JP4133843B2 - Industrial robot - Google Patents

Description

  The present invention relates to an articulated industrial robot capable of turning at a plurality of joints.

  In the present invention, the term “swivel” includes a rotation that is an angular displacement of 360 degrees or more and an angular displacement of less than 360 degrees, and the term “tilt” is an angle between two axes that is greater than 0 degree and less than 90 degrees. Means a state in range.

  FIG. 7 is a front view showing the industrial robot 9 of the first conventional technique. FIG. 8 is a skeleton diagram schematically showing the industrial robot 9. The industrial robot 9 is a robot used as a painting robot called a three-roll wrist robot, and has first to sixth joint portions 1 to 6 that can freely turn around first to sixth axes L1 to L6. The fourth to sixth joint parts 4 to 6 constituting the wrist joint are arranged close to each other. The first axis L1 is vertical, the second axis L2 is perpendicular to the first axis L1, the third axis L3 is parallel to the second axis L2, and the fourth axis L4 is the third axis L3. The fifth axis L5 is inclined with respect to the fourth axis L4, and the sixth axis L6 is inclined with respect to the fifth axis L5.

  Such an industrial robot 9 has an advantage that the wrist joint is a three-roll wrist joint, the wrist joint has a hollow structure into which a cable such as an air hose can be inserted, and the outer diameter can be reduced to a small size. There is. Furthermore, the industrial robot 9 can obtain a large movable range S9 of the free end portion 8 of the arm because the first to third axes L1 to L3 are in the relationship as described above. FIG. 7 shows the movable range in the case of not turning around the first axis L1, and actually the free end portion 8 of the arm is obtained by turning this movable range S9 around the first axis L1. It is possible to move within a range corresponding to the rotating body. Taking advantage of such advantages, the industrial robot 9 is suitably used as a painting robot (see, for example, Patent Document 1).

  FIG. 9 is a skeleton diagram schematically showing an industrial robot 9A of the second conventional technology. Parts corresponding to those of the first conventional technique are denoted by the same reference numerals. The industrial robot 9A is different from the industrial robot 9 in the configuration of the fourth to sixth joint portions 4 to 6, the fifth axis L5 is perpendicular to the fourth and sixth axes L4 and L6, and the fourth The sixth axes L4 to L6 intersect at one point.

  FIG. 10 is a skeleton diagram schematically showing an industrial robot 9B according to the third prior art. Parts corresponding to those of the first conventional technique are denoted by the same reference numerals. The industrial robot 9B is different from the industrial robot 9 in the configuration of the first to third joint portions 1 to 3, the second axis L2 is perpendicular to the first and third L1, L3, and the first to first The three axes L1 to L3 intersect at one point.

JP-A-11-277472

  The industrial robot 9 of the first prior art can secure the effect by the above-described three-roll wrist joint and can obtain a large movable range of the free end portion 8 of the arm, but the analytical inverse transformation is executed. It has a problem that it cannot be done. Therefore, the angular position of each joint part 1-6 is analytically determined from the position of the free end part 8 of the arm by using an expression expressing the position of the free end part 8 of the arm by the angular position of each joint part 1-6. I can't. In a vertical articulated robot having a three-roll wrist joint, it is a well-known fact that the inverse transformation solution cannot be obtained analytically because the three adjacent axes do not intersect at one point. The vertical articulated robot is generally a robot having joints having an axis configuration such as first to third axes L1 to L3 in FIG.

  Therefore, the industrial robot 9 must use a control device having a convergence calculation function, which increases the cost of the control device and does not allow high-speed and high-precision positioning. Furthermore, since it becomes difficult to grasp singular points, it takes time to develop and it becomes difficult to handle in practical use. When a tool such as an injector is arranged parallel to the sixth axis and the fourth and sixth axes are swung in the opposite direction of the same angle, the analytical reverse is specially performed. Although it is possible to perform the conversion, the industrial robot 9 cannot be fully utilized in such a limited operation.

