Wire-shaped object gripping method, control device, and wire-shaped object gripping system

Abstract

To provide a method for gripping a thin, flexible and easily deformable linear object by a robot hand even in a situation where it cannot be recognized by a stereo camera.SOLUTION: A laser is emitted from a laser displacement sensor 40 mounted on an arm 31 of a robot 30 along a measurement line crossing a linear object W, and reflected light is received by the laser displacement sensor to measure a distance to a reflection point. Acquiring a reflection-point profile including information on a distance from the laser displacement sensor to the reflection point and a position and a direction of the laser displacement sensor, calculating a corrected reflection-point profile by converting the reflection-point profile into a coordinate system that does not change depending on a posture of the arm, determining a holding position of the line member based on the corrected reflection-point profile, and holding the holding position with the hand 32 attached to the tip of the arm or another hand.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method, a control device and a system for gripping a linear object such as a cable with the hand of a robot. [Background technology]

[0002] Robots are being used to automate the handling of thin, flexible, and easily deformable linear objects in various tasks. For example, when crimping terminals, fastening connectors and other components, soldering, welding, connecting, and other processes are performed on cables such as electric wires, optical fibers, and various types of thin-diameter tubes, the linear workpiece is grasped by a robot hand and moved to the target processing device, inspection device, connector, etc.

[0003] For example, Patent Document 1 describes a method for measuring the three-dimensional shape of a linear object using a stereo camera. Patent Document 2 describes a method for measuring the three-dimensional shapes of multiple flexible, shape-undefined linear objects using a stereo camera, determining whether one of the linear objects can be grasped by a robot hand without interfering with the other linear objects, and then grasping the object.

[0004] As for sensors other than stereo cameras, Patent Document 3, while not intended for flexible linear objects, describes a method in which workpieces such as steel pipes are piled up, a laser position sensor is used to scan one end of the pile in the width direction, the coordinates of one end of the highest workpiece are determined, and that end is pushed toward the other end with a pusher. The workpiece pushed toward the other end has its other end protruding from the other workpieces and grasped by a second robot, the second robot is raised and pushed back toward the one end, and its one end protruding from the other workpieces and grasped by a first robot, which then lifts and transports it with the first and second robots. Patent Document 4 also describes a method in which long agricultural produce such as asparagus and green onions are stacked in a tray, a laser sensor or other sensor is used to scan across the produce to detect the position of the highest workpiece, and the highest workpiece is then picked up by a suction device and moved to a weighing machine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 017360 [Patent Document 2] International Publication No. 2019 / 098074 [Patent Document 3] Japanese Patent Application Publication No. 2019-116342 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-132530 Summary of the Invention [Problem to be solved by the invention]

[0006] The 3D measurement of linear objects using a stereo camera described in Patent Documents 1 and 2 has various advantages. For example, using a stereo camera allows a distance image containing distance information to each point on the image to be obtained with a single capture, and allows the use of information other than distance information, such as color information on the image. However, a problem with stereo cameras is that they cannot measure distance unless the edges of a linear object can be recognized in the image. For example, when a black cable is placed in front of a dark background, the edges of the linear object may not be recognized if the colors of the linear object and the background are very similar. Furthermore, when cables whose outermost layer is a protective tube made of woven synthetic fibers are stacked, it may be difficult to distinguish one linear object from adjacent linear objects.

[0007] On the other hand, the laser displacement sensors described in Patent Documents 3 and 4 have the advantage of being able to measure the distance to an object regardless of its color or pattern. The devices described in Patent Documents 3 and 4 perform a single scan with the sensor, determine the position coordinates of a single point on the workpiece, and then push the workpiece with a hand or pick it up with a suction device. However, Patent Document 3 targets steel pipes and the like, and Patent Document 4 targets agricultural crops such as asparagus. As described in these documents, when the workpieces are aligned in one direction, the scanning position of the laser displacement sensor can be fixed, allowing the gripping position to be calculated without complex coordinate transformation. However, in cable routing tasks during wire harness assembly, cables oriented in various directions must be grasped, and the position and orientation of the laser displacement sensor must be varied for scanning, necessitating a complex method of calculating the gripping position.

