Mobile system and position estimation method

Abstract

The servo motor (20) is driven, whereby the machine (10) is moved via the ball screw (30). The first detection sensor (50) detects the presence or absence of the machine (10) at the first reference position (P) whose position has been previously identified. When the machine (10) is detected by the first detection sensor (50), the control device (60) stores the state of the servo motor (20) detected by the encoder (40) as reference state information. The control device (60) estimates the position of the machine (10) based on the state of the servo motor (20) detected by the encoder (40) and the reference state information.

Description

Technical Field

[0001] The present invention relates to a mobile system and a position estimation method. Background Art

[0002] In a production line of a factory, a system is known in which machines such as robots and working devices move according to operation processes to process and convey a workpiece as a processing object. In the above-described system, in order to avoid contact between the machines and operators, equipment, etc., it is important to accurately detect the position of a moving object such as a moving machine. As a technique for detecting the position of a moving object such as a moving machine, various techniques are known.

[0003] For example, Patent Document 1 discloses the following technique: detecting the position of a moving object such as a machine tool by a linear scale. In addition, the following technique is also known: detecting the position of a moving object by a detection sensor provided at a predetermined position.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-337037 Summary of the Invention

[0005] In the method described in Patent Document 1, although highly accurate position detection can be performed, since it is necessary to arrange a linear scale over the entire moving path of the machine, the system as a whole becomes large-sized and the cost increases.

[0006] On the other hand, in the case of using a detection sensor, in order to achieve highly accurate position detection, it is necessary to uniformly arrange many detection sensors on the moving path of the machine, so the cost increases.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to obtain a mobile system and a position estimation method capable of estimating the position of a moving object at a lower cost and more accurately than in the past.

[0008] To achieve the above object, the mobile system according to the present invention includes:

[0009] A drive unit that drives to move a moving object;

[0010] A first detection unit that detects the presence or absence of the moving object at a first reference position whose position has been previously identified;

[0011] A state detection unit that detects the state of the drive unit; and a control device that receives information input from the first detection unit and the state detection unit,

[0012] The control device includes:

[0013] A reference state storage unit that stores, as reference state information, the state of the drive unit detected by the state detection unit when the moving object is detected by the first detection unit; and

[0014] A position estimation unit that estimates the position of the moving object based on the state of the drive unit detected by the state detection unit and the reference state information.

[0015] Effects of the Invention

[0016] According to the present invention, it is possible to estimate the position of a moving object more accurately and at lower cost than in the past. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a diagram showing the configuration of a mobile system according to Embodiment 1 of the present invention.

[0018] Figure 2 It is a block diagram showing the configuration of a control device according to Embodiment 1 of the present invention.

[0019] Figure 3 It is a diagram showing information stored in a secondary storage device of a control device according to Embodiment 1 of the present invention.

[0020] Figure 4 It is a diagram showing an example of information stored in a sensor information storage unit according to Embodiment 1 of the present invention.

[0021] Figure 5 It is a diagram showing an example of information stored in an encoder information storage unit according to Embodiment 1 of the present invention.

[0022] Figure 6 It is a diagram showing an example of information stored in a region information storage unit according to Embodiment 1 of the present invention.

[0023] Figure 7 It is a flowchart of a reference state registration process according to Embodiment 1 of the present invention.

[0024] Figure 8 It is a flowchart of a position estimation process according to Embodiment 1 of the present invention.

[0025] Figure 9 It is a diagram showing the configuration of a mobile system according to Embodiment 2 of the present invention.

[0026] Figure 10 It is a flowchart of a position estimation process according to Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Next, each embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same or corresponding parts in the drawings are denoted by the same reference numerals.

[0028] <Embodiment 1>

[0029] Figure 1 FIG. 1 is a diagram showing the overall structure of a mobile system 100 according to Embodiment 1 of the present invention. The mobile system 100 is, for example, arranged on a production line in a factory and is a system for moving a moving object such as a robot or a working device, that is, a machine 10. The mobile system 100 includes a servo motor 20, a servo amplifier 21, a servo driver 22, a ball screw 30, an encoder 40, a first detection sensor 50, a control device 60, a display device 70, and a sound output device 80.

