JPH07214482A - Articulated arm mechanism - Google Patents

Abstract

PURPOSE:To reduce dead-weight of an actuator and a load by a cable, to decrease power of the actuator, to miniaturize a working robbot, and to improve lightening and controllability. CONSTITUTION:A singular point is avoided by providing two sets of parallel link means in parallel on a cantilever articulated arm mechanism by combination of parallel links constituted by connecting four arms in a parallelogram shape by a horizontal pivotal shaft free to revolve to each other. Additionally, an actuator 19 to work the parallel link means is arranged on the pivotal shaft positioned at the side of the extreme base end part. Furthermore, actuators 29, 30 to actuate the parallel link means are arranged on one of the pivotal shafts of the parallel link means so that they work as counter balances against the free end side (grip 31). In the meantime, a cable arranged along the arms is arranged by passing it through a through hole formed coaxially with the pivotal shaft of the parallel link means at a joint part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-joint arm mechanism adopted for work robots and the like. When working in an environment that is dangerous to humans, such as outer space and nuclear facilities, it is difficult for humans to directly work, so a work robot operated by master / slave remote control is used.

This work robot is, for example, as shown in FIG. 10, a slave arm (device) 1 which is a multi-joint robot arranged in an extreme environment, and a multi-joint robot arranged in a safe environment. A master arm (device) 2 which is connected by a communication line 3 or the like, and an operator (human) 4 operates the master arm 2 to trace its movement to operate the slave arm 1. , A robot that does the work.

In these articulated robots (slave arms, master arms), a plurality of arms are appropriately rotatably connected via pivots (joints) according to the degree of freedom required for the work to be realized. An actuator such as a drive motor is arranged at the joint, and generally has a cantilever structure. The present invention relates to a multi-joint arm mechanism adopted in a work robot of this type.

[0004]

2. Description of the Related Art In a conventional cantilever type multi-joint robot, an actuator is directly installed at a joint (a connecting portion of the arm) to which an arm to be operated is connected. Wiring for actuators and other devices is provided along the arm, and play (margin) is provided in the joint portion so as not to interfere with the rotation of the joint.

[0005]

However, in the cantilever type robot, since the actuator is arranged also on the free end side opposite to the supported base end side, the weight of the free end side is large, The increase in the moment of inertia causes a decrease in response speed.

For the same reason, it is necessary to increase the rigidity of the arm and the power of the actuator arranged on the base end side, resulting in an increase in weight and an increase in size of the work robot.

As a countermeasure, there is a case where an actuator is arranged as close to the base end as possible so that the actuator and the arm to be operated are connected by a power transmission mechanism such as a gear. However, in a power transmission mechanism such as a gear, there is a drawback that vibration occurs due to backlash and the like, and controllability is deteriorated, which is not an effective countermeasure.

Further, due to the influence of the cable routed along the arm, the elastic force of the cable acts on the arm when the arm is rotated, and this force varies depending on the rotation angle of the arm. Therefore, the control characteristic depends on the angle. Differently, the controllability was lowered.

The present invention has been made in view of the above circumstances. An object of the present invention is to reduce the weight of the actuator and the load on the actuator due to the cable, reduce the power of the actuator, and reduce the size of the work robot. The aim is to reduce weight and weight. It also aims to improve the controllability of the work robot.

[0010]

In order to solve the above problems, the following articulated arm mechanism is provided. (1) That is, in a cantilever type multi-joint arm mechanism constituted by a plurality of parallel link means in which four arms are rotatably connected in a parallelogram shape by a horizontal pivot,
The two parallel link means are provided in parallel,
When the arms of the one parallel link means are positioned on a straight line, the arms of the other parallel link means are integrally linked with each other in a state where they are not positioned on the straight line.

