rotation angle.

A link actuation device, comprising:

a proximal-end-side link hub;
a distal-end-side link hub;
three or more link mechanisms each coupling the distal-end-side link hub to the proximal-end-side link hub such that a posture of the distal-end-side link hub is changeable relative to the proximal-end-side link hub, wherein each of the three or more link mechanisms includes:
a proximal-side end link member having one end rotatably coupled to the proximal-end-side link hub,
a distal-side end link member having one end rotatably coupled to the distal-end-side link hub,
a proximal-side intermediate link member having one end rotatably coupled to another end of the proximal-side end link member, and
a distal-side intermediate link member having one end rotatably coupled to another end of the distal-side end link member, and another end rotatably coupled to another end of the proximal-side intermediate link member,
wherein
a first central axis of a first revolute pair of the proximal-side end link member and the proximal-side intermediate link member intersects with a second central axis of a second revolute pair of the distal-side end link member and the distal-side intermediate link member at a single point,
the another end of the proximal-side intermediate link member and the another end of the distal-side intermediate link member are rotatably coupled to each other at a rotation axis of the proximal-side intermediate link member and the distal-side intermediate link member that is a third central axis of a third revolute pair of the proximal-side intermediate link member and the distal-side intermediate link member so that an angle formed by the first and second central axes of the first and second revolute pairs is changeable,
for each of the link mechanisms, a geometric model that represents the link mechanism with straight lines has such a shape that a proximal side part and a distal side part are symmetrical to each other with respect to the rotation axis of the proximal-side intermediate link member and the distal-side intermediate link member;
actuators, provided to three or more link mechanisms among the three or more link mechanisms, configured to change a posture and a distance from the distal-end-side link hub to the proximal-end-side link hub;
and
a control unit configured to control the actuators,
wherein
in the proximal side part, a point at which a fourth central axis of a fourth revolute pair of the proximal-end-side link hub and the proximal-end-side link member intersects with the first central axis of the first revolute pair is referred to as a center of a proximal-end-side spherical link, and a line that passes through the center of the proximal-end-side spherical link and orthogonally intersects with the fourth central axis is referred to as a fifth central axis of the proximal-end-side link hub,
in the distal side part, a point at which a sixth central axis of a fifth revolute pair of the distal-end-side link hub and the distal-side end link member intersects with the second central axis of the second revolute pair is referred to as a center of a distal-end-side spherical link, and a line that passes through the center of the distal-end-side spherical link and orthogonally intersects with the sixth central axis is referred to as a seventh central axis of the distal-end-side link hub,
the control unit is configured to calculate a rotation angle βn of the proximal-side end link member from a targeted posture (θ, φ) of the distal-end-side link hub relative to the proximal-end-side link hub and a targeted distance D between the center of the proximal-end-side spherical link and the center of the distal-end-side spherical link by inversely converting equation 1 below, such that relationships represented by equations 1, 2, and 3 below are satisfied, and control the respective actuators so as to attain the calculated rotation angle βn,
the proximal side part includes:
an axial angle α formed by the first central axis of the first revolute pair and the fourth central axis of the fourth revolute pair,
a distance La from a first projection line obtained by vertically projecting the rotation axis of the proximal-side intermediate link member and the distal-side intermediate link member onto a plane including the first central axis of the first revolute pair and the fourth central axis of the fourth revolute pair, to the center of the proximal-end-side spherical link, and
a distance Lb from the first projection line to the rotation axis of the proximal-side intermediate link member and the distal-side intermediate link member,
the distal side part includes:
the axial angle α formed by the second central axis of the second revolute pair and the sixth central axis of the fifth revolute pair,
the distance La from a second projection line obtained by vertically projecting the rotation axis of the proximal-side intermediate link member and the distal-side intermediate link member onto a plane including the second central axis of the second revolute pair and the sixth central axis of the fifth revolute pair, to the center of the distal-end-side spherical link, and
the distance Lb from the second projection line to the rotation axis of the proximal-side intermediate link member and the distal-side intermediate link member,
the proximal-side end link member has the rotation angle βn (n=1, 2, 3, . . . ) relative to the proximal-end-side link hub;
the seventh central axis of the distal-end-side link hub is inclined at a vertical angle θ relative to the fifth central axis of the proximal-end-side link hub;
the seventh central axis of the distal-end-side link hub is inclined at a horizontal angle φ relative to the fifth central axis of the proximal-end-side link hub;
the center of the proximal-end-side spherical link has the distance D from the center of the distal-end-side spherical link;
the first central axis of the first revolute pair forms an angle γ relative to the second central axis of the second revolute pair;
respective proximal-side end link members among the three or more link mechanisms are separated from each other at a separation angle δn (n=1, 2, 3, . . . ) in a circumferential direction with respect to a proximal-side end link member of the respective proximal-side end link members which serves as a reference;
each first projection line on a respective proximal side part among the three or more link mechanisms is separated from each other at a separation angle εn (n=1, 2, 3, . . . ) in the circumferential direction with respect to a reference phase on a circumference through which the first projection lines pass;
a first projection line on one of the proximal side parts that serves as a reference has a separation angle ε0 in a state where the posture of the distal-end-side link hub relative to the proximal-end-side link hub is at an origin position (θ=0, φ=0),
wherein
⁢
[
Math
⁢
⁢
4
]
(
cos
⁡
(
γ
/
2
)
⁢
cos
⁢
⁢
ɛ
⁢
⁢
0
±
sin
⁢
⁢
α
⁢
⁢
cos
⁢
⁢
β
⁢
⁢
n
sin
⁢
⁢
α
⁢
⁢
sin
⁢
⁢
β
⁢
⁢
n
)
=
(
cos
⁡
(
ϕ
-
δ
⁢
⁢
n
)
-
sin
⁡
(
ϕ
-
δ
⁢
⁢
n
)
0
sin
⁡
(
ϕ
-
δ
⁢
⁢
n
)
cos
⁡
(
ϕ
-
δ
⁢
⁢
n
)
0
0
0
1
)
⁢
(
cos
⁡
(
θ
/
2
)
0
sin
⁡
(
θ
/
2
)
0
1
0
-
sin
⁡
(
θ
/
2
)
0
cos
⁡
(
θ
/
2
)
)
⁢
(
cos
⁡
(
ϕ
-
δ
⁢
⁢
n
)
sin
⁡
(
ϕ
-
δ
⁢
⁢
n
)
0
-
sin
⁡
(
ϕ
-
δ
⁢
⁢
n
)
cos
⁡
(
ϕ
-
δ
⁢
⁢
n
)
0
0
0
1
)
⁢
(
cos
⁡
(
γ
/
2
)
⁢
cos
⁢
⁢
ɛ
⁢
⁢
n
cos
⁡
(
γ
/
2
)
⁢
sin
⁢
⁢
ɛ
⁢
⁢
n
sin
⁡
(
γ
/
2
)
)
equation
⁢
⁢
1
⁢
γ
2
=
sin
-
1
(
D
2
⁢
La
2
+
Lb
2
)
-
tan
-
1
⁡
(
Lb
La
)
equation
⁢
⁢
2
⁢
ɛ
0
=
±
sin
-
1
(
sin
2
⁢
α
-
sin
2
⁡
(
γ
/
2
)
cos
2
⁡
(
γ
/
2
)
)
.
equation
⁢
⁢
3

328 more elements

Link actuating device having a proximal-end-side link hub, a distal-end-side link hub, and three or more link mechanisms

Life of this patent

Link actuating device having a proximal-end-side link hub, a distal-end-side link hub, and three or more link mechanisms

Life of this patent

Abstract

Claims6