Robot control device, robot system, and robot control program
The robot control device stabilizes sensor outputs by integrating photoelectric sensors and encoders to address inaccurate detection in robot systems, enabling precise object packing.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- FANUC LTD
- Filing Date
- 2024-12-10
- Publication Date
- 2026-06-18
Smart Images
Figure JP2024043662_18062026_PF_FP_ABST
Abstract
Description
Robot control device, robot system, and robot control program 【0001】 The present disclosure relates to a robot control device, a robot system, and a robot control program. 【0002】 Conventionally, there is known a robot system that detects a container (box) flowing on a conveyor by a photoelectric tube sensor (photoelectric sensor), and a robot follows the detected container and packs an object (work). That is, a robot system that packs an object by a robot with respect to a container conveyed from upstream to downstream by a conveying device such as a conveyor is used in various fields. 【0003】 Here, the arrival of a container for any robot is calculated based on, for example, detection by a camera or a photoelectric tube sensor provided upstream of the robot, or the moving amount of the conveyor obtained from the value of an encoder provided in the conveying device. 【0004】 Conventionally, various proposals have been made for a robot system that packs an object by a robot with respect to a container conveyed from upstream to downstream by a conveying device. 【0005】 Japanese Patent Application Laid-Open No. 2018-001312, Japanese Patent Application Laid-Open No. 2019-086398 【0006】 By the way, since the output of an actual photoelectric tube sensor is not stable, there are problems such as it being difficult to detect the correct start point and end point of a container, and it being difficult to pack an object at an accurate position. 【0007】 Therefore, in a robot system that packs an object by a robot, there is a demand for accurately recognizing the position of the object and performing the packing of the object with high precision. 【0008】 According to an embodiment of the present disclosure, there is provided a robot control device to which a photoelectric tube sensor that detects an object conveyed on a conveyor and an encoder that detects the moving amount of the conveyor are connected, and that selects whether or not the object has actually arrived based on the output of the photoelectric tube sensor and the moving amount of the conveyor. 【0009】Figure 1 is a diagram illustrating the processing of each robot in an example of a robot system. Figure 2 is a diagram schematically showing the configuration of each robot in the robot system shown in Figure 1. Figure 3 is a diagram illustrating the operation in an example of a robot system to which a robot control device is applied. Figure 4 is a diagram illustrating the movable range of the robot control device in an example of the robot system shown in Figure 3. Figure 5 is a schematic block diagram showing one embodiment of the robot system according to this embodiment. Figure 6 is a diagram illustrating an example of the control flow of the position determination unit in the robot system according to this embodiment. Figure 7 is a diagram illustrating another example of the control flow of the position determination unit in the robot system according to this embodiment. 【0010】 First, before detailing embodiments of the robot control device, robot system, and robot control program according to this embodiment, an example of a robot system to which the robot control device is applied and its problems will be described with reference to Figures 1 to 4. 【0011】 Figure 1 is a diagram illustrating the processing of each robot in an example of a robot system, and Figure 2 is a schematic diagram showing the configuration of each robot in the robot system shown in Figure 1. It goes without saying that Figures 1 and 2 are merely examples of robot systems and are capable of various modifications and changes. 【0012】 In Figures 1 and 2, reference numeral 1 denotes a robot, 1a denotes an arm, 2 denotes a robot control device, 11, ..., 1m denotes the first, ..., m-th robots, 21, ..., 2m denotes the first, ..., m-th robot control devices, 3 denotes a container, and 4 denotes the object (workpiece). Furthermore, reference numeral 5 denotes a conveyor for transporting containers, 6 denotes a conveyor for transporting object, 50 and 60 denotes encoders, 61 denotes a camera (vision sensor), 71 denotes the first photocell sensor, and 7m denotes the m-th photocell sensor. 【0013】Reference numerals A1, ..., Am indicate the areas (work areas) where robots 11, ..., 1m can perform work, respectively. In the robot system 100 shown in Figure 1, the container transport conveyor 5 and the object transport conveyor 6 transport the container 3 and the object 4, respectively, from left (upstream) to right (downstream) in the figure. Here, robots 11, ..., 1m, robot control devices 21, ..., 2m, and photoelectric sensor sensors etc. 71, ..., 71m may each be a single unit. 