Patent ID: 12220812

MODE FOR CARRYING OUT THE DISCLOSURE

Hereinafter, one embodiment is described with reference to the drawings.

FIG.1illustrates a robot device1according to this embodiment. The robot device1includes a pedestal2and an articulated robotic arm3. The pedestal2is fixed on a horizontal installation surface, for example. The robotic arm3includes a swivel base4, an arm5, a first link11, a second link12, and a hand part15.

The swivel base4is supported by the pedestal2so as to be rotatable on a swivel axis A1. The arm5is supported by the swivel base4at a base-end part, and rotatably supports the first link11at a tip-end part. The arm5includes a lower arm6and an upper arm7. A base-end part of the lower arm6is supported by the swivel base4so as to be swingable on a lower arm axis A2. The upper arm7is supported by a tip-end part of the lower arm6so as to be swingable on an upper arm axis A3.

A base-end part of the first link11is supported by the tip-end part of the arm5(the upper arm7). The first link11rotates on a first axis L1. The second link12is supported by a tip-end part of the first link11so as to be rotatable on a second axis L2. The hand part15is supported by a tip-end part of the second link12. An end effector80(seeFIG.6) is detachably attached to a tip-end part of the hand part15. The hand part15includes a third link13and a fourth link14. The third link13is supported by the second link12so as to be rotatable on a third axis L3. The fourth link14is supported by the third link13so as to be rotatable on a fourth axis L4. The end effector80is attached to the fourth link14, and it is rotatable with the fourth link14on the fourth axis L4with respect to the third link13.

When the pedestal2is installed horizontally, the swivel axis A1is oriented vertically and the upper and lower arm axes A2and A3are oriented horizontally. The upper and lower arm axes A2and A3are parallel to each other. The first axis L1is coaxial with the center axis of the first link11. The second axis L2is located in a twisted position to the first axis L1. The second axis L2extends in parallel with a direction perpendicular to the first axis L1, does not intersect with the first axis L1, and is deviated from the first axis L1. The layout of the second axis L2will be described later (seeFIGS.3-5). The third axis L3is parallel to the second axis L2. The third axis L3and the fourth axis L4are perpendicular to each other.

The robotic arm3has a plurality of link members, a plurality of joints each of which couples the adjacent link members to each other rotatably on the corresponding rotation axis, and a plurality of joint actuators corresponding to the joints. Each joint actuator includes a servo driver, a servomotor, a rotation angle detector, and a speed reducer. Each servomotor rotates the corresponding link member on the corresponding rotation axis.

In this embodiment, the robot device1has seven link members4,6,7, and11-14, and seven joints. Seven rotation axes A1-A3and L1-L4correspond to the seven joints, and seven servomotors are provided corresponding to the seven joints. Rotation of each servomotor is servo-controlled by a control device50(seeFIG.2). The rotation angle about the seven rotation axes A1-A3and L1-L4(that is, postures of the seven link members4,6,7, and11-14) can be controlled independently from each other.

As illustrated inFIG.2, the control device50includes a memory51such as a ROM and/or a RAM, a processor52such as a CPU, and a servo controller53. The control device50is a robot controller provided with a computer, such as a microcontroller, for example. The control device50may be comprised of a sole control device50which carries out a centralized control, or may be comprised of a plurality of control devices50which collaboratively carry out a distributed control.

The memory51stores a basic program as a robot controller, and information such as various fixed data. The processor52controls various operations of the robot device1by reading and executing software, such as the basic program stored in the memory51. For example, the control device50controls operation of the robotic arm3based on the program stored in the memory51in advance or manipulation inputted by a worker. That is, the processor52generates a control command for the robot device1and outputs it to the servo controller53. The servo controller53controls the drive of the servomotor corresponding to each joint of the robotic arm3based on the control command generated by the processor52.

FIGS.3and4illustrate the first link11and the second link12according to this embodiment. Referring toFIGS.1,3, and4, a line space40where a supply line85for supplying electricity and/or material is disposed is provided to the first link11and the second link12. The supply line85may be a cable for supplying electricity, a hose for supplying material, or an integrated line which bundles the cable and the hose. The cable supplies electric power to the servomotor (particularly, what drives the hand part15), or the end effector80(seeFIG.6). The hose supplies to the end effector80the material required for the work performed by the robot device1. The material may be a welding wire required for a welding work, or paint required for a painting work.

