JP2716062B2 - Origin return method for moving members - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arm mechanism of an industrial robot, and more particularly to a first member rotatably supported around a predetermined axis. There is a second member rotatably supported about a predetermined axis of the second member. The rotation of the first member is not affected by the rotation of the second member, but the second member is When the rotation of the first member is affected by the rotation of the first member, the first and second members return to their respective origins, and the second member returns to the original member in a short time. The present invention relates to a method of restoring the system so as not to deviate from a predetermined operation area under the influence of an operation. 2. Description of the Related Art A conventional example is the same in appearance as an embodiment to be described later, and the configuration and the main points of operation will be described with reference to FIGS. 1 and 3 showing the embodiment. FIG. 1 is a perspective view of an industrial articulated robot, in which a swivel cylinder 7 at the tip of an arm mechanism is provided with an axis 6a of a support base 6.
Are supported so as to be rotatable as indicated by an arrow U. Further, a rotation shaft 8 is supported so as to be rotatable as indicated by an arrow V around the axis 7a of the rotation cylinder 7. A gripper (not shown) is provided at the tip of the rotating shaft 8 to grip an article. In this case, the turning motion of the turning cylinder 8 is not affected by the turning of the turning shaft 8, but, conversely, the turning motion of the turning shaft 8 around the axis 7 a is caused by the turning motion of the turning tube 7. Is affected. This state will be described with reference to FIG. FIG. 3 is a cross-sectional view of the revolving cylinder 7, the rotating shaft 8, and parts related thereto. According to this figure, first, when the turning cylinder 7 is turned, the turning shaft 8 is turned under the influence thereof, and then, when the turning shaft 8 is turned, the turning tube 7 is turned. The fact that they are not affected will be explained. When the drive shaft 71 rotates, the bevel gear shaft 72 rotates about the XX axis (corresponding to the axis 6a in FIG. 1) via the bevel gears 71a and 72a, and is thus connected thereto. The turning cylinder 7 is simultaneously turned around the XX axis. Moreover, the rotating shaft 8
Is fixed to the bevel gear 82b, the bevel gear 82b meshes with the bevel gear 82b.
At the same time, the rotating shaft 8 is also rotated around its YY axis (corresponding to the axis 7a in FIG. 1). That is, the rotating shaft 8 is affected by the turning motion of the turning cylinder 7. On the other hand, when the drive shaft 81 rotates, the bevel gears 81a and 82a
, The bevel gear shaft 82 is rotated, and the bevel gear 82b at the right end of the bevel gear shaft 82, and the rotary shaft 8 via the bevel gear 8b
-Is rotated around the Y axis, but this rotation is
Has no effect on the rotation about the Y-Y axis. As described above, in a complicatedly entangled mechanism, as long as a power transmission mechanism using gears is used, the movement of one movement member does not affect the movement of another member. Inevitable. One way to avoid this effect is to use a motor-directed individual drive system. However, this creates new problems in terms of miniaturization and cost. Now, in FIG. 3, considering the case where the origin is returned from the turning cylinder 7 first, the turning shaft 8 is turned around the Y-Y axis under the influence of the turning motion. There is a danger of movement beyond the working area of the vehicle, which could collide with nearby members and damage both. Conversely, if the rotation shaft 8 is returned to the original position first, and then the turning cylinder 7 is returned to the original position, the turning cylinder 7 is not affected by the movement of the rotation shaft 8, which is good. The rotation shaft 8 is rotated by being affected by the home return operation of the turning cylinder 7. In this case, as described above, the rotating shaft 8 may move beyond its operation area, and the origin position may be shifted. Therefore, the returning operation of the rotating shaft 8 to the original position must be performed again. In the home position return method performed in three stages, there is a risk that the rotating shaft 8 may collide with peripheral members, and it takes a long time to return to the home position. SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems of the prior art, and to return the movement positions of the first and second members to the respective origins. In addition, the present invention provides a moving member return-to-origin return method that can return in a short time without returning to a predetermined operation region due to the influence of the return operation of the first member. It is in. Means for Solving the Problems In order to achieve the above object, in the present invention, the first
Are movably supported and driven, and the second
Are movably supported and driven, and the movement of the first member is not affected by the movement of the second member, and the movement of the second member is affected by the movement of the first member. When returning each member of 2 to each origin, the second
The original return speed of the member is set to be higher than the return speed of the second member under the influence of the movement of the first member, and the first and second members sandwich each origin. And a detector for detecting which side is located in the region. Based on the detection output of the detector, the first and second members are arranged so that each of the first and second members is located on either one side with respect to each origin. , The first and second members are always driven toward each origin, and after the first member is first returned to its origin,
The second member is returned to its origin. [Operation] The first member and the second member are simultaneously operated, and the original return speed of the second member is faster than the original position return speed due to the movement of the first member of the second member. So that
Since the home return operation is performed, complete return to the home position cannot be expected of the second member until the first member returns to the home position, but at least the second member is prevented from largely deviating from the operation area. Then, after the first member returns to the original position, the second member can perform the final return to the original position without being affected by the movement of the first member. At this time, it is only necessary to detect which side the first and second members are located on each side with respect to the respective origins, and it is determined whether each member needs to be driven or not, and the direction of driving. Is done. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an industrial articulated robot to which an embodiment is applied, and the configuration and operation of the embodiment will be described based on the perspective view. This robot has six joints (six rotation axes), and has a gripper (not shown) attached to the tip thereof to grip an article. First, there is a pedestal 1, and a turntable 2 is provided so that the turntable 2 can rotate around an axis 1 a of the pedestal 1.