  In the configuration in which the three adjacent swiveling axes, specifically, the fourth to sixth axes L4 to L6 intersect at one point as in the industrial robot 9A of the second conventional technology, the analytical inverse transformation In the industrial robot 9A, it is possible to achieve the effect by enabling the analytical reverse conversion. Therefore, it is possible to reduce the cost of the control device, perform high-speed and high-accuracy positioning, and also make it easier to grasp the singularity, so that the time required for development is shortened and a robot that is easy to handle in practical use. Can be realized. The industrial robot 9A has such advantages, but the effect of the three-roll wrist joint cannot be obtained.

  Therefore, it is conceivable that the three-roll wrist joint is left and the first to third axes L1 to L3 intersect at one point as in the industrial robot 9B of the third prior art. With such a configuration, the effect of the three-roll wrist joint can be achieved, and the effect of enabling analytical reverse conversion can be achieved, but the movable range S9B becomes extremely small. Although only a part of the movable range S9B is shown in FIG. 10, the movable range S9B is a substantially ellipsoidal surface-like region, which is a region like a thin shell. The thickness dimension T9 of the movable range S9B depends on the distance D9 between the fourth and sixth joint portions 4 and 6, and if this distance D9 is increased, the thickness dimension T9 is increased and the movable range is increased. However, if the effect of the three-roll wrist joint is to be achieved, the distance D9 must be reduced, so that a large movable range cannot be obtained.

  Therefore, the object of the present invention is to perform the inverse analysis of the wrist regardless of the structure of the wrist joint to obtain the angular position of each joint from the position of the free end of the arm. An industrial robot capable of obtaining a large movable range is provided.

The present invention comprises a base,
An arm including first to sixth arm bodies arranged in series in order from the base;
The first arm body is used as a base, and the first joint portion that is pivotably connected around the first axis that does not pass through the intersection of the second axis to the fourth axis , and the second to sixth arm bodies are adjacent to the base side. The arm body includes second to sixth joint portions that are pivotally connected around second to sixth axes, the third and fourth axes are perpendicular to each other, and the second axis is relative to the third axis The industrial robot is characterized by including a plurality of joint portions that intersect at an angle and intersect at a second point.

According to the present invention, the second to fourth axes, which are adjacent three swivel axes, intersect at one point, and the first to sixth joint parts from the position of the free end part of the arm by analytical inverse transformation. It is possible to determine the relative angular position of two members connected at each joint part. In order to enable such analytical inversion, the mutual arrangement of the three pivot axes, specifically the second to fourth axes, arranged so as to intersect at one point constitutes the wrist joint. It does not affect the mutual arrangement of the fourth to sixth axes, which are the pivot axes of the fourth to sixth joint portions. Therefore, it is possible to enable analytical inverse transformation irrespective of the structure of the wrist joint constituted by the fourth to sixth joint portions. Furthermore, the second to fourth axes are not simply configured to intersect at a single point, but the first axis does not pass through the intersection of the second to fourth axes, and the third and fourth axes are perpendicular to each other. configured such that the second axis intersect inclined against the third. As a result, the movable range of the free end of the arm can be increased.

The present invention includes a fifth axis intersects inclined relative fourth axis, axis 6 is characterized that you cross inclined relative to the fifth axis.

According to the present invention, the fifth axis intersects inclined relative fourth axis, the sixth axis, you cross inclined relative to the fifth axis. By setting it as such a structure, a wrist joint can be made into a three roll wrist joint.

According to the present invention, since the second to fourth axes are configured to intersect at one point, the analytical inverse transformation is performed regardless of the wrist joint structure, and each position is determined from the position of the free end of the arm. The angular position of the joint can be obtained. Therefore, the cost of the control device can be reduced, high-speed and high-accuracy positioning can be performed, the singularity can be easily grasped, the time required for development can be shortened, and a robot that is easy to handle in practice can be realized. be able to. Furthermore, the first axis without passing through the intersection of the second axis to fourth shaft, third and fourth axes are perpendicular to each other, since the second shaft is configured to intersect inclined against the third Regardless of the wrist joint structure, the movable range of the free end of the arm can be increased.

  Further, according to the present invention, the wrist joint is a three-roll wrist joint, and after achieving the effect of the three-roll wrist joint, the above-described excellent effects can be achieved together.

