JPH1177577A - Wire driving type manipulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manipulator which furnishes a simple structure, can realize a small size and a light weight, and has a low manufactural cost. SOLUTION: A universal coupling 6 with a pair of spherical surface is provided to a base 1, and tilting frames 57 are provided at three positions making the same angle each other on a circumference making the universal coupling 6 as the center. A wire winding device 5 is installed to each tilting frame 57. A travelling plate 2 is provided at the lower side of the base 1, a center rod 3 is supported by the universal coupling 6 to allow the movement in the axial direction, and the front end of the center rod 3 is fixed at the center of the upper surface of the travelling plate 2. The front end of each wire 4 installed to each wire winding device 5 is connected to the peripheral edge of the travelling plate 2 through the universal coupling 8. A compression coil spring 7 is provided around the center rod 3, and one end of the compression coil spring 7 is received to the universal coupling 6 in the compressed condition, and its other end is received to the travelling plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a manipulator for holding an end effector such as a tool and controlling its three-dimensional position and attitude in an industrial robot or the like.

[0002]

2. Description of the Related Art A manipulator based on a so-called parallel link mechanism has excellent characteristics such as high rigidity, high speed, and high accuracy, and is being considered for application to machine tools, robots, and the like, and is attracting attention. As an example of the parallel link mechanism, a “Stuart platform” in which two upper and lower platforms (base and traveling plate) are connected by six telescopic link mechanisms, or a base and a base described in Japanese Patent Publication No. 6-57394. The traveling plate has three link mechanisms and one
An “arm device” connected by a center rod is known.

In these apparatuses, a traveling plate on which an end effector is mounted is attached to a base.
The three-dimensional position and attitude of the traveling plate are controlled by connecting the universal joint and three or three sets of rods and controlling the amounts of these rods independently using ball screws. However,
Such a structure using a rod as a connecting means has a problem in that the structure is complicated, so that the device becomes large, the weight increases, and the cost increases.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the above-mentioned conventional manipulators, and an object of the present invention is to provide a simple structure, miniaturization and weight reduction. It is an object of the present invention to provide a manipulator which can be manufactured and whose manufacturing cost is relatively low.

[0005]

SUMMARY OF THE INVENTION A wire driven manipulator of the present invention comprises a base, a universal joint mounted on the base, and at least three mounted on the base or a member in fixed relation to the base. A wire winding device, a guide disposed on the base so as to surround a periphery of the universal joint, and a guide for movably holding the wires unreeled from the wire winding device, and the base facing the base. A traveling plate disposed below the end plate, an end effector attached to the traveling plate, and one end side supported by the base via the universal joint so as to be tiltable, and the other end side connected to the center of the traveling plate. A center rod whose other end side is configured to be movable in the axial direction with respect to the universal joint. A wire connecting portion that is disposed on the traveling plate so as to surround the periphery of the connecting portion on the other end side of the center rod, and that connects a tip of the wire that is fed out through the guide; Wire tension means for applying a force in a direction of pulling away from the base to the traveling plate, thereby applying a tension to each of the wires, and controlling the feeding amount of each of the wires by using each of the wire winding devices And controlling the position of the traveling plate with respect to the base.

[0006] Preferably, the wire winding device is attached to the base so as to be tiltable in accordance with the direction of the wire fed out through the guide, and the wire is always kept straight before and after the guide. Like

[0007] The center rod consists of one shaft,
A method in which the one end side is supported by the universal joint so as to be movable in the axial direction, or is made of an expandable and contractable member,
There is a method in which the one end side is connected to the universal joint, and the other end side of the center rod may be fixedly connected to the traveling plate, or may be tiltably connected.

Incidentally, as the wire tensioning means, for example, the following structure can be used. (1) A compression coil spring provided so as to be located between the universal joint and the traveling plate along the center rod, and a tension is applied to each of the wires by using a force in a direction in which the compression coil spring extends. Or (2) a second base (lower base) is arranged below the traveling plate, and a tension applying means such as a tension coil spring is arranged opposite to the wire, and one end of the tension applying means is provided. Is connected to the traveling plate so as to surround the connecting portion of the center rod, the other end is connected to the lower base, and tension is applied to each of the wires by using the tension applying means.

Further, the wire-driven manipulator of the present invention can be constructed without using a center rod. In this case, the construction is such that an upper base and an upper base are disposed below and opposed to the upper base. At least one provided on the upper base or a member in a fixed relationship with the base, and the other provided on the lower base or a member in a fixed relationship with the base. Three sets of wire take-up devices, guides respectively arranged on the upper and lower bases in pairs, and guides for respectively holding the wires fed from the wire take-up devices so as to be freely movable, and the upper base and the lower base. A traveling plate placed between
An end effector attached to the traveling plate, and a wire connecting portion that is arranged in a pair near the upper and lower peripheral portions of the upper and lower surfaces of the traveling plate and that connects the tips of the wires fed out through the guides. The position of the traveling plate with respect to the base is controlled by controlling the feeding amount of each set of wires using the set of wire winding devices.

