JP6919622B2 - Control systems, control methods, and control programs - Google Patents

Description

The present disclosure relates to a technique for positioning a work based on the position of the work measured by a visual sensor.

In FA (factory automation), various technologies (positioning technology) for aligning the position of an object with a target position have been put into practical use. At this time, as a method of measuring the deviation (distance) between the position of the object and the target position, there is a method of using an image captured by a visual sensor.

Japanese Patent Laying-Open No. 2017-24134 (Patent Document 1) describes a visual sense in which a movable table, a moving mechanism for moving the movable table, and a work mounted on the movable table are repeatedly imaged and the position of the work is repeatedly detected. A work positioning device including a sensor is disclosed. The work positioning device calculates the difference between the detected position and the target position each time the position is detected by the visual sensor, and when it is determined that the difference is within the permissible range, the movable table is moved. Stop. The work positioning device calculates the difference between the position detected by the visual sensor and the target position after the movable table has stopped moving, and determines whether or not the calculated difference is within the permissible range. When it is determined that the difference is out of the permissible range, the moving direction of the movable table that reduces the difference is determined, and the moving mechanism is controlled so as to move the movable table in the determined moving direction.

JP-A-2017-24134

The interval at which the actual position of the work is measured by the visual sensor is shorter than the interval at which the command value is output to the moving mechanism. Therefore, in order to drive the moving mechanism more smoothly, the command value output to the moving mechanism is interpolated by some means between the time when the visual sensor measures the actual position of the work and the time when the actual position is measured next. There is a need to.

The present disclosure has been made to solve the above-mentioned problems, and an object in a certain aspect is to be able to drive a moving mechanism driven based on a measurement position of a visual sensor more smoothly. It is to provide a control system. An object in another aspect is to provide a control method capable of more smoothly driving a moving mechanism driven based on the measurement position of the visual sensor. An object in another aspect is to provide a control program capable of more smoothly driving a moving mechanism driven based on the measurement position of the visual sensor.

In one example of the present disclosure, the control system images the object based on the movement mechanism for moving the object and the reception of the imaging instruction, and the actual position of the object is obtained from the image obtained by the imaging. A visual sensor for measuring the above, a calculation unit for calculating the required movement distance of the movement mechanism for moving the object from the actual position to a predetermined arrival target position, and the required movement distance and time. Is defined as a predetermined interval shorter than the interval at which the imaging instruction is output to the visual sensor based on the target trajectory represented by the multi-order function with the target position of the moving mechanism as the objective variable. Each control cycle includes a position determination unit for determining a target position corresponding to the current time, and a movement control unit for moving the movement mechanism to the target position determined by the position determination unit.

According to this disclosure, the control system can interpolate the target position of the moving mechanism between the time when the visual sensor measures the actual position of the object and the next time when the actual position of the object is measured. Can be driven more smoothly.

In one example of the present disclosure, the multi-order function is a function of degree 5 or higher.
According to this disclosure, the target position of the moving mechanism becomes smoother because the multiple-order function is defined by a function of the fifth order or higher.

In one example of the present disclosure, the positioning unit generates the target trajectory so that the acceleration of the moving mechanism does not exceed a predetermined maximum acceleration.

According to this disclosure, the control system can suppress a sudden change in the speed of the moving mechanism.

In one example of the present disclosure, the position-determining unit generates the target trajectory each time the visual sensor measures the actual position of the object, and the target previously generated by the newly generated target trajectory. Update the orbit.

According to this disclosure, the error of the target trajectory is corrected for each imaging cycle of the visual sensor.
In one example of the present disclosure, the position-determining unit generates a new target trajectory so that the speed of the moving mechanism does not change before and after the update of the target trajectory.

According to this disclosure, in the process of updating the target trajectory, slippage of the object on the moving mechanism and residual vibration after positioning of the moving mechanism are suppressed, and as a result, the alignment time of the object is shortened.

In one example of the present disclosure, the control system includes a detection unit for detecting the actual position of the moving mechanism for each control cycle, and an actual position detected by the detection unit at the timing of updating the target trajectory. A correction unit for correcting the required movement distance by the position deviation from the target position of the movement mechanism at the timing is further provided.

According to this disclosure, in the process of updating the target trajectory, the error in the position of the moving mechanism is absorbed, and the speed of the moving mechanism is prevented from suddenly changing. As a result, slippage of the object and residual vibration after positioning of the moving mechanism are suppressed, and as a result, the alignment time of the object is shortened.