  FIG. 1 is a sectional view showing an industrial robot 30 according to an embodiment of the present invention in a state where a partial internal structure appears. FIG. 2 is a front view showing the wrist joint 29 of the industrial robot 30. FIG. 3 is a skeleton diagram schematically showing the industrial robot 30. The industrial robot 30 includes a base 37, a plurality of first to sixth arm bodies 31 to 36 in the present embodiment, a plurality of first to sixth joint portions 41 to 46 in the present embodiment, and an end. An articulated robot having an effector 40.

  The industrial robot 30 is a robot in which the wrist joint 29 is a three-roll wrist joint, and can be suitably used as, for example, a painting robot. It can be applied to various uses such as a robot that performs the above processing. In the present embodiment, the industrial robot 30 is a painting robot. The wrist joint 29 includes an end portion 33a of the third arm body 33 near the fourth arm body 34, fourth to sixth arm bodies 34 to 36, and fourth to sixth joint portions 44 to 46.

  The base 37 is fixed to an installation object 38 such as a factory floor. The arm bodies 31 to 36 are provided side by side in series from the first arm body 31 to the sixth arm body 36, and an arm 39 is configured by the arm bodies 31 to 36. The arm 39 is connected to the base 37 at one end of the first arm body 31 that is the base end of the arm 39.

  Each joint part 41-46 connects each arm body 31-36 so that turning is possible around the 1st-6th axis | shafts L41-L46. Each joint part 41-46 is comprised using a bearing etc., for example. The first to sixth axes L41 to L46 are turning axes.

  One end portion of the first arm body 31 is connected to the base 37 by the first joint portion 41 so as to be rotatable around the first axis L41. The first axis L41 is perpendicular to the surface of the installation object 38 such as a floor surface, and is a vertical axis in the present embodiment. The first arm body 31 extends from the first joint portion 41 in a direction inclined with respect to the first axis L1.

  One end portion of the second arm body 32 is connected to the other end portion of the first arm body 31 by the second joint portion 42 so as to be rotatable around the second axis L42. The second axis L42 is an axis that is inclined with respect to the first axis L41. The inclination angle (hereinafter referred to as “second axis angle”) θ42 of the second axis L42 with respect to the first axis L41 is, for example, an angle in the range of greater than 0 degrees and equal to or less than 45 degrees, and in the present embodiment, 22.5 degrees. It is. The second arm body 32 extends from the second joint portion 42 in a direction inclined at the same angle as the second axis angle θ42 with respect to the second axis L42.

  One end portion of the third arm body 33 is connected to the other end portion of the second arm body 32 by the third joint portion 43 so as to be rotatable around the third axis L43. The third axis L43 is an axis inclined with respect to the second axis L42. An inclination angle (hereinafter referred to as “third axis angle”) θ43 of the third axis L43 with respect to the second axis L42 is an angle obtained by subtracting the second axis angle θ42 from 90 degrees, for example, and in this embodiment, 67.5 Degree. The third arm body 33 extends from the third joint portion 43 in a direction perpendicular to the third axis L43.

  One end portion of the fourth arm body 34 is connected to the other end portion of the third arm body 33 by the fourth joint portion 44 so as to be rotatable around the fourth axis L44. The fourth axis L44 is an axis perpendicular to the third axis L43. Therefore, the angle (hereinafter referred to as “fourth axis angle”) θ44 formed by the fourth axis L44 with respect to the third axis L43 is, for example, 90 degrees in the present embodiment. The fourth arm body 34 extends from the fourth joint portion 44 in a direction inclined with respect to the fourth axis L44.

  One end portion of the fifth arm body 35 is connected to the other end portion of the fourth arm body 34 by the fifth joint portion 45 so as to be rotatable around the fifth axis L45. The fifth axis L45 is an axis that is inclined with respect to the fourth axis L44. In the present embodiment, the inclination angle of the fifth axis L45 with respect to the fourth axis L44 is, for example, 60 degrees.