[0008] The present invention has been made in consideration of the above, and aims to provide a method for grasping a thin, flexible, and easily deformed linear object with a robot hand, even in situations where the linear object to be grasped cannot be recognized by a stereo camera and is facing in various directions. [Means for solving the problem]

[0009] The linear object gripping method of the present invention includes the steps of: emitting a laser from a laser displacement sensor attached to an arm of a robot along a measurement line that intersects with the linear object; receiving reflected light with the laser displacement sensor to measure the distance to a reflection point; and acquiring a reflection point profile that includes information about the distance from the laser displacement sensor to the reflection point and the position and orientation of the laser displacement sensor; converting the reflection point profile into a coordinate system that does not change depending on the posture of the arm to calculate a corrected reflection point profile; determining a gripping position of the linear object based on the corrected reflection point profile; and gripping the linear object at the gripping position with a hand attached to the tip of the arm or another hand.

[0010] Here, the reflection point profile and corrected reflection point profile indicate position information of the reflection points along the measurement line. The coordinate system that does not change depending on the posture of the arm is, for example, the base coordinate system of the robot or the world coordinate system. The other hand includes a hand attached to the tip of an arm other than the one to which the laser displacement sensor is attached when the robot is a dual-arm robot, and a hand provided on a robot other than the robot to which the laser displacement sensor is attached.

[0011] This method allows the robot's hands to grasp flexible and easily deformed linear objects even when the linear object to be grasped cannot be recognized by a stereo camera, or when the linear object is bent or facing in various directions.

[0012] Preferably, in the above-mentioned linear object grasping method, the process of acquiring the reflection point profile and the process of calculating the corrected reflection point profile are performed for a plurality of the measurement lines, and the grasping position is determined based on the plurality of the corrected reflection point profiles.

[0013] Here, the multiple corrected reflection point profiles are corrected reflection point profiles for each of the multiple measurement lines.

[0014] This method makes it possible to estimate the position and orientation of the portion of a linear object sandwiched between the measurement lines. As a result, it is possible to grasp thin, flexible, and easily deformed linear objects, whose bending due to deformation is relatively large compared to their diameter, compared to steel pipes or agricultural crops such as asparagus, by adjusting the orientation of the hand to match the orientation of the linear object at the grasping position.

[0015] In the step of acquiring a reflection point profile in any of the above linear object grasping methods, the laser displacement sensor may emit a beam-shaped laser in one direction, and scan the laser displacement sensor along the measurement line by moving the arm.

[0016] Alternatively, in the step of acquiring a reflection point profile in any of the above linear object gripping methods, the laser displacement sensor may emit a line laser.

[0017] The control device of the present invention is a control device that uses a laser displacement sensor attached to a robot arm to calculate a gripping position for gripping a linear object with a hand attached to the tip of the arm or another hand, and instructs the robot to operate the arm so that the target of the laser emitted from the laser displacement sensor moves along a measurement line that intersects with the linear object, instructs the laser displacement sensor to emit the laser and measure the distance to a reflection point of the laser, receives from the laser displacement sensor the distance from the laser displacement sensor to the reflection point, and receives information about the position and orientation of the laser displacement sensor from the robot, thereby obtaining a reflection point profile including information about the distance from the laser displacement sensor to the reflection point and the position and orientation of the laser displacement sensor, converts the reflection point profile into a coordinate system that does not change depending on the posture of the arm to calculate a corrected reflection point profile, and calculates the gripping position of the linear object based on the corrected reflection point profile.

[0018] The linear object grasping system of the present invention comprises the above-mentioned control device, the robot, and the laser displacement sensor, and the control device instructs the robot to grasp the grasping position with the hand attached to the tip of the arm.

