JP5453590B2 - Robot hand control method and workpiece transfer robot system - Google Patents

Description

  The present invention relates to a method for controlling a hand of a robot that conveys a workpiece between a plurality of positions, and a workpiece conveyance robot system.

  Conventionally, there are robots that transport workpieces such as semiconductor wafers and glass substrates between cassettes. This robot is previously taught a predetermined operation necessary for conveyance, and performs a predetermined teaching operation according to the teaching data. For example, the semiconductor wafer stored in the cassette is taken out by the transfer arm of the robot, and the transfer arm is moved in this state to supply the semiconductor wafer to another cassette or inspection table. The semiconductor wafer supply destination needs to be supplied in a state where it is accurately positioned on the transfer arm. As a technique relating to such positioning, for example, there is a technique disclosed in Patent Document 1.

  The semiconductor wafer positioning apparatus disclosed in Patent Document 1 linearly moves the semiconductor wafer toward photoelectric sensors installed at two locations along the moving direction of the transfer arm of the robot, and is based on the outer peripheral edge of the semiconductor wafer. The response position of the photoelectric sensor is acquired as the coordinates of the robot that holds the semiconductor wafer. As a response position of the photoelectric sensor, a total of four response positions are acquired, that is, two rising points at which the detection state is switched to the detection state and two falling points at which the detection state is switched to the non-detection state. Thereafter, the deviation between the center of the semiconductor wafer and the ideal semiconductor wafer holding position of the robot is calculated as a deviation amount based on the response position of the photoelectric sensor and the installation conditions of the photoelectric sensor based on the distance from the reference trajectory and the installation coordinates.

  In addition, for example, a robot that passes a semiconductor wafer so as to draw an arc trajectory with respect to one point or a plurality of sensors, and a sensor holding position of the response position of the sensor based on the outer peripheral edge of the semiconductor wafer. Some of them are acquired as the coordinates (see, for example, Patent Document 2). At this time, the response position of the sensor is the same as that of Patent Document 1 described above.

JP 2000-012657 A Japanese Patent Laying-Open No. 2005-297072

  However, each of the above-described conventional techniques treats the rise and fall responses of the sensor equivalently, and does not consider the response difference (hysteresis) that is a characteristic characteristic of the sensor. Therefore, in the calculation for calculating the deviation amount, an error due to a difference in sensor response is added.

  Also, when using a total of four response positions, two rising points and two falling points, until the semiconductor wafer has passed over the sensor (because the falling point response position cannot be obtained), The amount of deviation cannot be determined.

  The present invention has been made in view of the above points, and an object of the present invention is to prevent an error due to a difference in response between sensors from being added, and to prevent a semiconductor wafer from passing over the sensor even if the semiconductor wafer has not passed over the sensor. An object of the present invention is to provide a robot hand control method and a workpiece transfer robot system capable of calculating the amount.

  In order to solve the above problems, the present invention provides the following.

(1) A method for controlling a hand of a robot that conveys a workpiece while positioning the workpiece from a first position to a second position, in a conveyance path that conveys the workpiece from the first position to the second position. In addition, a plurality of sensors for detecting different edges of the workpiece are arranged based on an alignment coordinate system that defines a movement position of the workpiece to be conveyed, and the first position to the second position are When conveying a workpiece, different edges of the workpiece are detected by using the plurality of sensors, and the plurality of sensors are detected by using a detection signal of either a rising response or a falling response of each of the plurality of sensors. A displacement amount of the movement position of the workpiece to be conveyed is calculated from a response state of the plurality of sensors based on the detection signal output from the sensor , and the displacement amount is calculated based on the movement amount of the robot. It converts to a robot coordinate system that defines a trajectory and controls the operation of the robot's hand, and the installation distance of the plurality of sensors in the alignment coordinate system and all of the plurality of sensors are turned off. Of one of the plurality of sensors and a state in which any of the plurality of sensors is on, and when the state changes from one state to another state. A method of controlling a hand of a robot, wherein the amount of deviation is calculated using an amount of movement of the robot.