  One end portion of the sixth arm body 36 is connected to the other end portion of the fifth arm body 35 by the sixth joint portion 46 so as to be rotatable around the sixth axis L46. The sixth axis L46 is an axis that is inclined with respect to the fifth axis L45. The inclination angle of the sixth axis L46 with respect to the fifth axis L45 is the same as the inclination angle of the fifth axis L45 with respect to the fourth axis L44.

  In the industrial robot 30, the wrist joint 29 is configured by the fourth to sixth joint portions 44 to 46. In the wrist joint 29, the fourth to sixth joint portions 44 to 46 are arranged close to each other, and the fourth to sixth axes are inclined to each other as described above, thereby forming a three-roll wrist joint. This three-roll wrist joint can realize a wrist joint having a hollow cylindrical shape and a small outer diameter.

  The industrial robot 30 has a configuration in which the second to fourth axes L42 to L44 intersect at a single point P. Further, the second to fourth axes L42 to L44 are set to the second to fourth axis angles θ42 to θ44 as described above, specifically, the third and fourth axes L43 and L44 are set to be vertical, and the second axis L42 is set to be vertical. The second and fourth arm bodies 32 are configured so that the second to fourth axes L42 to L44 intersect at a single point P by being inclined with respect to the third and fourth axes L43 and L44. 33, in other words, the distance D32 between the second joint portion 42 and the third joint portion 43 and the distance D33 between the third joint portion 43 and the fourth joint portion 44 can be increased.

  The end effector 40 is fixed to the other end portion of the sixth arm body 36 serving as the free end portion of the arm 39. The end effector 40 is a device corresponding to the application of the industrial robot 30 and may be, for example, a welding torch and a handling device. In the present embodiment, the industrial robot 30 is a painting robot, and the end effector 40 is an injector that injects a painting fluid onto a workpiece.

  The industrial robot 30 has a driving means for relatively turning the arm bodies 31 to 36 at the joint portions 41 to 46. The drive means has one or a plurality of drive sources 48, in the present embodiment, a plurality of electric motors. One drive source 48 may be provided for each joint portion 41 to 46, or one drive source may be shared for a plurality of joint portions. In the present embodiment, a drive source 48 is provided for each joint portion 41 to 46. In FIG. 1, only the drive source 48 for the turning drive in the 1st-3rd joint parts 41-43 is shown. Other motors are omitted for ease of illustration, but are similarly built in the arm 39.

  The base 37 and each arm body 31-36 are formed in the shape of a hollow cylinder, and a drive means is incorporated in at least any one of the base and each arm body 31-36. Further, one or a plurality of cables are provided so as to be inserted through the arm bodies 31 to 36. The cable is a cable for transmitting power and command signals necessary for operating an industrial robot. For example, a cable for supplying electric power to an electric motor that is a servo motor, a cable for receiving a sensor signal, and an end effector A cable for supplying electric power and a command signal to the cable, and a cable for guiding a fluid used in the end effector.

  The turning mechanism for turning each of the arm bodies 31 to 36 by the driving means may be the same as the mechanism of the robot having the tilt joint portion of the prior art as shown in FIG. As a specific example, a hollow wave gear mechanism such as a harmonic drive (registered trademark) may be used. The wave gear mechanism includes an input side member and an output side member, and they rotate relatively. The input side member is connected to one of two members (base and arm body) connected by the joint portions 41 to 46, and the output side member is connected to the other of the two members. When rotation from the drive source is given to the input side member, the input side member and the output side member rotate relatively, and the two members rotate relatively. Accordingly, the arm bodies 31 to 36 are turned.

  Since the driving means and the mechanism for driving can have various configurations, the configuration is not limited to the configuration of the specific example described above.

  The industrial robot 30 includes a drive unit having such a base 37, an arm 39, joints 41 to 46, and a drive source 48, and a robot main body 49 is configured, and a control device 50 that controls the robot main body 49. Further included. The control device 50 includes an input unit 51 and a central processing unit 52. The input unit 51 is realized by a keyboard or the like, and instruction information for instructing one of the position and posture of the free end of the arm 39 is input by an operation of the operator, and the input instruction information is input to the central processing unit 52. To give. The central processing unit 52 is realized by, for example, a CPU and a memory, and the operation of the main body 49 necessary for moving the free end portion of the arm 39 based on the input instruction information, specifically, the instruction information. The angle position in each joint part 41 to 46 in the case of the position and posture to be expressed and the turning angle for turning to this angle position are calculated and obtained, and information indicating the calculation result is used as an operation command for the articulated robot 1. Give to drive means.