[0010] Also in this case, preferably, the wire winding device is attached to the upper base or the lower base such that the wire winding device can be tilted in accordance with the direction of the wire fed out through the guide. Always keep it straight before and after the guide.

[0011] According to the wire-driven manipulator of the present invention, the position of the traveling plate relative to the base (or the upper base) (accordingly, the position of the traveling plate is controlled by independently controlling the wire feeding amount using the wire winding device). , End effector position) is controlled. The wire winding device has a simple structure, is light in weight, can be reduced in size, and is inexpensive, as compared with a ball screw used for driving the expansion and contraction of a rod in a conventional device.

Further, if the wire winding device is attached to the base so that it can be tilted in accordance with the direction of the wire to be unwound, even if the direction of the wire changes, the unwinding amount is not affected. This improves the accuracy of the position of the end effector.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) FIG. 1 shows an example of a wire-driven manipulator according to the present invention. The base 1 is provided with a spherical pair even joint 6 at the center thereof, and a spherical pair even tilting frame 57 is provided at three locations on the circumference around the universal joint 6 which are equiangular with each other. I have. The wire winding devices 5 (two of them are shown in FIG. 1) are attached to these three tilting frames 57, respectively. The traveling plate 2 is arranged below the base 1. The center rod 3 is supported by the universal joint 6 so as to be movable only in the axial direction, and the tip of the center rod 3 is fixed to the center of the upper surface of the traveling plate 2. At the periphery of the upper surface of the traveling plate 2, universal joints 8 are respectively arranged at three locations on the circumference around the fixed position of the tip of the center rod 3 at equal angles to each other. The tip of each wire 4 unreeled from each wire winding device 5 is
It is connected to the periphery of the traveling plate 2 via a universal joint 8 as a wire connection.

A compression coil spring 7 is arranged around the center rod 3. In a compressed state, the compression coil spring 7 has one end received by the universal joint 6 and the other end received by the traveling plate 2. Each traveling wire 4 is pressed by pressing the traveling plate 2 downward using the force in the direction in which the compression coil spring 7 extends.
Is tensioned.

An end effector 9 (tool or work) is attached to the center of the lower surface of the traveling plate 2. This end effector 9 can be
Traveling plate 2 so that position and posture can be adjusted
It is also possible to attach to.

FIG. 2 shows an outline of the structure of the wire winding device 5. As shown in FIG. 2A, the wire winding device 5 is configured by connecting a winding drum 54 to a servomotor 51 via a worm wheel 53 and a worm 52. By controlling the rotation angle of the winding drum 54 by the servomotor 51, the feeding amount of the wire 4 is controlled. The wire take-up device 5 is attached to the base 1 via the tilting frame 57 of a pair of spherical surfaces as described above, and can tilt around the tilting center 59 of the tilting frame 57 as shown in FIG. it can. The base end of the wire 4 is wound around a winding drum 54, and the wire 4 is fed out of the tilting frame 57 via a guide 56 provided at an opening of the tilting frame 57. Note that the tilting center 59 is located on a line connecting the base 56 from which the wire 4 is fed from the winding drum 54 and the guide 56, and when tension is applied to the wire 4, the tilt center 59 depends on the feeding direction of the wire 4. As a result, the tilting frame 57 is tilted, and the wire 4 is fed out on a straight line passing through the tilting center 59 regardless of the feeding direction of the wire 4.

Next, a method of operating the wire-driven manipulator shown in FIG. 1 will be described. Since the traveling plate 2 is fixed to the distal end of the center rod 3, it can be three-dimensionally moved on a concentric spherical surface centered on the universal joint 6 while maintaining a relative attitude with respect to the concentric spherical surface. The three-dimensional position of the traveling plate 2 (position in the longitudinal direction of the center rod 3) and posture (angle), that is, the position of the traveling plate 2
, And an angle detector (not shown) attached to the universal joint 6.

Based on the difference between the command value of the position and posture of the traveling plate 2 and the measured value of the position and posture obtained from the output of the detector, the servo motor 51 is feedback-controlled to feed out each wire 4. Control the amount.

Since the traveling plate 2 is pressed downward by the coil spring 7, each wire 4 is always kept in a straight state. Therefore, the extension amount of each wire 4 and the position and posture of the traveling plate 2 correspond one-to-one.

The wire winding device 5 is, as described above,
Since it is attached to the base 1 via the tilting frame 57 so as to tilt in accordance with the direction of the wire 4 to be fed,
Even if the direction of each wire 4 changes according to the position and posture of the traveling plate 2, the wire 4 keeps a linear state,
This does not cause an error in the amount of wire 4 to be fed out. If the relationship between the amount of rotation of the winding drum 54 and the amount of feeding of the wire 4 is determined in advance, the amount of feeding of the wire 4 can be accurately controlled.