In another example of the present disclosure, the control method of the moving mechanism for moving the object is to output an imaging instruction to a visual sensor and obtain the actual position of the object from the image obtained by imaging the object. At least the step of causing the visual sensor to measure, the step of calculating the required movement distance of the movement mechanism for moving the object from the actual position to the predetermined arrival target position, and the required movement distance and time. Every predetermined control cycle shorter than the interval at which the imaging instruction is output to the visual sensor based on the target trajectory represented by the multi-order function with the target position of the moving mechanism as the explanatory variable. In addition, a step of determining a target position corresponding to the current time and a step of moving the moving mechanism to the target position determined in the determination step are provided.

According to this disclosure, the control system can interpolate the target position of the moving mechanism between the time when the visual sensor measures the actual position of the object and the next time when the actual position of the object is measured. Can be driven more smoothly.

In another example of the present disclosure, the control program of the moving mechanism for moving the object is obtained by outputting an imaging instruction to the visual sensor to the controller for controlling the moving mechanism and imaging the object. A step of causing the visual sensor to measure the actual position of the object from the obtained image, and a step of calculating the required movement distance of the moving mechanism for moving the object from the actual position to a predetermined target position. The imaging instruction is output to the visual sensor based on the target trajectory represented by the multi-order function with the required movement distance and time as at least explanatory variables and the target position of the movement mechanism as the objective variable. For each predetermined control cycle shorter than the interval, the step of determining the target position corresponding to the current time and the step of moving the moving mechanism to the target position determined in the determination step are executed.

According to this disclosure, the control system can interpolate the target position of the moving mechanism between the time when the visual sensor measures the actual position of the object and the next time when the actual position of the object is measured. Can be driven more smoothly.

In a certain aspect, the moving mechanism driven based on the measurement position of the visual sensor can be driven more smoothly.

It is a schematic diagram which shows the outline of the control system according to embodiment. It is a figure which shows an example of a target trajectory. Ru Figure showing one example of a device configuration of a control system according to an embodiment. It is a schematic diagram which shows an example of the hardware configuration of the image processing apparatus according to an embodiment. It is a schematic diagram which shows the hardware configuration of the controller according to embodiment. It is a figure which further embodies the functional structure of the control system shown in FIG. It is a figure which shows the target trajectory before update and the target trajectory after update. It is a flowchart which shows a part of the control process executed by the controller which follows an embodiment.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following description, the same parts and components are designated by the same reference numerals. Their names and functions are the same. Therefore, the detailed description of these will not be repeated.

<A. Application example>
First, an example of a situation in which the present invention is applied will be described with reference to FIG. FIG. 1 is a schematic diagram showing an outline of a control system 1 according to the present embodiment.

The control system 1 uses image processing to perform alignment. Alignment typically means a process of arranging an object (hereinafter, also referred to as "work W") at an original position of a production line in a manufacturing process of an industrial product or the like. As an example of such alignment, the control system 1 positions the glass substrate with respect to the exposure mask before the printing process (exposure process) of the circuit pattern on the glass substrate in the liquid crystal panel production line.

The control system 1 includes, for example, a visual sensor 50, a controller 200, a servo driver 300, and a moving mechanism 400. The moving mechanism 400 includes, for example, a servomotor 410 and a stage 420.

The visual sensor 50 performs an imaging process of capturing an image of a subject existing in the imaging field of view and generating image data, and images the work W mounted on the stage 420. The visual sensor 50 performs imaging in response to the imaging trigger TR from the controller 200. The visual sensor 50 captures the work W based on the reception of the imaging trigger TR, and measures the actual position PVv of the work W by performing image analysis on the image data obtained by the imaging. The actual position PVv is output to the controller 200 each time it is measured.

The controller 200 is, for example, a PLC (programmable logic controller) and performs various FA controls. The controller 200 includes a calculation unit 250, a position determination unit 252, and a movement control unit 254 as an example of the functional configuration.

The calculation unit 250 moves the work W from the actual position PVv to the arrival target position SP based on the actual position PVv of the work W detected by the visual sensor 50 and the predetermined arrival target position SP. The required travel distance L is calculated. The calculated required movement distance L is output to the position-fixing unit 252.

In a certain aspect, the arrival target position SP is detected by the visual sensor 50 performing predetermined image processing. In this case, the visual sensor 50 detects a predetermined mark from the image and recognizes the mark as the arrival target position SP. In another aspect, the target position SP to be reached is predetermined for each production process.

The position-determining unit 252 currently uses the required movement distance L and the time t as explanatory variables, and the target position SP (t) of the movement mechanism 400 as the objective variable based on the target trajectory TG represented by a quadratic function. The target position SP (t) at time t is determined.

FIG. 2 is a diagram showing an example of the target trajectory TG. As shown in FIG. 2, the target trajectory TG defines the target position SP (t) of the moving mechanism 400 for each control cycle Ts. As shown in FIG. 2, the initial value of the target position SP (t) is the required movement distance L, and the final value of the target position SP (t) is zero. The target position SP (t) is output to the movement control unit 254 every control cycle Ts shorter than the imaging cycle Tb. As an example, the imaging cycle Tb varies depending on the imaging condition and the like, and is, for example, about 60 ms. The control cycle Ts is fixed, for example 1 ms.