According to the present invention, in the method for controlling the hand of a robot that takes out a work (wafer) from a first position such as a cassette and transfers it to a second position (predetermined supply destination), the first position A plurality of sensors that detect different edges of the workpiece are arranged in the middle of the conveyance path for conveying the workpiece from the second position to the second position based on an alignment coordinate system that defines the movement position of the workpiece to be conveyed . After detecting different edges of the workpiece by the sensor and calculating the deviation amount of the movement position of the workpiece conveyed from the detection signal, the deviation amount is converted into a robot coordinate system that defines the movement trajectory of the robot. Thus, it is possible to prevent an error due to a difference in sensor response from being added.

That is, by detecting different edges of a workpiece by a plurality of sensors arranged based on an alignment coordinate system that defines a reference position of the workpiece, a position deviation (based on the coordinates of the plurality of sensors with equivalent response characteristics of the sensor) It is possible to calculate (geometrically) the displacement amount of the movement position of the work to be conveyed . Therefore, unlike the conventional positioning device, it is not necessary to use the response positions of the rising point and the falling point, and it is possible to prevent an error due to a difference in sensor response from being added.

  If it is not necessary to use the response positions of the rising and falling points, half of the outer peripheral edge of the workpiece is to be detected, so the amount of deviation can be calculated even if the workpiece does not finish passing over the sensor. As a result, the process for detecting the amount of deviation can be shortened.

  In the present invention, the “several sensors” need only be arranged based on the alignment coordinate system that defines the reference position of the workpiece, and may not necessarily be arranged on the circumference or straight line. .

(2) The alignment coordinate system is an orthogonal coordinate system in which an axis parallel to a straight line connecting the plurality of sensors is an X axis, the workpiece is circular, and the edges of the workpiece are on the plurality of sensors. The circle simultaneously located at the center is the ideal circle, the center is the reference position, the center point when the workpiece at the reference position is the ideal circle is the origin of the Cartesian coordinate system, and the plurality of sensors are the ideal circle A method for controlling a robot hand, which is arranged on a circle.

According to the present invention, the alignment coordinate system described above is an orthogonal coordinate system having an X axis as an axis parallel to a straight line connecting a plurality of sensors, and a circular workpiece at the reference position is an ideal circle. The center point of is the origin of the Cartesian coordinate system, and the multiple sensors are arranged on the circumference of the ideal circle. By detecting different edges of the workpiece with these multiple sensors, the circular shape It is possible to calculate how much the workpiece is deviated from the ideal circle (positional deviation). Thus, by making the alignment coordinate system an orthogonal coordinate system having an X-axis as an axis parallel to a straight line connecting a plurality of sensors, the number of coordinate transformations can be reduced, thereby contributing to a reduction in processing load. be able to.

The control method of the hand of the robot of the present invention, prior SL with either the detection signal of the rising response or falling response of the sensor, and detects the shift amount.

  According to the present invention, since the deviation amount is detected using the detection signal of either the rising response or the falling response of the sensor described above, even if the workpiece does not end on the sensor, the deviation is detected. The amount can be calculated, and as a result, the process of detecting the deviation amount can be shortened.

( 3 ) A workpiece transfer robot system that transfers a workpiece while placing the workpiece on the hand from the first position to the second position, the robot coordinate system defining the movement trajectory of the hand, and the robot coordinates An alignment coordinate system that defines a movement position of the workpiece to be conveyed and a conveyance path that conveys the workpiece from the first position to the second position. And a plurality of sensors for detecting different edges of the workpiece, and a rising response of each of the plurality of sensors when the workpiece is transported from the first position to the second position. or using either one of the detection signal of the falling response from said plurality of sensors mutual response state based on the detection signal output from the serial plurality of sensors, prior to being transported Means for calculating a displacement amount of the movement position of the workpiece, and means for converting the displacement amount into a coordinate displacement in the robot coordinate system, the installation distance of the plurality of sensors in the alignment coordinate system, and the plurality One of a state in which all of the sensors are OFF, a state in which any of the plurality of sensors is ON, and a state in which any of the plurality of sensors is ON And a movement amount of the robot when the state is changed to another state, to calculate the deviation amount.

