Robot with movable stopper for a joint

Abstract

Robot, comprising: a robot main body (1) comprising a first element (6), a second element (5) and a joint provided between the first member (6) and the second member (5), the joint connecting the first member (6) and the second member (5) to each other so that they are relatively rotatable about a prescribed axis (J1); a fixed stopper (2) attached to the first element (6); an adapter (4) which can be releasably attached to the second element (5); and a movable stopper (3) which can be attached to the adapter (4) and which can be attached directly to the second element (5), wherein the second element (5) has a main body-side fastening part (13) to which either the adapter (4) or the movable stopper (3) is selectively fastened, the adapter (4) has one or more adapter-side fastening parts (4c) to which the movable stopper (3) can be fastened, wherein the one or more adapter-side fastening parts (4c) is or are arranged in a different position than the main body-side fastening part (13) in the circumferential direction around the axis (J1) while the adapter (4) is in a state in which it is fastened to the main body-side fastening part (13), and wherein a relative rotation angle range of the first member (6) and the second member (5) is limited as a result of the fixed stopper (2) and the movable stopper (3) abutting against each other around the axis (J1), the movable stopper (3) being fixed to the main body-side fixing part (13) or to the adapter-side fixing part (4c) or the plurality of adapter-side fixing parts (4c) of the adapter (4) fixed to the main body-side fixing part (13).

Description

Technical FieldThe present invention relates to a robot.Prior ArtA stopper is known from the related art that mechanically restricts a movable range (rotational angle range) of a joint of a robot (see, for example, PTL 1 to PTL 3). In PTL 2 and PTL 3, a plurality of fixing holes for fixing the stopper are provided around the hinge. By changing the attachment positions of the stopper, it is possible to change the restriction angle of the hinge defined by the stopper.Patent Literature cited:PTL 1: JP 2014-46 447 APTL 2: JP H10-156 786 APTL 3: JP 2015-163 414 AFurthermore, WO 2017 / 094 632 A1 describes a robot arm mechanism having a column-like support part which forms a cylindrical body, wherein the cylindrical body accommodates a first joint part having a vertical axis of rotation. The first hinge part has a rotating base designed as a fixed part. A rotor is rotatably installed in an inner region of the rotating base. According to WO 2017 / 094 632 A1, stopper structures are provided on an upper surface of the rotor and on an upper surface of the rotary base in order to restrict the rotation of the rotor. Here, stopper blocks are mounted on a block mounting part on the upper surface of the rotary base, and a stopper arm is mounted on the upper surface of the rotor.In addition, a device for limiting the range of movement of an industrial robot is described in U.S. Pat. No. 4,828,094 A. A range limiting member that is movably provided on a stationary side of an axle portion about which pivotal movement can be made and provided with a run-over detection cam and a stopper is described. Further, a fixed member is described which is provided on a movable side of the shaft portion and prevents excessive pivoting when abutting the stopper.SUMMARY OF THE INVENTIONTechnical ProblemIn order to provide a plurality of fastening holes, it is necessary to expose a region around the hinge to form these fastening holes; however, in some situations, exposing such a region may be difficult. For example, if a robot is made relatively slender or the construction of the robot has been simplified, there is not enough space around the joint in some situations. In other situations, the design in the vicinity of the joint may be limited by a region for mounting holes kept free around the joint. Accordingly, in some situations, it may be difficult to simultaneously implement both mounting of the mounting holes and a desired design.In view of the above-described circumstances, it is an object of the present invention to provide a robot having a stopper that restricts the range of movement of a joint and is capable of changing the restriction angle of the range of movement of the joint even when the space provided in the vicinity of the joint is restricted.Solution of the ProblemIn order to achieve the above-described object, the present invention provides the following possibilities.An aspect of the present invention is a robot including: a robot main body including a first member, a second member, and a joint provided between the first member and the second member, the joint connecting the first member and the second member to each other so as to be relatively rotatable about a prescribed axis; a fixed stopper fixed to the first member; an adapter detachably attachable to the second member; and a movable stopper detachably attachable to the adapter and directly attachable to the second member, wherein the second member has a main body-side attachment part to which either the adapter or the movable stopper