The movement control unit 254 generates a movement command MV for moving the movement mechanism 400 to the target position SP (t) corresponding to the current time t for each control cycle Ts, and outputs the movement command MV to the servo driver 300. do. The movement command MV is, for example, either a command position, a command speed, or a command torque with respect to the servo driver 300.

The servo driver 300 drives the movement mechanism 400 according to the movement command MV received for each control cycle Ts. More specifically, the servo driver 300 acquires the encoder value PVm detected by the encoder 412 (see FIG. 6) described later, and the speed / position of the stage 420 specified from the encoder value PVm approaches the target value. The servomotor 410 is feedback-controlled so that the movement command MV approaches. The encoder value PVm detected by the encoder is input to the controller 200 in the same cycle as the control cycle Ts.

As described above, in the present embodiment, the position-determining unit 252 is a multi-order function in which the required movement distance L and the time t are at least explanatory variables and the target position SP (t) of the movement mechanism 400 is the objective variable. Based on the represented target trajectory TG, the target position SP (t) corresponding to the current time t is determined. The target position SP (t) is output to the movement control unit 254 every control cycle Ts shorter than the imaging cycle Tb. As a result, the movement command output to the moving mechanism 400 can be interpolated between the time when the visual sensor 50 measures the actual position PVv of the work W and the time when the actual position PVv is measured next, and the moving mechanism 400 can be made smoother. It becomes possible to drive.

<B. Device configuration of control system 1>
3, Ru FIG showing one example of a device configuration of the control system 1. As shown in FIG. 3, the control system 1 includes a visual sensor 50, a controller 200, one or more servo drivers 300 (servo drivers 300X, 300Y in the example of FIG. 3), and a moving mechanism 400. .. The visual sensor 50 includes an image processing device 100 and one or more cameras (cameras 102 and 104 in the example of FIG. 3).

The image processing device 100 detects the feature portion 12 (for example, a screw hole) of the work W based on the image data obtained by photographing the work W by the cameras 102 and 104. The image processing device 100 detects the position of the detected feature portion 12 as the actual position PVv of the work W.

One or more servo drivers 300 (servo drivers 300X, 300Y in the example of FIG. 3) are connected to the controller 200. The servo driver 300X drives the servomotor 410X to be controlled in accordance with the movement command in the X direction received from the controller 200. The servo driver 300Y drives the servomotor 410Y to be controlled in accordance with the movement command in the Y direction received from the controller 200.

The controller 200 gives the servo driver 300X a target position in the X direction as a command value according to the target trajectory TGx generated in the X direction. Further, the controller 200 gives the servo driver 300Y a target position in the Y direction as a command value according to the target trajectory TGy generated in the Y direction. The work W is moved to the arrival target position SP by sequentially updating the target positions in the X and Y directions.

The controller 200 and the servo driver 300 are connected by a daisy chain via a field network. For the field network, for example, EtherCAT (registered trademark) is adopted. However, the field network is not limited to EtherCAT, and any communication means can be adopted. As an example, the controller 200 and the servo driver 300 may be directly connected by a signal line. Further, the controller 200 and the servo driver 300 may be integrally configured.

The moving mechanism 400 includes base plates 4 and 7, ball screws 6 and 9, a stage 420, and one or more servomotors 410 (servomotors 410X and 410Y in the example of FIG. 3).

A ball screw 6 for moving the stage 420 along the X direction is arranged on the base plate 4. The ball screw 6 is engaged with a nut included in the stage 420. When the servomotor 410X connected to one end of the ball screw 6 is rotationally driven, the nut included in the stage 420 and the ball screw 6 rotate relative to each other, and as a result, the stage 420 moves along the X direction.

A ball screw 9 for moving the stage 420 and the base plate 4 along the Y direction is arranged on the base plate 7. The ball screw 9 is engaged with a nut included in the base plate 4. When the servomotor 410Y connected to one end of the ball screw 9 is rotationally driven, the nut included in the base plate 4 and the ball screw 9 rotate relative to each other, and as a result, the stage 420 and the base plate 4 move along the Y direction.

Although FIG. 3 shows a two-axis drive moving mechanism 400 by the servomotors 410X and 410Y, the moving mechanism 400 is a servomotor that drives the stage 420 in the rotation direction (θ direction) on the XY plane. May be further incorporated.

<C. Hardware configuration>
With reference to FIGS. 4 and 5, the hardware configurations of the image processing device 100 and the controller 200 constituting the visual sensor 50 will be described in order.