The first pivotable table 2 is pivotable about the axis 2a of the pivot table 2.
Rotary discs 5 are respectively mounted so that the second arm 4 can pivot around its axis 4a so that the arm 3 can pivot around its axis 3a. A support base 6 is fixed to the turntable 5, and a turning cylinder 7 is provided so as to be rotatable around an axis 6 a of the support base 6. Further, a turning shaft 8 is rotatably mounted around an axis 7a of the turning cylinder 7. Note that arrows P, Q, R, S, U, and V indicate directions of rotation or turning, respectively. With respect to each of the above-described motion members except for the turning cylinder 7 and the rotation shaft 8, the motion is independent of each other. That is, the movement does not affect the movement of the other members, and is not affected by the movement of the other members. Therefore, the origin return operation of these members is simple since it is sufficient to perform each operation individually. The problem lies in the turning cylinder 7 and the rotating shaft 8, which is as already described in the conventional example. Specific structures and operations of the turning cylinder 7, the rotating shaft 8, and related members will be described later. FIG. 2 shows the motion function of the above-mentioned robot by a graphic symbol of a unit operation. A diagonal square symbol indicates a "rotate" operation, and a double circle symbol indicates a "turn" operation. In this figure, a gripping tool 9 provided at the tip of the rotating shaft 8 is shown. The other description is the same as that described above, and is omitted here. Next, the specific structure and operation of the turning cylinder 7, the turning shaft 8, and related members will be described with reference to the cross-sectional view of FIG. In FIG. 3, when viewed from the power transmission system, this system is the first system.
The system includes a system using the drive shaft 71 as an input shaft and a system using the second drive shaft 81 as an input shaft. Bevel gear 71a at the end of the drive shaft 71
The bevel gear 72a meshing with the bevel gear 72a is
Belongs to. The bevel gear shaft 72 has the left end surface of the bevel gear 72a in contact with the right side surface of the revolving cylinder 7 and is attached to the revolving cylinder 7 by a fixing screw 73. A bevel gear is provided at the end of the drive shaft 81.
A bevel gear 82a meshing with the bevel gear shaft 82a is provided.
And is located almost in the center. The right end of the bevel gear shaft 82 is a bevel gear 82b, and the left end is a shaft, which is supported by radial ball bearings 83 and 84. Note that radial ball bearings 8
4 is mounted on the left side wall of the swivel cylinder 7. Therefore, the bevel gear shaft 72, the revolving cylinder 7, and the bevel gear shaft 82 are integrally connected, and this combined body is connected to the XX axis by radial ball bearings 74, 83 at the left and right coaxial ends (FIG. 1). Axis 6a)
Supported rotatably around the The rotating shaft 8 is provided at its upper and lower ends with radial ball bearings 85 and 86, respectively.
