Conveyance system and program storage medium

Abstract

To quickly and highly accurately convey an object to a target position attitude, while suppressing complication of arithmetic processing.SOLUTION: A conveyance system includes an actuator for conveying an object, and a control device for controlling the actuator, and conveying the object to a predetermined target position so that it becomes a target attitude. The control device includes an error information storage part for performing sequence control on the actuator, and previously storing error information indicating a relation between an error between the target position and the target attitude (hereinafter collectively referred to as target position attitude) of the object and an actual position and attitude (hereinafter collectively referred to as actual position attitude) when the object is conveyed so that it becomes the target position attitude, and the target position attitude; and a target position attitude correction part for correcting the target position attitude on the basis of the error information.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transport system and a program storage medium. [Background technology]

[0002] When assembling a part to a product body using an actuator, a target position and orientation are set in advance, for example, by calculation from a layout drawing, and the part is transported so as to be in this target position and orientation and is then assembled to the product body.

[0003] However, in reality, a part that was thought to have been transported to a target position and orientation may actually deviate from that target position and orientation. This error can be caused by a number of factors, including calibration accuracy that cannot be read from the layout diagram, but since it is particularly likely to occur when the part is heavy, insufficient rigidity of the actuator is thought to be a major factor.

[0004] Patent Document 1 discloses a transport system that can correct this error, in which a camera is provided that can photograph the workpiece held by an actuator, and the position of the workpiece is corrected in real time via feedback based on image data obtained by the camera during transport.

[0005] However, the conveying system according to Patent Document 1 cannot be used in situations where it is not possible to capture an image with a camera, such as when an object is inserted into a hole. In addition, since image data must be constantly processed during conveying, a high-performance image processing device is required, and if this capacity is insufficient, the calculation time may become a bottleneck in the conveying speed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-782 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above-mentioned problems, and is intended to enable an object to be transported to a target position and orientation quickly and with high accuracy while suppressing the complexity of calculation processing. [Means for solving the problem]

[0008] That is, the transport system according to the present invention comprises an actuator for transporting an object, and a control device for controlling the actuator to transport the object to a predetermined target position and to a target attitude, and the control device is characterized in that it comprises an error information storage unit that stores in advance error information indicating the relationship between an actual position and attitude (hereinafter, these will be collectively referred to as the actual position and attitude) that occurs when the object is transported to the target position and attitude (hereinafter, these will be collectively referred to as the target position and attitude) by sequentially controlling the actuator, and the target position and attitude, and a target position and attitude correction unit that corrects the target position and attitude based on the error information.

[0009] According to the present invention, since the object is transported to the target position and orientation by incorporating the transport error by the actuator in advance, it can be used even in a situation where it is not possible to capture an image with a camera. In addition, since the complexity of the calculation process can be suppressed, the object can be transported to the target position and orientation quickly and with high accuracy.

[0010] The more prerequisites there are, the more work it takes to create error information.

[0011] Therefore, the control device may have a first control unit that controls the actuator to transport the object to an intermediate position and intermediate posture (hereinafter, these will be collectively referred to as an intermediate position and posture) that are determined based on the target position and posture, and a second control unit that transports the object from the intermediate position and posture to the target position and posture, and the error information storage unit may store error information indicating a relationship between the error and the actual position and posture that occurs when the object is transported from the intermediate position and posture to the target position and posture by sequence control, and the target position and posture.

[0012] With this configuration, when creating error information, the position and orientation of the object relative to the target position and orientation can be fixed, which reduces prerequisites and reduces the effort required for creation.

[0013] Errors also occur when the object is transported to an intermediate position and orientation. For this reason, if the object is transported to an intermediate position and orientation by sequence control, it is necessary to create error information separately, which increases the amount of work required.

[0014] Therefore, the object may further include a position and orientation detection sensor that detects the position and orientation of the object, and the first control unit may utilize the position and orientation detection sensor to feedback control the actuator, and the second control unit may perform sequence control of the actuator.

[0015] With this configuration, there is no need to create separate error information regarding errors that occur when an object is transported to an intermediate position and orientation. Here, feedback control is a control that, after the transport of an object starts, compares the detected position and orientation with a target position and orientation while referring to the position and orientation detected by a position and orientation detection sensor, and operates an actuator to move the object closer to the target position and orientation. On the other hand, sequence control is a control that, after the transport of an object starts, operates an actuator to transport the object to the target position and orientation without referring to the position and orientation detected by a position and orientation detection sensor.

[0016] Furthermore, if the object is transported to the intermediate position and posture using only feedback control, the transport speed may decrease.