is selectively attached, the adapter has an adapter-side attachment part or a plurality of adapter-side attachment parts to which the movable stopper is attachable, wherein the one or more adapter-side fixing parts is disposed at a position other than the main body-side fixing part in a circumferential direction about the axis while the adapter is in a state of being fixed to the main body-side fixing part, and a relative rotational angle range of the first member and the second member is limited as a result of the fixed stopper and the movable stopper abutting each other about the axis, the movable stopper being fixed to the main body-side fixing part or the adapter-side fixing part or the plurality of adapter-side fixing parts of the adapter fixed to the main body-side fixing part.According to this aspect, when the first member and the second member rotate relative to each other due to the movement of the hinge, the rotation angle defined by the fixed stopper fixed to the first member and the movable stopper fixed to the main body side fixing part of the second member, abutting each other, prevents the first member and the second member from rotating relatively beyond the rotation angle. With these arrangements, it is possible to mechanically limit the range of movement of the joint.In this situation, by means of the adapter, it is possible to change the position of the movable stopper in the circumferential direction about the axis. Accordingly, it is possible to change the restriction angle of the movable range of the joint defined by the fixed stopper and the movable stopper. In other words, by attaching the adapter instead of the movable stopper to the main body side attachment part and attaching the movable stopper to any adapter side attachment part of the adapter, it is possible to change the position of the movable stopper to a position different from that of the main body side attachment part.As explained above, both the movable stopper and the adapter can be selectively attached to the common main body side fixing member. Accordingly, by attaching the adapter to the main body side attachment part, it is possible to add an attachment position of the movable stopper at a position different from that of the main body side attachment part. In the vicinity of the joint, therefore, it is sufficient to provide only one main body-side fastening part to the second element. Therefore, it is possible to change the restriction angle of the joint even when the space in the vicinity of the joint is restricted.Moreover, the machining process required to provide the adapter with the adapter-side fixing part is simpler than the machining process required to provide the robot main body with the main body-side fixing part. Accordingly, it is possible to reduce the cost of the robot main body by minimizing the number of main body-side fixing parts. In addition, it is possible to produce a plurality of adapters with different number and position of the adapter-side fastening parts in a simple and cost-effective manner. It is thus possible to realize various delimiting angles desired by the users at low cost.In the above-described aspect, another arrangement is also acceptable in which the adapter is in the form of an arc arranged along a circumferential direction about the axis, and two or more of the adapter-side fixing parts are arranged in a circumferential direction of the adapter.With this arrangement, when the single adapter is used, it is possible to change the restriction angle of the movable range of the joint to a plurality of angles.In the above-described aspect, another arrangement is also acceptable in which one of the first and second members is a base fixed to a floor, another one of the first and second members is a rotating drum disposed above the base, the hinge couples the base and the rotating drum such that the rotating drum rotates about a vertical axis with respect to the base.With this arrangement, by using the fixed stopper and the movable stopper, it is possible to limit the range of the rotation angle of the rotating drum with respect to the base.Advantageous Effect of the InventionAccording to the present invention, with respect to the robot having the stopper that restricts the movable range of the joint, an advantageous effect is obtained in that it is possible to change the restriction angle of the movable range of the joint even when the space in the vicinity of the joint is restricted.Brief Description of the DrawingsFIG. 