【0014】 Each photoelectric sensor 71, ..., 7m is equipped with a light receiving unit 71a, ..., 7ma and a light emitting unit 71b, ..., 7mb, and recognizes the presence of the container 3 when the container 3 blocks the light output from the light emitting units 71b, ..., 7mb. Furthermore, encoders 50, 60 and a camera 61, as well as the first, ..., m robot control devices 21, ..., 2m, etc., control the loading of objects 4 into the container 3 by the first, ..., m robots 11, ..., 1m. 【0015】 As described above, the robot system 100 shown in Figures 1 and 2 is configured to pack multiple (a predetermined number) objects 4 into containers 3 that are transported from upstream to downstream by a container transport conveyor 5, using m robots 11 to 1m. In Figure 1, only two photoelectric sensors 71 and 7m are shown, but the number of robots 1 and photoelectric sensors (70) can be appropriately changed depending on the work object and specifications to be applied. In addition, the camera 61 can be installed not only upstream of the first robot 11 but also near the downstream robot (for example, the mth robot), and the status of the object 4 being packed into the containers 3 can be checked by each camera. 【0016】Furthermore, the first photocell sensors 71, ..., and the mth photocell sensor 7m have a similar configuration and each comprises a light receiving unit 71a, ..., 7ma and a light emitting unit 71b, ..., 7mb. When a container 3 is placed between the light receiving unit 71a, ..., 7ma and the light emitting unit 71b, ..., 7mb, the light receiving unit 71a, ..., 7ma becomes unable to receive light from the light emitting unit 71b, ..., 7mb, and the position information of the container 3 is acquired from the moment the container 3 blocks the light. Note that the photocell sensors 71, ..., 7m are not limited to transmissive photocell sensors as shown in the figure, but may also be retroreflective or diffuse reflective photocell sensors. Moreover, the photocell sensors 71, ..., 7m are not limited to photocell sensors, and various other sensors, such as visual sensors, can be applied as long as they can detect the container 3 being transported by the container transport conveyor 5 and acquire its position information. 【0017】 The container transport conveyor 5 is equipped with an encoder (movement information acquisition sensor) 50 for acquiring movement information such as the movement speed and distance of the transported container 3. Furthermore, the encoder 50 does not necessarily need to be installed on the transport belt of the container transport conveyor 5, as long as it can acquire movement information of the container 3 by the container transport conveyor 5; for example, it may be installed on the drive motor of the container transport conveyor 5. Moreover, as long as the encoder 50 can acquire movement information of the container 3 by the container transport conveyor 5, various other means can also be applied. 【0018】 Figure 3 is a diagram illustrating the operation of an example robot system to which a robot control device is applied, where Figure 3(a) shows an ideal waveform and Figure 3(b) shows an actual waveform. Figure 4 is a diagram illustrating the movable range of the robot control device in the example robot system shown in Figure 3, and corresponds to the waveform in Figure 3(b) described above. In other words, Figures 3 and 4 are for illustrating the problems in the robot system 100 described with reference to Figures 1 and 2. 【0019】As explained with reference to Figures 1 and 2, a robot system 100 is known in which, for example, a photoelectric sensor 71, ..., 7m detects containers 3 flowing on a container transport conveyor 5, and a robot 11, ..., 1m follows the detected containers 3 and packs objects 4 into them. However, as shown in Figure 3(b), for example, the output of the actual photoelectric sensor 71, ..., 7m is not stable, making it difficult to detect the correct starting and ending points of the container 3, and thus difficult to pack the objects 4 into the precise positions of the containers 3. Here, in Figures 3(a) and 3(b), the vertical axis represents the sensor signal (output of the photoelectric sensor 71, ..., 7m), and the horizontal axis represents time / distance. 【0020】 In other words, as shown in Figure 3(a), the output (ideal waveform) of the photocell sensor is such that, for example, when a component (container 3) comes in front of the photocell sensor 71, ..., 7m, a normal polarity trigger for setting the first rising edge rises, and when container 3 is no longer in front of the photocell sensor 71, ..., 7m, an inverted polarity trigger for setting the first falling edge falls. At this time, as shown in Figure 3(b), the actual waveform of the photocell sensor may, for example, incorrectly output an inverted polarity trigger (component detection / non-detection signal) for setting the first falling edge for a predetermined time after container 3 (component) has come in front of the photocell sensor 71, ..., 7m. Alternatively, as shown in Figure 3(b), incorrectly output a component detection / non-detection signal for a predetermined time after component is no longer in front of the photocell sensor 71, ..., 7m. 