In this structure, the actuator for activating the parallel link means may be arranged coaxially with the pivot shaft located closest to the base end side among the pivot shafts of the parallel link means. . (2) Further, in a cantilever type multi-joint arm mechanism including parallel link means in which four arms are rotatably connected to a parallelogram shape by a horizontal pivot, a free end side of the arm mechanism is provided. The actuator is arranged on one of the axes of the parallel link means so as to act as a counterbalance with respect to. (3) Further, in a cantilever type multi-joint arm mechanism including parallel link means in which four arms are rotatably connected to each other in a parallelogram shape by a horizontal pivot, a pivot of the parallel link means is provided. A through hole is formed in the cable, and a cable wired along the arm is wired so as to penetrate the through hole.

[0012]

[Action]

(1) According to the present invention, since the power is transmitted by the actuator by the parallel link means, there is no vibration due to backlash or the like and the controllability is improved as compared with the conventional power transmission mechanism such as a gear.

Further, the parallel link means serves as a singular point when the arms are arranged in a straight line, and if stopped in this state, it may not be possible to start the movement thereafter. In order to avoid this, in the present invention, two sets of parallel link means are provided in parallel and the phases of the parallel link means are made different from each other so that they are integrally interlocked, so that one parallel link means becomes a singular point. Also, the other parallel link means is prevented from becoming a singular point, and the problem at this singular point is solved.

By disposing the actuator coaxially with the pivot located closest to the base end side, the weight of the free end side of the arm mechanism can be reduced, the response characteristic due to the moment of inertia can be prevented from deteriorating, and the arm can be prevented. Since the rigidity of can be improved and the power of the actuator can be reduced,
The weight and size of the work robot as a whole can be reduced. (2) Further, since the actuator is arranged coaxially with one of the axes of the parallel link means so as to act as a counter balance with respect to the free end side of the arm mechanism, the balance of the work robot as a whole. Can be improved, the deterioration of response characteristics can be prevented, the power of the actuator can be decreased, and the weight and size of the work robot as a whole can be reduced. (3) Furthermore, the cables for various devices arranged on the free end side of the arm mechanism are generally routed along the arm, and these cables exert unnecessary force on the joint (pivot) portion of the arm. Since the force changes depending on the rotation angle of the arm, the controllability of the arm was reduced, but for this, a through hole was formed coaxially with the pivot of the parallel link means, and the through hole should be penetrated. Since the cable is routed to, the influence of the cable is reduced even if the arm rotates, and the controllability is improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. (1) FIGS. 1 and 2 are views for explaining the first embodiment of the present invention.

In FIG. 1A, 11 is a column,
A first main arm 12 is rotatably attached near the top of the column 11 via a horizontal pivot axis θ1, and a second main arm 13 is provided near the tip of the first main arm 12 so that the second main arm 13 is pivotable.
It is rotatably attached via 2.

Near the tip of the second main arm 13, one end of the first sub arm 14a is rotatably attached via a pivot shaft θ3. One end of a second sub arm 15a is rotatably attached to the other end of the first sub arm 14a via a pivot, and the second sub arm 15a is the second main arm 1a.
It is arranged in parallel with 3.

One end of a third sub arm 16a is rotatably attached to the other end of the second sub arm 15a via a pivot, and the other end of the third sub arm 16a is connected to the second main arm 13. It is rotatably attached coaxially with the pivot axis θ2 regardless of the rotation of the first main arm 12 and the second main arm 13. The third sub arm 16a is the first sub arm 14a.
Are arranged in parallel to.

Further, one end of a fourth sub arm 17a is rotatably mounted on the pivot of the second sub arm 15a and the third sub arm 16a.
Are arranged parallel to the first main arm 12.

One end of a fifth sub arm 18a is rotatably attached to the other end of the fourth sub arm 17a via a pivot, and the other end of the fifth sub arm 18a is attached to the first main arm 12. It is rotatably attached to the shaft. The fifth sub arm 18a is arranged parallel to the third sub arm 16a.

The first main arm 12, the fifth sub arm 18a,
The first by the fourth sub arm 17a and the third sub arm 16a
A parallel link is formed, and the second main arm 13, the third sub arm 16a, the second sub arm 15a, and the first sub arm 14a.
To form a second parallel link.