According to the present invention, the robot coordinate system that defines the movement trajectory of the hand and the alignment coordinate system that is independent of the robot coordinate system and defines the movement position of the workpiece to be transported are defined. A plurality of sensors that detect different edges of the workpiece are arranged based on the alignment coordinate system, and after calculating the shift amount of the movement position of the conveyed workpiece from the detection signals output from the plurality of sensors, the shift amount is Since the conversion is made into the coordinate shift in the robot coordinate system, it is possible to prevent the error due to the difference in the response of the sensor from being added and to shorten the process of detecting the shift amount.

According to the control method and the workpiece transfer robot system of the hand of the robot according to the present invention, the response characteristic of the sensor is based on coordinates of the equivalent multiple sensors, is possible to calculate the amount of deviation of the movement position of the workpiece to be transported As a result, it is possible to prevent an error due to a difference in sensor response from being added. Further, since it is not necessary to use the response positions of the rising point and the falling point, it is possible to shorten the process for detecting the deviation amount.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Work transfer robot system]
FIG. 1 is a configuration diagram of a workpiece transfer robot system according to an embodiment of the present invention. FIG. 2 is a block diagram showing an electrical configuration of the robot 100 and the robot controller 200 in the workpiece transfer robot system shown in FIG. 1 and FIG. 2 is an example, and the present invention is not limited to this configuration. For example, although not particularly shown in FIGS. 1 and 2, the robot 100 is connected to a teaching operation terminal (by wire such as a serial cable or wirelessly such as infrared communication or short-range wireless communication). Can be remotely controlled.

  First, as shown in FIGS. 1 and 2, the workpiece transfer robot system includes a robot 100, a robot controller 200, and two sensors 301 and 302). In the present embodiment, as shown in FIG. 1, a SCARA (horizontal articulated) robot is employed as the robot 100.

  The robot 100 includes a base 11 and an arm 15. The arm 15 has a hand fork portion 16a and a hand base end portion 16b. The arm 15 is rotatably connected by the first joint portion 17a, the second joint portion 17b, and the third joint portion 17c, so that the rotational force from the rotational drive source can be transmitted to perform a desired operation. It has become.

  The arm 15 is rotatably arranged on the base 11. That is, the arm 15 can rotate Θ around the Z axis. The arm 15 is configured to be slidable up and down (movable in the Z-axis direction in the figure).

  As described above, the arm 15 provided in the robot 100 includes the first arm portion 18 and the first arm portion together with the three joint portions (the first joint portion 17a, the second joint portion 17b, and the third joint portion 17c). 18 and a second arm portion 19 coupled to 18.

  The proximal end of the first arm portion 18 constitutes a rotatable first joint portion 17a. In addition, the base end of the second arm portion 19 that is the tip of the first arm portion 18 is connected via a drive shaft to constitute a rotatable second joint portion 17b. Further, the distal end of the second arm portion 19 and the hand base end portion 16b are connected via a drive shaft to constitute a rotatable third joint portion 17c.

  The arm 15 rotates the first joint portion 17a, the second joint portion 17b, and the third joint portion 17c by a rotation drive source (not shown), so that the hand fork portion 16a and the hand base end portion 16b are moved to the workpiece 10. Move in the take-out / supply direction (X direction). At this time, in the arm 15, due to its mechanism, the hand fork portion 16a and the hand base end portion 16b face one direction, and the first arm portion 18 and the second arm portion 19 are fully extended, The arm portion 18 and the second arm portion 19 are folded, and an expansion / contraction operation is performed so as to linearly move between the contraction positions. That is, in this embodiment, it reciprocates in the X direction in FIG. Then, the substrate (work 10) is stored in the cassette 500 located at the extended position, or the work 10 is carried out to the contracted position. In addition, such a mechanism includes, for example, a timing pulley provided in each of the first joint portion 17a, the second joint portion 17b, and the third joint portion 17c, and the timing pulleys are connected by a timing belt. It is comprised so that predetermined | prescribed rotation can be performed.