[0017] Therefore, the device may further include a position and orientation detection sensor that detects the position and orientation of the object, and the first control unit may have a temporary transport control unit that transports the object to the vicinity of the intermediate position and orientation, and a final transport control unit that transports the object from the vicinity of the intermediate position and orientation to the intermediate position and orientation, the temporary transport control unit sequentially controls the actuator, and the final transport control unit may sequentially control or feedback control the actuator by utilizing the position and orientation detection sensor.

[0018] With this configuration, the object is first transported to the vicinity of the intermediate position and orientation using sequence control, and then transported to the intermediate position and orientation using sequence control or feedback control, so the transport section due to feedback control is reduced and the drop in transport speed is kept to a minimum. Incidentally, when the transport control unit performs sequence control, there is a risk of errors occurring in the transport, but since the transport section is short, the errors are negligible in terms of work. Therefore, there is no need to take the trouble of creating error information. Incidentally, when the transport control unit performs sequence control, it is sufficient to configure the transport control unit to transport the object to the intermediate position and orientation based on the positional relationship between the position and orientation of the object transported to the vicinity of the intermediate position and orientation detected by the position and orientation detection sensor and the intermediate position and orientation.

[0019] A specific example of the position and orientation detection sensor is an imaging device.

[0020] In order to further reduce the prerequisites, for example, the intermediate posture may be determined so that at least one of six coordinates specifying the target position posture is coincident, the intermediate posture may be set so that only the phase angle around the line connecting the intermediate position and the target position is shifted from the target posture, or the control device may further include a gripping location control unit that causes the actuator to grip a predetermined position of the target object from a predetermined direction.

[0021] The program storage medium according to the present invention is a program storage medium having stored therein a program used by a control device that controls an actuator that transports an object, and transports the object so that it reaches a predetermined target position and has a target attitude, the program storage medium having stored therein the program that causes the control device to function as an error information storage unit that stores in advance error information indicating the relationship between an error between an actual position and attitude (hereinafter, when these are collectively referred to as an actual position and attitude) that occurs when the object is transported to a predetermined target position and attitude (hereinafter, when these are collectively referred to as a target position and attitude), and the target position and attitude, and a target position and attitude correction unit that corrects the target position and attitude based on the error information. Effect of the Invention

[0022] According to the transport system configured in this manner, it is possible to transport an object to a target position and orientation quickly and with high accuracy while suppressing the complexity of calculation processing. [Brief description of the drawings]

[0023] [Figure 1] 1 is a perspective view showing a schematic configuration of a transport system according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a functional block diagram showing functions of a control device in the embodiment. [Diagram 3] 10 is a flowchart showing an operation of the transport system in the embodiment. [Figure 4] FIG. 2 is a partially enlarged perspective view illustrating a schematic configuration of the transport system according to the embodiment. [Diagram 5] 11 is an explanatory diagram showing an operation of changing a part from an intermediate posture to a target posture in the conveying system in the embodiment. FIG. [Figure 6] 11 is table data showing error information in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] <Embodiment> An embodiment of a transport system according to the present invention will be described below.

[0025] The conveying system according to the present invention conveys an object to a target position so that the object assumes a target attitude, and is used, for example, when simply conveying an object or when assembling an object to another object.

[0026] 1, the conveying system 100 according to this embodiment is installed in the middle of a manufacturing line L, and when a product body W1 traveling along the manufacturing line L reaches an assembly position P, a part W2 is assembled to the product body W1. The part W2 corresponds to an object in the claims. Note that, hereinafter, the position and the posture are collectively referred to as the position and posture.

[0027] Before describing the details of the conveying system 100, the product body W1 and the part W2 of this embodiment will be described. The product body W1 is cylindrical, and a fitting hole W1h with a rectangular cross section is formed in the center of one end face that serves as the mounting surface W1s of the part W2. The part W2 is a rod with a rectangular cross section, and is fitted into the fitting hole W1h of the product body W1. The product body W1 is then placed on a jig J with the mounting surface W1s facing horizontally, and is conveyed along the manufacturing line L. For this reason, the phase angle around the axis shifts for each product body W1. Therefore, when inserting the part W2 into the fitting hole W1h to assemble it to the product body W1, in addition to adjusting the position of the part W2, it is necessary to adjust the posture by shifting the phase angle around the axis of the part W2.

[0028] Next, the transport system 100 will be described in detail. As shown in FIG. 1, the transfer system 100 includes a position sensor S, an actuator 10, a position and orientation detection sensor 20, and a control device 30 (see FIG. 2).