1 is a drawing illustrating a robot main body of a robot according to an embodiment of the present invention. FIG. 2 is a perspective view of the vicinity of a first joint of the robot as illustrated in FIG. 1, and shows a fixed stopper fixed to a rotating drum, and an adapter and a movable stopper fixed to a base. FIG. 3 is a perspective view of the vicinity of the first joint of the robot as illustrated in FIG. 1, and illustrates the fixed stopper fixed to the rotating drum and the adapter and the movable stopper fixed to the base. FIG. 4 is a perspective view viewed diagonally above the base of the robot illustrated in FIG. 1. FIG. 5 is a drawing illustrating how the movable stopper is fixed to a fixing surface of the base illustrated in FIG. 4. FIG. 6( a) is a plan view and FIG. 6( b) is a front view of the movable stopper illustrated in FIGS. 2 and 3. FIG. 7 is a plan view of the adapter shown in FIGS. 2 and 3.DESCRIPTION OF THE EMBODIMENTA robot according to an embodiment of the present invention will be explained below with reference to the drawings.As illustrated in FIGS. 1 to 3, the robot according to the present embodiment includes: a 6-axis multi-joint robot main body 1 provided with six joints each having joint axes (axes) J 1, J 2, J 3, J 4, J 5, and J 6; a pair of stoppers 2 and 3 provided around a first joint and mechanically restricting the range of movement of the first joint; and an adapter 4 used for changing a restriction angle of the range of movement of the first joint.FIGS. 2 and 3 each illustrate the vicinity of the first joint of the robot main body 1 to which the adapter 4 is attached.The robot main body 1 includes: a base 5 fixed to a floor; a rotating drum 6 disposed above the base 5 and coupled to the base 5 via the first joint; a first arm 7 coupled to the rotating drum 6 via a second joint; a second arm 8 coupled to a tip end of the first arm 7 via a third joint and a fourth joint; and a tip end part 9 coupled to a tip end of the second arm 8 via a fifth joint and a sixth joint. It is possible to attach an end effector such as a hand to the tip end part 9.The first joint has a servo motor (not illustrated in the drawings) so that the servo motor rotates (rotates) the rotating drum 6 about the first axis J 1 extending in the vertical direction with respect to the base 5.The second joint includes a servo motor (not illustrated in the drawings) such that the servo motor rotates (pivots) the first arm 7 about the second axis J 2 extending horizontally with respect to the rotating drum 6.The third joint includes a servo motor (not illustrated in the drawings) such that the servo motor rotates (pivots) the second arm 8 about the third axis J 3 extending parallel to the second axis J 2 with respect to the first arm 7.The fourth joint includes a servo motor (not illustrated in the drawings) such that the servo motor rotates the second arm 8 about the fourth axis J 4 that is the longitudinal axis of the second arm 8 with respect to the first arm 7.The fifth joint includes a servo motor (not illustrated in the drawings) such that the servo motor rotates (pivots) the tip end part 9 about the fifth axis J 5 extending orthogonally to the longitudinal axis of the second arm 8 with respect to the second arm 8.The sixth joint includes a servo motor (not illustrated in the drawings) such that the servo motor rotates the tip end part 9 about the sixth axis J 6 extending orthogonally to the fifth axis J 5 with respect to the second arm 8.As illustrated in FIG. 4, on the upper surface of the base 5, there are provided: a mounting surface 10 which is planar, has a circular shape, and on which the rotating drum 6 can be mounted; and mounting surfaces 11 and 12 which are planar and are positioned on the outer side, in the radial direction, of the mounting surface 10. The first axis J 1 extends through the center of the mounting surface 10.The mounting surfaces 11 and 12 are provided on the front and back of the base 5, respectively. The front-side positioned mounting surface 11 is provided with a pair of threaded holes (a main body-side mounting part) 13 to which a movable stopper 3 and an adapter 4 can be selectively fixed. The rear side positioned mounting surface 12 is provided with a pair of threaded holes 13 to which the adapter 4 can be mounted. Moreover, also to the pair of threaded holes 13 formed in the mounting surface 12, the adapter 4 and the movable stopper 3 can be selectively fixed.Each of the fastening surfaces 11 and 12 may be provided with a hole for fastening a member other than the movable stopper 3 and the adapter 4 in addition to the threaded holes 13.As shown in FIGS. 2 and 3, one of the stoppers, i.e., the stopper 2, is a fixed stopper fixed to an outer peripheral part in a lower end part of the rotating drum (the first member) 6 and protruding downward. The fixed stopper 2 is fixed on the rear side of the rotating drum 6. FIGS. 2 and 3 each illustrate a state in which the rotating drum 6 has rotated by about 90° with respect to the base 5.The other stopper, i.e., the stopper 3, is a movable stopper that can be detachably fastened to the pair of threaded holes 13 formed in the fastening surface 11 on the front side of the base (the second member) 5 and a pair of threaded holes 4 c(as will be explained later) formed in the adapter 4.The movable stopper 3 is made of, for example, high-rigidity metal. The fixed stopper 2 is formed of an elastic material such as rubber or metallic materials such as screws. The materials of the stoppers 2 and 3 may be changed accordingly. The stoppers 2 and 3 may each be formed of a combination of two or more materials.As shown in FIGS. 6( a) and 6( b), the movable stopper 3 has a fixing part 3 awhich is flat and a protruding part 3 bwhich protrudes from the upper surface of the fixing part 3 ain a direction perpendicular