[0030] The servo motor 20 is driven based on a control signal received from the control device 60 via the servo driver 22 and the servo amplifier 21. When the servo motor 20 is driven, the machine 10 is moved via the ball screw 30 described later. The servo motor 20 is an example of the drive unit of the present invention.

[0031] The ball screw 30 includes a screw shaft, a nut, balls, etc. (not shown). The screw shaft of the ball screw 30 is connected to the shaft of the servo motor 20 via a coupling (not shown). The machine 10 is fixed to a workbench (not shown) provided on the nut of the ball screw 30. When the servo motor 20 is driven, the screw shaft of the ball screw 30 rotates, and the machine 10 can be moved in the range from the start end A to the terminal end B of the ball screw 30 in the left - right direction along the screw shaft direction, that is, Figure 1 in the left - right direction shown in FIG. 1. The ball screw 30 is an example of the moving unit of the present invention.

[0032] The encoder 40 is a rotary encoder installed on the servo motor 20. The encoder 40 detects the state of the servo motor 20 every 1 second and outputs it to the control device together with the detection date and time. Specifically, the encoder 40 detects the rotation amount of the servo motor 20 as the state of the servo motor 20. As described above, the machine 10 can be moved by driving the servo motor 20, so the rotation amount of the servo motor 20 corresponds to the displacement of the machine 10. The displacement amount of the machine 10 per unit rotation amount is calculated in advance. The encoder 40 is an example of the state detection unit of the present invention. When the machine 10 moves Figure 1 in the right direction, the rotation amount of the servo motor 20 is represented by a positive value, and when it moves in the left direction, the rotation amount of the servo motor 20 is represented by a negative value.

[0033] The first detection sensor 50 is a photoelectric switch, proximity switch, etc. The first detection sensor 50 detects the presence or absence of the machine 10 at the first reference position P every 1 second, and outputs the detection result and the detection time to the control device 60. In addition, the first reference position P is recognized as a position on the system through a pre-setting process. The first detection sensor 50 is an example of the first detection unit of the present invention.

[0034] In addition, the encoder 40 and the first detection sensor 50 achieve time synchronization, perform detection at the same time, and output the detection results to the control device 60. As an example of the method for performing time synchronization, a method implemented based on standards standardized such as IEEE802.1AS and IEEE1588 is cited. In this method, the first detection sensor 50 and the encoder 40 receive a signal for time synchronization from an external server, thereby synchronizing the clocks stored inside. Thereby, highly accurate position estimation can be performed.

[0035] The control device 60 is connected to the first detection sensor 50, the encoder 40, the display device 70, the sound output device 80, and the servo driver 22 by wire or wirelessly. The control device 60 is a computer that performs the following processes: a process of driving the servo motor 20 by sending a control signal to the servo motor 20 via the servo driver 22 to move the machine 10, and a position estimation process of estimating the position of the moving machine 10, etc. The control device 60 is as Figure 2 shown, and has an interface 61, a CPU 62, a ROM 63, a RAM 64, and a secondary storage device 65. These structural parts are connected to each other via a bus 66.

[0036] The interface 61 is an interface for the control device 60 to connect to the first detection sensor 50, the encoder 40, the servo driver 22, the display device 70, and the sound output device 80.

[0037] The CPU 62 centrally controls the control device 60. In the position estimation process described later, the CPU 62 estimates the position of the machine 10 based on the rotation amount indicated by the reference state information and the rotation amount of the servo motor 20 obtained by the encoder 40, determines whether the estimated position is within a specific area, and if it is within the area, executes a process corresponding to the area. The CPU 62 is an example of the position estimation unit, area determination unit, and area processing unit of the present invention.