[0019] Another linear object grasping system of the present invention has the above-mentioned control device, the robot, and the laser displacement sensor, wherein the robot is a dual-arm robot, and the control device instructs the dual-arm robot to grasp the grasping position with the other hand attached to the tip of the other arm.

[0020] Yet another linear object grasping system of the present invention comprises the above-mentioned control device, the robot, the laser displacement sensor, and a second robot, and the control device instructs the second robot to grasp the grasping position with the other hand provided on the second robot. [Effects of the Invention]

[0021] According to the linear object grasping method, control device, or linear object grasping system of the present invention, a thin, flexible, and easily deformed linear object can be grasped by a robot hand even if the linear object to be grasped cannot be recognized by a stereo camera, is facing in various directions, or is not aligned in a single direction. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a diagram showing the configuration of a linear object gripping system for carrying out a linear object gripping method of a first embodiment. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the linear object gripping system. [Figure 3] FIG. 2 is a process flow diagram of the linear object gripping method of the first embodiment. [Figure 4] 1A to 1C are diagrams for explaining a linear object gripping method according to a first embodiment. [Figure 5] 10A and 10B are diagrams for explaining a method for gripping a linear object with a hand. [Figure 6] 10A and 10B are diagrams for explaining a linear object gripping method according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] A first embodiment of a linear object gripping method, a control device, and a linear object gripping system according to the present invention will be described with reference to FIGS.

[0024] 1, a linear object grasping system 10 of this embodiment includes a robot 30, a laser displacement sensor 40, and a control device 20. The control device 20 performs various calculations, which will be described later, and controls the entire linear object grasping system 10. The linear object grasping system 10 measures a linear object W using the laser displacement sensor 40, and based on the calculation results by the control device 20, grasps the linear object W with a hand 32 attached to the tip of an arm 31 of the robot 30.

[0025] The robot 30 is preferably a vertical articulated robot. The robot 30 includes an arm 31 and a hand 32. The hand 32 is configured to be able to grasp a linear object W. The hand 32 preferably grasps the linear object W by pinching it between a pair of fingers. This is because the linear object W can be grasped more reliably than by grasping it by suction, and the grasped linear object is less likely to fall off.

[0026] The laser displacement sensor 40 is attached to the tip of the arm 31 of the robot 30 with the laser emission direction facing the tip of the arm. The laser displacement sensor 40 emits a laser toward the space where the measurement target is located, receives the reflected light returning from an object in the space, and measures the distance to the reflection point where the laser light is reflected. There are no particular limitations on the type of laser displacement sensor, and various types such as well-known triangulation methods, confocal methods, and spectral interference methods can be used. The laser displacement sensor 40 of this embodiment emits a laser beam in one direction.

[0027] Referring to FIG. 2, the control device 20 includes a calculation unit 21, a storage unit 22, and a communication unit 23. The calculation unit 21 performs various calculations. The calculations performed by the calculation unit 21 include creating a reflection point profile indicating the position information of the laser reflection points from the measurement results of the laser displacement sensor 40, converting the reflection point profile into a coordinate system that does not change depending on the posture of the arm 31 to calculate a corrected reflection point profile, and determining the gripping position of the linear object W based on the corrected reflection point profile. The storage unit 22 stores information necessary for the above calculations and the progress of the calculations. The information stored in the storage unit 22 includes information necessary for converting the reflection point profile based on the laser displacement sensor 40 into a coordinate system that does not change depending on the posture of the arm 31. The communication unit 23 communicates with the robot 30 and the laser displacement sensor 40. The control device 20 transmits instructions to the robot and the laser displacement sensor and receives necessary information from the robot and the laser displacement sensor via the communication unit 23. The content of the communication will be described in the description of the linear object gripping method.