The line space40includes a first insertion hole41, a second insertion hole42, and a gap space43. The first insertion hole41is formed in a central part of the first link11, and it opens in the tip-end part of the first link11. The second insertion hole42is formed in a central part of the second link12, and it opens in a base-end part of the second link12. The gap space43is formed between a tip-end opening41aof the first insertion hole41and a base-end opening42aof the second insertion hole42.

As one example of the structure of the first link11and the second link12, the first link11has a cylindrical part11aand a forked part11b. The cylindrical part11ahas a length as long as the lower arm6, and a base-end part of the cylindrical part11ais supported by the arm5(the upper arm7). The first axis L1is coaxial with the center axis of the cylindrical part11a. The forked part11bis formed in a tip-end part of the cylindrical part11a, and constitutes the tip-end part of the first link11. The second link12has a base-end forked part12a, a cylindrical part12b, and a tip-end forked part12c. The cylindrical part12bis shorter than the cylindrical part11a. The base-end forked part12aconstitutes the base-end part of the second link12, and the tip-end forked part12cconstitutes the tip-end part of the second link12. The second link12is supported at both ends by the forked part11bin a state where a pair of outer surfaces of the base-end forked part12acontact a pair of inner surfaces of the forked part11b, respectively. A tip-end face of the cylindrical part11awhich is the root part of the forked part11bis separated from a base-end face of the cylindrical part12bwhich is the root part of the base-end forked part12a. Note that the tip-end forked part12crotatably supports the third link13at both ends.

The first insertion hole41extends inside the cylindrical part11aalong the center axis of the cylindrical part11a(that is, the first axis L1). The tip-end opening41aof the first insertion hole41opens in the tip-end face of the cylindrical part11a(the root part of the forked part11b). The second insertion hole42extends inside the cylindrical part12balong the center axis of the cylindrical part12b. The base-end opening42aof the second insertion hole42opens in the base-end face of the cylindrical part12b(the root part of the base-end forked part12a). The gap space43is formed between the cylindrical parts11aand12b, and is formed between the base-end forked part12a. The tip-end opening41aand the base-end opening42aopen in the gap space43. The center of the tip-end opening41ais on the center axis of the cylindrical part11a(the first axis L1). The center of the base-end opening42ais on the center axis of the cylindrical part12b.

The supply line85is disposed inside the first insertion hole41, and is disposed inside the second insertion hole42through the tip-end opening41a, the gap space43, and the base-end opening42a. When the second link12rotates, the position or posture of the base-end opening42awith respect to the tip-end opening41achanges about the second axis L2. Inside the gap space43, the supply line85is bent so as to follow the posture of the second link12. Below, a part of the supply lines85inside the gap space43is referred to as a “bendable part85a.”

FIG.5illustrates a first link911and a second link912according to a comparative example. This embodiment and the comparative example are the same in the structure of the first link and the second link, but are different in the layout of the second axis with respect to the first axis. Below, a state where the second link extends in parallel to the first axis is referred to as “a reference posture of the second link.” In the illustrated example, the first axis is horizontal, and the second link also extends horizontally in the reference posture. Below, one direction perpendicular to the first axis is referred to as a “first perpendicular direction Y,” and a direction perpendicular to both the first axis and the first perpendicular direction Y is referred to as a “second perpendicular direction Z.” In the illustrated example, the first axis is oriented in the left-and-right direction of the drawing sheet. The first perpendicular direction Y corresponds to a direction perpendicular to the drawing sheet, and is horizontal. The second perpendicular direction Z corresponds to the up-and-down direction of the drawing sheet, and is vertical.

In a robot device900according to the comparative example, a second axis L2′ is perpendicular to a first axis L1′. The second axis L2′ is oriented in the first perpendicular direction Y, and intersects with the first axis L1′. When the second link912is rotated downwardly from the reference posture on the second axis L2′, the second link912can be rotated to a first limit angle θ1′. When the second link912is rotated upwardly from the reference posture on the second axis L2′, the second link912can be rotated to a second limit angle θ2′. The first limit angle θ1′ and the second limit angle θ2′ have substantially the same value.

The center axis of the second link912passes through an intersection between the first axis L1′ and the second axis L2′. When the second link912is in the reference posture, not only the center of a tip-end opening941aof a first insertion hole941but the center of a base-end opening942aof a second insertion hole942is also located on the first axis L1′.

