Robot system

Abstract

To provide a robot system capable of easily calculating a scale factor and applying the scale factor to conveyor tracking.SOLUTION: A robot system 1 includes: a conveyor 12 on which a workpiece 2 is placed; a robot 10 for performing prescribed processing to the workpiece 2; an encoder 13 for outputting a pulse value corresponding to a feed rate of the conveyor 12; and a control device 17 for controlling operation of the robot 10 by using the pulse value of the encoder 13. The control device 17 includes: an acquisition part for acquiring speed information on the conveyor 12; a specification part for specifying a scale factor corresponding to the acquired speed information by using correspondence information obtained by associating the scale factor with the speed of the conveyor 12; an estimation part for estimating the position of the workpiece 2 placed on the conveyor 12 and moved, by using the pulse value and the scale factor; and an execution part for operating the robot 10 in accordance with the estimated position of the workpiece 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a robot system including a conveyor on which a workpiece is placed and a robot that performs a predetermined process on the workpiece. [Background technology]

[0002] In conveyor tracking, a robot operates by following a workpiece that is placed on a conveyor and moves.

[0003] For example, Patent Document 1 discloses that laser sensors are provided on the upstream and downstream sides, and a scale factor is calculated from the encoder value at the time when the workpiece passes the position of each laser sensor, thereby performing tracking correction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-79075 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, when the speed is changed, it may be necessary to recalculate the scale factor using each laser sensor again.

[0006] In view of the above problems, an object of the present invention is to provide a robot system that can easily calculate a scale factor and be applied to conveyor tracking. [Means for solving the problem]

[0007] In order to solve the above problem, the robot system of the present invention comprises a conveyor on which a workpiece is placed, a robot that performs a predetermined processing on the workpiece, an encoder that outputs a pulse value corresponding to the feed amount of the conveyor, and a control device that controls the operation of the robot using the pulse value of the encoder, wherein the control device comprises an acquisition unit that acquires speed information of the conveyor, an identification unit that, when the ratio of the pulse value to the movement distance on the conveyor is defined as a scale factor, identifies the scale factor that corresponds to the acquired speed information using correspondence information in which the scale factor and the speed of the conveyor are associated, an estimation unit that uses the pulse value and the scale factor to estimate the position of the workpiece that is placed on the conveyor and moving, and an execution unit that operates the robot in accordance with the estimated position of the workpiece.

[0008] In addition, in the robot system, the estimation unit estimates the position of the workpiece relative to the reference position on the conveyor by using the pulse value counted from the timing when the workpiece passes the reference position on the conveyor.

[0009] In the robot system, the correspondence information is information obtained by interpolating a plurality of samples in which the scale factor and the speed of the conveyor are associated with each other.

[0010] In the robot system, the sample is data in which three or more different speeds of the conveyor are associated with the scale factor.

[0011] In addition, in a robot system, the scale factor of the sample is the average value of a plurality of scale factors corresponding to the same velocity. [Effects of the Invention]

[0012] According to the robot system of the present invention, the scale factor can be easily calculated and applied to conveyor tracking. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram illustrating an example of an overall configuration of a robot system according to an embodiment of the present invention. [Figure 2] 2 is a block diagram showing an example of various functions of the control device of FIG. 1. FIG. [Figure 3] 3 is a diagram showing an example of correspondence information set in the setting unit of FIG. 2. FIG. [Figure 4] 3 is a diagram showing an example of the position of a workpiece estimated by the estimation unit in FIG. 2. FIG. [Figure 5] 2 is a flowchart showing an example of a processing flow by the control device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicate descriptions will be omitted where appropriate.

[0015] === Implementation form === <Overall structure> 1 is a diagram schematically illustrating the configuration of a robot system 1 according to an embodiment of the present invention (hereinafter referred to as "this embodiment"). The robot system 1 performs conveyor tracking and executes a predetermined process on a workpiece 2. As shown in FIG. 1, the robot system 1 mainly includes a robot 10, a conveyor 12, an encoder 13, a first sensor 14, a second sensor 15, a third sensor 16, and a control device 17.

[0016] The robot 10 is an articulated robot and has multiple arms 21 and multiple joints 22. Each joint 22 is provided with a drive motor (not shown). The robot 10 moves by controlling the drive motor provided in each joint 22 of the robot 10. Note that the configuration of the robot 10 in FIG. 1 is just an example, and robots 10 with other configurations may also be used.