(Example 2) FIG. 3 shows another example of a wire-driven manipulator according to the present invention. In this example, as a means for applying tension to the wire 4, the following configuration is adopted instead of the configuration shown in FIG.

Below the base 1, a second base (lower base) 11 is disposed so as to face the base 1. The traveling plate 2 is disposed between the base 1 and the lower base 11. A tension coil spring 17 is disposed corresponding to each wire 4, and one end of each tension coil spring 17 is located at a peripheral edge of the lower surface of the traveling plate, at a position corresponding to the back side of the universal joint 8 to which the tip of each wire 4 is connected. The other end is connected to the lower base 11.
Using the force in the direction in which each tension coil spring 17 contracts,
The traveling plate 2 is pulled downward to apply tension to each wire 4.

The tension coil springs 17 do not need to correspond one-to-one with each wire 4. One tension coil spring 17 may act on a plurality of wires 4 in common.

(Example 3) FIG. 4 shows another example of a wire-driven manipulator according to the present invention. In this example, instead of using a center rod, the traveling plate 2 is supported by attaching a wire 14 to the periphery of the lower surface of the traveling plate 2 instead.

A lower base 11 is arranged below the upper base 1 so as to face the upper base 1. The traveling plate 2 is disposed between the upper base 1 and the lower base 11. Universal joints 8 and 18 are attached to the upper surface and the lower surface at three locations on the periphery of the traveling plate 2, respectively. Three wire winding devices 5 and 15 are provided on the upper base 1 and the lower base 11 corresponding to the universal joints 8 and 18, respectively. The wire winding devices 5 and 15 are arranged so as to form a pair, one of which is provided on the upper base 1 and the other 15 is provided on the lower base 11. The wire take-up device 5 provided on the upper base 1 side and the universal joint 8 provided on the upper surface of the peripheral portion of the traveling plate 2 are connected via the wire rope 4, and likewise on the upper base 11 side. Provided wire winding device 15 and traveling plate 2
Is connected via a wire rope 14 to a universal joint 18 provided on the lower surface of the peripheral portion of.

By controlling the feeding amounts of the wires 4 and 14 of each pair by using the wire winding devices 5 and 15 of each pair, the tensioned state of each wire 4 and 14 is always maintained. At the same time, the three-dimensional position and orientation of the traveling plate 2 with respect to the upper base 1 are controlled.

Example 4 FIGS. 5 and 6 show still another example of the wire-driven manipulator according to the present invention. In this example, the base 1 is attached to the lower surface of the top plate 20, and the wire winding device 5 is fixed and attached to an unillustrated device frame to which the top plate 20 is attached. The wire 4 fed from the wire winding device 5 is connected to the traveling plate 2 via a guide 56 attached to the upper surface of the base 1.

As shown in FIG. 6, the center rod 3 has its upper end connected to the base 1 by a cross-shaped universal joint 61 so as to be tiltable, and its lower end is fixed to the traveling plate 2. The center rod 3 is composed of a cylinder 31 and a rod 32 movably engaged in the axial direction.
The relative rotation of the cylinder 31 and the rod 32 is regulated by a spline or a key (not shown).
Is also a cross-shaped universal joint that regulates relative rotation, so that the rotation of the traveling plate 2 about the center rod 3 is regulated.

A compression coil spring 7 for tensioning the wire 4 is provided between the cylinder 63 and the rod 64. In this example, the wire winding device 5 is not attached to be tiltable, but the amount of the rod 64 extended and the universal joint 6
1 is used to measure the inclination angle of the center rod 3 and feed back the wire 4 by the wire winding device 5 to control the position and orientation of the traveling plate 2 and to generate dust and the like. Since the winding device 5 is separated from the end effector 9, it is suitable for, for example, a medical robot that does not generate dust.

The present invention is not limited to the configuration shown in each of the above examples, but can be applied with various modifications. For example, the universal joint 6 in Examples 1 and 2 may be a cross-shaped universal joint. Similarly, the tilt frame 57
May be a cross-shaped universal joint. Further, instead of the compression coil spring 7 or the tension coil spring 17, a pressing force or tension force applying means such as a fluid pressure device including a cylinder and a piston can be used. Further, the tension coil spring 17 of FIG. 3 may be fixed at a position corresponding to the back surface side of each intermediate portion of the universal joint 8.

[0031]

According to the wire-driven manipulator of the present invention, the structure is simpler and lighter than a conventional manipulator driven by using a rod and a ball screw.
It can be miniaturized and manufactured at low cost.