Referring toFIG.3, in this embodiment, the second axis L2extends in parallel with the first perpendicular direction Y, and is deviated in the second perpendicular direction Z from the first axis L1. In the illustrated example, the second axis L2is located below the first axis L1. Below, a rotating direction when the second link12rotates from the reference posture so that a tip end of the second link12is oriented to the deviating side of the second axis L2(downwardly in the illustrated example) is referred to as a “first rotating direction R1.” A rotating direction when the second link12rotates from the reference posture so that the tip end of the second link12is oriented to the opposite side (upwardly in the illustrated example) from the deviating side of the second axis L2is referred to as a “second rotating direction R2.”

In this embodiment, when the second link12rotates in the first rotating direction R1, the second link12can rotate from the reference posture to a first limit angle θ1, without the second link12interfering with the first link11. Since the second axis L2is deviated, the first limit angle θ1becomes larger than the first limit angle θ1′ of the comparative example. That is, the movable range of the second link12in the first rotating direction R1increases. Accompanying with this, the movable ranges of the hand part15and the end effector80provided to the tip-end part of the second link12also increase. When the second link12rotates in the second rotating direction R2, the second link12can rotate from the reference posture to a second limit angle θ2. The first limit angle θ1is larger than the second limit angle θ2.

Note that an amount of deviation of the second axis L2from the first axis L1(a distance in the second perpendicular direction Z) is set as a distance which exceeds a range of manufacturing error. The amount of deviation is 20 mm to 50 mm, for example. The second axis L2does not intersect with the first axis L1within the range of manufacturing error (e.g., about 1 mm).

As a result of this axial layout, in the reference posture of the second link12, the center axis of the second link12separates from the first axis L1and extends in parallel with the first axis L1. Therefore, the center of the base-end opening42aof the second insertion hole42is deviated in the second perpendicular direction Z from the center of the tip-end opening41aof the first insertion hole41. An amount of deviation of the opening is equivalent to the amount of deviation of the axis.

FIG.4illustrates a state where the second link12rotates in the first rotating direction R1from the reference posture by the first limit angle θ1′ of the comparative example. When the second link12rotates from the reference posture by the same rotation angle, the distance from the center of the tip-end opening41ato the base-end opening42abecomes longer than that of the comparative example. Therefore, a curvature r of the bendable part85abecomes smaller than a curvature r′ in the comparative example. When the second link12rotates in the first rotating direction R1from the reference posture, the curvature of the bendable part85ais eased and the protection of the supply line85increases.

FIG.6illustrates one example of a work performed using the robot device1. Here, a spray gun for painting is adopted as the end effector80, and a work in which the workpiece90is painted by the spray gun is illustrated. The spray gun injects paint which is supplied through the supply line85(seeFIGS.3and4). The workpiece90has an opening91. The pedestal2is installed outside the workpiece90. A part to be painted is an inner surface of the workpiece90, and it is located below the opening91.

Upon the painting work, the control device50controls the servomotors corresponding to the upper and lower arm axes A2and A3so that the first link11becomes in the posture extending substantially horizontally. The first link11is inserted into the opening91, and the tip-end part of the first link11is positioned inside the workpiece90. The control device50drives the servomotor corresponding to the second axis L2so that the second link12extends substantially vertically and becomes in a posture where it is bent downwardly with respect to the first link11. The control device50controls the servomotor corresponding to the third axis L3so that the hand part15extends substantially horizontally and becomes in a posture where it is bent with respect to the second link12. As a result, a part from the swivel base4to the first link11takes a posture of a relatively large inverted L-shape. Inside the workpiece90, the second link12and the hand part15take a posture of a relatively small L-shape. Therefore, the end effector80can oppose to the inner surface of the workpiece90below the opening91, and can inject the paint to the part to be painted.

The control device50controls the servomotor corresponding to the first axis L1so that the second perpendicular direction Z is oriented vertically and the second axis L2is deviated below the first axis L1. Therefore, when performing the painting work below the opening91, the movable range of the second link12(as a result, the end effector80) increases and the workability improves. Moreover, the curvature of the bendable part85aof the supply line85is eased, and the supply line85can be protected.

Note that it is similar when performing the work above the opening91. The control device50controls the servomotor corresponding to the first axis L1so that the second axis L2becomes a posture where it is deviated above the first axis L1.

The embodiment described above is one example. Modification, addition, and/or deletion may suitably be possible for the configuration described above within the scope of the present disclosure.