On the other hand, in the vicinity of the tip of the second main arm 13,
One end of the first sub arm 14b is rotatably attached via a pivot θ3. One end of a second sub arm 15b is rotatably attached to the other end of the first sub arm 14b via a pivot, and the second sub arm 15b is arranged in parallel with the second main arm 13. .

One end of a third sub arm 16b is rotatably attached to the other end of the second sub arm 15b via a pivot, and the other end of the third sub arm 16b is connected to the second main arm 13. It is rotatably attached coaxially with the pivot axis θ2 regardless of the rotation of the first main arm 12 and the second main arm 13. The third sub arm 16b is the first sub arm 14b.
Are arranged in parallel to.

Further, one end of a fourth sub arm 17b is rotatably mounted on the pivot of the second sub arm 15b and the third sub arm 16b.
Are arranged parallel to the first main arm 12.

One end of a fifth sub arm 18b is rotatably attached to the other end of the fourth sub arm 17b via a pivot, and the other end of the fifth sub arm 18b is attached to the first main arm 12. The fifth sub arm 18a is rotatably attached to the first main arm 12 via a pivot. This fifth
The sub arm 18b is arranged parallel to the third sub arm 16b.

The first main arm 12, the fifth sub arm 18b,
The fourth sub-arm 17b and the third sub-arm 16b allow the third
A parallel link is formed, and the second main arm 13, the third sub arm 16b, the second sub arm 15b, and the first sub arm 14b.
This constitutes a fourth parallel link.

And, these third parallel link and fourth
The parallel link is linked to the first parallel link and the second parallel link described above with a predetermined phase difference so that the main arm 1
They are integrally connected to each other at a pivot portion with respect to 1 and 12. That is, when the arm of the first or second parallel link is located on a straight line, the corresponding third or fourth parallel link is arranged so that its arm is not located on a straight line. The angle formed with the sub arm 14b is always constant.

Further, the actuator 19 having one degree of freedom at the tip (free end of this arm mechanism) θ3 of the second main arm 13 has the fourth sub arm 17a and the fifth sub arm 17a in this embodiment.
It is provided on the pivot with the sub arm 18a.

When the actuator 19 is actuated, the rotational force of the actuator 19 is a pair of parallel first and second parallel links or third and fourth parallel links sharing the third sub arm 16a or 16b. Transmitted by FIG.
As shown in (A) and (B), the base end (support 11)
The rotational force by the actuator 19 provided on the side can be transmitted to the pivot shaft θ3 near the tip of the second main arm 13. Note that, as shown in FIG. 1B, the rotational force can be transmitted by the actuator 19 regardless of the rotational positions of the first main arm 12 and the second main arm 13.

The parallel link has a peculiar point in that, when the arms forming the parallel link are stopped at positions overlapping in a straight line, the arms are locked even if restarted from this position. However, in this embodiment, by providing the third and fourth parallel links having the same structure as the first and second parallel links in parallel,
Even if one of them becomes a singular point, the other does not become a singular point, and therefore the rotational force by the actuator 19 can always be favorably transmitted to the free end of the arm mechanism.

Further, since the actuator 19 is arranged on the pivot located on the most proximal end (post 11) side of the parallel link, the weight on the free end side of the arm mechanism can be reduced,
Since it is possible to prevent the response characteristic from being deteriorated due to the moment of inertia, and to reduce the rigidity of the arm and the power of the actuator, it is possible to reduce the weight and the size of the entire device. (2) FIGS. 3 and 4 are views for explaining the second embodiment of the present invention.

In FIG. 3 (A), 21 is a column,
An intermediate portion of the first arm 22 is rotatably attached to the top of the column 21 by a horizontal pivot θ4. Also,
One end of the second arm 23 is integrally fixed to the top of the column 21.

At the other end of the second arm 23, the third arm 2
One end of 4 is rotatably attached by a pivot,
One end of a fourth arm 25 is rotatably attached to the other end of the third arm 24 by a pivot.

The other end of the fourth arm 25 is connected to the first arm 22.
Is pivotally attached to one end of the first arm 22 and one end of the fifth arm 26 is pivotally attached to one end of the first arm 22.