[0017] The robot 10 performs a predetermined process on the workpiece 2 that is placed on and moving on the conveyor 12. In this embodiment, a transport hand 23 is provided at the tip of the robot 10. The robot 10 grasps the workpiece 2 with the transport hand 23 and transports it to a predetermined target position. Note that the robot 10 may also perform processes on the workpiece 2 other than transportation. Since the robot 10 processes the workpiece 2 on the conveyor 12, conveyor tracking is performed by the control device 17, which will be described later.

[0018] The conveyor 12 is a transport device on which a workpiece 2 as a transport object is placed and which transports the workpiece 2. The direction in which the conveyor 12 transports the workpiece 2 is referred to as a transport direction F1. The conveyor 12 includes an endless belt 25 and guide rollers 26. The endless belt 25 is circular in side view, and the workpiece 2 is placed on the upper surface thereof which moves in the transport direction F1. The endless belt 25 is rotated by the guide rollers 26. A motor 27 is provided on the guide roller 26 on the downstream side. For example, the motor 27 is driven and controlled based on a speed setting value set by the user, and the conveyor 12 is driven.

[0019] The encoder 13 is provided, for example, for the guide roller 26 on the upstream side of the conveyor 12. The encoder 13 is, for example, a rotary encoder. The encoder 13 converts the mechanical displacement caused by the rotation of the guide roller 26 into a pulse signal. Therefore, the encoder 13 outputs a pulse value as a value obtained by counting the pulse signal. In other words, the pulse value indicates the amount of rotation of the guide roller 26. Furthermore, because the guide roller 26 drives the conveyor 12 by its rotation, the pulse value is a parameter corresponding to the feed amount (transport movement amount) of the conveyor 12. The encoder 13 then outputs the pulse value to the control device 17.

[0020] The first sensor 14 and the second sensor 15 are detection devices (limit sensors) that are provided relative to the conveyor 12 and detect the passage of the workpiece 2. The first sensor 14 and the second sensor 15 are fixed in position and do not change position relative to the movement of the conveyor 12. The first sensor 14 is provided upstream of the second sensor 15 in the conveying direction F1. A distance L is set between the first sensor 14 and the second sensor 15.

[0021] The first sensor 14 and the second sensor 15 are, for example, reflective laser sensors that emit a laser in a direction approximately perpendicular to the conveying direction F1. The first sensor 14 detects the arrival of the workpiece 2 when it reaches a first position P1 in the conveying direction F1. The second sensor 15 detects the arrival of the workpiece 2 when it reaches a second position P2 in the conveying direction F1. In this way, the first sensor 14 and the second sensor 15 detect the passage of the workpiece 2 through the first position P1 and the second position P2, respectively. Detection signals from the first sensor 14 and the second sensor 15 are output to the control device 17.

[0022] The third sensor 16 is a detection device that is provided for the conveyor 12 and detects the passage of the workpiece 2. For example, the third sensor 16 is fixed in position like the first sensor 14 and the second sensor 15, and a reflective laser sensor is used.

[0023] When the workpiece 2 reaches a reference position P0 in the conveying direction F1, the third sensor 16 detects this arrival. The reference position P0 is a position set upstream of the position where the robot 10 processes the workpiece 2, and is a position that serves as a reference for estimating the position of the workpiece 2, which will be described later. For example, the reference position P0 is set to the starting position (start point) from which the conveyor 12 starts moving the workpiece 2. In this way, the third sensor 16 detects the passage of the workpiece 2 through the reference position P0. A detection signal from the third sensor 16 is output to the control device 17.

[0024] The control device 17 is an information processing device that controls the operation of the robot 10. The control device 17 uses the pulse value of the encoder 13 to operate the robot 10 in accordance with the position of the workpiece 2 that is placed on and moving on the conveyor 12 (conveyor tracking). The control device 17 is configured with, for example, a CPU, memory, a communication interface, and a storage device.

[0025] ≪Functional configuration≫ 2 is a block diagram showing an example of various functions of the control device 17. As shown in the figure, the control device 17 mainly includes a setting unit 31, an acquisition unit 32, a specification unit 33, an estimation unit 34, and an execution unit 35. The setting unit 31 is a functional unit for setting the robot 10 before the robot 10 moves, and the acquisition unit 32, the specification unit 33, the estimation unit 34, and the execution unit 35 are functional units for causing the robot 10 to move based on the set information.

[0026] The setting unit 31 performs settings for the operation of the robot 10. Specifically, the setting unit 31 sets correspondence information in which the speed of the conveyor 12 and the scale factor S are associated with each other.