[0029] The position sensor S is installed on the production line L and detects when the product body W1 reaches the assembly position P.

[0030] The actuator 10 transports the part W2 and assembles it into the product body W1. Specifically, the actuator 10 includes an arm 11 and a hand 12 provided at the tip of the arm 11, and grips the part W2 with the fingertips of the hand 12. The actuator 10 in this embodiment is a vertical multi-joint type, but is not limited to this and may be, for example, a horizontal multi-joint type (SCARA type), a parallel link type, or an orthogonal type.

[0031] The position and orientation detection sensor 20 detects the position and orientation of the part W2, and is, for example, an imaging device such as a camera or a scanner. For example, the position and orientation detection sensor 20 detects the position and orientation of the part W2 on six coordinates (X, Y, Z, Rx, Ry, Rz) with an arbitrary point in a preset space as the origin.

[0032] The position and orientation detection sensor 20 of this embodiment is a camera installed on the actuator 10. Then, the relative position and orientation of the part W2 with respect to the product body W1 is detected from image data of the product body W1 captured by the camera. More specifically, as shown in Fig. 4, the central axis of the part W2 is set as the Z axis in advance, and six coordinates are set with the intersection of the central axis and one end face of the part W2 as the origin. Then, the position and orientation of the product body W1 on the six coordinates is detected from the image data of the product body W1 captured by the camera, thereby detecting the relative position and orientation of the part W2 with respect to the product body W1.

[0033] The control device 30 is, for example, a general-purpose or dedicated computer equipped with a CPU, a program storage medium, an input means, an output means, a display, etc., and controls the actuator to transport the part to an intermediate position P1 and an intermediate posture (hereinafter collectively referred to as the intermediate position and posture), and then to a target position P2 and target posture (hereinafter collectively referred to as the target position and posture).

[0034] Before describing the control device 30 in detail, the target position and posture and the intermediate position and posture will be described.

[0035] The target position and orientation is a position and orientation to which the part W2 is actually to be conveyed, and in this embodiment, is a position and orientation in which the part W2 fits into the fitting hole W1h of the product main body W1. This target position and orientation is set in advance based on the relative position and orientation of the part W2 with respect to the product main body W1 detected by the position and orientation detection sensor 20.

[0036] The intermediate position and posture are positions and postures determined based on the target position and posture, and are set in advance together with the target position and posture. For example, the intermediate position and posture are set so that at least one of six coordinates specifying the target position and posture coincides. In this embodiment, the intermediate position and posture are set so that X, Y, Rx, and Ry among the six coordinates specifying the target position and posture coincide. Therefore, the intermediate posture is set so that only the phase angle around the straight line connecting the intermediate position P1 and the target position P2 (around the Z axis in this embodiment) is shifted from the target posture.

[0037] Next, the control device 30 will be described in detail. The control device 30 is configured to perform the functions of a gripping location control unit 31, a first control unit 32, and a second control unit 33, as shown in Figure 2, by executing a program stored in a memory, which is a program storage medium.

[0038] The operation of the control device 30 will be described below with reference to the flow chart of FIG.

[0039] First, when the gripping position control unit 31 receives a detection signal from the position sensor S, it controls the actuator 10 to grip a predetermined position of the part W2 from a predetermined direction (S1). Specifically, a gripping position where the fingertips of the hand unit 12 grip the part W2 is set in advance, the position and orientation detection sensor 20 detects the relative position and orientation of the part W2 with respect to the fingertips of the hand unit 12, and feedback control is performed so that the fingertips of the hand unit 12 approach the gripping position of the part W2 from the predetermined direction. As a result, the gripping position of the part W2 is gripped by the fingertips of the hand unit 12 from the predetermined direction, and the hand unit 12 is placed in a state of gripping the predetermined position of the part W2 from the predetermined direction.

[0040] Next, the first control unit 32 feedback-controls the actuator 10 to transport the part W2 to the intermediate position and posture (S2). Specifically, the position and posture detection sensor 20 detects the relative position and posture of the part W2 with respect to the product body W1, and feedback-controls the position and posture of the part W2 to approach the intermediate position and posture. As a result, the position of the part W2 shifts from the target position P2 only in the direction of a straight line connecting the intermediate position P1 and the target position P2 (in this embodiment, the Z-axis direction), as shown in Fig. 5, and the posture of the part W2 shifts from the target posture only by a phase angle θ around the straight line (in this embodiment, around the Z-axis).