to the upper surface. The fixing member 3a is provided with a pair of through holes 3c which pass through the fixing member 3a and correspond to the pair of threaded holes 13. As illustrated in FIG. 5, it is possible to directly fix the movable stopper 3 to the fixing surface 11 by positioning the movable stopper 3 on the fixing surface 11 such that the lower surface of the fixing part 3 ais in contact with the fixing surface 11, inserting screws 14 into the pair of threaded holes 13 through the through holes 3 c, and screwing the screws 14 into the threaded holes 13.The movable stopper 3 fixed to the fixing surface 11 restricts the range of movement (rotation angle range) of the first joint within a predetermined angle range (e.g., ±17°). For example, as a result of the fixed stopper 2 abutting in a circumferential direction against the protruding part 3 bof the movable stopper 3, when the rotating drum 6 has rotated + 170° or -170° with respect to the base 5, the rotation of the rotating drum 6 is mechanically restricted beyond this range.As shown in FIG. 7, the adapter 4 includes a pair of members 4 aand 4 b, each of which is flat and has the shape of a semicircular arc. In each of the members 4 aand 4 b, a plurality of threaded holes 4 care formed, which are arranged at intervals in an array in the circumferential direction. The threaded holes 4 care provided in a plurality of positions including the both end portions of each of the members 4 aand 4 band positions between the both end portions.The distance between the pair of threaded holes 4 carranged side by side in the circumferential direction is equal to the distance between the pair of threaded holes 13 formed in the mounting surface 11. Further, it is possible to fix a same screw 14 in the threaded hole 13 and threaded hole 4c. Accordingly, it is possible to fix the movable stopper 3 to the fixing surface 11 in the same manner as the movable stopper 3 by inserting the screws 14 into each of the two threaded holes 4 c(the adapter-side fixing member) that are juxtaposed via the through holes 3 cformed in the movable stopper 3 and fixing the screws 14 into the threaded holes 4 c.As illustrated in FIGS. 2 and 3, one of the members, i.e., the member 4 ais disposed around the mounting surface 10 such that both end parts thereof are positioned on the mounting surfaces 11 and 12 and are fixed on the mounting surfaces 11 and 12 by fastening the bolts 14 in the threaded holes 4 cformed in the both end parts and in the threaded holes 13 formed in the mounting surfaces 11 and 12. Likewise, the other member, i.e., the member 4b, is fixed to the fixing surfaces 11 and 12 with the screws 14. Thereby, the members 4 aand 4 bare arranged around the mounting surface 10 along the circumferential direction around the first axis J 1, so that the adapter 4 having a ring shape is fixed around the mounting surface 10 substantially along the entire circumference thereof. In this state, the threaded holes 4 care arranged in an array along the entire circumference around the mounting surface 10.It is possible to appropriately change the length of each of the members 4a and 4b in the circumferential direction. For example, each of the members 4 aand 4 bmay have the shape of an arc shorter than a semicircular arc, so that it is possible to mount the adapter 4 in certain areas around the mounting surface 10.Next, an operation of the robot structured as described above will be explained.The moving range of each of the joints of the robot main body 1 is limited by a robot control unit (not illustrated in the drawings) using a control program that controls the robot main body 1. In a standard state of the robot, the control program with the range of movement of the first joint is set to be either the predetermined angle range or a range smaller than the predetermined angle range while the movable stopper 3 is fixed to the pair of threaded holes 13 formed in the front-side fixing surface 11 which is a standard position as illustrated in FIG. 5.In the above-described standard state, when the rotating drum 6 has rotated to the restriction angle, the fixed stopper 2 abuts on the movable stopper 3, so that the rotating drum 6 is prevented from rotating outside this range by the movable stopper 3. Therefore, even if the limitation of the movable range of the first joint by the robot controller does not function properly for some reason, it is possible to prevent the rotation of the rotating drum 6 beyond the limitation angle by mechanically limiting the movable range of the first joint by the stoppers 2 and 3.When the user desires to change the restriction angle of the movable range of the first joint from ±17° to another angle, the user can change the attachment position of the movable stopper 3 to the adapter 4 along the circumferential direction about the first axis J 1.First, the movable stopper 3 is removed from the mounting surface 11 by taking out the screws 14 from the two threaded holes 13. Further, as illustrated in FIGS. 2 and 3, the adapter 4 is fixed to the two threaded holes 13 formed in the fixing surface 11 and to the two threaded holes 13 formed in the fixing surface 12 by using