US20110107866A1 - Robot - Google Patents

Abstract

A robot includes a base and an arm formed by a plurality of members connected by a plurality of joints. The arm has an offset portion where a rotation axis of a certain joint is offset from a rotation axis of the next joint in a predetermined direction and the rotation axis of the next joint is offset from a rotation axis of a joint next to the next joint in a direction opposite the predetermined direction.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2009-257212, filed Nov. 10, 2009. The contents of the application are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a robot having a plurality of joints.
• 2. Description of the Related Art
• In most typical vertical articulated robots, an arm mounted on a base includes six or seven rotary joints, and portions provided on distal-end sides (robot-hand sides) of the joints are rotated or turned.
• The moving range of the hand of such a robot can be widened by increasing the length of the arm. Meanwhile, if the arm is folded so that the hand of the robot is placed in an area near the base, it is necessary to prevent the hand from interfering with the arm. For this reason, the moving range of the hand of the robot is set such as not to include the area near the base.
• In recent years, there has been a demand for a robot that can perform more complicated operation and moving range. Hence, the robot is required to operate in a manner such that the hand can be placed both at positions sufficiently distant from the base and positions closer to the base.
• As a technique for solving this problem, Japanese Patent Laid-Open Publication No. 2008-272883 discloses a structure for offsetting the rotation axis of an arm in a middle portion of the arm. According to this disclosed technique, even in a state in which the arm is folded, a wide moving range can be ensured wile avoiding interference between the arm portions.
SUMMARY OF THE INVENTION
• The robot is required to have a more compact size while ensuring a wider moving range. Particularly when the robot is not in use, the arm takes a substantially straight attitude in order to minimize an area where the arm interferes with surrounding objects.
• However, when the rotation axis of the arm is offset, as in the technique ofPatent Literature 1, even if the arm can be made in a straight form by moving the joints of the arm, the arm protrudes owing to the offset. This limits enhancement of the space saving performance of the robot.
• Accordingly, an object of the invention is to provide a robot and a robot system that can enhance space-saving performance while widening a moving range.
• According to one aspect of the present invention, a robot includes a base; and an arm including a plurality of members connected by a plurality of joints. The arm includes an offset portion where a rotation axis of any one of the joints is offset from a rotation axis of the next joint in a predetermined direction and the rotation axis of the next joint is offset from a rotation axis of a joint next to the next joint in a direction opposite the predetermined direction.
BRIEF DESCRIPTION OF THE DRAWINGS
• The present invention will be described in further detail with reference to the accompanying drawings wherein:
• FIG. 1 is a side view illustrating a configuration of a robot according to a first embodiment;
• FIG. 2 is a side view illustrating the configuration of the robot of the first embodiment;
• FIG. 3 is a side view illustrating a configuration of a robot according to a second embodiment;
• FIG. 4 is a side view illustrating a configuration of a robot according to a third embodiment; and
• FIG. 5 is a top view illustrating the configuration and a moving range of the robot of the third embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTSFirst EmbodimentOverall Configuration
• A first embodiment will be described below with reference to the drawings.
• As illustrated inFIG. 1, arobot system100 according to the first embodiment includes a seven-axis vertical articulatedrobot1, arobot controller2, and acable3 that connects therobot1 and therobot controller2.
• Therobot controller2 is formed by a computer including a memory, an electronic processor, and an input (all of them not illustrated), and is connected to below-described actuators in therobot1 by thecable3. Thecable3 is formed by bundling and sheathing signal communication lines between therobot controller2 and the actuators and power feeding lines for supplying power from a power supply (not shown) to the actuators.
• Therobot1 includes abase10 fixed to a mounting surface (e.g., floor or ceiling)101, and an arm. In the arm, an arm member (first member)11, an arm member (second member)12, an arm member (third member)13, an arm member (fourth member)14, an arm member (fifth member)15, an arm member (sixth member)16, and a flange (seventh member17) are connected by rotary joints (first to seventh joints) in order from thebase10 to a leading end of therobot1. That is, the arm is constituted by thearm members11 to17 and the rotary joints.
• More specifically, thebase10 and thearm member11 are connected by a first actuator (first joint)11A, and thearm member11 is rotated by driving of thefirst actuator11A. Thearm member11 and thearm member12 are connected by a second actuator (second joint)12A, and thearm member12 is pivoted by driving of thesecond actuator12A.
• Thearm member12 and thearm member13 are connected by a third actuator (third joint)13A, and thearm member13 is rotated by driving of thethird actuator13A. Thearm member13 and thearm member14 are connected by a fourth actuator (fourth joint)14A, and thearm member14 is pivoted by driving of thefourth actuator14A.