【0021】 Figure 4 is a diagram illustrating the movable range of the robot control device in an example of the robot system shown in Figure 3, and corresponds to the waveform in Figure 3(b) described above. In Figure 4, rectangular waveform-shaped false detection portions L, L before and after the detection signal D of the container 3 by the photoelectric sensors 71, ..., 7m may occur, for example, due to deformation of the edges of the container 3, and may represent several percent to 10 percent of the detection signal D (these are exaggerated in Figure 4). 【0022】Thus, if the detection signal D of the container 3 (output of photoelectric sensors 71, ..., 7m) is not output correctly, there is a problem in that it becomes difficult to pack the object 4 into the container 3. In other words, in a robot system in which multiple robots 11, ..., 1m pack multiple object 4 into a container 3 transported by a transport device 5, it is difficult to accurately recognize the position of the object 4 and to pack the object 4 with high precision. 【0023】 Hereinafter, embodiments of the robot control device, robot system, and robot control program according to this embodiment will be described in detail with reference to the accompanying drawings. In each drawing, identical or similar components are denoted by the same or similar reference numerals. Furthermore, the embodiments described below do not limit the technical scope of the invention and the meaning of terms as described in the claims. 【0024】 Figure 5 is a schematic block diagram showing one embodiment of the robot system according to this embodiment. As shown in Figure 5, one embodiment of the robot system according to this embodiment comprises a robot 1, a robot control device 2, an encoder 50, and a photoelectric sensor 70. The robot control device 2 comprises a signal receiving unit 201, an encoder receiving unit 202, an operation program 203, a position determination unit 204, an operation control unit 205, a queue management unit 206, a queue 207, and a robot drive unit 208. 【0025】The signal receiving unit 201 receives the output of the photoelectric sensor 70 (71, ..., 7m), detects, for example, the container 3 being transported by the container transport conveyor 5, and outputs it to the position determination unit 204. The encoder receiving unit 202 receives the output of the encoder 50, acquires information about the container 3 being transported by the container transport conveyor 5, and outputs it to the position determination unit 204. The position determination unit 204 receives the output of the signal receiving unit 201 and the output of the encoder receiving unit 202, determines the position of the container 3, acquires information about the object 4 in the container 3, etc., and outputs it to the queue management unit 206. Here, the queue management unit 206 receives the output of the encoder receiving unit 202 along with the output of the position determination unit 204, manages the queue, holds the queue data in the queue 207, and further controls the robot 1 via the motion control unit 205 and the robot drive unit 208. 【0026】 Here, the motion control unit 205 controls the robot 1 via the robot drive unit 208 based on, for example, an operation program 203 that has been stored in the memory of the robot control device 2 in advance. It should be noted that the robot system shown in Figure 5 is merely an example, and it goes without saying that the robot system according to this embodiment can be modified and transformed in various ways. 【0027】 In one embodiment of the robot system according to this embodiment, for example, as described with reference to Figure 1, the object transport conveyor 6 transports multiple objects 4 in the same direction as the container transport conveyor 5 (from left (upstream) to right (downstream) in the figure), but the configuration is not limited to this. That is, in Figure 1, the multiple objects 4 that the multiple robots 11, ..., 1m pack into the container 3 are supplied to each robot 11, ..., 1m using the object transport conveyor 6, but the objects 4 can be supplied by various means. 【0028】Furthermore, in Figure 1 mentioned above, only two robots (the upstream robot 11 and an arbitrary robot 1m) are depicted for the sake of simplicity, but an actual robot system 100 can be equipped with many more robots 1. Also, each robot 11, ..., 1m in Figure 1 corresponds to, for example, the robot 1 shown in Figure 2, and each robot control device 21, ..., 2m in Figure 1 corresponds to the robot control device 2 shown in Figure 2. Here, the container 3 is a tray made of cardboard, synthetic resin, or metal, and the object 4 can be various items such as various parts, products (finished products), materials, or processed goods. Specifically, the object 4 may be various items such as parts of various industrial products, or products such as food, pharmaceuticals, and cosmetics, or fresh food. 