[0028] The robot control unit 35 of the robot 30 controls the entire robot 30, including the arm 31 and the hand 32. The robot control unit 35 includes a robot calculation unit 36 ​​and a robot communication unit 37. The robot calculation unit 36 ​​performs various calculations, such as determining joint variables for causing the arm 31 to assume a required posture and for causing the hand 32 to reach a target position. The robot communication unit 37 communicates with the communication unit 23 of the control device 20.

[0029] The sensor control unit 45 of the laser displacement sensor 40 controls the on / off of laser light emission, etc. The sensor control unit 45 includes a sensor calculation unit 46 and a sensor communication unit 47. The sensor calculation unit 46 performs various calculations required for distance measurement, such as calculating the distance from the position on the light receiving element of the received reflected light to the reflection point in the case of a triangulation method. The sensor communication unit 47 communicates with the communication unit 23 of the control device 20.

[0030] The linear object W that is the target of the linear object gripping method of this embodiment is a flexible thin wire. The diameter of the linear object is preferably 0.05 to 10.0 mm, more preferably 0.5 to 5.0 mm. Examples of linear objects include metal wires, metal wires coated with resin, and objects made entirely of resin, such as coated electric wires used in wiring and wire harnesses for electrical appliances, various wires, cables, optical fibers, and resin tubes used in medical devices such as catheters. The linear object gripping method of this embodiment is particularly suitable for handling linear objects that are easily deformed or easily bent. "Easily bent" means that the object is easily deformed and, once deformed, does not easily return to its original shape.

[0031] Next, a linear object grasping method of this embodiment using the linear object grasping system 10 will be described with reference to FIGS. 4 and 5 along the flow of FIG.

[0032] Here, as shown in Fig. 4, a case will be described in which one linear object is grasped from a pile of linear objects. The linear object grasping method of this embodiment is outlined as follows: The robot arm 31 is moved along the first measurement line 51 to move the laser displacement sensor 40 and obtain a first reflection point profile (S1). The first reflection point profile is converted into a coordinate system that does not change depending on the posture of the arm 31 to calculate a first corrected reflection point profile (S2). Similarly, a second reflection point profile along the second measurement line 52 is obtained (S3), and a second corrected reflection point profile is calculated (S4). The position and orientation of the linear object are estimated based on the first and second corrected reflection point profiles (S5), a grasping position G of the linear object is determined (S6), and the linear object is grasped with the hand 32 (S7).

[0033] (S1: Acquisition of the first reflection point profile) A first reflection point profile along a first measurement line 51 that intersects with the linear object W is calculated.

[0034] First, a first measurement line 51 that intersects with the linear object W is set in space. The first measurement line 51 is the target of the laser light emitted from the laser displacement sensor 40. The direction of the first measurement line 51 does not need to be determined precisely; it can be set so that it intersects with the linear object based on previously obtained position information of the linear object. Although it is difficult to accurately determine the intersection angle between the first measurement line and the deformed linear object W, the first measurement line is set so that the intersection angle with the linear object W is preferably approximately 45 degrees or more, more preferably approximately 60 degrees or more. The position and direction of the previously set first measurement line can be stored in the memory unit 22 of the control device 20.

[0035] If the orientation of the linear object W cannot be predicted at all from previously obtained information, the first corrected reflection point profile is calculated for the arbitrarily set first measurement line according to the following procedure. As described below, the first corrected reflection point profile gives the outline of the cross section of the linear object W in the section where the laser reflection point is on the surface of the linear object W. Therefore, if the curvature is small (if the radius of curvature is large), it can be determined that the intersection angle between the first measurement line and the linear object W was small. If the curvature is extremely small, the gripping position G cannot be determined with the required accuracy, so the first measurement line can be reset and steps S1 and S2 can be repeated. To reset the measurement line, measurements can be taken multiple times in the expected measurement area while changing the orientation of the measurement line, and the measurement results of the measurement line that produced the best results can be used. For example, a measurement is performed on a 1B measurement line, which is rotated 30 degrees clockwise from the first measurement line (here, 1A measurement line), and then a measurement is performed on a 1C measurement line, which is rotated 30 degrees counterclockwise from the first measurement line. Of the first corrected reflection point profiles obtained from the 1B measurement line and the 1C measurement line, the measurement line that has a radius of curvature close to the radius of the linear object to be measured is newly set as the first measurement line, and the measurement result for the newly set first measurement line is used.