• Thearm member14 and thearm member15 are connected by a fifth actuator (fifth joint)15A, and thearm member15 is rotated by driving of thefifth actuator15A. Thearm member15 and thearm member16 are connected by a sixth actuator (sixth joint)16A, and thearm member16 is pivoted by driving of thesixth actuator16A.
• Thearm member16 and theflange17 are connected by a seventh actuator (seventh joint)17A, and theflange17 and an end effecter (not shown), such as a hand, which is attached to theflange17 are pivoted by driving of theseventh actuator17A.
• As illustrated inFIG. 1, thearm member13 includes a receiving portion (receiving portion A)20A that receives thethird actuator13A, a connecting portion (connecting portion A)20B obliquely extending from thereceiving portion20A to the upper right side of the figure (in the R-direction and a direction towards the leading end), and a receiving portion (receiving portion B)20C that receives thefourth actuator14A. Thereceiving portion20A, the receiving portion20C, and the connectingportion20B form a continuous internal space, where thecable3 is stored.
• Thearm member14 includes a receiving portion (receiving portion A)21A that receives thefourth actuator14A, a connecting portion (connecting portion B)21B obliquely extending from thereceiving portion21A to the upper left side of the figure (in the L-direction and a direction towards the leading end), and a receiving portion (receiving portion D)21C that receives thefifth actuator15A. Thereceiving portion21A, thereceiving portion21C, and the connectingportion21B form a continuous internal space.
• That is, thereceiving portion20A, the receiving portion20C, the connectingportion20B, thereceiving portion21A, thereceiving portion21C, and the connectingportion21B correspond to the offset portion.
• Each of the first toseventh actuators11A to17A is formed by a servo motor with built-in reduction gears. The servo motor has a hole through which thecable3 can extend. The first toseventh actuators11A to17A are connected to therobot controller2 by thecable3.
• When therobot1 takes an attitude such that rotation axes A1, A3, and A5 (referred to as rotation axes in the rotating direction) are perpendicular to the mounting surface101 (a state illustrated inFIG. 1), rotation axes A2, A4, A6, and A7 (rotation axes in the pivot direction) are at an angle of 90 degrees to the rotation axes in the rotating direction. Further, the rotation axis A6 is at an angle of 90 degrees to the rotation axis A7.
• The rotation axis A1 of thefirst actuator11A and the rotation axis A3 of thethird actuator13A are substantially aligned with each other. Also, the rotation axis A1 and the rotation axis A3 are orthogonal to the rotation axis A2 of thesecond actuator12A.
• The rotation axes A1 and A3 do not intersect the rotation axis A4 of thefourth actuator14A, and are offset from the rotation axis A4 by a length d1 in a direction horizontal to the mounting surface101 (in a R-direction with reference to the rotation axis A3).
• In other words, the offset refers to a state in which a rotation axis different from a rotation axis at a base end is shifted from the rotation axis at the base end in the orthogonal direction when the robot or the arm takes an attitude such that the projection area thereof on the mounting surface is the smallest.
• Further, the rotation axis A4 does not intersect the rotation axis A5 of thefifth actuator15A, and is offset from the rotation axis A5 by a length d2 in the direction horizontal to the mounting surface101 (in the rightward direction of the figure with reference to the rotation axis A4).
• Therefore, the rotation axis A3 and the rotation axis A5 are offset by a length |d1−d2| in the direction horizontal to the mounting surface101 (in the rightward direction of the figure with reference to the rotation axis A3).
• In the first embodiment, the length d1 is set to be larger than the length d2 (that is, d1>d2). The width of thearm member13 is larger than the width of thearm member15.
• Thebase10 has a cable insertion hole (not shown). As illustrated inFIG. 2, thecable3 passes, in order, through the interior of thebase10, the hole of thefirst actuator11A, thearm member11, the hole of thesecond actuator12A, thearm member12, the hole of thethird actuator13A, the receivingportion20A, the connectingportion20B, the receiving portion20C, the hole of thefourth actuator14A, the receivingportion21A, the connectingportion21B, the receivingportion21C, the hole of thefifth actuator15A, thearm member15, the hole of thesixth actuator16A, thearm member16, and the hole of theseventh actuator17A. Further, thecable3 is connected to the end effecter (not shown) via a hole of theflange17.
• Since therobot system100 of the first embodiment has the above-described configuration, when therobot system100 operates with theflange17 being placed near the base10 or thearm member11, in a state in which thefourth actuator14A is greatly rotated, as illustrated inFIG. 2, the rotation axis A3 and the rotation axis A5 are offset from each other by the sum of the length d1 and the length d2 (that is, d1+d2), which increases the offset amount between the rotation axis A3 and the rotation axis A5. For this reason, even when thefourth actuator14A is bent to obtain an attitude such that the rotation axis A3 and the rotation axis A5 become substantially parallel to each other, it is possible to prevent thearm member13 and thearm member15 from touching and interfering each other and to allow theflange17 to reach a lower position near thearm member11.
• In contrast, during a standby state of therobot system100, therobot1 is operated so that the rotation axis A1, the rotation axis A3, and the rotation axis A5 become perpendicular to the mountingsurface101. This can minimize the amount of protrusion of therobot1 in the direction horizontal to the mountingsurface101. In this case, the offset amount of the rotation axes A1 and A3 from the rotation axis A4 is limited to the length d1.