[0027] The scale factor S is a parameter that indicates the ratio between the pulse value of the encoder 13 and the feed amount, which is the moving distance of the workpiece 2 on the conveyor 12. Specifically, the scale factor S is calculated by the following formula (1).

[0028]

number

[0029] In equation (1), Pe is the pulse value when the second position P2 on the movement path is passed (when the arrival is detected by the second sensor 15). Ps is the pulse value when the first position P1 on the movement path is passed (when the arrival is detected by the first sensor 14). In this case, Pe is a value greater than Ps. L is the distance L between the first position P1 and the second position P2, and is the movement distance of the workpiece 2 moving from the first position P1 to the second position P2. In other words, the scale factor S is a positive value.

[0030] That is, the scale factor S is a parameter that indicates the pulse value per unit distance. The scale factor S may be defined as the reciprocal of equation (1). In this case, the scale factor S is a parameter that indicates the distance traveled per unit pulse value (1 count).

[0031] First, samples are acquired to set the correspondence information. The samples are data (information) associated with three or more different speeds of the conveyor 12. In this embodiment, a case where three speeds, low speed, medium speed, and high speed, are used will be described as an example. Note that, with the medium speed as the reference, the low speed is slower than the medium speed, and the high speed is faster than the medium speed. As an example, the low speed is 100 mm / sec, the medium speed is 250 mm / sec, and the high speed is 400 mm / sec. Note that the specific speeds of the low speed, medium speed, and high speed are not limited to those described above.

[0032] Then, the conveyor 12 is operated at low, medium, and high speeds, and the scale factor S corresponding to each speed is calculated and associated using equation (1). That is, as samples, each of the three speeds is associated with a scale factor S. For example, the scale factor S for low speed is 187651 pulses / mm, the scale factor S for medium speed is 187645 pulses / mm, and the scale factor S for high speed is 187642 pulses / mm. "Pulse" is the unit of pulse value (count value of pulse signal).

[0033] It is preferable that the scale factor S of a sample be the average value of multiple scale factors S corresponding to the same speed. For example, it is more preferable to operate the conveyor 12 at a low speed, calculate the scale factor S multiple times (e.g., 10 times), and use the average value as the scale factor S corresponding to the low speed. In other words, it is preferable that the scale factors S corresponding to each of the three speeds in the sample be set as average values.

[0034] The setting unit 31 then sets the correspondence information using three types of samples. FIG. 3 is a diagram showing an example of an interpolation formula D1 as the correspondence information. In FIG. 3, the horizontal axis represents the speed of the conveyor 12, and the vertical axis represents the scale factor S. Note that each value and unit (dimension) is an example. As shown in FIG. 3, the setting unit 31 calculates the interpolation formula D1 using S1, a sample corresponding to a low speed, S2, a sample corresponding to a medium speed, and S3, a sample corresponding to a high speed. The interpolation formula D1 is, for example, a linear curve (linear formula). That is, each of the samples S1, S2, and S3 is approximated by a linear formula and shown as the interpolation formula D1. As a result, the interpolation formula D1 associates the speed of the conveyor 12 at positions other than the sample positions (for example, between the samples) with the scale factor S. That is, the interpolation formula D1 is information obtained by interpolating multiple samples in which the scale factor S is associated with the speed of the conveyor 12. Although the interpolation formula D1 in FIG. 3 is set up to the sample positions (positions S1 and S3) at both ends, the interpolation formula D1 may be set beyond the range of the samples.

[0035] In this way, the correspondence information associates the speed of the conveyor 12 with the scale factor S. Therefore, based on the correspondence information, it is possible to identify the scale factor S corresponding to the speed of the conveyor 12. Note that by setting the correspondence information as described above, the scale factor S is set in consideration of deterioration such as wear and stretching of the conveyor 12, pulsation, etc.

[0036] In this way, the setting unit 31 sets the correspondence information as a pre-setting for the operation of the robot 10. In the above example, the setting unit 31 sets the correspondence information using a plurality of samples, but the correspondence information may also be set by a person.

[0037] In the above example, the correspondence information is an interpolation formula D1 as shown in Figure 3, but as long as the correspondence relationship is indicated, the correspondence information can be set in various formats such as an equation (function), table data, graph information, etc.

[0038] Returning to FIG. 2, the acquisition unit 32 acquires speed information of the conveyor 12. The speed information is information indicating the speed of the conveyor 12 during operation. The speed information is the transport speed of the workpiece 2 by the conveyor 12, and is, for example, a speed setting value (speed target value). The speed setting value is a value set by the user as the speed at which the conveyor 12 is operated.