[0036] (S11) The control device 20 instructs the robot 30, and the robot 30 adjusts the posture of the arm 31 to move the laser displacement sensor 40 to a position where the laser light emitted from the laser displacement sensor 40 passes through the first measurement line 51. The control device 20 instructs the laser displacement sensor 40, and the laser displacement sensor 40 emits a laser beam 41 toward a point on the first measurement line 51 and measures the distance to the reflection point.

[0037] (S12) The control device 20 receives the measurement result of the distance from the laser displacement sensor 40 to the reflection point from the laser displacement sensor, and receives information about the position and orientation of the laser displacement sensor at that time from the robot 30. Information about the position and orientation of the laser displacement sensor is, for example, the rotation angle of each joint of the robot. Because the laser displacement sensor is fixed to the robot's arm 31, the position and orientation of the laser displacement sensor can be determined if the posture of the arm is known. The control device 20 stores a set of information about the distance from the laser displacement sensor 40 to the reflection point and the position and orientation of the laser displacement sensor in the memory unit 22.

[0038] (S13) The control device 20 commands the robot 30 to move the laser displacement sensor 40 along the first measurement line 51 to the next measurement position.

[0039] The above steps S11 to S13 are repeated over a predetermined range on the first measurement line 51. This provides information on the distance from the laser displacement sensor 40 to the reflection point along the first measurement line, and the position and orientation of the laser displacement sensor when measuring the distance. The entire series of information forms a first reflection point profile along the first measurement line.

[0040] (S2: Calculation of the first corrected reflection point profile) The calculation unit 21 of the control device 20 converts the first reflection point profile acquired in step S1 and stored in the memory unit 22 into a coordinate system that does not change depending on the posture of the arm 31, calculates a first corrected reflection point profile, and stores it in the memory unit 22. The coordinate system that does not change depending on the posture of the arm 31 is, for example, the base coordinate system of the robot 30 or the world coordinate system.

[0041] The distance from the laser displacement sensor 40 to the reflection point included in the first reflection point profile is measured while moving the laser displacement sensor attached to the arm 31. In this process, this first reflection point profile is converted into a first corrected reflection point profile that does not depend on the posture of the arm, that is, that is unrelated to the position and orientation of the laser displacement sensor. Through this conversion, the first corrected reflection point profile becomes, for example, a line connecting the heights of the reflection points from the floor surface on which the robot 30 is installed. In the section where the laser reflection point is on the surface of the linear object W, the first corrected reflection point profile gives the outline of the cross section of the linear object.

[0042] The first corrected reflection point profile may be calculated by converting the entire first reflection point profile all at once after the entire first reflection point profile along the first measurement line has been acquired, or may be calculated by sequentially adding the profiles by performing conversion each time a point is measured by the laser displacement sensor 40. In the latter case, the first reflection point profile and the first corrected reflection point profile are completed at the same time.

[0043] (S3: Acquisition of the second reflection point profile) A second measurement line 52 that intersects with the linear object W is set in space parallel to the first measurement line, with a gap between the first measurement line and the linear object W in the longitudinal direction, and a second reflection point profile along the second measurement line is obtained. The gap between the first and second measurement lines depends on the diameter and bendability of the linear object W, but is preferably 1 mm to 10 mm, and more preferably 2 mm to 5 mm. The other explanations regarding the first measurement line also apply to the second measurement point. The method for obtaining the second reflection point profile is the same as the method (S1) for obtaining the first reflection point profile.