[0038] The ROM (Read Only Memory) 63 stores multiple firmware and data used during the execution of these firmware, and the CPU 62 stores control programs and the like for executing various processes described later. The RAM (Random Access Memory) 64 is used as the working area of the CPU 62.

[0039] The secondary storage device 65 is composed of a rewritable non-volatile semiconductor memory such as an EEPROM or a flash memory, or an HDD. As Figure 3 shown, the secondary storage device 65 has a sensor information storage unit 651, an encoder information storage unit 652, a reference state storage unit 653, and a region information storage unit 654.

[0040] In the sensor information storage unit 651, as Figure 4 shown, the detection results are stored in time series in association with the detection date and time. The detection results are received from the first detection sensor 50 every 1 second and indicate the presence or absence of the machine 10. That is, information from the first detection sensor 50 is input to the control device 60.

[0041] In the encoder information storage unit 652, as Figure 5 shown, the information indicating the rotation amount of the servo motor 20 received from the encoder 40 every 1 second is stored in time series in association with the detection date and time. That is, information from the encoder 40 is input to the control device 60.

[0042] The reference state storage unit 653 stores reference state information. The reference state information represents the state of the servo motor 20 when the machine 10 is at the first reference position P. In the present embodiment, the reference state information is represented by the rotation amount of the servo motor 20. The reference state storage unit 653 is an example of the reference state storage unit of the present invention.

[0043] In the region information storage unit 654, region information defining specific regions set within the range where the machine 10 can move is stored. For example, as Figure 6 shown, the region information consists of a region name, coordinate values of the start and end points of the region, and the execution process. In addition, the coordinate values of the start and end points in this figure are values in a one-dimensional coordinate system with the start end A of the ball screw 30 set to 0 and the end B set to 100. According to Figure 6 the shown coordinate values, it can be known that the range of region a is the region enclosed by the Figure 1 shown dashed line. The in-region process represents the process executed when the machine 10 is in this region. In addition, in Figure 6Only 1 area is defined in the area information shown, but multiple areas can also be defined as area information. The area information storage unit 654 is an example of the area information storage unit of the present invention.

[0044] Return to Figure 1 , the display device 70 is, for example, an LCD (Liquid Crystal Display). The display device 70 displays various information based on an instruction from the control device 60. For example, the position of the machine 10 estimated by the position estimation process described later is displayed on the display device 70.

[0045] The sound output device 80 is, for example, a speaker. The sound output device 80 outputs various sounds such as a notification sound and an alarm sound based on an instruction from the control device 60.

[0046] Next, the processing executed by the control device 60 of the mobile system 100 will be described. First, the reference state registration process will be described. When the power is first turned on to the control device 60 or when the setting of the control device 60 is reset and the reference state information stored in the reference state storage unit 653 is deleted, etc., the control device 60 executes Figure 7 the reference state registration process shown.

[0047] First, the CPU 62 of the control device 60 sends a control signal for moving the machine 10 to the first reference position P to the servo motor 20 via the servo driver 22 and the servo amplifier 21 (step S101). The servo motor 20 is driven based on the received control signal, and the screw shaft of the ball screw 30 rotates. Thereby, the machine is moved to the first reference position P.

[0048] Next, if the machine 10 that has moved to the first reference position P is detected by the first detection sensor 50, the CPU 62 acquires the rotation amount of the servo motor 20 detected by the encoder 40 at the same time as the detection time (step S102). Then, the CPU 62 stores the rotation amount acquired in step S102 as reference state information in the reference state storage unit 653 (step S103). The above reference state registration process ends.

[0049] Next, use Figure 8 the flowchart of to describe the position estimation process executed by the control device 60. For example, during the operation of the production line in the factory and the movement of the machine 10 according to the operation process, the position estimation process is repeatedly executed every 1 second.

[0050] First, the CPU 62 of the control device 60 refers to the encoder information storage unit 652 and acquires the current rotation amount of the servo motor 20 (step S201).