[0039] The speed information is not limited to a speed setting value, and may be a measured value obtained by measuring the speed of the conveyor 12, for example, if a sensor is provided on the conveyor 12. The speed information is also not limited to a speed value, and may be information on the stepwise speed setting (for example, low speed) if the conveyor 12 has stepwise speed settings such as low speed and medium speed.

[0040] The determination unit 33 determines the scale factor S corresponding to the speed information acquired by the acquisition unit 32. Specifically, the determination unit 33 uses correspondence information such as that shown in Fig. 3 to determine the scale factor S corresponding to the acquired speed information.

[0041] For example, if the acquired speed information indicates a speed SP1, the scale factor S1 is identified. The identified scale factor S is information indicating the pulse value per unit distance corresponding to the speed information.

[0042] The estimation unit 34 estimates the position of the workpiece 2 that is placed and moving on the conveyor 12. Specifically, the estimation unit 34 uses the pulse value and the scale factor S to perform position estimation.

[0043] The estimation unit 34 uses the pulse value counted from the timing when the workpiece 2 passes the reference position P0 on the conveyor 12. When conveyor tracking is performed, the encoder 13 starts counting when the workpiece 2 passes the reference position P0 on the movement path. When the workpiece 2 passes the reference position P0, the third sensor 16 detects this and causes the encoder 13 to start counting. In this way, the estimation unit 34 uses the pulse value counted from the timing when the workpiece 2 passes the reference position P0.

[0044] The estimation unit 34 then estimates the position of the workpiece 2 relative to the reference position P0 on the conveyor 12 using the pulse value and the scale factor S. FIG. 4 is a diagram showing an example of the position of the workpiece 2 corresponding to the pulse value. As described above, the pulse value indicates the increase from the time when the workpiece 2 passed the reference position P0. Furthermore, the scale factor S indicates the pulse value per unit distance. Therefore, the estimation unit 34 calculates the position of the workpiece 2 by multiplying the pulse value by the reciprocal of the scale factor S. By performing this calculation, the movement amount M of the workpiece 2 from the reference position P0 is estimated corresponding to the pulse value counted from the time when the workpiece 2 passed the reference position P0. In this way, the position of the workpiece 2 during movement is estimated.

[0045] Returning to FIG. 2 , the execution unit 35 operates the robot 10 in accordance with the estimated position of the workpiece 2. The execution unit 35 operates the robot 10 so that the robot 10 can execute processing for the position of the workpiece 2 moved by the conveyor 12. For example, when performing an operation to grip the workpiece 2 with the transport hand 23 of the robot 10, the robot 10 is operated so that the transport hand 23 of the robot 10 corresponds to the estimated position of the workpiece 2. This allows the robot 10 to grip the workpiece 2 moved by the conveyor 12. Conveyor tracking is performed in this manner.

[0046] <Processing flow> 5 is a flowchart showing an example of the flow of processing by the control device 17 of the robot system 1 according to this embodiment. The processing of each of the following steps is started, for example, when the workpiece 2 passes through the reference position P0 on the conveyor 12. Note that the order and content of each of the following steps can be changed as appropriate.

[0047] (Step SP10) The acquisition unit 32 acquires speed information of the conveyor 12. Specifically, the acquisition unit 32 acquires the speed setting value of the conveyor 12 set by the user. Then, the process proceeds to step SP11.

[0048] (Step SP11) The determination unit 33 uses the set correspondence information to determine the scale factor S that corresponds to the acquired speed information, and then the process proceeds to step SP12.

[0049] (Step SP12) The estimation unit 34 acquires the pulse value counted from the timing when the workpiece 2 passes through the reference position P0 on the conveyor 12. Then, the process proceeds to step SP13.

[0050] (Step SP13) The estimation unit 34 estimates the position of the workpiece 2 relative to the reference position P0 on the conveyor 12. Specifically, the estimation unit 34 uses the acquired pulse value and the identified scale factor S to estimate the amount of movement of the workpiece 2 from the reference position P0 corresponding to the pulse value. Then, the process proceeds to step SP14.

[0051] (Step SP14) The execution unit 35 operates the robot 10 in accordance with the estimated position of the workpiece 2.

[0052] In this way, conveyor tracking is performed using the correspondence information.