(C1. Hardware configuration of image processing device 100)
FIG. 4 is a schematic view showing an example of the hardware configuration of the image processing device 100 constituting the visual sensor 50. With reference to FIG. 4, the image processing apparatus 100 typically has a structure that follows a general-purpose computer architecture, and the processor executes a pre-installed program to perform various types as described later. Realize image processing.

More specifically, the image processing device 100 includes a processor 110 such as a CPU (Central Processing Unit) and an MPU (Micro-Processing Unit), a RAM (Random Access Memory) 112, a display controller 114, and a system controller 116. , Includes an I / O (Input Output) controller 118, a hard disk 120, a camera interface 122, an input interface 124, a controller interface 126, a communication interface 128, and a memory card interface 130. Each of these parts is connected to each other so as to be capable of data communication, centering on the system controller 116.

The processor 110 realizes a target arithmetic process by exchanging programs (codes) and the like with the system controller 116 and executing them in a predetermined order.

The system controller 116 is connected to the processor 110, the RAM 112, the display controller 114, and the I / O controller 118 via a bus, and exchanges data with each unit and processes the entire image processing device 100. Controls.

The RAM 112 is typically a volatile storage device such as a DRAM (Dynamic Random Access Memory), and includes a program read from the hard disk 120 and camera images (image data) acquired by the cameras 102 and 104. Holds processing results for camera images, work data, and so on.

The display controller 114 is connected to the display unit 132, and outputs signals for displaying various information to the display unit 132 according to an internal command from the system controller 116.

The I / O controller 118 controls data exchange between a recording medium and an external device connected to the image processing device 100. More specifically, the I / O controller 118 is connected to the hard disk 120, the camera interface 122, the input interface 124, the controller interface 126, the communication interface 128, and the memory card interface 130.

The hard disk 120 is typically a non-volatile magnetic storage device, and stores various setting values and the like in addition to the control program 150 executed by the processor 110. The control program 150 installed on the hard disk 120 is distributed in a state of being stored in a memory card 136 or the like. Instead of the hard disk 120, a semiconductor storage device such as a flash memory or an optical storage device such as a DVD-RAM (Digital Versatile Disk Random Access Memory) may be adopted.

The camera interface 122 corresponds to an input unit that receives image data generated by photographing the work, and mediates data transmission between the processor 110 and the cameras 102 and 104. The camera interface 122 includes image buffers 122a and 122b for temporarily storing image data from the cameras 102 and 104, respectively. A single image buffer that can be shared between cameras may be provided for a plurality of cameras, but in order to speed up processing, it is preferable to arrange a plurality of independently in association with each camera.

The input interface 124 mediates data transmission between the processor 110 and an input device such as a keyboard 134, a mouse, a touch panel, and a dedicated console.

Controller interface 126 mediates data transmission between processor 110 and controller 200.

The communication interface 128 mediates data transmission between the processor 110 and another personal computer, server device, or the like (not shown). The communication interface 128 typically comprises Ethernet (registered trademark), USB (Universal Serial Bus), or the like.

The memory card interface 130 mediates data transmission between the processor 110 and the memory card 136, which is a recording medium. The memory card 136 is distributed in a state in which the control program 150 or the like executed by the image processing device 100 is stored, and the memory card interface 130 reads the control program from the memory card 136. The memory card 136 is derived from a general-purpose semiconductor storage device such as SD (Secure Digital), a magnetic recording medium such as a flexible disk, an optical recording medium such as a CD-ROM (Compact Disk Read Only Memory), and the like. Become. Alternatively, a program downloaded from a distribution server or the like may be installed in the image processing device 100 via the communication interface 128.

When using a computer having a structure according to the general-purpose computer architecture as described above, in addition to the application for providing the function according to the present embodiment, the OS for providing the basic function of the computer ( Operating System) may be installed. In this case, the control program according to the present embodiment may call the necessary modules in a predetermined order and / or timing among the program modules provided as a part of the OS to execute the process. good.

Further, the control program according to the present embodiment may be provided by being incorporated into a part of another program. Even in that case, the program itself does not include the modules included in the other programs to be combined as described above, and the processing is executed in cooperation with the other programs. That is, the control program according to the present embodiment may be a form incorporated in such another program.

Alternatively, a part or all of the functions provided by executing the control program may be implemented as a dedicated hardware circuit.

(C2. Hardware configuration of controller 200)
FIG. 5 is a schematic view showing the hardware configuration of the controller 200. With reference to FIG. 5, the controller 200 includes a main control unit 210. FIG. 5 shows servomotors 410X, 410Y, 410θ for three axes, and a number of servo drivers 300X, 300Y, 300θ corresponding to the number of axes are provided.

The main control unit 210 includes a chipset 212, a processor 214, a non-volatile memory 216, a main memory 218, a system clock 220, a memory card interface 222, a communication interface 228, an internal bus controller 230, and a fieldbus. Includes controller 238. The chipset 212 and the other components are respectively connected via various buses.