  Further, the movement of each of the X axis, Y axis, Z axis, and Θ axis in the drawing is servo controlled by the robot 100 and is controlled by servo motors 110b1 to 110bn (see FIG. 2) described later. As shown in FIG. 1, the workpiece 10 is stored in a cassette 500.

  As shown in FIG. 2, the robot controller 200 includes a CPU 101, a ROM 102, a RAM 103, an EEPROM 104, a communication I / F 105, an external input / output I / F 106, and a servo control unit 110. Connected by bus.

  The CPU 101 controls the robot controller 200 and performs integrated control of the robot controller 200. The ROM 102 stores a system program that supports the basic functions of the robot controller 200. The RAM 103 functions as a working area for the CPU 101. That is, in the RAM 103, writing and reading of variable values are performed at random. The EEPROM 104 can be electrically erased and written any number of times, and can retain the memory without supplying power from the outside.

  The communication I / F 105 is connected to a teaching operation terminal (not shown; other information processing apparatus such as a personal computer) as an information processing terminal, and inputs and outputs various data and programs for robot control. Although not shown, the external input / output I / F 106 is connected to a sensor provided in the robot, an actuator of a peripheral device, or the like.

  In particular, in this embodiment, detection signals from two sensors 301 and 302 arranged at predetermined positions are input to the CPU 101 through the external input / output I / F 106. Then, the CPU 101 calculates the amount of deviation from the reference position of the workpiece 10 based on this detection signal. Details of the calculation of the deviation amount will be described later in [Control Method of Robot Hand].

  The servo control unit 110 includes servo controllers 1 to n (n: the total number of axes of the robot plus the number of movable axes of the tool), and arithmetic processing (trajectory creation and interpolation, reverse) In response to the control command created through the conversion or the like, the servo motors 110b1 to 110bn constituting the actuator of each axis mechanism unit of the robot are controlled via the servo amplifiers 110a1 to 110an.

  As described above, the workpiece transfer robot system according to the present embodiment is a system in which the workpiece 10 is placed on the hand (arm 15) and transferred from the predetermined first position to the predetermined second position. It is.

[Robot hand control method]
FIG. 3 is a flowchart showing a method of controlling the hand (arm 15) of the robot 100 according to the embodiment of the present invention. FIG. 4 is an explanatory diagram for explaining the arrangement relationship between the two sensors 301 and 302. 5 to 7 are explanatory diagrams for explaining the calculation theory of the deviation amount. In the description after FIG. 3, a circular shape is considered as the shape of the workpiece 10. Further, the x-axis and the y-axis shown in FIG. 4 are separate axes from the X-axis and the Y-axis shown in FIG.

  Before explaining the control method shown in FIG. 3, first, the outline and concept (premise) of this control method will be explained using FIG.

  In FIG. 4, a circle in which the outer periphery of the workpiece 10 is simultaneously positioned on the two sensors 301 and 302 is defined as a “reference circle”, and its center (a position where the x axis and the y axis intersect) is defined as a reference position O. Therefore, the deviation from the reference position O becomes the correction amount. Specifically, the center point of the circle (the outer periphery of the workpiece 10) that can be recognized by the position where the sensor is turned on when passing over the two sensors 301 and 302 is calculated as the deviation from the reference position O, and is calculated. The hand of the robot 100 is controlled using the corrected amount, and the storage position of the workpiece 10 is corrected. Further, by operating the hand (arm 15) of the robot 100 at a constant direction and at a constant speed including the coordinates of the reference position O (as described above, for the arm 15, the hand fork portion 16a and the hand base end). The part 16b faces in one direction, the extended position where the first arm part 18 and the second arm part 19 are fully extended, and the contracted position where the first arm part 18 and the second arm part 19 are folded. Perform telescopic motion so that it moves linearly between them) and perform sensing. The position deviation is calculated by marking the coordinates at which each of the two sensors 301 and 302 is turned on during the operation of the robot 100, and the installation distance of the two sensors 301 and 302 and the mark position (two points). And depending on the operating distance.