【0029】 As shown in Figure 1, the work area A1 of the robot 11 includes the areas of both the container transport conveyor 5 and the object transport conveyor 6. Also, as shown in Figure 2, the robot 11, for example, uses a gripping mechanism provided at the tip (hand) 1b of the arm 1a to grip an object 4 transported by the object transport conveyor 6 and loads it into a container 3 transported by the container transport conveyor 5. Similarly, the work area Am of the robot 1m includes the areas of both the container transport conveyor 5 and the object transport conveyor 6, and the robot 1m, for example, uses a gripping mechanism provided at the tip 1b of the arm 1a to grip an object 4 transported by the object transport conveyor 6 and loads it into a container 3 transported by the container transport conveyor 5. It goes without saying that the robot system according to this embodiment is not limited to that described with reference to Figures 1 and 2. 【0030】In other words, according to this embodiment, a robot control device 2 is provided that controls an object 4 to be packed into a container 3, and which connects photoelectric sensor sensors 71, ..., 7m that detect containers 3 being transported on a conveyor (container transport conveyor) 5 and an encoder 50 that detects the amount of movement of the container transport conveyor 5, and which selects whether an object 4 has actually arrived based on the output of the photoelectric sensor sensors 71, ..., 7m and the amount of movement of the container transport conveyor 5. Specifically, the position of the container 3 (object 4) is determined based on the input of the photoelectric sensor sensors 71, ..., 7m and the amount of movement of the container transport conveyor 5. Specifically, for example, when detecting the arrival of a container 3 (length D) with a signal ON, if the section where the signal is unstable is L, it can be determined that the container 3 (object 4) has arrived only if the signal is ON when passing L after the signal has turned ON. Here, if it is determined that an object has arrived, the next signal ON is ignored after the signal ON until D + L has passed. Note that D and L may be either length [mm] or time [ms]. 【0031】 In this way, by ignoring the signal on in sections where the signal output is unstable (for example, section L in Figure 4), it becomes possible to pack the object 4 into the container 3 at the correct position. Furthermore, by determining that the object 4 has arrived only when the signal is on after passing section L, false detections can be prevented, thus preventing the robot 1 from packing the object 4 into a location where the container 3 does not actually exist. 【0032】 Figure 6 is a diagram illustrating an example of the control flow of the position determination unit in the robot system according to this embodiment. As shown in Figure 6, when an example of the control flow of the position determination unit (204) in the robot system according to this embodiment starts, in step ST1, the unit waits until the photoelectric sensor (for example, 7m) turns on, and when it is determined that the photoelectric sensor 7m is on (YES), the unit proceeds to step ST2. In step ST2, it is determined whether the conveyor 5 has moved by a distance L, and when it is determined that the conveyor 5 has moved by a distance L (YES), the unit proceeds to step ST3, and when it is determined that the conveyor has not moved by a distance L (NO), the unit returns to step ST1. 【0033】In step ST3, it is determined whether the photocell sensor 7m is turned on. If it is determined that the photocell sensor 7m is turned on (YES), the process proceeds to step ST4. If it is determined that the photocell sensor 7m is not turned on (NO), the process returns to step ST1 and the same processing as described above is performed. In step ST4, the information of the object 4 is entered into the queue management unit 206 and the process proceeds to step ST5. In step ST5, the process waits until the conveyor 5 has moved a distance D+L. Then, in step ST5, if it is determined that the conveyor 5 has moved a distance D+L, the process returns to step ST1 and the same processing is performed. 【0034】 As described above, in an example of the control flow of the position determination unit 204 in the robot system according to this embodiment, if it is determined that the photocell sensor is turned on in step ST1 (YES), the conveyor has moved a distance L in step ST2 (YES), and the photocell sensor 7m has turned on in step ST3 (YES), then in step ST4, information about the object 4 is sent to the queue management unit 206. Then, the process proceeds to step ST5, and the system waits until the conveyor 5 has moved a distance D+L. Thus, according to the robot system according to this embodiment, if it is determined that the conveyor 5 has moved a distance L and the photocell sensor 7m has turned on, then in step ST4, information about the object 4 is sent to the queue management unit 206. As a result, when detecting the arrival of the object 4 (length D) by turning on the signal, the section where the signal is unstable is defined as L, and it is possible to determine that the object 4 has arrived only if the signal is turned on when the object has passed distance L after the signal has turned on. If it is determined that object 4 has arrived, the next signal is ignored after the signal is turned on until distance D+L has passed. Note that D and L may be either length [mm] or time [ms]. 