• In other words, the offset amount corresponding to d1+d2 can be obtained in the state where thefourth actuator14A is bent, and the offset amount can be limited to d1 (d1<d1+d2) in the standby state. Thus, a wide moving range of theflange17 can be ensured by the offset, and moreover space saving can be achieved.
• Thecable3 passes through the hole of thethird actuator13A, is gently bent in the connectingportion20B, passes through the hole of thefourth actuator14A, is gently bent in the connectingportion21B, and is then guided to the hole of thefifth actuator15A. Therefore, even if the angle between thearm member13 and thearm member14 is made more acute by greatly rotating thefourth actuator14A, the curvature of thecable3 can be limited to a relatively small value. Hence, it is possible to reduce damage to thecable3 due to the increase in curvature of thecable3.
• In the first embodiment, thefifth actuator15A rotates thearm member15, thesixth actuator16A pivots thearm member16, and theseventh actuator17A rocks theflange17 at an angle of 90 degrees to the pivot direction of thearm member16. Hence, unlike the case in which theseventh actuator17A rotates theflange17, it is possible to prevent an out-of-control point (singular point) from being caused by overlapping of the rotation axis A5 and the rotation axis A7. For this reason, it is unnecessary to perform an operation for avoiding the singular point in the attitude such that thefourth actuator14A is bent (state ofFIG. 2). This increases the degree of flexibility in operation of therobot1.
Second Embodiment
• Next, a second embodiment will be described. As illustrated inFIG. 3, arobot system200 of the second embodiment is different from therobot1 of the first embodiment only in an attachment direction of aseventh actuator27A (seventh joint) and aflange27. Therefore, in the following description, for convenience of explanation, redundant descriptions are appropriately omitted, and like components are denoted by like reference numerals.
• In the second embodiment, anarm member16 is connected to theflange27 by theseventh actuator27A, and theflange27 and an end effecter (not shown), such as a hand, attached to theflange27 are rotated by driving of theseventh actuator27A.
• Since therobot system200 of the second embodiment has the above-described configuration, in contrast to therobot1 of the first embodiment, it is necessary to avoid a singular point caused when afourth actuator14A is bent, but it is possible to easily rotate the end effecter attached to theflange27 by simply driving theseventh actuator27A. Thus, the second embodiment is suitable for an application in which the end effecter is rotated.
Third Embodiment
• Next, a third embodiment will be described. As illustrated inFIGS. 4 and 5, the third embodiment is different from the first embodiment in that the base adopted in the first embodiment is removed and the body is provided with a pair of (two)arms400 having a structure similar to that of the arm of therobot1. Therefore, descriptions overlapping with the first embodiment are appropriately omitted, and like components are denoted by like reference numerals.
• In arobot system300 of the third embodiment, twoarms400 are attached to a body301 (corresponding to the base) fixed to a mountingsurface101.
• Thebody301 includes abase portion301A fixed to the mountingsurface101, and a turning body portion (main body)301B that turns relative to thebase portion301A via anactuator301C.
• The turningbody portion301B obliquely extends upward (to the upper right ofFIG. 4) from theactuator301C, and has an opening where the pair ofarms400 can be attached.
• A rotation axis Ab of theactuator301C is offset from rotation axes A1 offirst actuators11A in thearms400 by a length d3 in a direction horizontal to the mounting surface101 (R-direction with reference to the rotation axis Ab).
• In the third embodiment, thearms400 are attached to the turningbody portion301B in a manner such that the rotation axes A1 of the respectivefirst actuators11A are arranged on the same straight line (the orientations of thearms400 can be changed appropriately). That is, the turningbody portion301B also functions as a bases for both of thearms400. Arobot controller302 is connected to thearms400 by acable303 so that the actuators of thearms400 operate according to commands from therobot controller302.
• Since therobot system300 of the third embodiment has the above-described configuration, it is possible to enlarge the moving range where the pair ofarms400 cooperate near the body, for example, during assembly of mechanical products. This achieves further space saving.
• Further, the turningbody portion301B obliquely extends upward and the pair ofarms400 are attached thereto. Thus, the offset between the rotation axis Ab and the rotation axis A1 allows theflanges17 of thearms400 to be moved to farther positions by rotating theactuator301C.
• In addition, ends of thearms400 can reach even a space formed near thebase portion301A and below the turningbody portion301B. Therefore, operation can be performed utilizing the space below the turningbody portion301B, and this achieves further space saving.
• While the embodiments of the present invention have been described above, the robot system of the present invention is not limited to the above embodiments, and appropriate modifications can be made without departing from the scope of the present invention.
• For example, while the robot of the first embodiment is attached to the body in the third embodiment, the arm attached to the body may be similar to the arm adopted in therobot system200 of the second embodiment.
• While the robot has seven joints in the above embodiments, it may have three joints. For example, the structures other than the third tofifth actuators13A,14A, and15A and thearm members13 to15 in the first embodiment may be removed from the robot.

