Patent Application
20230041313
The present invention relates to a control device for controlling a conveyance robot and a conveying system including the same.
Self-propelled conveyance robots such as automated guided vehicles (AGVs) and automated guided forklifts (AGFs) used in factories, warehouses, etc. have been proposed. A plurality of such conveyance robots are controlled by a control device through wireless communication to form a conveying system that realizes automation of conveyance in factories, etc.
The control device appropriately assigns conveyance instructions to the plurality of conveyance robots to realize the desired conveyance work. However, in a conveying system such as a factory or a warehouse, a large number of conveyance robots are usually deployed in order to handle a large number of conveyed objects. These conveyance robots may be in various states, and even if the control device transmits a conveyance instruction to a specific conveyance robot, a response may not be returned. The cause may be a problem in communication quality or a problem inherent in the conveyance robot itself.
However, in the past, it has not been clearly considered whether the cause is a problem in communication quality or a problem inherent in the conveyance robot, and regarding the issuance of instructions to the conveyance robot, no measures were taken in consideration of this point. The present invention has been made in view of such circumstances on one aspect, and an object of the present invention is to realize a control device of a conveying system that can evaluate the quality of communication between the control device and the conveyance robot in a mode suitable for the conveying system, thereby optimizing the assignment of conveyance instructions.
The present invention adopts the following configuration in order to solve the above-mentioned problems. The control device according to one aspect of the present invention is a control device for controlling a conveyance robot. The control device includes: a master communication unit that performs wireless communication with the conveyance robot; a communication quality determination unit that determines quality of the wireless communication based on a communication state of a telegram generated by the conveyance robot, which is received by the master communication unit; and an instruction state determination unit that determines an instruction state regarding whether to transmit an instruction for controlling the conveyance robot depending on the quality of the wireless communication.
According to the control device according to one aspect of the present invention, it is possible to realize a control device that can evaluate the quality of communication between the control device and the conveyance robot in a mode suitable for the conveying system, thereby optimizing the assignment of conveyance instructions.
Hereinafter, embodiments according to one aspect of the present invention will be described with reference to the drawings.
An example of a situation to which the present invention is applied will be described with reference to
The factory 100 is equipped with a conveyance robot 20 for conveying the conveyed objects such as products, semi-finished products, parts, tools, jigs, packing materials, and cassettes for storing these. As an example, the conveyance robot 20 is a self-propelled conveyance robot provided with a robot arm (manipulator) for gripping the conveyed object. However, the conveyance robot 20 may be an automated guided vehicle, an AGF or a self-propelled conveyance device in other forms.
A shelf 30 on which the conveyed object can be placed is installed in the factory 100. Further, a production facility that applies required processing such as assembly, machining, assembling, and inspection to place the conveyed object in a predetermined pick-up port when placing the conveyed object in a predetermined receiving port is also installed in the factory 100. Depending on the production facility, the receiving port and the pick-up port may be shared.
The conveyance robot 20 of the conveying system that includes the control device according to this application example can convey the conveyed object between these facilities. The conveyance robot 20 is provided with a telegram generator that generates a telegram, and a slave communication unit. The control device according to this application example is not shown in the floor map of
The control device according to this application example is further provided with a communication quality determination unit that determines the quality of wireless communication based on a communication state of the telegram received by the master communication unit. In addition, the control device according to this application example is provided with an instruction state determination unit that changes an instruction state regarding whether to transmit an instruction for controlling the conveyance robot depending on the quality of wireless communication.
In the control device according to this application example, the quality of communication between the control device and the conveyance robot 20 is evaluated based on the communication state of the telegram transmitted from the side of the conveyance robot 20 to the control device. Such a telegram may be a report for the conveyance robot 20 to notify the control device of the state, which is necessary for the control device to grasp the condition of each conveyance robot 20 and then assign a job.
Accordingly, the quality of communication can be evaluated by the state of communication actually performed by the control device and the conveyance robot for control, regardless of physical parameters such as wireless radio wave strength and physical communication speed. Therefore, such a communication quality evaluation method is suitable as an evaluation scale for allowing the control device to appropriately control the conveyance robot 20.
Further, in the control device according to this application example, the quality of communication between the control device and the conveyance robot 20 is evaluated, and based on the result, the instruction state regarding whether to transmit an instruction for controlling the conveyance robot is changed. Thus, the evaluation related to the quality of communication is performed separately from the problem inherent in the conveyance robot 20 to change the instruction state, so the conveying system can be operated appropriately.