the bolts 14.Subsequently, a pair of threaded holes 4 care selected from the plurality of threaded holes 4 cformed in the adapter 4 to fix the movable stopper 3 to the selected pair of threaded holes 4 cwith the bolts 14. Thereby, it is possible to change the restriction angle of the movable range of the first joint to a desired angle by the movable stopper 3. The number of movable stoppers 3 fixed to the adapter 4 may be only one; however, it is also permissible to attach two movable stoppers 3 to two locations of the adapter 4 if necessary. As shown in FIG. 2, when the movable stopper 3 is fastened to a pair of threaded holes 4 cformed in the fastening surface 11 or 12, the movable stopper 3 and the adapter 4 are connected to each other by the bolts 14.If a mounting surface were provided extending over the entire circumference around the mounting surface 10 and a large number of tapped holes were formed in the mounting surface, then the cost for the robot main body 1 would increase because it would be necessary to cut as many threads as there are tapped holes. Further, if the base 5 is of a slender and simple design, then there could be no space around the mounting surface 10 and it would be impossible in some situations to leave free an area which serves as a mounting surface around the mounting surface 10. Or if a mounting surface surrounded the mounting surface 10 over the entire circumference, then the design around the first joint would be limited, and it would be difficult to implement a design required of the base 5 in some situations.In contrast, according to the present embodiment, it is possible to fix the movable stopper 3 and the adapter 4 to the pair of common tapped holes 13 in the fixing surface 11. Further, by fixing the adapter 4 to the pair of threaded holes 13 formed in the fixing surface 11 and to the pair of threaded holes 13 formed in the fixing surface 12, the threaded holes 4c used for fixing the movable stopper 3 are added to the positions different from the standard positions. Accordingly, it is sufficient to provide only the two pairs of tapped holes 13 to the robot main body 1. In addition, the small areas provided only on the front and back sides of the mounting surface 10 are sufficient to serve as fastening surfaces 11 and 12 in which the two pairs of threaded holes 13 are formed.In other words, even if the base 5 has a slender and simple design, it is possible to provide the mounting surfaces 11 and 12 in the limited space around the mounting surface 10 without impairing the design of the base 5. In addition, it is possible to prevent the fastening surfaces 11 and 12 from restricting the design of the base 5. As explained herein, an advantageous effect is obtained when it is possible to achieve, at the same time, both a high degree of freedom for design in the vicinity of the first joint of the robot main body 1 and the possibility of providing the plurality of attachment positions for the movable stopper 3.Moreover, the machining process required for forming the threaded holes 4 cin the adapter 4 is simpler than the machining process required for forming the threaded holes 13 in the robot main body 1. Accordingly, another advantageous effect is obtained when it is possible to reduce the cost of the robot main body 1 by minimizing the number of the tapped holes 13 formed in the robot main body 1.Further, it is possible to easily change the number and positions of the threaded holes 4c formed in the adapter 4. It is therefore possible to inexpensively produce a plurality of adapters 4 having different numbers and positions of the threaded holes 4c. In other words, it is possible to manufacture the adapter 4 such that a mounting position of the movable stopper 3 is added at an arbitrary position according to the user's requirements. Accordingly, by manufacturing a custom adapter 4 according to each user's requirements while simultaneously using the same robot main body 1, an advantageous effect is obtained for all users because it is possible to realize various restriction angles desired by different users easily and inexpensively.Comparing the situation where the movable stopper 3 is directly fixed to the fixing surface 11 with the situation where the movable stopper 3 is fixed to the adapter 4, the height of the movable stopper 3 differs as much as the thickness of the adapter 4.In order to compensate for the difference in height of the movable stopper 3, it is also acceptable to arrange a spacer having the same thickness as that of the adapter 4 between the movable stopper 3 and the mounting surface 11 when the movable stopper 3 is mounted on the mounting surface 11. Alternatively, it is also acceptable to prepare two kinds of movable stoppers 3 having different heights to selectively use one kind of movable stopper 3 when the movable stopper 3 is directly fixed to the fixing surface 11 and when the movable stopper 3 is fixed to the adapter 4.In the present embodiment, the example in which the adapter 4 surrounds the mounting surface 10 substantially along the entire circumference thereof, while the threaded holes 4 care provided around the mounting surface 10 along the entire