[0044] (S4: Calculation of the second corrected reflection point profile) The second reflection point profile is converted into a coordinate system that does not change depending on the posture of the arm 31 to calculate a second corrected reflection point profile, and stored in the storage unit 22. The method is the same as the method (S2) for calculating the first corrected reflection point profile.

[0045] (S5: Estimation of the position and orientation of linear objects) In this process, the position and orientation of the linear object to be grasped are estimated based on the first and second corrected reflection point profiles. In the example of Figure 4, the linear objects are piled up, so the linear object Ws at the highest position in the measured area is selected, and its position and orientation are determined. Specifically, when the calculation unit 21 of the control device 20 connects the highest point 51p of the first corrected reflection point profile and the highest point 52p of the second corrected reflection point profile with a line 53, the center of the linear object Ws between the two corrected reflection point profiles is located below this line 53 by the radius of the linear object. This makes it possible to estimate the position and orientation of the linear object Ws. Furthermore, if necessary, the shape can also be estimated. The shape of the linear object Ws can be estimated, for example, by assuming that a virtual cylinder with the same diameter as the diameter of the linear object Ws is arranged along the line 53.

[0046] In the above explanation, it is assumed that the hand 32 will approach from above, and the linear object Ws at the highest position is selected. However, if the hand 32 approaches and grasps the linear object W from an oblique angle due to the presence of other components in the vicinity, the points on the first and second corrected reflection point profiles that are closest to the hand in the direction in which the hand approaches the linear object are selected, and by connecting these two points, the position and orientation of the linear object W in the portion sandwiched between the two corrected reflection point profiles, and furthermore, if necessary, its shape, can be estimated.

[0047] (S6: Determining the grip position of the linear object) The calculation unit 21 of the control device 20 determines the gripping position G of the linear object Ws based on the position of the linear object estimated in step S5 and, if necessary, the shape. The gripping position G is determined to be on or near the straight line 53. For example, it is determined to be the midpoint between the highest point 51p of the first corrected reflection point profile and the highest point 52p of the second corrected reflection point profile. If the linear object Ws is thin, it can be sufficiently gripped even if the gripping position is determined on the straight line 53. Furthermore, for example, if the center of the linear object Ws is to be the gripping position, it can be determined to be a position further down by the radius of the linear object Ws from the midpoint between the highest point 51p of the first corrected reflection point profile and the highest point 52p of the second corrected reflection point profile.

[0048] (S7: Grasping of linear objects) The hand 32 of the robot 30 grasps the linear object Ws at the grasping position G determined in step S6.

[0049] The control device 20 notifies the robot 30 of the coordinates of the determined gripping position G and the orientation of the linear object Ws at the gripping position. The robot 30 adjusts the position and posture of the hand 32 to the position of the gripping position G and the orientation of the linear object Ws at the gripping position, and grips the linear object Ws with the hand 32.

[0050] When the hand 32 pinches the linear object Ws between the two fingers 33, 33, the coordinates (x g ,y g ,z g ), and the direction of the linear object Ws at the grasping position G (vector g = (a g ,b g ,c g )), the inclination of the pair of fingers 33, 33 of the hand in the width direction (vector t = (a t ,b t ,c t The hand 32 is moved to the near position by aligning the gripping center T with the direction of the linear object Ws at the gripping position G. The near position is a position where the hand 32 starts to move forward in a straight line with the gripping center T toward the gripping position G. Next, the hand is moved forward from the near position toward the gripping position G, and the position (x t ,y t ,z t ) to the gripping position G, and close the fingers 33, 33.

[0051] When linear objects W are piled up or densely packed, in order to grasp one of the multiple thin, flexible, and easily deformed linear objects, it is necessary to form the tips of the fingers 33, 33 of the hand 32 thin and to approach and grasp the linear object with the fingers 33, 33 in a slightly open state. For this reason, it is difficult to grasp a linear object with the hand simply by aligning the positions of the linear object and the hand, but grasping is possible by aligning both the position and orientation.