The processor 214 and the chipset 212 typically have a configuration that follows a general purpose computer architecture. That is, the processor 214 interprets and executes the instruction code sequentially supplied from the chipset 212 according to the internal clock. The chipset 212 exchanges internal data with various connected components and generates instruction codes necessary for the processor 214. The system clock 220 generates a system clock having a predetermined period and provides the system clock to the processor 214. The chipset 212 has a function of caching data and the like obtained as a result of executing arithmetic processing on the processor 214.

The main control unit 210 has a non-volatile memory 216 and a main memory 218 as storage means. The non-volatile memory 216 non-volatilely holds the OS, system program, user program, data definition information, log information, and the like. The main memory 218 is a volatile storage area, holds various programs to be executed by the processor 214, and is also used as a working memory when executing various programs.

The main control unit 210 has a communication interface 228, an internal bus controller 230, and a fieldbus controller 238 as communication means. These communication circuits transmit and receive data.

The communication interface 228 exchanges data with the image processing device 100.
The internal bus controller 230 controls the exchange of data via the internal bus 226. More specifically, the internal bus controller 230 includes a buffer memory 236, a DMA (Dynamic Memory Access) control circuit 232, and an internal bus control circuit 234.

The memory card interface 222 connects the memory card 224, which is detachable to the main control unit 210, and the processor 214.

The fieldbus controller 238 is a communication interface for connecting to a field network. The controller 200 is connected to the servo driver 300 (for example, the servo drivers 300X, 300Y, 300θ) via the fieldbus controller 238. For the field network, for example, EtherCAT (registered trademark), EtherNet / IP (registered trademark), CompoNet (registered trademark) and the like are adopted.

<D. Target trajectory TG update process>
The above-mentioned position-determining unit 252 (see FIG. 1) generates a target trajectory TG for each imaging cycle Tb of the visual sensor 50. At this time, the position determining unit 252 updates the previously generated target trajectory TG with the newly generated target trajectory TG. That is, the target trajectory TG is updated every time the actual position of the work W is measured by the visual sensor 50. As a result, the error of the target trajectory TG is corrected for each imaging cycle Tb of the visual sensor 50.

Typically, the position-determining unit 252 generates a new target trajectory TG so that the speed of the moving mechanism 400 does not change before and after the update of the target trajectory TG. Hereinafter, the update process of the target trajectory TG will be described with reference to FIGS. 6 and 7.

FIG. 6 is a diagram further embodying the functional configuration of the control system 1 shown in FIG. As shown in FIG. 6, the controller 200 includes a calculation unit 250, a correction unit 251X, 251Y, a position determination unit 252X, 252Y, and a movement control unit 254X, 254Y.

The correction unit 251X, the position determination unit 252X, and the movement control unit 254X are functional configurations for the servo driver 300X that performs drive control in the X-axis direction. The correction unit 251Y, the position determination unit 252Y, and the movement control unit 254Y are functional configurations for the servo driver 300Y that performs drive control in the Y-axis direction. Regarding other points, the functions of the correction units 251X and 251Y are the same, the functions of the position-fixing units 252X and 252Y are the same, and the functions of the movement control units 254X and 254Y are the same.

The calculation unit 250 moves the work W from the actual position PVv to the arrival target position SP based on the actual position PVv of the work W detected by the visual sensor 50 and the predetermined arrival target position SP. The required travel distance L is calculated. After that, the calculation unit 250 decomposes the required movement distance L of the movement mechanism 400 into the required movement distance Lx in the X-axis direction and the required movement distance Ly in the Y-axis direction, and outputs the required movement distance Lx to the correction unit 251X. , The required movement distance Ly is output to the correction unit 251Y.

The correction unit 251X specifies the actual position of the moving mechanism 400 based on the encoder value PVm for detecting the actual position of the moving mechanism 400 from the encoder 412X (detecting unit). More specifically, the encoder 412X generates a pulse signal according to the amount of movement of the servomotor 410X. The counter included in the servomotor 410X receives a pulse signal from the encoder 412X, counts the number of pulses included in the pulse signal, and measures the movement amount of the moving mechanism 400 as the encoder value PVm. The encoder value PVm is input to the controller 200 in the correction unit 251 for each control cycle Ts. The correction unit 251 specifies the actual position of the moving mechanism 400 in the X direction based on the encoder value PVm corresponding to the moving amount of the moving mechanism 400.

The correction unit 251X calculates the position deviation En (t) between the actual position of the moving mechanism 400 and the target position SP (t) as an error. Then, the correction unit 251X corrects the required movement distance Lx with the position deviation En (t), and outputs the corrected required movement distance Lm to the position determination unit 252X. Similar to the correction unit 251X, the correction unit 251Y outputs the required movement distance Lm in the Y direction to the position determination unit 252Y based on the encoder value PVm from the encoder 412Y.