  Further, as a coordinate system, a robot coordinate system that defines the movement trajectory of the hand and an alignment coordinate system that defines the reference position of the workpiece 10 that are independent of the robot coordinate system are considered. Examples of the robot coordinate system include a cylindrical coordinate system and an orthogonal coordinate system. On the other hand, as the alignment coordinate system, an orthogonal coordinate system is exemplified, and for example, an axis parallel to a straight line connecting the sensor 301 and the sensor 302 can be set as the x axis. The origin position is the center point of an ideal circle (a circle that passes simultaneously on the sensor 301 and the sensor 302. Reference circle) (see FIG. 4). The radius of the ideal circle is the radius of the workpiece 10. Further, the two sensors 301 and 302 described above are arranged based on the alignment coordinate system in the conveyance path for conveying the workpiece 10 from the first position to the second position, and different edges of the workpiece 10 are arranged. It has a function to detect.

  The relationship between the robot coordinate system and the alignment coordinate system is positioned as follows. That is, when the robot coordinate system is a cylindrical coordinate system, the 0 degree direction of the turning direction is the x-axis + direction, and when the robot coordinate system is an orthogonal coordinate system, the x-axis + direction of the robot coordinate system is the alignment coordinate. The x-axis + direction of the system. The basic correction value is calculated geometrically on the alignment coordinate system. The calculation result is converted into a robot coordinate system and used as a correction amount.

  The center coordinates of the workpiece 10 based on the outer periphery of the workpiece 10 that linearly operates on the alignment coordinate system (orthogonal coordinate system), the coordinates at which the sensors 301 and 302 are turned on, and the coordinates at which the sensors 301 and 302 are installed. To consider. During sensing, it is divided into the following three states. That is, both the two sensors 301 and 302 are OFF, the one of the two sensors 301 and 302 is ON, and the two sensors 301 and 302 are both It is in the state of being turned on.

  In FIG. 4, a reference circle (chain line) is a circle in which both of the two sensors 301 and 302 are ON at the same time. A circle indicated by “Sensor1 on” indicates that only the sensor 301 is ON. A circle in a state of being in a state (two-dot chain line) and indicated by “Sensor2 on” is a circle in which only the sensor 302 is ON (two-dot chain line). The coordinates of the reference position O are represented by (X0, Y0), the coordinates of the sensor 301 are represented by (Xs1, Ys1), and the coordinates of the sensor 302 are represented by (Xs2, Ys2). The coordinates at which the coordinates (Xs1, Ys1) of the sensor 301 transition when the workpiece 10 moves from the circle indicated by “Sensor1 on” to the circle indicated by “Sensor2 on” are (Xs1 ′, Ys1 ′). Then, the distance between (Xs1, Ys1) and (Xs1 ′, Ys1 ′) is equal to the distance (= Δl) from the center of the circle indicated by “Sensor1 on” to the center of the circle indicated by “Sensor2 on”. The center coordinates (ΔX, ΔY) of the circle indicated by “Sensor2 on” with respect to the reference position O are the shift amount of the workpiece 10.

  This control method tries to calculate the correction amount of the workpiece 10 (correcting only ΔX for the x axis and ΔY for the y axis) using only the initial value as a parameter and the movement distance (Δl) of the robot. To do. Based on the above, the details (basic principle) of this control method will be described along the flowchart of FIG.