[0052] In this embodiment, the corrected reflection point profile is calculated along the first measurement line 51 and the second measurement line 52, but the number of measurement lines may be three or more. In that case, after step S4 above, the reflection point profile and the corrected reflection point profile are obtained along the third and subsequent measurement lines, and in step S5 above, the highest points of each corrected reflection point profile are interpolated with a curve to estimate the position and shape of the linear object in the portion sandwiched between the two corrected reflection point profiles with the greatest distance. Increasing the number of measurement lines allows for more precise estimation of the shape of the linear object, but if there are too many measurement lines, the effect of improving estimation accuracy will reach a plateau. Therefore, the number of measurement lines is preferably five or less, and more preferably three or less.

[0053] Conversely, the number of measurement lines may be one. When there is only one linear object W and there is a certain amount of space around it, the gripping position can be determined based on one corrected reflection point profile. Specifically, for example, in steps S5 and S6, the highest point of the one corrected reflection point profile can be determined as gripping position G, and in step S7, the object can be gripped at gripping position G with the hand 32.

[0054] Next, a second embodiment of the linear object gripping method of the present invention will be described with reference to FIG.

[0055] The linear object grasping system for implementing the linear object grasping method of this embodiment is similar to the linear object grasping system 10 of the first embodiment, except that the laser displacement sensor emits a line laser.

[0056] Referring to FIG. 6, the laser displacement sensor 42 of this embodiment emits a line laser 43. A line laser is also called a sheet laser, and is a laser beam that spreads out in a sheet shape. There are no particular limitations on the method for forming the line laser, and any known method can be used. For example, a line laser can be formed by stretching a beam-shaped laser in one direction using a cylindrical lens. The laser displacement sensor 42 can be a known two-dimensional triangulation type.

[0057] The linear object gripping method of this embodiment differs from the first embodiment in the steps of acquiring a reflection point profile (steps S1 and S3 in FIG. 3) due to the difference in the form of the laser light.

[0058] (S1': Acquisition of the first reflection point profile) After setting the first measurement line 51, the robot 30 receives an instruction from the control device 20 and adjusts the posture of the arm 31 so that the line laser emitted from the laser displacement sensor 42 overlaps with the first measurement line 51. This allows the laser displacement sensor 42 to measure the distance to multiple points where the line laser 43 is reflected.

[0059] The control device 20 receives the measurement results of the distance from the laser displacement sensor 42 to the group of reflection points from the laser displacement sensor 42, and receives information about the position and orientation of the laser displacement sensor 42 at that time from the robot 30, and stores these as a set in the memory unit 22.

[0060] If a reflection point profile over the required range can be obtained by emitting the line laser 43 from one location, there is no need to further move the laser displacement sensor 42 and repeat the measurement. If a reflection point profile over the required range cannot be obtained by emitting the line laser 43 from one location, move the laser displacement sensor 42 along the first measurement line 51 to the next measurement position and repeat the measurement.

[0061] The step of acquiring the second reflection point profile, which corresponds to step S3 in the first embodiment, is also the same as step S1'. The other steps (steps S2, S4, S5 to S7 in FIG. 3) are the same as those in the first embodiment.

[0062] Comparing the first embodiment using a beam-shaped laser with the second embodiment using a line laser, the first embodiment has the advantage that the laser displacement sensor 40 is smaller and less expensive, and the second embodiment has the advantage that the operation time is shorter because movement of the laser displacement sensor 42 is unnecessary or reduced when acquiring a reflection point profile. In either embodiment, by using the laser displacement sensors 40, 42, it is possible to recognize a linear object W even in situations where it cannot be recognized by a stereo camera, and by performing measurements along multiple measurement lines 51, 52 provided at two or more locations in the longitudinal direction of the linear object W, it is possible to estimate the position and orientation of the gripping position G and grip the linear object W with the hand 32, even if the linear object W is thin, flexible, and easily deformed.