[0041] Next, the second control unit 33 sequentially controls the actuator 10 to transport the part W2 to the target position and orientation (S4). Specifically, the position and orientation of the part W2 is detected by the position and orientation detection sensor 20, and the sequence is controlled so that the position and orientation of the part W2 becomes the target position and orientation. As a result, the position of the part W2 is shifted in the linear direction to the target position P2, and the orientation of the part W2 is rotated around the linear direction to become the target orientation.

[0042] Therefore, the target position and orientation is not set with the above-mentioned error taken into consideration, and therefore even if the part W2 is transported to this target position and orientation, the above-mentioned error may occur, and the part W2 may not be assembled into the product body W1.

[0043] Therefore, the control device 30 of this embodiment is configured to further function as an error information storage unit 34 and a target position / attitude correction unit 35, so that the target position / attitude is corrected based on the error before the second control unit 33 performs sequence control of the actuator 10.

[0044] The error information storage unit 34 is set in a predetermined area of ​​the memory, and stores error information indicating the relationship between the error between the actual position and posture (hereinafter, these are collectively referred to as the actual position and posture) that occurs when the actuator 10 is sequence-controlled to transport the part W2 to a target position and posture, and the target position and posture. The error information in this embodiment indicates the relationship between the error between the actual position and posture that occurs when the part is transported from an intermediate position and posture to a target position and posture, and the target position and posture. Specifically, the error information is stored as table data or a calculation formula.

[0045] This error information is generated by transporting the part W2 from an intermediate position and orientation to a target position and orientation in advance, and measuring how much the position and orientation of the part W2 after transport deviates from the target position and orientation. This operation is performed before the transport system is put into operation.

[0046] Specifically, a second position and orientation detection sensor is provided to detect the relative position and orientation of the part W2 transported from the intermediate position and orientation to the target position and orientation with respect to the part body W1. The second position and orientation detection sensor is, for example, an imaging device such as a camera or a scanner, and specifically, a fixed-point camera provided in a space in which the transport system 100 is installed. The second position and orientation detection sensor detects the actual position and orientation (real position and orientation) of the part W2 transported from the intermediate position and orientation to the target position and orientation by the actuator 10 as the relative position and orientation with respect to the part body W1, and measures the error by comparing the actual position and orientation with the target position and orientation. In this embodiment, the phase shifts for each part body W1. Then, when the phase of the part body W1 shifts, the target position and orientation also changes, so the error is measured for each target position and orientation, and the relationship between the target position and orientation and the error is stored together in table data.

[0047] More specifically, as shown in FIG. 6, the error information in this embodiment is stored as table data in which a single reference target position and posture (hereinafter also referred to as a reference target position and posture) is set in advance, and the deviation amount (specifically, the phase deviation amount) of the target position and posture from the reference target position and posture is associated with the error corresponding to the deviation amount.

[0048] Then, the target position and orientation correcting unit 35 corrects the target position and orientation based on the error information (S3).

[0049] According to the conveying system 100 of the present embodiment, the part W2 is conveyed to the target position and orientation by incorporating the conveying error by the actuator 10 in advance, so that it can be used even in a situation where it is not possible to capture an image with a camera. In addition, since the complexity of the calculation process can be suppressed, the part W2 can be conveyed to the target position and orientation quickly and with high accuracy.

[0050] In addition, the error information indicates the relationship between the error that occurs when transferring from an intermediate position and posture to a target position and posture and the target position and posture, and this intermediate position and posture are set so that some of the six coordinates match the target position and posture, thereby reducing the prerequisites for creating the error information and the effort required.

[0051] Similarly, since the actuator 10 grips the part W2 at a predetermined position from a predetermined direction, the prerequisites for creating error information are reduced, and the effort required is reduced.

[0052] Other Embodiments The transport system according to the present invention is not limited to the above-described embodiment. In the above-described embodiment, the position and orientation detection sensor is installed on the actuator, but it may be, for example, a fixed camera.

[0053] In addition, in the above embodiment, six coordinates are used to specify the position and orientation of the part or the product body, but for example, pulses required to move each axis of an actuator may be used instead of the six coordinates.

[0054] In the above embodiment, the intermediate position and posture are set so that X, Y, Rx, and Ry of the six coordinates that specify the target position and posture are coincident with each other, but the present invention is not limited to this. For example, only one coordinate may be set so that it coincides with the intermediate position and posture, or another combination of coordinates may be set so that it coincides with the intermediate position and posture.