  In FIG. 3, first, edge detection is performed (step S1). Specifically, as shown in FIG. 5, the CPU 101 of the robot controller 200 is a circle when the outer periphery of the workpiece 10 passes over the sensor 302, that is, “Sensor2 on” in which only the sensor 302 is ON. Detect the indicated circle. Then, in addition to P0 (reference position O described above), P1 (x1, y1) = (Xs1, Ys1), and P2 (x2, y2) = (Xs2, Ys2), P0 ′ (ΔX, ΔY) And P1 ′ (x1 ′, y1 ′) = (Xs1 ′, Ys1 ′) is obtained.

  Next, the CPU 101 calculates a deviation amount (step S2). The calculation of the deviation amount will be described in detail with reference to FIGS. As an initial value, the radius of the workpiece 10 is r, and the pitch between the sensor 301 and the sensor 302 is Pitch. Further, as an operation amount, an operation distance where the sensor 302 is turned ON from the ON of the sensor 301 is L. Let S be the robot's approach angle (signed) between the sensors. In addition, an angle formed by the pitch direction (X axis) between the sensors from the penetration angle S is defined as α.

  First, the apparent pitch (= distance between P2 (x2, y2) and P1 ′ (x1 ′, y1 ′)) is calculated. α is represented by 90 ° -S, and the motion amount L can be decomposed as follows for each component of each axis. That is, dX = L × cos α and dY = L × sin α. When the angle P1′P2P1 = θ, this θ can be expressed by θ = tan−1 {(L × sin α) / (A + L × cos α)}. Also, the apparent pitch (= A ′) at this time is A ′ = (A + L × cos α) × cos θ + L × sin α × cos {π / 2−θ} = A × cos θ + L × cos α × cos θ + L × sin α × sin θ = A × cos θ + L × cos (α−θ) (from the addition theorem).

  Next, assuming that the angle P0′P2P1 ′ = θ2, the relationship between the sine and cosine theorem of the half angle and the tangent and the length of the side is used, and θ2 = 2tan−1 [sqrt {(A ′ + r) (2r) / (A ′ + 2r) (A ′ + r)}] = 2tan−1 [sqrt {(2r) / (A ′ + 2r)}]. Similarly, when the angle P0′P2P1 ″ = θ1, θ1 = 2tan−1 [sqrt {(2r) / (A + 2r)}]. Note that sqrt represents a square root.

  Here, if the angle P1 ″ P2P1 = θ ′, then θ ′ = θ + θ1-θ2 is established. L ′ becomes L ′ = A × sqrt {2 (1-cos θ ′)} using the second cosine theorem. As described above, the deviation amounts of the X axis and the Y axis are ΔX = L ′ × r / A × cos {(1/2) × (π + θ ′) − θ1}, ΔY = L ′ × r / A × sin {( 1/2) × (π + θ ′) − θ1}.

  In this way, after calculating the shift amount, the CPU 101 performs coordinate conversion of ΔX and ΔY as necessary (step S3), and based on the correction amount after the coordinate conversion, the CPU 101 passes the hand of the hand through the servo control unit 110. The operation is controlled (step S4). Thereby, it is possible to control the operation of the hand while preventing an error due to the difference in response of the sensors from being added.

  As shown in step S2 and step S3, when the CPU 101 transports the workpiece 10 from the first position to the second position, the CPU 101 detects the workpiece from the detection signals output from the two sensors 301 and 302. A function of calculating a deviation amount (ΔX, ΔY) from ten reference positions O and a function of converting the deviation amount into a coordinate deviation in the robot coordinate system.

  Information necessary for sensing and correction value calculation is acquired by executing calibration. Specifically, it is a sensor-to-sensor distance error (compared with the set value), a sensing angle error for the sensor (compared with the set value), or a dynamic position deviation from the teaching point (two sensors are turned on) Position).