The position-determining unit 252X generates a target trajectory TG from the required movement distance Lm based on the arrival of the imaging cycle Tb of the visual sensor 50. FIG. 7 is a diagram showing a target trajectory TG1 before the update and a target trajectory TG2 after the update.

As shown in FIG. 7, at time t5, the actual position PVv of the work W is measured by the visual sensor 50, and the target trajectory is updated. The correction unit 251X corrects the required movement distance L by the position deviation En (t) between the actual position of the moving mechanism 400 detected at the timing of updating the target trajectory and the target position of the moving mechanism 400 at the timing. In the example of FIG. 7, the required movement distance L is corrected to the required movement distance Lm by adding the position deviation En (t5) to the required movement distance L. After that, the position-determining unit 252X generates a new target trajectory TG2 based on the corrected required movement distance Lm.

As a result, in the process of updating from the target trajectory TG1 to the target trajectory TG2, the error in the position of the moving mechanism 400 is absorbed, and the speed of the moving mechanism 400 is prevented from suddenly changing. As a result, the slip of the work W on the moving mechanism 400 and the residual vibration after the positioning of the moving mechanism 400 are suppressed, and as a result, the alignment time of the work W is shortened.

The position determination unit 252X determines the target position SP (t) corresponding to the current time t based on the updated target trajectory TG2, and sets the target position SP (t) to the movement control unit 254X for each control cycle Ts. Output. Since the function of the movement control unit 254X is the same as that of the movement control unit 254 described with reference to FIG. 1, the description thereof will not be repeated.

<E. Control structure of controller 200>
The control structure of the controller 200 will be described with reference to FIG. FIG. 8 is a flowchart showing a part of the control process executed by the controller 200. The process shown in FIG. 8 is realized by the processor 214 of the controller 200 executing the program. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

The process shown in FIG. 8 represents a control flow in a certain axial direction. That is, in reality, the processes other than steps S130 and S150 shown in FIG. 8 are executed in parallel by the amount in the axial direction.

In step S110, the processor 214 initializes the measurement time t (current time) to zero.

In step S130, the processor 214 determines whether or not the visual sensor 50 has received the information indicating that the position measurement of the work W has been completed. When the processor 214 determines that the information indicating that the position measurement of the work W has been completed has been received from the visual sensor 50 (YES in step S130), the processor 214 switches the control to step S131. Otherwise (NO in step S130), processor 214 switches control to step S138.

In step S131, the processor 214 actually performs the work W as the above-mentioned calculation unit 250 (see FIG. 1) based on the actual position PVv of the work W detected by the visual sensor 50 and the predetermined target position SP. The required movement distance L of the movement mechanism 400 for moving from the position PVv to the arrival target position SP is calculated.

In step S132, the processor 214 adds the position deviation En (t) at the measurement time t to the required travel distance L and corrects the required travel distance L to the required travel distance Lm as the above-mentioned correction unit 251 (see FIG. 6). do. Since the method of correcting the required movement distance L is as described in FIG. 7, the description will not be repeated.

In step S134, the processor 214 initializes the measurement time t to zero.
In step S136, the processor 214 calculates the orbital time T. The orbit time T represents the time required to move the moving mechanism 400 from the start point to the end point of the target orbit TG. As an example, the orbital time T is calculated based on the following equation (1).

T = max {f (A _max ), T _min } ... (1)
_{"A max} " represented by the above formula (1) represents the maximum acceleration. “F ()” is a function for obtaining the orbital time T required when the required movement distance L is moved to the movement mechanism 400 at _{the maximum acceleration A max.} “T _min ” is a predetermined minimum orbit time. “Max (α, β)” is a function for obtaining the maximum value from the numerical values α and β.

According to the above equation (1), the orbital time T is determined so as not to be less than the _{minimum orbital time T min.} If the minimum orbit time T _min is not provided, the moving mechanism 400 will reach the target position immediately when the required moving distance L is very short, so that the time until the next imaging timing is wasted. become. However, since the minimum orbit time T _min is provided, when the required movement distance L is very short, the movement mechanism 400 moves at an acceleration lower than the maximum acceleration, and the movement mechanism 400 moves smoothly. be able to. As an example, the orbital time T _min is calculated by multiplying the average imaging interval by a fixed percentage (eg, 50%).

In step S138, the processor 214, as the position-determining unit 252 (see FIG. 1) described above, is based on the corrected required travel distance Lm obtained in step S132 and the orbit time T calculated in step S136. The target position SP (t) corresponding to the current time t is calculated. As an example, the target position SP (t) is calculated based on the following equation (2).