circumference thereof will be explained. Alternatively, another arrangement is also allowed in which the adapter 4 is provided only in a portion of the area around the mounting surface 10, while the threaded holes 4 care provided only in a portion of the area around the mounting surface 10.For example, the adapter 4 may be structured with only one of the elements (either 4a or 4b) having the shape of a semi-circular arc. In another example, the elements 4 aand 4 bmay each have a shape different from an arc.In the present embodiment, the example in which the mounting surfaces 11 and 12 are provided on both the front side and the back side of the base 5 will be explained; however, the positions and the number of the mounting surfaces may be changed according to the shape of the adapter 4 or the like.For example, the mounting surfaces 11 and 12 may be provided at positions other than the front and back of the base 5. Alternatively, the adapter 4 may be fixed only to the pair of threaded holes 13 disposed in the fixing surface 11 on the front side, while the fixing surface 12 on the rear side is not provided.In the present embodiment, the example in which the fixed stopper 2 is fixed to the rotating drum 6, while the movable stopper 3 and the adapter 4 are detachably fixed to the base 5, respectively, will be explained. Alternatively, another arrangement is also allowed in which the fixed stopper 2 is fixed to the base (the first member) 5, while the movable stopper 3 and the adapter 4 are detachably fixed to the rotating drum (the second member) 6, respectively.In the present embodiment, the example in which the movable stopper 3 is fixed at the two points to the fixing surface 11 and the adapter 4 by using the bolts 14 will be explained. Alternatively, it is also acceptable to fix the movable stopper 3 at only one point or at three or more points.In the present embodiment, the example in which the stoppers 2 and 3 are provided around the first joint to restrict the range of movement of the first joint will be explained. However, the stoppers 2 and 3 may be provided around any other joint to limit the movable range of the other joint instead of or in addition to the first joint.In the present embodiment, the example in which the robot main body 1 is a 6-axis multi-joint industrial robot will be explained; however, the robot main body 1 may be any robot type having a joint, such as a scalar robot or a parallel robot.List of reference characters1 Robot main body 2 Fixed stopper 3 Movable stopper 3 a Befestigungs part 3 b Vorstehend part 3 cThrough hole 4 Adapter 4 a, 4 bElement 4 c Gewindeloch hole (adapter-side fixing part) 5 Base (second element) 6 Rotating drum (first element) 7 First arm (element) 8 Second arm (element) 9 Tip end part (element) 10 Mounting surface 11, 12 Mounting surface 13 Threaded hole (main body-side fixing part) 14 Screw J 1, J 2, J 3, J 4, J 5, J 6 Joint axis (axis)

Claims

A robot comprising: a robot main body (1) comprising a first member (6), a second member (5) and a joint provided between the first member (6) and the second member (5), the joint connecting the first member (6) and the second member (5) to each other so as to be relatively rotatable about a prescribed axis (J1); a fixed stopper (2) fixed to the first member (6); an adapter (4) detachably attachable to the second member (5); and a movable stopper (3) attachable to the adapter (4) and directly attachable to the second member (5), wherein the second member (5) has a main body-side attachment part (13) to which either the adapter (4) or the movable stopper (3) is selectively attached, the adapter (4) has an adapter-side fixing part (4c) or a plurality of adapter-side fixing parts (4c) to which the movable stopper (3) is fixable, wherein the one adapter-side fixing part (4c) or the plurality of adapter-side fixing parts (4c) is or are arranged in a position other than the main body-side fixing part (13) in the circumferential direction about the axis (J1) while the adapter (4) is in a state of being fixed to the main body-side fixing part (13), and a relative rotational angle range of the first member (6) and the second member (5) is limited as a result of the fixed stopper (2) and the movable stopper (3) abutting each other about the axis (J1), wherein the movable stopper (3) is fixed to the main body side fixing part (13) or the adapter side fixing part (4c) or the plurality of adapter side fixing parts (4c) of the adapter (4) fixed to the main body side fixing part (13).The robot according to claim 1, wherein the adapter (4) is in the form of an arc arranged along a circumferential direction around the axis (J1), and the plurality of adapter-side fixing parts (4c) are arranged in the circumferential direction of the adapter (4).The robot according to claim 1 or 2, wherein one of the first and second members (5, 6) is a base fixed to a floor, another one of the first and second members (5, 6) is a rotating drum disposed above the base, and the joint couples the base and the rotating drum such that the rotating drum rotates about a vertical axis (J1) with respect to the base.

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