[Main effects of the embodiment]
As described above, the method for controlling the hand of the robot 100 according to the present embodiment is a control method for conveying the workpiece 10 while positioning the workpiece 10 from the first position to the second position. Two sensors 301 and 302 for detecting different edges of the workpiece 10 are arranged based on an alignment coordinate system that defines the reference position O of the workpiece 10 in the conveyance path for conveying the workpiece 10 to the second position. When the workpiece 10 is transported from the first position to the second position, different edges of the workpiece 10 are detected by using the two sensors 301 and 302 (step S2 in FIG. 3). From the detection signal output from 302, the CPU 101 calculates the amount of deviation of the workpiece 10 from the reference position O, and the amount of deviation is converted into a robot coordinate system that defines the movement trajectory of the robot 100. After the conversion (step S3 in FIG. 3), since the operation of the hand of the robot 100 is controlled (step S4 in FIG. 3), the position deviation is calculated based on the coordinates of the sensors 301 and 302 having the equivalent response characteristics of the sensors. It can be calculated geometrically. Therefore, unlike the conventional positioning device, it is not necessary to use the response positions of the rising point and the falling point, and it is possible to prevent an error due to a difference in sensor response from being added.

  Further, if it is not necessary to use the response positions of the rising point and the falling point, since the half of the outer peripheral edge of the workpiece is a detection target, even if the workpiece 10 does not pass over the sensors 301 and 302, the deviation amount Thus, the process for detecting the amount of deviation can be shortened. In addition, it is possible to move to the next process at an early stage.

  In addition, since the conventional positioning device is based on the premise that the wafer (work) passes over the sensor, there is a possibility that the shape of the wafer holding part of the robot is greatly limited in order to obtain the detection position. It was. However, according to the method for controlling the hand of the robot 100 according to the present embodiment, the restriction on the shape of the wafer holding unit (arm 15) of the robot 100 can be reduced.

  Further, in the case of a conventional positioning device, a reference coordinate system is defined, and there is a possibility that it cannot be applied successfully in a different coordinate system. However, according to the control method of the hand of the robot 100 according to the present embodiment, the coordinates of the robot 100 whose position is not constrained by the motion trajectory of the robot 100 by performing calibration on a certain two sensor sets. A coordinate system (alignment coordinate system) having a unique reference position different from the system can be defined. As a result, the present invention can be applied regardless of the type of the coordinate system of the robot 100 by converting the processing result on the alignment coordinate system into data of the robot coordinate system.

  Further, in the conventional positioning device, it is a condition that the sensor is accurately installed on the trajectory of the robot 100, and it is necessary to correct the installation position of the sensor when the installation position of the robot 100 is deviated. However, according to the method for controlling the hand of the robot 100 according to the present embodiment, since the amount of deviation is calculated on the alignment coordinate system, fine sensor installation accuracy with respect to the movement trajectory of the robot 100 becomes unnecessary. That is, even when the position condition changes, such as when the installation position of the robot 100 is shifted or when the installation position of the sensor is shifted, by performing calibration, the position of the robot, the sensor position, etc. No physical adjustment is necessary.

  The alignment coordinate system is an orthogonal coordinate system in which the axis parallel to the straight line connecting the two sensors 301 and 302 is the x axis, and the workpiece 10 is circular, and the workpiece 10 at the reference position O is The center point in the case of an ideal circle is the origin of the Cartesian coordinate system (see FIG. 4). Since the two sensors 301 and 302 are arranged on the circumference of the ideal circle, the circular workpiece 10 is How much (ΔX, ΔY) is deviated from the ideal circle can be calculated.

  In particular, by making the alignment coordinate system an orthogonal coordinate system in which the axis parallel to the straight line connecting a plurality of sensors is the X axis, the number of coordinate transformations can be reduced, which in turn contributes to a reduction in processing load. it can.