Hereinafter, more specific configuration examples and operations of the control device and the conveying system will be described.
The control device 10 is an information processing system that manages conveyance, which is sometimes called by a name such as a conveying system server (AMHS server: Automated Material Handling System Server). The control device 10 transmits a more specific conveyance instruction to the conveyance robot 20 in the conveying system 1 based on a command from a host information processing system or the like. The control device 10 may be an information processing system capable of executing such processing, and does not need to be a device physically contained in one housing.
When the scene to which the conveying system 1 is applied is a production factory, the host information processing system that manages the production of products in the production factory may be referred to as a manufacturing execution system server (MES server). When the scene to which the conveying system 1 is applied is a distribution warehouse, the host information processing system that manages the receipt and delivery of stored items in the distribution warehouse may be referred to as a warehouse management system server (WMS server).
As shown in
The telegram generator 22 is a functional block that generates a telegram including information of the inherent state of the conveyance robot 20 for reporting to the control device 10 and notifies the control device 10 through the slave communication unit 21. The inherent state monitoring unit 23 is a functional block that acquires the inherent state of the conveyance robot 20. Here, the inherent state of the conveyance robot 20 refers to a state related to the individual conveyance robot itself, and for example, refers to a state related to the operation of the conveyance robot 20 and other internal states such as the current position, the state of operation, the state of loading of the conveyed object, and the remaining battery level.
The instruction receiver 24 is a functional block that receives an instruction regarding conveyance from the control device 10 to the conveyance robot 20 through the slave communication unit 21. The operation controller 25 is a functional block that controls the mechanism unit 26 based on the instruction received by the instruction receiver 24 and causes the conveyance robot 20 to execute a required operation.
The mechanism unit 26 is a mechanism for the conveyance robot 20 to execute the conveyance operation. The mechanism unit 26 includes at least a traveling mechanism for the conveyance robot 20 to move. Further, the mechanism unit 26 may have a mechanism such as a robot arm for picking up or placing the conveyed object.
As shown in
The communication quality determination unit 12 is a functional block that determines the quality of wireless communication with the conveyance robot 20 based on the communication state of the telegram from the conveyance robot 20, which is received by the master communication unit 11. The communication quality determination unit 12 includes a time series determination unit 121, a reception determination unit 122, a reception success rate calculation unit 123, and a quality classification unit 124. The functions and operations of each of these units will be described later.
The instruction state determination unit 13 is a functional block that changes the instruction state regarding whether to transmit an instruction for controlling the conveyance robot based on the determination result of the quality of wireless communication obtained by the communication quality determination unit 12. The slave monitoring unit 14 is a functional block that monitors the inherent state of the conveyance robot 20 in the conveying system 1. The slave monitoring unit 14 monitors the inherent state of the conveyance robot 20 at least based on the content of the telegram from the conveyance robot 20 received by the master communication unit 11.
The instruction generator 15 assigns a job regarding conveyance of the conveyed object in consideration of the inherent state of each conveyance robot 20 acquired by the slave monitoring unit 14 to the conveyance robot 20 in the conveying system 1 based on a command from the host information processing system or the like. Further, the instruction generator 15 generates an instruction such as conveyance to the conveyance robot 20 to which the job is assigned, and transmits the instruction through the master communication unit 11.
At that time, the instruction generator 15 also considers the instruction state determined by the instruction state determination unit 13 to execute assignment of a job regarding conveyance of the conveyed object and transmission of an instruction such as conveyance to the conveyance robot 20. The details will be described later. Here, the following is given as an example of assigning a job in consideration of the inherent state of the conveyance robot 20.
For example, when a certain conveyed object is to be moved, the job is assigned to the conveyance robot 20 whose operation state is not in the process of executing a job and is located near the place where the conveyed object is placed. Alternatively, the job is assigned by selecting the conveyance robot 20 having a sufficient battery level for conveyance.
Hereinafter, the characteristic operations of the control device 10 and the conveying system 1 according to the first embodiment will be described in detail. The telegram generator 22 of the conveyance robot 20 creates a telegram including the information of the inherent state of the conveyance robot 20 acquired by the inherent state monitoring unit 23 and time series information. At that time, the telegram may further include information regarding the radio wave strength of the wireless communication with the control device 10. The time series information may be information of time or may be the order in which the telegram is created. In the specific example of the first embodiment, it is assumed that the time series information is the information of time.