If the wire take-up device is mounted on the base so that it can be tilted in accordance with the direction of the wire to be unwound, the unwinding amount does not change even if the direction of the wire changes, so that control is simplified. The accuracy of at least the three-dimensional position of the end effector is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a wire-driven manipulator according to the present invention.

2A is a partially enlarged view of a wire winding device constituting the wire-driven manipulator of FIG. 1, and FIG. 2B is a diagram illustrating a state in which a tilting frame is tilted according to a wire feeding direction. .

FIG. 3 is a schematic configuration diagram showing another example of a wire-driven manipulator according to the present invention.

FIG. 4 is a schematic configuration diagram showing another example of a wire-driven manipulator according to the present invention.

FIG. 5 is a schematic configuration diagram showing still another example of a wire-driven manipulator according to the present invention.

FIG. 6 is a detailed view of a center rod portion shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper frame, 2 ... Traveling plate, 3 ... Center rod, 4 ... Wire, 5 ...
Wire take-up device, 6 universal joint, 7 coil spring, 8 universal joint, 9 end effector, 1
DESCRIPTION OF SYMBOLS 1 ... Lower frame, 14 ... Wire, 15 ...
Wire take-up device, 17: coil spring, 18: universal joint, 31: cylinder, 32: rod, 51
... Servo motor, 52 ... worm, 53 ...
Worm wheel, 54 ... winding drum, 56 ...
Guide, 57: tilt frame, 59: tilt center, 61
... Universal joints.

Claims (11)

[Claims] 1. A base, a universal joint attached to the base, at least three wire winding devices attached to the base or a member fixed to the base, and a periphery of the universal joint. A guide that is arranged on the base so as to surround it, and that movably holds a wire that is respectively fed from the wire winding device; a traveling plate that is arranged below the base so as to face the base; and the traveling plate And an end effector mounted on the base, one end of which is tiltably supported by the base via the universal joint, the other end of which is connected to the center of the traveling plate, and the other end of which is pivotally connected to the universal joint. A center rod configured to be movable in the direction, and around a connecting portion on the other end side of the center rod. A wire connecting portion that is arranged on the traveling plate so as to surround and connects a tip of the wire that is fed out through the guide, and that acts on the traveling plate in a direction in which the traveling plate is separated from the base; A wire tensioning means for applying a tension to each of the wires, and controlling a position of the traveling plate with respect to the base by controlling a feeding amount of each of the wires by using each of the wire winding devices. A wire-driven manipulator characterized by the following: 2. The wire winding device is mounted on the base so as to be tiltable in accordance with the direction of the wire fed out through the guide, and the wire is always kept straight before and after the guide. The wire-driven manipulator according to claim 1, wherein the wire-driven manipulator is configured as follows. 3. The center rod according to claim 1, wherein the center rod comprises a single shaft, and the one end is supported by the universal joint so as to be movable in an axial direction. A wire-driven manipulator as described. 4. The wire-driven manipulator according to claim 1, wherein the center rod is made of an extendable member, and the one end is connected to the universal joint. 5. The wire-driven manipulator according to claim 3, wherein the other end of the center rod is fixedly connected to the traveling plate. 6. The wire-driven manipulator according to claim 3, wherein the other end of the center rod is connected to the traveling plate so as to be tiltable. 7. The compression coil spring according to claim 1, wherein said wire tensioning means is provided between said universal joint and said traveling plate along said center rod. The wire-driven manipulator according to any one of the above. 8. The traveling plate, further comprising a lower base below the traveling plate, wherein the wire tensioning means is arranged to face the wire, and one end of the traveling plate surrounds a periphery of the connecting portion of the center rod. The wire-driven manipulator according to any one of claims 1 to 6, wherein the wire driving type manipulator is connected to the lower base and the other end is a tensile force applying means connected to the lower base. 9. The wire-driven manipulator according to claim 8, wherein the tension applying means is a tension coil spring. 10. An upper base, a lower base opposed to and below the upper base, and arranged in pairs with each other, one of which is in a fixed relationship with the upper base or the base. And at least three sets of wire winding devices each provided on the lower base or a member fixedly related to the base, and the wire winding device disposed on the upper and lower bases in pairs. A guide for holding the wires respectively drawn from the traveling base, a traveling plate arranged between the upper base and the lower base, an end effector attached to the traveling plate, and upper and lower surfaces of the traveling plate. The wires arranged in pairs near the peripheral portion and fed out through the guides And a wire connection unit for connecting each end of the ear, and controlling the position of the traveling plate with respect to the base by controlling the feeding amount of each set of wires using each set of wire winding devices. A wire-driven manipulator. 11. The wire winding device is attached to the upper base or the lower base so as to be tiltable in accordance with the direction of the wire fed out through the guide, and the wire is always in a straight line before and after the guide. The wire-driven manipulator according to claim 10, wherein the wire-driven manipulator is configured to be maintained in a shape.