  Furthermore, if the amount of deviation is detected using one of the detection signals of the rising response or falling response of the sensor, the amount of deviation can be calculated even if the workpiece 10 does not finish passing over the sensor. The process for detecting the shift amount can be shortened.

  Note that a teaching point may be acquired by the above-described principle calculation by installing a sensor on the robot 100 and preparing a dummy workpiece or the like (automatic teaching operation). Further, the accuracy of the robot 100 main body may be measured by installing a sensor in the robot 100 main body and scanning a reference portion.

  As described above, the present invention is useful as a device capable of controlling a robot hand while preventing an error due to a difference in sensor response from being added.

It is a block diagram of the workpiece conveyance robot system which concerns on embodiment of this invention. It is a block diagram which shows the electrical structure of the robot and robot controller in the workpiece conveyance robot system shown in FIG. It is a flowchart which shows the control method of the hand of the robot which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the arrangement | positioning relationship etc. of two sensors. It is explanatory drawing for demonstrating the calculation theory of deviation | shift amount. It is explanatory drawing for demonstrating the calculation theory of deviation | shift amount. It is explanatory drawing for demonstrating the calculation theory of deviation | shift amount.

Explanation of symbols

100 robot 200 robot controller

Claims (3)

A method for controlling a robot hand that conveys a workpiece while positioning a workpiece from a first position to a second position,
A plurality of sensors that detect different edges of the workpiece in a conveyance path that conveys the workpiece from the first position to the second position have an alignment coordinate system that defines a movement position of the workpiece to be conveyed. Arranged based on
When conveying the workpiece from the first position to the second position, different edges of the workpiece are detected using the plurality of sensors,
Using the detection signal of either the rising response or the falling response of each of the plurality of sensors, the plurality of sensors are conveyed from the mutual response state based on the detection signals output from the plurality of sensors. Calculate the shift amount of the movement position of the workpiece,
Converting the deviation amount into a robot coordinate system defining an operation trajectory of the robot, and controlling the operation of the robot hand;
Installation distances of the plurality of sensors in the alignment coordinate system;
One of a state where all of the plurality of sensors are OFF, a state where all of the plurality of sensors are ON, and a state where any of the plurality of sensors is ON. The amount of movement of the robot when it changes from the state to another state,
A method for controlling a hand of a robot, wherein the amount of deviation is calculated using The alignment coordinate system is an orthogonal coordinate system having an axis parallel to a straight line connecting the plurality of sensors as an X axis, and the workpiece is circular, and the edges of the workpiece are simultaneously positioned on the plurality of sensors. A circle to be an ideal circle, the center thereof as a reference position, and the center point when the workpiece at the reference position is an ideal circle is the origin of the Cartesian coordinate system,
2. The robot hand control method according to claim 1, wherein the plurality of sensors are arranged on a circumference of the ideal circle. A workpiece transfer robot system for transferring a workpiece while placing the workpiece on a hand while positioning the workpiece from a first position to a second position,
A robot coordinate system that defines the motion trajectory of the hand;
An alignment coordinate system that is independent of the robot coordinate system and defines a movement position of the workpiece to be conveyed;
A plurality of sensors arranged on the basis of the alignment coordinate system and detecting different edges of the workpiece in a conveyance path for conveying the workpiece from the first position to the second position;
When the workpiece is transported from the first position to the second position, output from the plurality of sensors using the detection signal of either the rising response or the falling response of each of the plurality of sensors. Means for calculating a shift amount of the movement position of the conveyed workpiece from the response state between the plurality of sensors based on the detected signal;
Means for converting the shift amount into a coordinate shift in the robot coordinate system,
Installation distances of the plurality of sensors in the alignment coordinate system;
One of a state where all of the plurality of sensors are OFF, a state where all of the plurality of sensors are ON, and a state where any of the plurality of sensors is ON. The amount of movement of the robot when it changes from the state to another state,
The workpiece transfer robot system, wherein the amount of deviation is calculated using

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