The telegram generator 22 periodically generates the above-mentioned telegram in order to sequentially transmit the inherent state of the conveyance robot 20 to the control device 10. The slave communication unit 21 of the conveyance robot 20 transmits the telegram as a telegram with an error correction code (so-called checksum) to the control device. A known method can be appropriately applied as error correction. For example, HMAC-SHA256 (Hash-based Message Authentication Code-Secure Hash Algorithm 256-bit) may be used as the error correction method.
When the master communication unit 11 of the control device 10 receives the telegram from the specific conveyance robot 20, the master communication unit 11 determines whether the received telegram has an error due to communication based on the error correction method and extracts the content of the telegram. Error correction may be executed if there is an error when extracting the content of the telegram. The content of the telegram is acquired by the slave monitoring unit 14. The time series determination unit 121 refers to the time series information of the telegram sequentially transmitted from the specific conveyance robot 20, and determines whether there is a telegram with time series of the received telegram different from the arrival time series.
The reception determination unit 122 determines whether the reception is successful based on the determination result of the time series determination unit 121 and the determination result of whether there is an error obtained by the master communication unit 11 for a certain telegram. The determination as to whether the reception is successful is that if there is no telegram with time series different from the arrival time series and there is no error, the reception is successful; otherwise, it is not successful.
The reception determination unit 122 counts the number of telegrams whose reception is successful within a predetermined period. It is also possible to determine whether the reception is successful only by the determination result of the time series determination unit 121. Alternatively, it is also possible to determine only by the determination result of whether there is an error obtained by the master communication unit 11.
The reception success rate calculation unit 123 calculates the reception success rate from the ratio of the number of telegrams received from the specific conveyance robot 20 to the number of telegrams successfully received within the predetermined period. Further, the reception success rate calculation unit 123 may also calculate the reception success rate by including determination as to whether a time difference between the time (time series information) of creating the telegram included in the telegram and the reception time of the telegram is within a predetermined time. Furthermore, the reception success rate calculation unit 123 may also calculate the reception success rate by including determination as to whether the radio wave strength of the information regarding the radio wave strength of the wireless communication with the control device 10 included in the telegram is equal to or greater than a predetermined value.
The quality classification unit 124 classifies and determines the communication quality according to the value of the reception success rate calculated by the reception success rate calculation unit 123 for each predetermined period. The classification of communication quality, for example, classifies a case where the reception success rate is equal to or greater than a first threshold value as a first category, a case where the reception success rate is equal to or less than a second threshold value as a third category, and a case between these as a second category.
Further, as an example, the first threshold value can be 70% and the second threshold value can be 30%. However, these threshold values are examples and are appropriately set according to the conveying system. As described above, the communication quality determination unit 12 determines the quality of communication according to the communication state of the telegram from the conveyance robot 20 received by the master communication unit 11.
Next, the instruction state determination unit 13 of the control device 10 determines the instruction state of the control device 10 according to the quality of communication determined by the quality classification unit 124 of the communication quality determination unit 12. The instruction state can be set to three states, for example, active (first state), pending (second state), and dead (third state) according to the first category, the second category, and the third category, respectively.
Active corresponds to a state considered to be a quality condition of communication in which the conveyance robot 20 can immediately receive an instruction such as conveyance. The control device 10 can execute the instruction to the conveyance robot 20 when the instruction state is active. That is, the instruction is permitted. Dead corresponds to a state considered to be a quality condition of communication in which the conveyance robot 20 cannot receive an instruction such as conveyance. The control device 10 does not execute the instruction to the conveyance robot 20 when the instruction state is dead. Further, when a response of the instruction to the conveyance robot 20 is not obtained, the job regarding the instruction is reassigned to another machine and the instruction is reissued.
Pending corresponds to a state considered to be an intermediate communication quality condition between active and dead. The control device 10 stands by for an instruction to the conveyance robot 20 when the instruction state is dead. Then, if the instruction state changes to active and the instruction can be made, the instruction of the conveyance robot 20 is executed, and if the instruction state changes to dead, the job is reassigned to another machine.
The instruction generator 15 assigns a job to a large number of conveyance robots 20 in the conveying system 1 according to the above-mentioned instruction state, and transmits an instruction to a specific conveyance robot 20. Therefore, in the control device 10 of the first embodiment, it is possible to optimize the assignment of the conveyance instruction and the timing of the instruction based on the quality of communication between the control device 10 and the conveyance robot 20.
In particular, in the conveying system 1, the above-mentioned pending state is provided between the instructable active instruction state and the non-instructable dead instruction state. Therefore, unnecessary operations in the conveying system, for example, job reassignment is repeated more than required or multiple conveyance robots 20 try to execute duplicate instructions, are suppressed.