One end of a sixth arm 27 is rotatably attached to the other end of the fifth arm 26 via a pivot. One end of a seventh arm 28 is rotatably attached to the other end of the sixth arm 27 by a pivot, and
The middle portion of the seventh arm 28 is rotatably attached to the other end of the first arm 22 by a pivot θ5.

The first, second, third and fourth arms 22, 2
3, 24, 25 form a parallel link, and the first,
The fifth, sixth, and seventh arms 22, 26, 27, 28 form another parallel link.

In this embodiment, the third arm 24
And a first actuator 29 on the axis of the fourth arm 25.
And the second actuator 30 is provided on the pivot axis of the fifth arm 26 and the sixth arm 27. By operating the first actuator 29, the posture shown in FIG.
By operating 0, the posture as shown in FIG.
By operating both of them, the posture shown in FIG. 4B can be obtained. Thereby, the movement of two degrees of freedom is realized at the tip (free end) of the seventh arm 28.

First and second actuators 29, 30
Is provided on the pivot axis of the third arm 24 and the fourth arm 25 and on the pivot axis of the fifth arm 26 and the sixth arm 27. In the case of such a combination of parallel links, the actuator 29, Gravity on 30 acts in a direction to lift the free end of the seventh arm 28 upward, and acts as a counterbalance against the gravity of the free end side of the seventh arm 28 (weight of the arm, attached device, etc.). Because it will work.

Therefore, since the balance of the arm mechanism as a whole is improved, the response characteristics are improved, and the power of the actuator can be lowered, so that the weight and size of the whole can be reduced. (3) FIGS. 5 to 8 are views for explaining the third embodiment of the present invention, and are schematic configurations when the master arm in FIG. 10 is configured by combining the first and second embodiments described above. FIG.

That is, the sixth arm 27 of FIG.
The first main arm 12 of (A), the seventh arm 28 of FIG. 3 (A) as the second main arm 13 of FIG. 1 (A), and the first to fourth parallel links of FIG. It is configured by applying. Therefore, the same parts as those of the first or second embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 5, reference numeral 31 denotes a grip manually operated by an operator. By gripping the grip 31 and operating it back and forth and up and down, although not shown, an axial force sensor (strain gauge) is shown. ) Detects the force and direction applied thereto, and controls the actuators 19, 29, 30 by a control device (not shown) to operate the master arm. In the figure, the support column 21 and the second arm 23 are integrally fixed via a pivot axis θ4.

That is, from the state shown in FIG. 5, the grip 3
When a force is applied to 1 so as to rotate it about the axis θ3, the actuator 19 is actuated in response to this force, and the posture shown in FIG. 6 is obtained. Also, FIG.
When a force is applied to the grip 31 such that the grip 31 is rotated about the pivot axis θ5 from the state shown in FIG. 7, the actuator 30 is actuated in accordance with this force, and the posture becomes as shown in FIG. Further, from the state shown in FIG. 5, when a force is applied to the grip 31 so as to rotate about the pivot axis θ4, the actuator 29 is actuated in response to this force, and the posture as shown in FIG. Become.

Then, these movements are converted into a predetermined control signal and, as shown in FIG.
To the slave arm 1 and the slave arm 1 traces the same operation as the master arm 2.

Since the actuators 19, 29, 30 are provided relatively close to the support column 21, it is possible to reduce the weight of the arm mechanism on the free end (grip 31) side, and at the same time, reduce the weight. The weight balance between the end side and the opposite side can be improved, and controllability can be improved.

Further, when a force is applied to the grip 31 in the direction of rotation about the pivot θ3, the rotational force of the actuator 19 is transmitted to the pivot θ3 via the first to fourth parallel links. At this time, even if one of the parallel links becomes a singular point, this is solved by another parallel link provided in parallel with it, so that a good operation can be realized.

Although this embodiment shows an example applied to a master arm, the present invention is not limited to this, and it goes without saying that it can be applied to a slave arm. (4) FIG. 9 is an explanatory view of the fourth embodiment of the present invention, and FIG.
The vicinity of the connecting portion of the first arm 22 and the seventh arm 28 in FIG.