  Here, the angular position of each joint portion 41 to 46 is the angle from the reference position of the member on the sixth arm body 36 side with respect to the member on the base 37 side among the two members connected by each joint portion 41 to 46. The displacement angle. For example, as shown in FIG. 1, the reference position is a position in a state where the free end portion of the arm 39 is located farthest from the installation target 38.

  The control operation in the central processing unit 52 is started when instruction information is input by operating the input unit 51. Next, the angular positions of the joint portions 41 to 46 in a state where the free end portion of the arm 39 is displaced to the position indicated by the instruction information are calculated, and the turning angle necessary for turning to the angular position is calculated. At this time, since the second to fourth axes L42 to L44 intersect at one point P, the angular positions of the joint portions 41 to 46 can be calculated by analytical inverse transformation. When such calculation is completed, based on the calculation result, the driving means is given to the driving means to control the driving means so as to turn the joints 41 to 46 by a necessary turning angle. finish. The robot body 49 operates according to the operation command and moves the free end portion of the arm 39.

  4 is a cross-sectional view showing the industrial robot 30 with the free end portion of the arm 39 moved from the state shown in FIG. 5 is a cross-sectional view showing the industrial robot 30 in another state different from FIG. 4 in which the free end portion of the arm 39 is moved from the state of FIG. FIG. 6 is a graph showing the movable range S30 of the industrial robot 30. As shown in FIG. The vertical axis in FIG. 6 is the expansion / contraction direction of the arm 39 parallel to the first axis L41, and the horizontal axis is one direction perpendicular to the first axis L41 and coincides with the surface of the installation object 38. In FIG. 6, the outline of the movable range S30 is indicated by a broken line. FIG. 6 shows a cross section in a plane including the first axis L41, and the actual movable range S30 has a surface having a shape as shown in FIG. 6 and a first axis L41 that coincides with the vertical axis of FIG. It is the same range as the rotating body rotated around.

  Thus, as shown in FIG. 4, the industrial robot 30 can move the free end portion of the arm 39 to the vicinity of the installation object 38 by turning around the third axis L43. Further, as shown in FIG. 5, the industrial robot 30 is turned around the second axis L42 to move the free end of the arm 39 away from the first axis L41 in a direction perpendicular to the first axis L1. Can be moved to. Such an industrial robot 30 can obtain a movable range as shown in FIG. 6 by combining the turning motions around the respective turning axes L41 to L46.

  When comparing the movable range S30 of the industrial robot 30 of the present embodiment with the movable range S9 of the industrial robot 9 shown in FIG. 7, at first glance, the movable range S30 of the industrial robot 30 of the present embodiment is 7 can be seen to be smaller than the movable range S9 of the industrial robot 9 of FIG. 7, but the industrial robot 30 of the present embodiment has substantially the same movable range as the industrial robot 9 of FIG. The same large movable range S30 can be obtained. That is, in the industrial robot 9 of FIG. 7, the region S9a that interferes with the installation target in the movable range S9 cannot be used, and the region S9b that overlaps when swung around the first axis L1 has a movable range. Does not contribute to enlargement. Therefore, as a usable movable range, the industrial robot 30 of the present embodiment can obtain a large movable range S30 comparable to the industrial robot 9 having a large movable range shown in FIG.

  According to the industrial robot 30 of the present embodiment, the second to fourth axes L42 to L44, which are adjacent three turning axes, intersect at one point P, and the free play of the arm 39 is performed by analytical inverse transformation. It is possible to obtain the angular position of each joint part 41 to 46 from the position of the end part, specifically, the relative angular position of two members connected by each joint part 41 to 46. Therefore, control is facilitated, the cost of the control device 50 is reduced, high-speed and high-accuracy positioning can be performed, the singularity can be easily grasped, development time is shortened, and practical use An easy-to-handle robot can be realized.

