Linear-motion telescopic mechanism and robot arm having linear-motion telescopic mechanism
A linear-motion telescopic mechanism according to the present invention includes a plurality of block members ( 22 ) by which an arbitrary arm length is achieved in such a manner that the plurality of block member ( 22 ) are rigidly connected to each other so as to elongate a linear-motion telescopic joint (J 3 ). On the other hand, by separating the plurality of block members ( 22 ) one by one from a rigid alignment of the plurality of block members ( 22 ), the linear-motion telescopic joint (J 3 ) is contracted. The block members ( 22 ) unfixed from the rigid alignment are still serially connected but not in a rigid manner. That is, the block members ( 22 ) thus unfixed can be flexed in any directions, and therefore can be housed inside a support member ( 1 ) in a compact manner. This arrangement can provide a linear-motion telescopic mechanism (i) which enhances safety by eliminating such a risk, inevitable for a typical robot arm having an elbow joint, that an object around the robot arm gets caught between arm sections when the elbow joint is closed, and (ii) which can reduce a space to be occupied by the robot arm.
1. A linear-motion telescopic mechanism comprising:
a block-member group including a plurality of block members;
moving means which moves the plurality of block members and which has a function of fixing a given block member to another block member in the block-member group and of unfixing fixed block members one by one,
the moving means causing a part of or all of the plurality of block members in the block-member group to align in a linear and rigid manner to form a rigid alignment, and unfixing a part of or all of the rigid alignment to disengage the block members one by one, so that the rigid alignment serves as a linear rigid arm section that is freely variable in length,
each of the plurality of block members has a corrugated structure on its surface as means for fixing said each of the plurality of block members to its adjacent block member so as to form the rigid arm section,
the linear-motion telescopic mechanism further comprising:
a flexible belt-like structural member (i) which extends along block members aligning to form the rigid arm section and (ii) which has a corrugated surface; and
a mechanism for engaging the corrugated structures of the plurality of block members with the corrugated surface of the flexible belt-like structural member,
wherein the block members have side-undulating structures configured to mesh with corresponding side-undulating structures in adjacent block members when the block members are disengaged from the belt-like structural member.
2. The linear-motion telescopic mechanism as set forth in claim 1 , further comprising, as means for unfixing a part of or all of the rigid arm section to disengage the block members in the rigid arm section one by one, a mechanism for separating the corrugated surface of the flexible belt-like structural member from the corrugated structures of the plurality of block members.
3. The linear-motion telescopic mechanism as set forth in claims 1 , wherein:
the moving means has a driving mechanism composed of a worm gear and an actuator for rotating the worm gear,
each of the plurality of block members has a corrugated structure on its surface facing the worm gear so that the corrugated structure engages with a tooth of the worm gear, thereby moving the plurality of block members in an alignment direction by rotation of the worm gear.
4. A robot arm comprising:
an installation section to be fixed to a desk or a floor;
a support member connected to the installation section via a first rotational joint;
a straight-link arm section connected to the support member via a second rotational joint that is rotatable in a vertical direction to the first rotational joint; and
an end effector provided at an end of the arm section,
the arm section having a linear-motion telescopic mechanism recited in claim 1 , (i) which allows the arm section to be elongated or contracted to an arbitrary arm length and (ii) which is constituted by structural members provided in advance to achieve a maximum arm length, the linear-motion telescopic mechanism being arranged to separate, from the arm section, a part of the structural members that is beyond the arbitrary arm length and to house the part into a space deviating from a central axis of the arm section along an elongate direction of the arm section.
5. The robot arm as set forth in claim 4 , wherein:
the end effector is composed of a gripping section including a grip-base portion, a grip-palm portion, and a plurality of finger portions,
the robot arm further comprising:
a fourth rotational joint provided between the grip-base portion and the linear-motion telescopic mechanism so as to be parallel to a longitudinal direction of the linear-motion telescopic mechanism;
a fifth rotational joint provided between the grip-base portion and the grip-palm portion so as to be vertical to the fourth rotational joint; and
rotational joints that are controlled independently provided between the grip-palm portion and a corresponding one of the plurality of finger portions.
6. The robot arm as set forth in claim 5 , wherein:
the plurality of finger portions provided in the gripping section is configured to hold another structure, and
the plurality of finger portions are configured to open or close in synchronization.
7. The robot arm as set forth in claim 4 , wherein:
the end effector is composed of a gripping section including a grip-base portion, a grip-palm portion, and a plurality of finger portions,
the robot arm further comprising:
a fourth rotational joint provided between the grip-base portion and the linear-motion telescopic mechanism so as to be parallel to a longitudinal direction of the linear-motion telescopic mechanism;
a fifth rotational joint provided between the grip-base portion and the grip-palm portion so as to be vertical to the fourth rotational joint;
a sixth rotational joint between the grip-palm portion and the plurality of finger portions so as to cause the plurality of finger portions to turn around in a collective manner; and
a seventh rotational joint(s) for adjusting a distance between one of the plurality of finger portions and the other(s) of the plurality of finger portions by independently operating the other(s) of the plurality of finger portions with respect to one of the plurality of finger portions, the seventh rotational joint(s) being provided between the grip-palm portion and the other(s) of the plurality of finger portions.
8. The robot arm as set forth in claim 4 , wherein:
the end effector is an image-capture device.