[0063] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the technical concept thereof.

[0064] In the above embodiment, the robot 30 has a single arm 31, measures a linear object with the laser displacement sensor 40 attached to the arm 31, and grasps the linear object W with the hand 32 attached to the same arm 31. However, the linear object may be grasped with another hand. For example, if the robot is a dual-arm robot, the linear object W may be grasped by a hand attached to the tip of an arm other than the arm to which the laser displacement sensor 40 is attached. Alternatively, the linear object W may be grasped by a hand of a robot other than the robot 30 to which the laser displacement sensor 40 is attached. [Explanation of symbols]

[0065] 10 Linear object grasping system 20 Control device 21 Arithmetic section 22 Memory section 23 Communications Department 30 Robot 31 Arm 32 hands 33 Finger 35 Robot control unit 36 Robot Calculation Unit 37 Robot Communications Department 40 Laser displacement sensor 41 Beam-shaped laser 42 Laser displacement sensor 43 line laser 45 Sensor control unit 46 Sensor calculation unit 47 Sensor communication unit 51 First measurement line 51p Highest point of the first corrected reflection point profile 52 Second measurement line 52p Highest point of the second corrected reflection point profile 53. The line connecting point 51p and point 52p G Grip position T-hand gripping center W, Ws linear object

Claims

1. a step of emitting a laser from a laser displacement sensor attached to an arm of a robot along a measurement line that intersects with a linear object, receiving reflected light with the laser displacement sensor to measure a distance to a reflection point, and acquiring a reflection point profile including information on the distance from the laser displacement sensor to the reflection point and the position and orientation of the laser displacement sensor; a step of converting the reflection point profile into a coordinate system that does not change depending on the posture of the arm, and calculating a corrected reflection point profile; determining a gripping position of the linear object based on the corrected reflection point profile; a step of holding the holding position with a hand attached to the tip of the arm or another hand; A linear object gripping method comprising the steps of:

2. the step of acquiring the reflection point profile and the step of calculating the corrected reflection point profile are performed for a plurality of the measurement lines; the gripping position is determined based on a plurality of the modified reflection point profiles. The linear object gripping method according to claim 1 .

3. the laser displacement sensor emits a beam-shaped laser in one direction, and scans the laser displacement sensor along the measurement line by moving the arm; The linear object gripping method according to claim 1 or 2.

4. The laser displacement sensor emits a line laser. The linear object gripping method according to claim 1 or 2.

5. A control device that uses a laser displacement sensor attached to an arm of a robot to calculate a gripping position for gripping a linear object with a hand attached to the tip of the arm or another hand, instructing the robot to operate the arm so that a target of the laser emitted from the laser displacement sensor moves along a measurement line that intersects with the linear object, instructing the laser displacement sensor to emit the laser and measure the distance to a reflection point of the laser, receiving the distance from the laser displacement sensor to the reflection point from the laser displacement sensor, and receiving information about the position and orientation of the laser displacement sensor from the robot, thereby obtaining a reflection point profile including information about the distance from the laser displacement sensor to the reflection point and the position and orientation of the laser displacement sensor; converting the reflection point profile into a coordinate system that does not change depending on the posture of the arm to calculate a corrected reflection point profile; calculating the gripping position of the linear object based on the corrected reflection point profile; Control device.

6. A control device comprising the control device according to claim 5, the robot, and the laser displacement sensor, the control device instructs the robot to grasp the grasping position with the hand attached to the tip of the arm; Linear object gripping system.

7. A control device comprising the control device according to claim 5, the robot, and the laser displacement sensor, the robot is a dual-arm robot, the control device instructs the dual-arm robot to grasp the grasping position with the other hand attached to the tip of the other arm. