Robot and parallel link robot

Provided is a robot including at least one joint, and at least two links and coupled with each other by the joint. At least one of the links and includes an inner layer made of carbon fiber reinforced plastic, and an outer layer made of elastic material and covering an outer peripheral surface of at least part of the inner layer in a longitudinal direction over an entire circumference, the layers being integrally stacked.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Application No. 2017-160339, the contents of which are incorporated herein by reference.

FIELD

The present invention relates to a robot and a parallel link robot.

BACKGROUND

In a known technology (for example, PTL 1), a link connecting joints of a robot is made of carbon fiber reinforced plastic (CFRP). According to Japanese Unexamined Patent Application, Publication No. 2014-237187, the link is preferably formed of lightweight material such as CFRP.

SUMMARY

The present invention provides the following solutions.

A robot according to an aspect of the present invention includes at least one joint, and at least two links coupled with each other by the joint. At least one of the links includes an inner layer made of carbon fiber reinforced plastic, and an outer layer made of elastic material and covering an outer peripheral surface of at least part of the inner layer in a longitudinal direction over an entire circumference, the layers being integrally stacked.

A parallel link robot according to another aspect of the present invention includes: a foundation unit; a movable unit; a plurality of arms coupling the foundation unit and the movable unit in parallel; and a plurality of actuators disposed in the foundation unit and configured to drive the respective arms. Each arm includes a drive link driven by the actuator, and a passive link coupled with the drive link by a joint. Each passive link includes two link members parallel to each other. At least one of the link members includes an inner layer made of carbon fiber reinforced plastic, and an outer layer made of elastic material and covering an outer peripheral surface of at least part of the inner layer in a longitudinal direction over an entire circumference, the layers being integrally stacked.

DETAILED DESCRIPTION

The following describes a parallel link robot (robot)1according to an embodiment of the present invention with reference to the accompanying drawings.

FIG. 1is a perspective view illustrating a parallel link robot1according to the present embodiment. As illustrated inFIG. 1, the parallel link robot1includes a foundation unit2housed in a housing8, a movable plate3(movable unit) having a circular disk shape, three arms10ato10ccoupling the foundation unit2and the movable plate3in parallel, three actuators4ato4cdisposed in the foundation unit2and configured to drive the respective arms10ato10c, an attachment member (wrist shaft)9attached to the movable plate3, a wrist actuator5, a drive shaft7configured to transfer drive power of the wrist actuator5to the attachment member9, a fixation member6fixing the wrist actuator5to the arm10a, and an universal joint UJ provided halfway through the drive shaft7.

The foundation unit2has a circular disk shape from which three substantially rectangular shapes are cut out to avoid contact with the three arms10ato10c. The three arms10ato10care disposed at equal intervals in the circumferential direction about a perpendicular axis passing through the center of the circular disk of the foundation unit2.

The actuators4ato4cand the wrist actuator5each include a servomotor and a decelerator. The actuators4ato4cswing the respective arms10ato10ccoupled therewith about horizontal axes aligned with the direction of the plane of the foundation unit2in the circular disk shape.

The position of the movable plate3is controlled by controlling drive of the actuators4ato4c. The actuators4ato4ccan translate the movable plate3while maintaining the posture of the movable plate3in parallel to the foundation unit2. The wrist actuator5rotates the attachment member9about the central axis of the circular disk of the movable plate through the drive shaft7. When the wrist actuator5is controlled, the rotation angle of the attachment member9relative to the movable plate3is controlled, and the rotation angle of an end effector (not illustrated) attached to the attachment member9is controlled.

The arms10ato10chave identical configurations, and thus, the following description will be made on the arm10a, but description of the arms10band10cwill be omitted. The arm10aincludes a drive link11ahaving one end attached to the actuator4a, and a passive link (link)15ahaving one end swingably connected with the other end of the drive link11a. The other end of the passive link is swingably connected with the movable plate3.

The passive link15aincludes two link members12aand13aparallel to each other. The link members12aand13aeach have both ends swingably connected with the drive link11aand the movable plate3through ball joints (joints) BJ. In other words, the drive link11a, the movable plate3, and the two link members12aand13aconstitute a parallel four-joint link. With this configuration, a rectangle connecting the four ball joints BJ with straight lines is constantly shaped in a parallelogram when the parallel four-joint link changes an angle relative to the drive link11a.

The link members12ato12cand13ato13chave identical structures, and each have a cylindrical shape over the length.FIG. 2illustrates a transverse sectional shape of the link member12aand an enlarged sectional shape of part thereof. As illustrated inFIG. 2, the link member12aincludes an inner layer LINas a stack of a plurality of layers made of carbon fiber reinforced plastic (hereinafter referred to as CFRP), and an outer layer LOUmade of nitrile rubber (hereinafter referred to as NBR) and covering the inner layer LINover the entire circumference.

The inner layer LINis formed by winding sheet CFRP around the outer peripheral surface of a round bar. The outer layer LOUis formed integrally with the inner layer LINby winding sheet NBR to cover the surface of the inner layer LINafter the inner layer LINis formed. After the outer layer LOUis formed, the round bar is pulled out to leave a hollow part in the link member12awhen completed. In the link member12aaccording to the present embodiment, the inner layer LINis covered by the outer layer LOUin a substantially entire range in the longitudinal direction.

FIG. 3illustrates a longitudinal sectional view indicating the relation between the inner layer LINand the outer layer LOUin the vicinity of one of the ball joints BJ. The ball joint BJ illustrated inFIG. 3couples the drive link11aand the link member12a. As illustrated inFIG. 3, the ball joint BJ includes a spherical ball head22, a substantially cylindrical ball stud21coupled with the drive link11aand connected with the ball head22, a reception portion23bhaving an inner spherical surface complementary with the spherical surface of the ball head22, and a coupling portion23including an insertion hole23aengaged with the link member12a.

The posture of the link member12acoupled with the coupling portion23can be optionally changed relative to the drive link11aby relatively sliding the ball head22and the reception portion23b.

Both ends of the link member12aare each formed into a cylindrical shape by accurately fabricating, by lathe turning or the like, the outer peripheral surface of the inner layer LINexposed by partially peeling off the outer layer LOU, and are each engaged with the insertion hole23aof the coupling portion23. In other words, in each of the link member12aand the other link members12b,12c, and13ato13c, the inner layer LINis covered by the outer layer LOUin a region except for both ends in the longitudinal direction.

FIG. 4is an enlarged perspective view illustrating the fixation member6and the vicinity thereof. As illustrated inFIG. 4, the fixation member6includes two long plate members61and62fixed in parallel separately from each other by two pairs of bolts BT1and separation members, and two clamp components65aand65bdisposed between the long plate members61and62and mounted on the respective link members12aand13a.

The clamp component65aincludes a metallic recess member66aincluding a recess engaged with the link member12a, a metallic flat plate member67adisposed on a side opposite to the recess member66awith respect to the link member12aengaged with the recess, and a bolt BT2fixing the flat plate member67aand the recess member66ato the link member12aby clamping.

The flat plate member67ais provided with a through-hole through which the bolt BT2penetrates. The recess member66ais provided with a screw hole for fastening the bolt BT2penetrating through the through-hole of the flat plate member67a. The clamp component65bhas a configuration same as that of the clamp component65a, and thus description thereof will be omitted.

A bracket BC provided at a tip of the wrist actuator5is disposed between the two long plate members61and62of the fixation member6and at the center in the longitudinal direction of the long plate members61and62. The recess members66aand66bof the clamp components65aand65band the bracket BC are provided with a shaft SH extending, in the direction of separation, from two facing side surfaces of the long plate members61and62(shafts of the recess members66aand66bare not illustrated). The long plate members61and62are provided with bearings BR including inner rings engaged with the shaft SH and rotatably supporting the recess members66aand66band the bracket BC (the bearings BR for the bracket BC are not illustrated). Each bearing BR may be a ball bearing or a slipping bearing.

In the parallel link robot1according to the present embodiment thus configured, when the link member12ais clamped by the clamp component65awith clamping force applied toward inside from outside in the radial direction, the outer layer LOUmade of NBR elastically deforms to disperse the clamping force, thereby protecting the CFRP of the inner layer LIN. Accordingly, the metallic clamp component65acan be directly attached to the link member12amade of CFRP to achieve a reduced weight, which eliminates the need to separately provide a protection component made of elastic material between the link member12aand each of opposing surfaces of the recess member66aand the flat plate member67a, thereby reducing the number of components. This leads to reduction of manufacturing cost of the robot and lowers the risk that when the clamp component comes off, the clamp component65a, particularly, a component made of NBR, which is difficult to sense, is mixed into an object handled by the robot.

The embodiment above exemplarily describes the link members12ato12cand13ato13ceach including the inner layer LINmade of CFRP and the outer layer LOUmade of elastic material, but the configurations of the link members12ato12cand13ato13cmay be modified in various manners.

For example, in the above-described embodiment, the link members12ato12cand13ato13ceach include the inner layer LINmade of CFRP and the outer layer LOUmade of NBR, but the link members12aand13ato which the clamp components65aand65bare attached may each include the outer layer LOUmade of NRB, and the other link members12b,12c,13b, and13cmay include no layer made of NRB. In each of the link members12aand13a, the outer layer LOUonly needs to be formed in a range in which the clamp components65aand65bare attached. No outer layer LOUmade of elastic material needs to be formed not only in the coupling portion for the ball joint BJ in the above-described embodiment but also in, for example, a part between the fixation member6and the ball joint BJ.

The elastic material of which the outer layer LOUis formed may be rubber material other than NBR or may be elastic material such as resin. Examples of the rubber material of which the outer layer LOUis formed include hydrogen nitrile rubber (HNBR), chloroprene rubber (CR), fluorine rubber, and silicone rubber. Examples of the resin material of which the outer layer LOUis formed include polyacetal (POM) and ultrahigh molecular weight polyethylene (UHMW-PE). In the above-described embodiment, the link members12ato12cand13ato13ceach include the inner layer LINmade of CFRP and the outer layer LOUmade of NBR, but may each include a layer made of another material on the inner side of the inner layer LINor between the inner layer LINand the outer layer LOU.

In the above-described embodiment, the wrist actuator5is fixed to the link member12aor the like by the fixation member6including the clamp components65aand65b, but, for example, a tube TB as another component may be fixed to the link member12aor the like by a clamp component65aaas illustrated inFIG. 5. In the configuration illustrated inFIG. 5, the tube TB is fixed to the link member12a, but no clamp component65bis mounted on the link member13a(not illustrated).

In the above-described embodiment and the configuration illustrated inFIG. 5, the clamp components65a,65b, and65aaare exemplarily described as components that apply clamping force to the link members12aand13ain the direction intersect to the longitudinal direction from outside in the radial direction, but other components (for example, clips) are applicable.

When another component is fixed to the link member12a, the outer layer LOUprovided over the length of the link member12aallows a user to fix the tube TB or the like at an optional position by using the metallic clamp component65aa. Alternatively, the outer layer LOUmay be partially provided only at a predetermined position on the link member12ain the longitudinal direction, and the tube TB or the like may be fixed at the position by the clamp component65aa.

In the above-described embodiment, what is called a delta-type parallel link robot including the three arms10ato10cis exemplarily described as a robot including the link members12ato12cand13ato13cin each of which the inner layer LINmade of CFRP and the outer layer LOUmade of elastic material are formed, but the present invention is also applicable to other robots. For example, the present invention is applicable to a parallel link robot including four or more arms or two arms and a serial link robot including no parallel arms.

From the above-described embodiments and modifications thereof, the present invention provides the following solutions.

A robot according to an aspect of the present invention includes at least one joint, and at least two links coupled with each other by the joint. At least one of the links includes an inner layer made of carbon fiber reinforced plastic, and an outer layer made of elastic material and covering an outer peripheral surface of at least part of the inner layer in a longitudinal direction over an entire circumference, the layers being integrally stacked.

According to the present aspect, each link includes the inner layer made of carbon fiber reinforced plastic, and thus and has light weight and high tensile strength. In addition, at least part of the inner layer is covered by the outer layer made of elastic material. With this configuration, when another component such as a cable is fixed to the part through, for example, a metallic clamp component, the outer layer protects the inner layer from damage, and the outer layer elastically deforms to disperse surface pressure applied on the inner layer by the clamp component.

Accordingly, damage on the inner layer, which is made of carbon fiber reinforced plastic and has light weight and high tensile strength, can be reduced by protecting the inner layer from a load in the direction intersecting the longitudinal direction, such as clamping force when another component such as a clamp component is mounted. Moreover, reduction of the number of components, which is achieved by integrally stacking the inner layer and the outer layer improves assembly easiness of the robot and reduces manufacturing cost of the robot.

A parallel link robot according to another aspect of the present invention includes: a foundation unit; a movable unit; a plurality of arms coupling the foundation unit and the movable unit in parallel; and a plurality of actuators disposed in the foundation unit and configured to drive the respective arms. Each arm includes a drive link driven by the actuator, and a passive link coupled with the drive link by a joint. Each passive link includes two link members parallel to each other. At least one of the link members includes an inner layer made of carbon fiber reinforced plastic, and an outer layer made of elastic material and covering an outer peripheral surface of at least part of the inner layer in a longitudinal direction over an entire circumference, the layers being integrally stacked.

In the present aspect, since the passive link includes the two link members, each link member is thin in some cases. However, in a link member in which the inner layer and the outer layer are stacked, the inner layer is made of carbon fiber reinforced plastic, and thus the link member has high tensile strength. In addition, since the outer layer of the link member is made of elastic material, mounting a clamp component or the like on the link member causes no damage on the inner layer, and surface pressure applied on the inner layer is dispersed.

Accordingly, damage on the inner layer can be reduced by protecting the inner layer from a load in the direction intersecting the longitudinal direction. Moreover, reduction of the number of components, which is achieved by integrally stacking the inner layer and the outer layer improves assembly easiness of the robot and reduces manufacturing cost of the robot.

In the above-described aspect, the link member other than the link member having a stack structure may be made of carbon fiber reinforced plastic.

With this configuration, a link member on which a clamp component or the like is not mounted does not need to include an outer layer made of elastic material, which leads to reduction of manufacturing cost of the robot.

In the above-described aspect, each link member may include the inner layer and the outer layer integrally stacked.

With this configuration, mounting a clamp component or the like on any of the link members causes no damage on the CFRP of the inner layer. This improves freedom in selection of the mounting position of another component such as a cable mounted through the clamp component. The same link member can be used as all link members, which leads to improved freedom of designing and reduction of manufacturing cost of the robot.

In the above-described aspect, the outer layer may cover an entire outer peripheral surface of the inner layer.

With this configuration, mounting a clamp component or the like at any position on a link member in the longitudinal direction causes no damage on the CFRP of the inner layer. This improves freedom in selection of mounting position of another component such as a cable mounted through the clamp component.

In the above-described aspect, the parallel link robot may include a wrist shaft attached to the movable unit, and a wrist actuator configured to drive the wrist shaft, and the wrist actuator may be attached to a fixation member fixed to each link member from an outer surface of the outer layer.

With this configuration, when the wrist actuator configured to drive the wrist shaft is fixed to each link member through the fixation member, the outer layer protects the inner layer from a load applied by the fixation member in the direction intersect to the longitudinal direction of the link member. Moreover, reduction of the number of components of the parallel link robot improves assembly easiness of the parallel link robot and reduces manufacturing cost of the parallel link robot.

Advantageous Effects of Invention

According to the present invention, an inner layer made of carbon fiber reinforced plastic is protected from a load in a direction intersecting the longitudinal direction to reduce damage thereon. Moreover, reduction of the number of components, which is achieved by integrally stacking the inner layer and an outer layer improves assembly easiness of a robot and reduces manufacturing cost of the robot.