  In order to enable such analytical inversion, the mutual arrangement of the three pivot axes, specifically the second to fourth axes L42 to L44 arranged so as to intersect at a single point is determined by the wrist joint. The fourth to sixth shafts L44 to L46, which are the pivot axes of the fourth to sixth joint portions 44 to 46 constituting the 29, are not affected. Therefore, it is possible to enable analytical reverse conversion regardless of the structure of the wrist joint 29 constituted by the fourth to sixth joint portions 44 to 46. Therefore, the wrist joint 29 is a three-roll wrist joint, and a small cable can be inserted, and the advantage of the three-roll wrist joint can be utilized to be suitably used as a painting robot.

  Furthermore, the second to fourth axes L42 to L44 are not simply configured to intersect at one point P, but the third and fourth axes L43 and L44 are perpendicular to each other, and the second axis L42 is the first and first axes. 3 and the fourth axes L43 and L44. Accordingly, the axial length of the second and third arm bodies 32 and 33 can be increased, and the movable range S30 of the free end portion of the arm 39 can be increased. As described above, it is possible to obtain a large movable range S30 comparable to a robot capable of obtaining a large movable range of the conventional technology.

  The second to fourth axis angles θ42 to θ44 are preferably set to the angles as described above. The movable range S30 can be further increased by setting the second to fourth shaft angles θ42 to θ44 as described above.

  Further, the fifth axis is inclined with respect to the fourth axis, the sixth axis is inclined with respect to the fifth axis, and the fourth to sixth joint portions are arranged close to each other. By setting it as such a structure, a wrist joint can be made into a three roll wrist joint.

  The above-described embodiment is merely an example of the present invention, and the configuration can be changed within the scope of the present invention. For example, an industrial robot may be used as a jig robot that holds a workpiece or a transfer robot that transfers a workpiece instead of a painting robot, or performs other processing on the workpiece such as welding the workpiece. It may be used as a robot for this purpose.

It is sectional drawing which shows the industrial robot 30 of one Embodiment of this invention in the state in which an internal structure appears partially. 3 is a front view showing a wrist joint 29 of the industrial robot 30. FIG. 2 is a skeleton diagram schematically showing an industrial robot 30. FIG. FIG. 3 is a cross-sectional view showing the industrial robot 30 in a state where a free end portion of an arm 39 is moved from the state of FIG. 1. FIG. 6 is a cross-sectional view showing another state different from FIG. 4 in which the industrial robot 30 is moved from the state shown in FIG. 5 is a graph showing a movable range S30 of the industrial robot 30. It is a front view which shows the industrial robot 9 of the 1st prior art. FIG. 3 is a skeleton diagram schematically showing the industrial robot 9. It is a skeleton figure showing typically industrial robot 9A of the 2nd conventional technology. It is a skeleton figure which shows typically industrial robot 9B of the 3rd conventional technology.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 Industrial robot 31 1st arm body 32 2nd arm body 33 3rd arm body 34 4th arm body 35 5th arm body 36 6th arm body 41 1st joint part 42 2nd joint part 43 3rd joint part 44 4th joint part 45 5th joint part 46 6th joint part 48 Drive source 50 Control device 52 Central processing unit L41 1st axis L42 2nd axis L43 3rd axis L44 4th axis L45 5th axis L46 6th axis S30 Range of movement

Claims (2)

The base,
An arm including first to sixth arm bodies arranged in series in order from the base;
The first arm body is used as a base, and the first joint portion that is pivotably connected around the first axis that does not pass through the intersection of the second axis to the fourth axis , and the second to sixth arm bodies are adjacent to the base side. The arm body includes second to sixth joint portions that are pivotally connected around second to sixth axes, the third and fourth axes are perpendicular to each other, and the second axis is relative to the third axis inclined to intersect, the second to fourth axes, industrial robot, which comprises a plurality of joints that cross at a single point. Fifth shaft intersects inclined relative fourth axis, the sixth axis, industrial robot according to claim 1, wherein that you cross inclined relative to the fifth axis.

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