[0051] Next, the CPU 62 estimates the current position of the machine 10 based on the amount of rotation obtained in step S201 and the amount of rotation indicated by the reference state information stored in the reference state storage unit 653 of the secondary storage device 65 (step S202). Specifically, the CPU 62 calculates the difference between the two amounts of rotation and estimates that the machine 10 is located at a location separated from the first reference position P by a distance corresponding to this difference.

[0052] Next, the CPU 62 refers to the area information stored in the area information storage unit 654 and determines whether the machine 10 is within the area (step S203). Specifically, the CPU 62 only needs to determine whether the position of the machine 10 estimated in step S202 is included within the range from the start point to the end point of the area indicated by the area information.

[0053] When the machine 10 is not within the area (step S203; No), the process proceeds to step S205. On the other hand, when the machine 10 is within the area (step S203; Yes), the CPU 62 executes the process corresponding to this area. Specifically, the CPU 62 executes the process specified by the in-area process of the corresponding area information. For example, when the machine 10 is Figure 6 within the indicated area a, the CPU 62 outputs an alarm sound from the sound output device 80. Then, the process proceeds to step S205.

[0054] In step S205, the CPU 62 displays the position of the machine 10 estimated in step S202 on the display device 70. As described above, the position estimation process is repeatedly executed every 1 second, so the estimated position of the current machine 10 is displayed on the display device 70 in real time. The above position estimation process ends.

[0055] As described above, according to the present embodiment, the encoder 40 that detects the state of the servo motor 20 and the first detection sensor 50 that detects the presence or absence of the machine 10 at the first reference position P can achieve time synchronization, store the state of the encoder 40 when the machine 10 detected by the first detection sensor 50 moves to the first reference position P as reference state information, and then when the servo motor 20 is driven and the machine 10 moves, the state of the encoder 40 is obtained again. Based on the state of the encoder 40 included in the reference state information and the state of the encoder 40 obtained again, the position of the machine 10 can be estimated. That is, there is no need for a large-sized device such as a linear scale or multiple detection sensors, etc., so the position of a moving object can be estimated at lower cost and more accurately than in the past.

[0056] <Embodiment 2>

[0057] Next, Embodiment 2 of the present invention will be described. Figure 9 FIG. is a diagram showing the overall structure of the mobile system 200 according to Embodiment 2. Compared with the mobile system 100 according to Embodiment 1, the mobile system 200 newly has a second detection sensor 90.

[0058] Similar to the first detection sensor 50, the second detection sensor 90 detects the presence or absence of the machine 10 at the second reference position Q every 1 second, and outputs the detection result and the detection time to the control device 60. The second detection sensor 90 is an example of the second detection unit of the present invention. In addition, the second reference position Q is identified on the system through a pre-setting process. The second detection sensor 90 can achieve time synchronization with the first detection sensor 50 and outputs the detection result to the control device 60 at the same timing. In the sensor information storage unit 651 of the control device 60, the detection results of the first detection sensor 50 and the second detection sensor 90 are stored separately.

[0059] In addition, the same position as the first reference position P may be set as the second reference position Q. In this case, the detection of the machine 10 at the first reference position P and the detection of the machine 10 at the second reference position Q can be performed only by the first detection sensor 50, so the second detection sensor 90 may not be provided.

[0060] Next, refer to Figure 10 the flowchart to describe the position estimation process performed in this embodiment. In addition, for the steps common to the position estimation process of Embodiment 1, the same step numbers are marked, and the description is appropriately simplified or omitted.

[0061] First, the CPU 62 of the control device 60 obtains the rotation amount of the servo motor 20 (step S201), and estimates the current position of the machine 10 (S202).

[0062] Next, the CPU 62 determines whether the position estimated in step S202 is the same as the position of the second reference position Q (step S206).

[0063] When the estimated position is the same as the position of the second reference position Q (step S206; Yes), the CPU 62 determines whether the machine 10 is detected by the second detection sensor 90 at this time (step S207).