[0055] In the embodiment, the first control unit is configured to feedback-control the actuator, but for example, the first control unit may have a provisional transport control unit that transports the object to the vicinity of the intermediate position and posture, and a final transport control unit that transports the object from the vicinity of the intermediate position and posture to the intermediate position and posture, and the provisional transport control unit sequentially controls the actuator, and the final transport control unit sequentially controls or feedback controls the actuator using a position and posture detection sensor. With such a configuration, the transport section that is feedback-controlled is shortened, so that a decrease in the transport speed can be suppressed. Specifically, for example, the provisional transport control unit transports the object by sequential control so that the object is at the intermediate position and posture. Then, an error occurs for the above-mentioned reason, and the object is transported to the vicinity of the intermediate position and posture that is shifted from the intermediate position and posture by the amount of this error. In other words, the vicinity of the intermediate position and posture can be said to be a position and posture in which the actuator is sequentially controlled to transport the object to the intermediate position and posture without considering the error. Then, in this transport control section, before starting transport, the position and orientation of the part in this state relative to the product body is detected by the position and orientation detection sensor, the deviation between the detected position and orientation and the intermediate position and orientation (i.e., this deviation is the deviation due to the error) is grasped, and the target object is transported by the amount of this deviation. In other words, when this transport control section performs sequence control, the part is transported to the intermediate position and orientation based on the position and orientation of the part that has been transported to the vicinity of the intermediate position and orientation detected by the position and orientation detection sensor.

[0056] Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0057] L...Production Line W1: Product body W2: Part (object) 100...Transportation system 10 Actuator 20 Position and orientation detection sensor (imaging device) 30 Control device 31 Grip location control section 32 First control section 33 Second control section 34...Error information storage section 35...Target position / orientation correction unit

Claims

1. An actuator for transporting an object; a control device that controls the actuator to transport the object to a predetermined target position so that the object has a target attitude; The control device includes: an error information storage unit that stores in advance error information indicating a relationship between an error between an actual position and attitude (hereinafter, these will be collectively referred to as an actual position and attitude) that occurs when the object is transported to the target position and attitude (hereinafter, these will be collectively referred to as a target position and attitude) by sequentially controlling the actuator and the target position and attitude; a target position and attitude correction unit that corrects the target position and attitude based on the error information.

2. The control device includes: a first control unit that controls the actuator to transport the object to an intermediate position and intermediate posture (hereinafter, these will be collectively referred to as an intermediate position and posture) that are determined based on the target position and posture, and a second control unit that transports the object from the intermediate position and posture to the target position and posture, 2. The transportation system according to claim 1, wherein the error information storage unit stores error information indicating a relationship between an error between an actual position and posture that occurs when the object is transported from the intermediate position and posture to the target position and posture by sequence control and the target position and posture.

3. The apparatus further includes a position and orientation detection sensor for detecting a position and orientation of the object, the first control unit performs feedback control of the actuator by utilizing the position and orientation detection sensor; The transport system according to claim 2 , wherein the second control unit sequentially controls the actuator.

4. The apparatus further includes a position and orientation detection sensor for detecting a position and orientation of the object, the first control unit has a temporary transport control unit that transports the object to a position near the intermediate position and posture, and a main transport control unit that transports the object from a position near the intermediate position and posture to the intermediate position and posture, 3. The transfer system according to claim 2, wherein the temporary transfer control unit performs sequence control of the actuator, and the main transfer control unit performs sequence control or feedback control of the actuator by utilizing the position and orientation detection sensor.

5. 5. The transfer system according to claim 3, wherein the position and orientation detection sensor is an imaging device.

6. 5. The transfer system according to claim 2, wherein the intermediate posture is determined so that at least one of six coordinates that specify the target position and posture coincides with the intermediate posture.

7. 5. The transfer system according to claim 2, wherein the intermediate posture is set so as to deviate from the target posture only in a phase angle about a straight line connecting the intermediate position and the target position.

8. 5. The conveying system according to claim 2, wherein the control device further comprises a gripping position control unit that causes the actuator to grip a predetermined position of the object from a predetermined direction.

9. A program storage medium storing a program used in a control device that controls an actuator that transports an object, and transports the object to a predetermined target position so that the object has a target attitude, an error information storage unit that stores in advance error information indicating a relationship between an error between an actual position and attitude (hereinafter, these will be collectively referred to as an actual position and attitude) that occurs when the object is transported to the target position and attitude (hereinafter, these will be collectively referred to as a target position and attitude) by sequentially controlling the actuator and the target position and attitude; a target position and attitude correction unit that corrects the target position and attitude based on the error information; and a program storage medium that stores the program for causing the control device to function as the target position and attitude correction unit.

Images