【0035】 Furthermore, the judgment that "object 4 has arrived only if the signal is on when a distance (time) L has passed after the signal is turned on" can also be changed to "the judgment of whether object 4 has arrived begins when a distance (time) L has passed after the signal is turned on." Specifically, for example, it is also possible to determine that object 4 has arrived if the section in which the signal is on from L to the time when L+La[mm] has passed is a predetermined proportion α or more. 【0036】 Furthermore, the timing for starting to wait for the next object may be when the conveyor has moved a predetermined distance (for example, L2:L2≧L) after the photoelectric sensor turns on. Alternatively, the timing can be the same regardless of whether or not the arrival of the object has been determined. As mentioned above, D and L may be either length [mm] or time [ms]. 【0037】 Figure 7 is a diagram illustrating another example of the control flow of the position determination unit in the robot system according to this embodiment. As shown in Figure 7, when another example of the control flow of the position determination unit (204) in the robot system according to this embodiment is started, the same processing as steps ST1 to ST3 in Figure 6 described above is performed. Then, in step ST3, it is determined whether the photoelectric sensor 7m is turned on or not. If it is determined that the photoelectric sensor 7m is turned on (YES), the process proceeds to step ST6. If it is determined that the photoelectric sensor 7m is not turned on (NO), the process returns to step ST1 and the same processing as described above is performed. 【0038】 In step ST6, the system waits until the photocell sensor 7m turns off, then proceeds to step ST7, where the information of the object 4 is input to the queue management unit 206 and the system returns to step ST1. In this way, in another example of the control flow of the position determination unit 204 in the robot system according to this embodiment, if it is determined in step ST3 that the photocell sensor 7m is ON (YES), the system waits in step ST6 until the photocell sensor 7m turns off. Then, the system proceeds to step ST7, where the information of the object 4 is input to the queue management unit 206 and the system returns to step ST1 to perform the same process. As mentioned above, there may be only one robot 11, ..., 1m, robot control devices 21, ..., 2m, and photocell sensors etc. 71, ..., 71m etc. 【0039】The robot control program according to the embodiment described above may be provided by recording it on a computer-readable non-temporary recording medium or non-volatile semiconductor memory, or it may be provided via wired or wireless connection. Examples of computer-readable non-temporary recording media include optical discs such as CD-ROMs (Compact Disc Read Only Memory) and DVD-ROMs, or hard disk drives. Examples of non-volatile semiconductor memory include PROMs (Programmable Read Only Memory) and flash memory. Furthermore, distribution from the server device may be via a wired or wireless LAN (Local Area Network), or via a WAN (Wide Area Network) such as the Internet. 【0040】 As described in detail above, the robot control device, robot system, and robot control program according to this embodiment enable accurate recognition of the position of an object and high-precision loading of the object. 【0041】 While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values or mathematical formulas are used in the description of the embodiments described above. 【0042】With respect to the above embodiments and modifications, the following additional notes are disclosed. [Addendum 1] A robot control device (2) connected to a photoelectric sensor (70; 71, ..., 7m) for detecting an object (4) being transported on a conveyor (5) and an encoder (50) for detecting the amount of movement of the conveyor (5), wherein the robot control device selects whether the object (4) has actually arrived based on the output of the photoelectric sensor (70; 71, ..., 7m) and the amount of movement of the conveyor (5). [Note 2] The robot control device according to Note 1, wherein when the conveyor (5) has moved a distance of a first distance (L) after the photoelectric sensor (70; 71, ..., 7m) has been turned on, a determination of whether the object (4) is present is started, and when the conveyor (5) has moved a distance of a second distance (L2) which is longer than or equal to the first distance (L) after the photoelectric sensor (70; 71, ..., 7m) has been turned on, waiting for the arrival of the next object (4) is started. [Note 3] The robot control device according to Note 1 or Note 2, wherein the object (4) is packed into a container (3), and the selection of whether the object (4) has actually arrived is made by determining whether the object (4) has actually arrived in the container (3). [Note 4] The robot control device according to any one of Notes 1 to 3, wherein the container (3) is transported on a container transport conveyor (5), the photoelectric sensor (70; 71, ..., 7m) and the encoder (50) are provided on the container transport conveyor (5), and the object (4) before being packed into the container (3) is transported by an object transport conveyor (6) different from the container transport conveyor (5). [Note 5] The robot control device according to any one of Notes 1 to 4, wherein the first distance (L) and the second distance (L2) are defined based on predetermined distances. [Note 6] The robot control device according to any one of Notes 1 to 4, wherein the first distance (L) and the second distance (L2) are defined based on predetermined time. [Note 7] A robot system comprising a robot control device (2; 21, ..., 2m) described in any one of Notes 1 to 6, and a robot (1; 11, ..., 1m) controlled by the robot control device (2; 21, ..., 2m).