[0064] When the machine 10 is not detected by the second detection sensor 90 (step S207; No), there may be an error in the position estimated through step S202. Therefore, the CPU 62 performs a predetermined process in this case (step S208). For example, as the predetermined process, the CPU 62 performs a process for outputting an alarm sound from the sound output device 80, a process for stopping or decelerating the movement of the machine 10, etc. Then the process proceeds to step S203. In addition, when the movement of the machine 10 is stopped by the predetermined process, the position estimation process can be forcibly ended.

[0065] On the other hand, when the machine 10 is detected by the second detection sensor 90 (step S207; Yes), the possibility of an error in the position estimated through step S202 is low, and the process proceeds to step S203.

[0066] Return to step S206. When the estimated position does not match the position of the second reference position Q (step S206; No), the CPU 62 determines whether the machine 10 is detected by the second detection sensor 90 at this time (step S209).

[0067] When the machine is detected by the second detection sensor 90 (step S209; Yes), there may be an error in the position estimated through step S202. Therefore, the CPU 62 performs a predetermined process (step S210). The predetermined process here can perform the same process as the predetermined process performed through step S208, or can perform a different process. Then the process proceeds to step S203.

[0068] On the other hand, when the machine 10 is not detected by the second detection sensor 90 (step S209; No), the possibility of an error in the position estimated through step S202 is low, and the process proceeds to step S203.

[0069] Step S203 and subsequent steps are the same as the position estimation process of Embodiment 1, so the subsequent description is omitted.

[0070] As described above, according to the present embodiment, when the machine 10 that has moved to the second reference position Q is detected by the second detection sensor 90, but it is estimated that the machine 10 is not in the second reference position Q, or when the machine 10 is not detected by the second detection sensor 90, but it is estimated that the machine 10 is in the second reference position, a predetermined process such as a warning process is performed. Thus, when the accuracy of position estimation is reduced due to the secular deterioration of the ball screw 30, the loosening of the coupling connecting the ball screw 30 and the servo motor 20, etc., it can be notified to the user in advance, so problems can be prevented.

[0071] <Modification Example>

[0072] In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

[0073] For example, in the position estimation process, when the machine 10 is detected by the first detection sensor 50, the reference position information stored in the reference state storage unit 653 can be updated with the rotation amount acquired by the encoder 40 at the same time. That is, even during the operation of the mobile systems 100 and 200, if the moving machine 10 is detected by the first detection sensor 50, the same processes as steps S102 and S103 of the reference state registration process can be sequentially performed, and the reference state information stored in the reference state storage unit 653 can also be updated. Thus, each time the machine 10 passes through the first reference position P, the reference position information is updated to the latest, so that errors in the moving position of the mechanical mechanism caused by the deflection of the ball screw 30, the relaxation of each component, etc. do not accumulate, and the accuracy of position estimation can be further improved.

[0074] In the above-described embodiments, the moving object is described as the machine 10, but the present invention does not limit the moving object to the machine 10. In addition, in the above-described embodiments, the servo motor 20 is exemplified as the drive unit for moving the machine 10, but the drive unit is not limited to the servo motor 20, and other types of motors, drive devices other than motors, etc. are also included in the present invention.

[0075] In the above-described embodiments, the position of the machine 10 is estimated using the rotation amount of the servo motor 20 detected by the encoder 40, but the position of the machine 10 can also be estimated using information other than the rotation amount that represents the state of the servo motor 20. For example, information corresponding to the displacement of the machine 10 such as the rotation speed and count value of the servo motor 20 detected by the encoder 40 can be used to estimate the position of the machine 10. Alternatively, the position of the machine 10 can be estimated based on the value obtained by multiplying the count value detected by the encoder 40 by the resolution of the encoder 40.