SP (t) = Lm * [1- (t / T) ³ {10-15 (t / T)} + 6 (t / T) ² }] ... (2)
The right side of the above equation (2) represents the target trajectory TG of the moving mechanism 400. As shown in the equation (2), the target trajectory TG is represented by a multi-order function having the required movement distance Lm and the time t as at least explanatory variables and the target position SP (t) of the movement mechanism 400 as the objective variable. NS.

In the equation (2), the target trajectory TG is represented by a quintic function at time t, but the order of the target trajectory TG may be represented by a multi-order function of 6th order or higher. Further, the target trajectory TG may be represented by a spline interpolation function.

When the maximum acceleration A _max is given, the orbital time T represented by the above equation (2) is calculated by the following equations (3) to (5).

f (A _max ) = C ₁ * Lm / A _max ... (3)
C ₁ = 60C ₂ (2C ₂ ² -3C ₂ + 1) ・ ・ ・ (4)
^{_{C 2 = 0.5-3 1/2 / 6 ···}} (5)
In step S140, the processor 214 generates a movement command MV for moving the movement mechanism 400 to the target position SP (t) obtained in step S138 as the movement control unit 254 (see FIG. 1) described above. The movement command MV is output to the servo driver 300.

In step S142, the processor 214 adds the control cycle Ts to the measurement time t to update the measurement time t.

In step S150, the processor 214 determines whether or not to end the update process of the target trajectory TG. As an example, the processor 214 ends the process shown in FIG. 8 based on the reception of the stop command of the update process of the target trajectory TG. When the processor 214 determines that the update process of the target trajectory TG is finished (YES in step S150), the processor 214 ends the process shown in FIG. Otherwise (NO in step S150), processor 214 returns control to step S130.

In the above description, an example in which the target position SP (t) is calculated for each control cycle Ts has been described, but the processor 214 is used until the moving mechanism 400 reaches the final target arrival position SP. The target position SP (t) at each time may be calculated collectively.

<F. Addendum>
As described above, the present embodiment includes the following disclosures.

[Structure 1]
A movement mechanism (400) for moving an object,
A visual sensor (50) for imaging the object based on the reception of the imaging instruction and measuring the actual position of the object from the image obtained by the imaging.
A calculation unit (250) for calculating the required movement distance of the movement mechanism (400) for moving the object from the actual position to a predetermined arrival target position.
The imaging instruction is output to the visual sensor based on a target trajectory represented by a quadratic function having the required movement distance and time as at least explanatory variables and the target position of the movement mechanism (400) as the objective variable. A position determination unit (252) for determining a target position corresponding to the current time for each predetermined control cycle shorter than the interval.
A control system including a movement control unit for moving the movement mechanism (400) to a target position determined by the position determination unit (252).

[Structure 2]
The control system according to configuration 1, wherein the multi-order function is a function of the fifth order or higher.

[Structure 3]
The control system according to configuration 1, wherein the position-determining unit (252) generates the target trajectory so that the acceleration of the moving mechanism (400) does not exceed a predetermined maximum acceleration.

[Structure 4]
The position-determining unit (252) generates the target trajectory each time the visual sensor (50) measures the actual position of the object, and the target previously generated by the newly generated target trajectory. The control system according to any one of configurations 1 to 3, which updates the trajectory.

[Structure 5]
The control system according to configuration 4, wherein the position-determining unit (252) generates a new target trajectory so that the speed of the moving mechanism (400) does not change before and after the update of the target trajectory.

[Structure 6]
The control system
A detection unit (412) for detecting the actual position of the movement mechanism (400) for each control cycle, and
A correction unit for correcting the required movement distance by the position deviation between the actual position detected by the detection unit at the update timing of the target trajectory and the target position of the movement mechanism at the timing is further provided. The control system according to configuration 5.

[Structure 7]
It is a control method of a moving mechanism (400) for moving an object.
A step of outputting an imaging instruction to a visual sensor and causing the visual sensor to measure the actual position of the object from an image obtained by imaging the object.
A step of calculating the required movement distance of the movement mechanism (400) for moving the object from the actual position to a predetermined arrival target position, and
The imaging instruction is output to the visual sensor based on a target trajectory represented by a quadratic function having the required movement distance and time as at least explanatory variables and the target position of the movement mechanism (400) as the objective variable. Steps to determine the target position corresponding to the current time for each predetermined control cycle shorter than the interval
A control method including a step of moving the moving mechanism (400) to a target position determined in the determination step.