In addition, the evaluation of the quality of communication is performed depending on the state of communication actually performed between the control device 10 and the conveyance robot 20 for control, regardless of physical parameters such as wireless radio wave strength and physical communication speed. Therefore, such a communication quality evaluation method is suitable as an evaluation scale for allowing the control device to appropriately control the conveyance robot 20.
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals are given to members having the same functions as the members described in the above embodiment, and the description thereof will not be repeated.
The control device 10 and the conveying system 1 according to the second embodiment have the same configurations as those of the first embodiment and operate in the same manner except that the operation of the quality classification unit 124 is different from that of the first embodiment. In the control device 10 according to the first embodiment, the quality classification unit 124 classifies and determines the communication quality according to the value of the reception success rate calculated by the reception success rate calculation unit 123. At that time, the quality classification unit 124 classifies the communication quality for each predetermined period according to the reception success rate in the period (current time).
On the contrary, in the control device 10 according to the second embodiment, the quality classification unit 124 of the communication quality determination unit 12 classifies and determines the communication quality by reflecting not only the reception success rate in the period (current time) but also the past reception success rate. The quality classification unit 124 of the second embodiment classifies the communication quality as follows based on the reception success rate.
The log odds L(t) obtained by converting the reception success rate P(t) at the time t by a logit function are calculated (the fourth column in
When the communication quality is classified by the method of the second embodiment, the classification is made by reflecting the past values of the reception success rate. Therefore, even if the reception success rate P(t) fluctuates greatly from time to time, the fluctuation of the instruction state is suppressed. In the case of the second embodiment, even if the reception success rate P(t) fluctuates greatly from time to time, such as time t=5 and thereafter in
In each of the above embodiments, the first threshold value and the second threshold value for classifying the communication quality need to be appropriately set so that the instruction state can be appropriately determined. These threshold values can be appropriate values determined by trial and error in a factory or the like to which the conveying system 1 is applied. However, for this purpose, it is necessary to acquire a large amount of data and modify it appropriately to find the most preferable values.
The third embodiment describes a method that can support determination of such threshold values. In the method of determining the threshold values according to the third embodiment, for various places (factories, warehouses, etc.) to which the conveying system is applied, places with similar communication characteristics are grouped (class determination) as belonging to the same group, and appropriate threshold values are held in advance for each of them. Then, when the conveying system is applied to a new place, the communication characteristics in the place are measured, and the threshold value of the group with the closest characteristics is adopted as the recommended value of the threshold value in the place.
Such grouping (class determination) in the third embodiment is characterized in that various probabilities regarding the parameters used for calculating the communication quality in each of the above embodiments are used as data to be examined. That is, the data to be examined includes the following.
Time series validity probability, which is the ratio of telegrams having no discrepancy in the reception time series to the telegrams within the period. Reliability probability, which is the ratio of telegrams having no error correction by the error correction method to the telegrams within the period. In-time arrival probability, which is the ratio of telegrams, in which the time difference between the time (time series information) of creating the telegram included in the telegram and the reception time of the telegram is within a predetermined time, to the telegrams within the period. Valid radio wave strength probability, which is the ratio of telegrams, in which the radio wave strength of information regarding the radio wave strength of the wireless communication with the control device 10 included in the telegram is equal to or greater than a predetermined value, to the telegrams within the period.
A subspace method can be applied as a method of grouping (class determination). Since this method is a known statistical method, it will be briefly described. First, a vector a(k) having each of the data to be examined (various probabilities) as an element is defined for each period k. Further, an in-system communication value matrix Ad in which n vectors a(k) are arranged is defined for the period k (k is an integer from 1 to n) in which measurement is performed.
The eigenvalue decomposition of the in-system communication value matrix Ad is performed to obtain the eigenvalue λ(k) and the eigenvector x(k). The average value vector b of n vectors a(k) is obtained. The inner product ω(k) of the vector a(k)-b and the eigenvector x(k) is obtained for each k. This inner product ω(k) is called the expansion count of the eigenvector. A vector Ω is derived in which the expansion counts ω(k) of the eigenvectors are arranged up to an appropriate dimension m in descending order of the eigenvalues λ(k). The Ω is referred to as an in-system communication feature vector.