And a bevel gear 8b fixed at an intermediate position of the rotating shaft 8 meshes with a bevel gear 82b at the right end of the bevel gear shaft 82. In addition, the two-dot chain line display shows the rotating disk 5 and the support base 6 in FIG. 1, and the first and second drive shafts 71 and 81 are mounted on the former via radial ball bearings 70 and 80, respectively. , In the latter,
The revolving cylinder 7, the rotating shaft 8, and other mechanism parts are mounted via radial ball bearings 74 and 83. The disk-shaped rotary seat 8a at the upper end of the rotary shaft 8 is a member to which a gripper corresponding to the hand or finger of the robot is mounted. With the above configuration, the operation of this mechanism is as follows. Power from the drive shaft 71 is transmitted to the turning cylinder 7 via bevel gears 71a and 72a, and the turning cylinder 7 is turned around the XX axis. In addition, by this turning operation, the rotating shaft 8
However, due to the engagement of the bevel gears 8b and 82b, the YY axis (first
It is rotated around 7a) in the figure. This rotation of the rotating shaft 8
This occurs even when power from the second drive shaft 81 is not transmitted, and is an operation affected by the so-called turning motion of the turning cylinder 7. That is, the driving shaft 71 performs the turning operation of the turning shaft 8 together with the turning operation of the turning cylinder 7. On the other hand, the power from the second drive shaft 81 is
Via a, 82a and 82b, 8b, it is transmitted only to the pivot 8 and rotates it about the YY axis. That is, the second
The rotation of the rotating shaft 8 by the drive shaft 81 does not affect the turning of the turning cylinder 7. Of course, the movement of the rotating shaft 8 when the rotations of the first and second drive shafts 71 and 81 are simultaneously received is the sum of the respective movements. In this case, the original rotation speed of the rotation shaft 8 by the second drive shaft 81 is determined to be faster than the rotation speed of the rotation shaft 8 by the rotation of the first drive shaft 71. Next, a brief description will be given, with reference to FIG. 4, of a detection decision having a role of tactile sense when the turning cylinder 7 and the rotating shaft 8 return to the origin. The detection decision is made up of a reflective photoelectric sensor 90 and an origin marker plate 91 installed correspondingly. The origin marker plate 91 is, for example, a disk-shaped member, and the periphery of one surface is white on one side 91a and black on the opposite side 91b across a position corresponding to the origin. That is, the position of the boundary line between white and black corresponds to the origin 91c. The origin mark plate for the turning cylinder 7 is provided on the right shaft portion of the bevel gear shaft 72,
The origin marker plates for the rotating shaft 8 are respectively attached to the lower ends of the rotating shafts 8 (for the sake of convenience, these origin marker plates are the same). Each of the sensors 90 is installed. The rotation range of the origin marker plate 91 is less than one rotation, and this range corresponds to the operation area of the turning cylinder 7 and the turning shaft 8 respectively. Now, when the reflection type photoelectric sensor 90 is opposed to the white region 91a of the origin marker plate 91, the reflection type photoelectric sensor 90 outputs a + a signal.
Similarly, at the origin 91c, the p signal is output. In the case of the + a signal, the revolving cylinder 7 or the rotating shaft 8 is rotated in the forward direction so that the origin 91c is directed in front of the reflection type photoelectric sensor 90, and conversely, in the case of the -a signal, in the negative direction. Rotated and the origin 91c is also the reflection type photoelectric sensor 9
It is decided to head straight to 0. The output is p
The turning cylinder 7 and the rotating shaft 8 are determined to be stopped as soon as a signal is issued. The operation of this embodiment will be described with reference to the flowchart of FIG. The symbols used in this flowchart are M1, M2: first member (slewing cylinder 7), second member
Member (rotating shaft 8), D1, D2: first drive shaft 71, second drive shaft 8
1, A1, A2: output signal of detection decision corresponding to first member, second
It is an output signal of a detection decision corresponding to a member. In FIG. 6, after the start, first, in step S1, preparation for returning to the origin of M1 is performed, and in step S11, preparation for returning to the origin of M2 is performed in parallel. Then, step S2
The following operations and the operations in and after step S12 are performed in parallel. In step S2, A1 = + a is determined. If YES, the process proceeds to step S3, and if NO, the process proceeds to step S7. In steps S3 and S4, D1 continues to rotate in the forward direction until A1 = p, that is, returns to the origin position, and then proceeds to step S5. In step S7, A1 = -a is determined. If YES, in steps S8 and S9, D1 continues to rotate in the negative direction until A1 = p, and if NO, the process immediately proceeds to step S5. In step S5, D1 is stopped, and then in step S6, D2 is stopped.
Is determined whether or not is stopped, if YES, the series of work is ended there, if NO, wait for D2 to stop,
Exit when stopped. Steps S12 to S15 and steps S17 to S19 work on D2 in exactly the same way as steps S2 to S5 and steps S7 to S9 in the case of D1. Therefore, their description is omitted. Next, in step S16, it is determined whether or not D1 is stopped. If YES, the process proceeds to the previous stage of step S6, and if NO, the process returns to the previous stage of step S11 and repeats the home position return operation. As a supplementary note here, the second member M2 continues to perform the home return operation at the same time as long as the first member M1 performs the home return operation, and the original speed of the return operation is the home position of the first member M1. Since the speed is determined to be faster than the return speed, the original second member is affected by the operation of the first member M1.
Deviations from the operating range of the M2 are avoided. When the first member M1 finishes returning, the second member M2 can also finish returning after a very short time.