Claims (10)

1. A robot comprising:

a base; and

an arm including a plurality of members connected by a plurality of joints,

wherein the arm has an offset portion where a rotation axis of any one of the joints is offset from a rotation axis of the next joint in a predetermined direction and the rotation axis of the next joint is offset from a rotation axis of a joint next to the next joint in a direction opposite the predetermined direction.

2. The robot according toclaim 1,

wherein the arm includes:

a first joint configured to rotate a first member relative to the base;

a second joint configured to pivot a second member relative to the first member;

a third joint configured to rotate a third member relative to the second member;

a fourth joint configured to pivot a fourth member relative to the third member;

a fifth joint configured to rotate a fifth member relative to the fourth member; and

a sixth joint configured to pivot a sixth member relative to the fifth member,

wherein a rotation axis of the third joint is offset from a rotation axis of the fourth joint by a first length in a predetermined direction, and a rotation axis of the fourth joint is offset from a rotation axis of the fifth joint by a second length in a direction opposite the predetermined direction.

3. The robot according toclaim 2, wherein the arm further includes a seventh joint configured to rotate the sixth member and a seventh member.

4. The robot according toclaim 2, wherein the arm further includes a seventh joint configured to rotate on a rotation axis orthogonal to a rotation axis of the sixth joint and to pivot a seventh member relative to the sixth member.

5. The robot according toclaim 2, further comprising:

a cable extending at least from the third joint to the fifth joint via the fourth joint.

6. The robot according toclaim 5, wherein each of the third joint, the fourth joint, and the fifth joint is formed by an electric motor having a hole that receives the cable.

7. The robot according toclaim 6,

wherein the third member includes:

a first receiving portion configured to receive the third joint;

a first connecting portion extending from the first receiving portion in the predetermined direction; and

a second receiving portion configured to receive the fourth joint, and

wherein the cable is stored in an internal space formed by the first receiving portion, the first connecting portion, and the second receiving portion.

8. The robot according toclaim 7,

wherein the fourth member includes:

a third receiving portion configured to receive the fourth joint;

a second connecting portion extending from the third receiving portion in the direction opposite the predetermined direction; and

a fourth receiving portion configured to receive the fifth joint, and

wherein the cable is stored in an internal space formed by the third receiving portion, the second connecting portion, and the fourth receiving portion.

9. The robot according toclaim 1, wherein a pair of the arms are attached to the base.

10. The robot according toclaim 9,

wherein the pair of arms are attached to a body in an asymmetrical form,

wherein the body includes

a base member fixed to a mounting surface, and

a body portion connected to the base member via a turning joint that turns relative to the base member, and

wherein a rotation axis of the turning joint is offset from the base of the robot.

Images