The in-system communication feature Ω is calculated for various places (factories, warehouses, etc.) to which the conveying system is applied, and is appropriately grouped for each gathering in the space where the in-system communication feature Ω exists. By a method such as obtaining the average vector of the in-system communication feature Ω for the place belonging to a specific group, the representative in-system communication feature Ωg representing the group is calculated.
When the conveying system is applied to a new place, the in-system communication feature Ω is calculated in the same manner, and to which group it belongs is determined depending on which group has the closest representative in-system communication feature vector Ωg. The threshold value set to the group is adopted as the recommended threshold value in the conveying system applied to the new place.
The control device according to the third embodiment further includes a threshold value calculation unit that calculates the threshold value by the above-mentioned method, in addition to the configuration of the control device described in the first embodiment with reference to
The functional blocks of the control device 10 (particularly, the master communication unit 11, the communication quality determination unit 12, the instruction state determination unit 13, the slave monitoring unit 14, and the instruction generator 15) or the functional blocks of the conveyance robot 20 (particularly, the slave communication unit 21, the telegram generator 22, the inherent state monitoring unit 23, the instruction receiver 24, and the operation controller 25) may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.
In the latter case, the control device 10 or the conveyance robot 20 includes a computer that executes instructions of a program that is software for realizing each function. The computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. Then, in the computer, the processor reads the program from the recording medium and executes the program, thereby achieving the object of the present invention.
For example, a CPU (Central Processing Unit) can be used as the processor. A “non-temporary tangible medium,” for example, a ROM (Read Only Memory) or the like, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, etc. can be used as the recording medium. Further, a RAM (Random Access Memory) for developing the program may be further included.
Furthermore, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. One aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.
The control device according to one aspect of the present invention is a control device for controlling a conveyance robot. The control device includes: a master communication unit that performs wireless communication with the conveyance robot; a communication quality determination unit that determines quality of the wireless communication based on a communication state of a telegram generated by the conveyance robot, which is received by the master communication unit; and an instruction state determination unit that determines an instruction state regarding whether to transmit an instruction for controlling the conveyance robot depending on the quality of the wireless communication.
According to the above configuration, it is possible to realize the control device of the conveying system that can evaluate the quality of communication between the control device and the conveyance robot in a mode suitable for the conveying system, thereby optimizing the assignment of conveyance instructions.
In the control device according to the one aspect, the telegram may include information regarding the conveyance robot and time series information. The communication quality determination unit may include: a time series determination unit that determines an arrival time series error of the telegram based on the time series information of a plurality of the telegrams from the conveyance robot; a reception success rate calculation unit that calculates a reception success rate of the wireless communication based on at least the number of occurrences of the arrival time series error; and a quality classification unit that classifies the quality of the wireless communication according to the reception success rate.
According to the above configuration, the quality of communication is specifically evaluated by the state of communication performed by the control device and the conveyance robot for control. In addition, such evaluation of communication is excellent as a scale for allowing the control device to appropriately control the conveyance robot, and the control device that can more appropriately assign conveyance instructions can be realized.
In the control device according to the one aspect, the reception success rate calculation unit may further include a configuration that calculates the reception success rate of the wireless communication based on the number of occurrences of error correction of the telegram. According to the above configuration, the quality of communication is specifically evaluated by the state of communication from a plurality of viewpoints performed by the control device and the conveyance robot for control. Therefore, the control device that can more appropriately assign conveyance instructions can be realized.
In the control device according to the one aspect, the quality classification unit may include a configuration that classifies the quality of the wireless communication by reflecting a past value and a current value of the reception success rate. According to the above configuration, the job assignment and instruction can be performed on the conveyance robot in the conveying system without being affected by small fluctuations in the communication state.
In the control device according to the one aspect, the instruction state may include a configuration that includes: a first state that permits transmission of a command to the conveyance robot; a second state that stands by for transmission of the command to the conveyance robot; and a third state that reassigns and transmits the command transmitted to the conveyance robot to another conveyance robot. According to the above configuration, unnecessary operations in the conveying system, for example, job reassignment is repeated more than required or multiple conveyance robots try to execute duplicate instructions, are suppressed.
A conveying system according to one aspect of the present invention includes: a conveyance robot provided with a telegram generator that generates the telegram and a slave communication unit that performs the wireless communication, and any of the above control devices. According to the above configuration, it is possible to realize the conveying system that can evaluate the quality of communication between the control device and the conveyance robot in a mode suitable for the conveying system, thereby optimizing the assignment of conveyance instructions performed by the control device.
The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the disclosed technical means.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-034048 | Feb 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/004691 | 2/9/2021 | WO |