As compared with the case where the member M2 is connected in series and performs the return operation sequentially, the entire return operation time can be significantly reduced. The correspondence between the components according to the present invention and the relationship between the components, and the members and the relationship in one embodiment is as follows. "The first member is movably supported and driven under a predetermined constraint": The turning cylinder 7 is supported at both ends of the bevel gear shafts 72 and 82 so as to be rotatable around the XX axis. And is driven by the first drive shaft 71, "the second member is supported and driven movably under a predetermined constraint": the rotation shaft 8 is rotatable around the YY axis. Are supported by radial ball bearings 85 and 86, and driven by a second drive shaft 81. "The second member is affected by the first member." By the turning around, it is rotated around the Y-Y axis via the bevel gears 8b and 82b. "Original origin return speed of the second member": the rotating shaft 8 is
Speed at which the drive shaft 81 rotates toward the origin, "Origin return speed due to the influence of the first member of the second member":
The speed at which the rotating shaft 8 is rotated toward the origin via the bevel gears 8b and 82b based on the turning motion of the turning cylinder 7 by the first drive shaft 71. FIG. 5 shows another example in which the movement of the first member affects the movement of the second member, but the movement of the second member does not affect the movement of the first member. In this figure, the rack 7A corresponds to the turning cylinder 7 in the first embodiment, and the gear 8A corresponds to the turning shaft 8 in the same manner. Now, the linear motion of the first drive member 71A in the direction of the arrow is transmitted to the rack 7A via a combination 72A of a rack and a gear unit (made of two gears and supported by a fixed shaft). Arrows indicate the direction of movement. At this time, at the same time, the gear 8A pivotally supported by the rack 7A is engaged with another rack 82A.
By the downward movement, the solid arrow direction (counterclockwise)
Is rotated. The gear 8A is also moved in the direction indicated by the dashed arrow (counterclockwise) due to the linear movement of the second drive member 81A in the direction indicated by the dashed line.
The gears stop at this point,
The rotation of 8A is not further transmitted to the rack 7A. That is, the movement of the gear 8A is affected by the movement of the rack 7A, but not in the opposite direction. As described above, it is only necessary to detect on which side the first and second members are located with respect to their respective origins (there is no need for complicated calculation processing). 2), the first member and the second member are simultaneously used, and the original return speed of the second member is higher than the original position return speed due to the movement of the first member of the second member. As described above, since the second member is returned to the original position, the second member is not expected to completely return to the original position until the first member returns to the original position. However, at least the second member is prevented from largely deviating from the operation region. And
First, after the first member returns to the original position, the second member can perform the final return to the original position without being affected by the movement of the first member. Therefore, according to the present invention, the following excellent effects are obtained as compared with the conventional one. (1) The second member greatly exceeds its operating area due to the movement of the first member during the home return operation.
That is prevented. Therefore, there is no danger of collision with surrounding members and damage due to the deviation from the operation area. In addition, since the origin return speed of the second member is selected so as to be higher than the origin return speed due to the influence of the movement of the first member, the function of preventing departure works sufficiently. (2) First, return the first member to the origin, and then
Therefore, the time required for starting the operation of both members at the same time and completing the return to the original position is shortened. (3) Since there are no additional hardware components, implementation is easy and cost performance is good.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an industrial articulated robot to which an embodiment according to the present invention is applied, and FIG. FIG. 3 is a cross-sectional view of a mechanism of one embodiment, FIG. 4 is a perspective view of a home return detector, FIG. 5 is a conceptual diagram of a mechanism of another embodiment, FIG. FIG. 5 is a flowchart showing the operation of the embodiment. Description of symbols 1: pedestal, 2: rotary table, 3: first arm, 4: second arm, 5: rotary table, 6: support table, 7: rotary cylinder, 8: rotary axis.

Claims (1)

(57) [Claims] A first member is movably supported and driven, a second member is movably supported and driven, and the movement of the first member is not affected by the movement of the second member; In the origin returning method of the moving member for returning the first and second members to the respective origins, wherein the movement of the second member is affected by the movement of the first member, the original origin returning speed of the second member Is set so as to be faster than the home position return speed under the influence of the movement of the first member that occurs when only the power source of the first member is driven, and that the first and second members are A detector is provided to detect which side of the region is located across the origin, and based on the detection output of this detector, the first and second members are positioned with respect to each of the origins. When located on one side, the first Always driving the second member toward each of the origins, first returning the first member to its origin, and then returning the second member to its origin. Return method. 2. 2. The method according to claim 1, wherein the movement of each of the first and second members is a rotational movement around an axis set for each member.