In the master arm and the like as shown in the third embodiment, cables for power supply or signal transmission are wired along each arm, but in this embodiment, a pivot (joint) is used. A through hole 32 that substantially coincides with the axis of the pivot is formed in the portion, and a cable 33 that is routed along the arms 22 and 28 by a fastener 34 or the like is routed through the through hole 32.

By doing so, the cable 33
The force acting on the joint portion of the arms 22 and 28 due to the elasticity of the arm 22 and the like is reduced, and the change in the force due to the line angle of the arms 22 and 28 can be reduced. Therefore, the controllability is improved, and the weight and size of the actuator can be reduced by reducing the power of the actuator. The same applies to the other pivot portions.

[0049]

Since the present invention is configured as described above, the self-weight of the actuator and the load on the actuator due to the cable can be reduced, the power of the actuator can be reduced, and the work robot can be reduced in size and weight. The controllability of the robot can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention, (A) is a diagram showing a configuration, and (B) is a diagram showing its operation.

2A and 2B are explanatory diagrams of the first embodiment of the present invention, where FIG. 2A is a diagram showing another operation of FIG. 1A and FIG. 2B is a diagram showing another operation.

3A and 3B are explanatory diagrams of a second embodiment of the present invention, FIG. 3A is a diagram showing a configuration, and FIG. 3B is a diagram showing its operation.

4A and 4B are explanatory diagrams of a second embodiment of the present invention, FIG. 4A is a diagram showing another operation of FIG. 3A, and FIG. 4B is a diagram showing another operation.

FIG. 5 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 6 is an explanatory diagram of the third embodiment of the present invention and is a diagram showing the operation of FIG. 5;

FIG. 7 is an explanatory diagram of the third embodiment of the present invention and is a diagram showing another operation of FIG. 5;

FIG. 8 is an explanatory diagram of the third embodiment of the present invention, and is a diagram showing still another operation of FIG. 5;

FIG. 9 is an explanatory diagram of the fourth embodiment of the present invention.

FIG. 10 is a diagram showing an outline of a work robot having a general master / slave configuration.

[Explanation of symbols]

 11 Strut 12 First Main Arm 13 Second Main Arm 14a, 14b First Sub Arm 15a, 15b Second Sub Arm 16a, 16b Third Sub Arm 17a, 17b Fourth Sub Arm 18a, 18b Fifth Sub Arm 19 Actuator 21 Post 22 First arm 23 Second arm 24 Third arm 25 Fourth arm 26 Fifth arm 27 Sixth arm 28 Seventh arm 29, 30 Actuator 31 Grip 32 Through hole 33 Cable 34 Fastener

Claims (4)

[Claims] 1. A cantilevered multi-joint arm mechanism comprising parallel link means in which four arms are rotatably connected to a parallelogram by a horizontal pivot, and the parallel link means comprises: With two sets in parallel,
A multi-joint arm characterized in that, when each arm of one parallel link means is positioned on a straight line, the arms of the other parallel link means are integrally linked to each other in a state where they are not positioned on a straight line. mechanism. 2. The multi-joint arm mechanism according to claim 1, wherein an actuator for operating the parallel link means is arranged coaxially with a pivot shaft located closest to a base end side among pivot shafts of the parallel link means. A multi-joint arm mechanism that is characterized. 3. A cantilever type multi-joint arm mechanism comprising parallel link means in which four arms are rotatably connected to each other in a parallelogram shape by a horizontal pivot, and a free end side of the arm mechanism is provided. A multi-joint arm mechanism in which an actuator is arranged coaxially with one of the axes of the parallel link means so as to act as a counter balance. 4. A cantilevered multi-joint arm mechanism comprising parallel link means in which four arms are rotatably connected to each other in a parallelogram shape by a horizontal pivot, and a pivot of the parallel link means is provided. Forming a through hole coaxially with
A multi-joint arm mechanism in which a cable is routed along the arm so as to pass through the through hole.