[0076] In the above-described embodiments, the encoder 40 is used to detect the state of the servo motor 20, but other devices capable of detecting the state of the servo motor 20 can also be used. For example, instead of the encoder 40, the rotation amount of the servo motor 20 can be detected by a resolver, a gyroscope, etc.

[0077] Without departing from the broad spirit and scope of the present invention, various embodiments and modifications can be implemented. Additionally, the above-described embodiments are used to explain the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is not the embodiments but is shown by the claims. Moreover, various modifications implemented within the scope of the claims and within the meaning of equivalent inventions are regarded as being within the scope of the present invention.

[0078] Industrial Applicability

[0079] The present invention can be suitably applied to a mobile system provided in a production line of a factory.

[0080] Explanation of Reference Numerals

[0081] 100, 200 Mobile systems, 10 Machine, 20 Servo motor, 21 Servo amplifier, 22 Servo driver, 30 Ball screw, 40 Encoder, 50 First detection sensor, 60 Control device, 70 Display device, 80 Sound output device, 90 Second detection sensor, P First reference position, Q Second reference position, 61 Interface, 62 CPU, 63 ROM, 64 RAM, 65 Secondary storage device, 651 Sensor information storage section, 652 Encoder information storage section, 653 Reference state storage section, 654 Area information storage section, 66 Bus.

Claims

1. A mobile system having: A drive unit that rotates to drive and thereby moves a moving object via a ball screw; A first detection unit that detects the presence or absence of the moving object at a first reference position whose position has been previously identified at a predetermined time interval; A second detection unit that detects the presence or absence of the moving object at a second reference position whose position has been previously identified at a predetermined time interval; A state detection unit that detects the rotation state of the drive unit at a predetermined time interval; And A control device that receives information input from the first detection unit and the state detection unit, The control device having: A reference state storage unit that stores, as reference state information, the rotation state of the drive unit detected by the state detection unit when the moving object is detected by the first detection unit; And A position estimation unit that estimates the position of the moving object based on the rotation state of the drive unit detected by the state detection unit and the reference state information, When the position of the moving object estimated by the position estimation unit when the moving object is detected by the second detection unit is different from the second reference position, or when the position of the moving object estimated by the position estimation unit when the moving object is not detected by the second detection unit is the same as the second reference position, a predetermined process is executed.

2. The mobile system according to claim 1, wherein The control device has: A region information storage unit that stores region information indicating a specific region provided within the range where the moving object can move; And A region determination unit that determines whether the moving object is in the specific region based on the position estimated by the position estimation unit and the region information.

3. The mobile system according to claim 2, wherein The control device has a region processing unit that executes a process corresponding to the specific region when the region determination unit determines that the moving object is in the specific region.

4. The mobile system according to claim 1, wherein Each time the moving object is detected by the first detection unit, the control device updates the reference state storage unit with the rotation state of the drive unit detected by the state detection unit at the time of the detection as new reference state information.

5. The mobile system according to claim 1, characterized in that The first detection unit, the second detection unit, and the state detection unit are synchronized with each other and detect the presence or absence of the moving object and the rotation state of the drive unit at the same timing.

6. A method for estimating a position, which is a method for estimating the position of a moving object that is driven by a driving unit to rotate and thus moves via a ball screw, characterized in that, Having: A first detection step of detecting the presence or absence of the moving object at a first reference position whose position has been previously identified at a predetermined time interval; The second detection step of detecting the presence or absence of the moving object at the second reference position whose position has been pre-identified at a pre-determined time interval; The state detection step of detecting the rotation state of the drive unit at a pre-determined time interval; The storage step of storing the rotation state of the drive unit when the moving object is detected at the first reference position as reference state information; The estimation step of estimating the position of the moving object based on the rotation state of the drive unit and the reference state information; And The processing execution step of executing pre-determined processing when the position of the moving object estimated by the estimation step is different from the second reference position when the moving object is detected at the second reference position, or when the position of the moving object estimated by the estimation step is the same as the second reference position when the moving object is not detected at the second reference position.

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