[Note 8] The robot system according to Note 7, further comprising a container transport conveyor (5) for transporting the container (3) and an object transport conveyor (6) for transporting the object (4). [Note 9] A robot control program in which a photoelectric sensor (70; 71, ..., 7m) for detecting an object (4) being transported on the conveyor (5) and an encoder (50) for detecting the amount of movement of the conveyor (5) are connected, wherein the arithmetic processing unit (2) is instructed to perform a process of selecting whether or not the object (4) has actually arrived based on the output of the photoelectric sensor (70; 71, ..., 7m) and the amount of movement of the conveyor (5). [Note 10] Furthermore, the robot control program described in Note 9 causes the processing unit (2) to start determining whether the object (4) is present when the conveyor (5) has moved a first distance (L) since the photoelectric sensor (70; 71, ..., 7m) turned on, and to start waiting for the arrival of the next object (4) when the conveyor (5) has moved a second distance (L2) which is longer than the first distance (L) since the photoelectric sensor (70; 71, ..., 7m) turned on. 【0043】 1; 11, ..., 1m Robot 2; 21, ..., 2m Robot control device 3 Container (box) 4 Object (workpiece) 5 Container transport conveyor 6 Object transport conveyor 50, 60 Encoder 61 Camera (visual sensor) 70 Photocell sensor 71, ..., 7m First photocell sensor, ..., mth photocell sensor 71a, ..., 7ma Light receiving unit 71b, ..., 7mb Light emitting unit 100 Robot system 201 Signal receiving unit 202 Encoder receiving unit 203 Operation program 204 Position determination unit 205 Operation control unit 206 Queue management unit 207 Queue 208 Robot drive unit A1, ..., Am Work area
Claims
1. A robot control device connected to a photoelectric sensor for detecting an object being transported on a conveyor and an encoder for detecting the amount of movement of the conveyor, wherein the robot control device determines whether the object has actually arrived based on the output of the photoelectric sensor and the amount of movement of the conveyor.
2. The robot control device according to claim 1, wherein the device starts determining whether an object exists when the conveyor has moved a first distance after the photoelectric sensor has been turned on, and starts waiting for the arrival of the next object when the conveyor has moved a second distance that is longer than or equal to the first distance after the photoelectric sensor has been turned on.
3. The object is packed into a container, and the sorting of whether the object has actually arrived is performed by sorting by whether the object has actually arrived in the container, according to claim 1 or claim 2.
4. The robot control device according to any one of claims 1 to 3, wherein the container is transported on a container transport conveyor, the photoelectric sensor and the encoder are provided on the container transport conveyor, and the object before being packed into the container is transported by an object transport conveyor different from the container transport conveyor.
5. The robot control device according to any one of claims 1 to 4, wherein the first distance and the second distance are determined based on predetermined distances.
6. The robot control device according to any one of claims 1 to 4, wherein the first distance and the second distance are determined based on a predetermined time.
7. A robot system comprising a robot control device according to any one of claims 1 to 6, and a robot controlled by the robot control device.
8. The robot system according to claim 7, further comprising a container transport conveyor for transporting the containers and an object transport conveyor for transporting the objects.
9. A robot control program comprising a photoelectric sensor for detecting an object being transported on a conveyor and an encoder for detecting the amount of movement of the conveyor, wherein the robot control program causes a processing unit to perform a process of determining whether the object has actually arrived based on the output of the photoelectric sensor and the amount of movement of the conveyor.
10. The robot control program according to claim 9, further comprising the process of causing the processing unit to start determining whether the object exists when the conveyor has moved a first distance since the photoelectric sensor turned on, and to start waiting for the arrival of the next object when the conveyor has moved a second distance which is longer than or equal to the first distance since the photoelectric sensor turned on.