[0053] <Action and effect> As described above, in this embodiment, the scale factor S can be identified using the correspondence information from the speed information of the conveyor 12, and the position of the workpiece 2 can be estimated. In other words, the scale factor S can be easily calculated and applied to conveyor tracking. Furthermore, for example, the speed of the conveyor 12 may be changed depending on the type of workpiece 2, but even in such cases, the scale factor S can be easily identified and applied to conveyor tracking. By making it easier to identify the scale factor S, it is possible to reduce the amount of work required.

[0054] Furthermore, by using the pulse value counted from the timing when the workpiece 2 passes the reference position P0 on the conveyor 12, the position of the workpiece 2 after movement relative to the reference position P0 can be effectively estimated.

[0055] Furthermore, since the correspondence information is information obtained by interpolating a plurality of samples, it is possible to specify an appropriate scale factor S in response to the speed of the conveyor 12 flexibly.

[0056] Furthermore, the correspondence information can be appropriately set by having samples corresponding to three or more different speeds of the conveyor 12. That is, the scale factor S can be specified with high precision.

[0057] Furthermore, by using the average value of a plurality of scale factors S corresponding to the same speed as a sample, it is possible to suppress variations and set the correspondence information appropriately.

[0058] <<Variations>> The present invention is not limited to the above-described embodiments. In other words, designs that are produced by those skilled in the art with appropriate design modifications to the above-described specific examples are also included within the scope of the present invention as long as they include the features of the present invention. Furthermore, the elements of the above-described embodiments and the following modifications can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they include the features of the present invention.

[0059] For example, in the above embodiment, three types of sample speeds, low speed, medium speed, and high speed, are used as an example, but the number of types of sample speeds is not limited to the above. A large number of sample speeds, such as 10 types, may be used.

[0060] Furthermore, in the above embodiment, the case where the interpolation formula D1 is a linear curve (linear formula) and linear interpolation (linear approximation) is performed has been described, but the interpolation formula may be a nonlinear interpolation (nonlinear approximation) or the like.

[0061] 5, steps SP10 and SP11 may be performed when the speed of the conveyor 12 is set, so as to identify the scale factor S in advance. That is, steps SP10 and SP11 do not have to be performed each time the flow is executed, and may be performed in advance.

[0062] In the above embodiment, FIG. 1 illustrates a case where the first sensor 14, the second sensor 15, and the third sensor 16 are provided. The first sensor 14, the second sensor 15, and the third sensor 16 are not limited to a system using lasers, as long as they can detect the passage of the workpiece 2. The first sensor 14 and the second sensor 15 may be provided when setting the correspondence information, and the first sensor 14 and the second sensor 15 may be omitted when the robot 10 is subsequently caused to perform conveyor tracking. The third sensor 16 may be omitted when setting the correspondence information, and the third sensor 16 may be provided when the robot 10 is subsequently caused to perform conveyor tracking. [Explanation of symbols]

[0063] 1: Robot system 2: Work 10: Robot 12: Conveyor 13: Encoder 17: Control device 32: Acquisition part 33: Specific part 34:Estimation part 35: Executive Department D1: Interpolation formula (support information) P0: Reference position S: Scale factor

Claims

1. a conveyor on which the workpiece is placed; a robot that performs a predetermined process on the workpiece; an encoder that outputs a pulse value corresponding to the feed amount of the conveyor; a control device that controls the operation of the robot using the pulse value of the encoder; Equipped with The control device an acquisition unit that acquires speed information of the conveyor; an identification unit that identifies a scale factor corresponding to the acquired speed information by using correspondence information in which the scale factor and the speed of the conveyor are associated, where the ratio of the pulse value to the moving distance of the conveyor is defined as a scale factor; an estimation unit that estimates a position of the workpiece that is placed on the conveyor and moving using the pulse value and the scale factor; an execution unit that operates the robot in accordance with the estimated position of the workpiece; A robot system comprising:

2. The robot system according to claim 1, wherein the estimation unit estimates the position of the workpiece relative to the reference position on the conveyor using the pulse value counted from the time the workpiece passes a reference position on the conveyor.

3. 3. The robot system according to claim 1, wherein the correspondence information is information obtained by interpolating a plurality of samples in which the scale factor and the speed of the conveyor are associated with each other.

4. 4. The robot system according to claim 3, wherein the sample is data in which three or more different speeds of the conveyor are associated with the scale factor.

5. 5. The robot system according to claim 4, wherein the scale factor of the sample is an average value of a plurality of the scale factors corresponding to the same velocity.

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