[Structure 8]
A control program for a moving mechanism (400) for moving an object.
The control program is applied to the controller (200) for controlling the moving mechanism (400).
A step of outputting an imaging instruction to a visual sensor and causing the visual sensor to measure the actual position of the object from an image obtained by imaging the object.
A step (S131) of calculating the required movement distance of the movement mechanism (400) for moving the object from the actual position to a predetermined arrival target position.
The imaging instruction is output to the visual sensor based on a target trajectory represented by a quadratic function having the required movement distance and time as at least explanatory variables and the target position of the movement mechanism (400) as the objective variable. Steps to determine the target position corresponding to the current time for each predetermined control cycle shorter than the interval
A control program that executes a step (S140) of moving the moving mechanism (400) to a target position determined in the determined step.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Control system, 4,7 base plate, 6,9 ball screw, 12 features, 50 visual sensor, 100 image processor, 102,104 camera, 110,214 processor, 112 RAM, 114 display controller, 116 system controller, 118 I / O controller, 120 hard disk, 122 camera interface, 122a image buffer, 124 input interface, 126 motion controller interface, 128,228 communication interface, 130,222 memory card interface, 132 display, 134 keyboard, 136,224 memory card, 150 control program, 200 controller, 210 main control unit, 212 chipset, 216 non-volatile memory, 218 main memory, 220 system clock, 230 internal bus controller, 232 control circuit, 234 internal bus control circuit, 236 buffer memory, 238 fields Bus controller, 250 calculation unit, 251,251X, 251Y correction unit, 252, 252X, 252Y position determination unit, 254,254X, 254Y movement control unit, 300, 300X, 300Y servo driver, 400 movement mechanism, 410, 410X, 410Y Servo motor, 421, 412X, 412Y encoder, 420 stages.

Claims (10)

A movement mechanism for moving an object,
A visual sensor for imaging the object based on the reception of the imaging instruction and measuring the actual position of the object from the image obtained by the imaging, and
Calculate the required movement distance of the moving mechanism for moving the object from the actual position to a predetermined target position , and the orbit time required to move the moving mechanism from the start point to the end point of the target trajectory. And the calculation part to do
And the track time and time and the required movement distance is at least explanatory variables, based on the target trajectory represented by the multidimensional function aimed variable target position of the moving mechanism, the imaging instruction is the visual sensor A position determination unit for determining the target position corresponding to the current time for each predetermined control cycle shorter than the output interval.
A control system including a movement control unit for moving the movement mechanism to a target position determined by the position determination unit. The control system according to claim 1, wherein the multi-order function is a function of the fifth order or higher. The control system according to claim 1, wherein the position-determining unit generates the target trajectory so that the acceleration of the moving mechanism does not exceed a predetermined maximum acceleration. The orbital time is the longer of the time required when the required moving distance is moved to the moving mechanism at the maximum acceleration and the predetermined minimum orbital time shorter than the average of the intervals. The control system according to claim 3. The position-fixing unit generates the target trajectory each time the visual sensor measures the actual position of the object, and updates the previously generated target trajectory with the newly generated target trajectory. Item 6. The control system according to any one of Items 1 to 4. The control system according to claim 5 , wherein the position-determining unit generates a new target trajectory so that the speed of the moving mechanism does not change before and after the update of the target trajectory. The control system
A detection unit for detecting the actual position of the moving mechanism for each control cycle,
A correction unit for correcting the required movement distance by the position deviation between the actual position detected by the detection unit at the update timing of the target trajectory and the target position of the movement mechanism at the timing is further provided. The control system according to claim 6. The control system according to any one of claims 1 to 7, wherein the explanatory variable includes a ratio of the time to the orbit time. It is a control method of a movement mechanism for moving an object.
A step of outputting an imaging instruction to a visual sensor and causing the visual sensor to measure the actual position of the object from an image obtained by imaging the object.
A step of calculating the required movement distance of the movement mechanism for moving the object from the actual position to a predetermined arrival target position, and
A step of calculating the orbital time required to move the moving mechanism from the start point to the end point of the target orbit, and
And the track time and time and the required movement distance is at least explanatory variables, based on the target trajectory represented by the multidimensional function aimed variable target position of the moving mechanism, the imaging instruction is the visual sensor A step of determining a target position corresponding to the current time for each predetermined control cycle shorter than the output interval, and
A control method including a step of moving the moving mechanism to a target position determined in the determination step. A control program for a movement mechanism for moving an object.
The control program is used as a controller for controlling the moving mechanism.
A step of outputting an imaging instruction to a visual sensor and causing the visual sensor to measure the actual position of the object from an image obtained by imaging the object.
A step of calculating the required movement distance of the movement mechanism for moving the object from the actual position to a predetermined arrival target position, and
A step of calculating the orbital time required to move the moving mechanism from the start point to the end point of the target orbit, and
And the track time and time and the required movement distance is at least explanatory variables, based on the target trajectory represented by the multidimensional function aimed variable target position of the moving mechanism, the imaging instruction is the visual sensor A step of determining a target position corresponding to the current time for each predetermined control cycle shorter than the output interval, and
A control program that executes a step of moving the moving mechanism to a target position determined in the determined step.

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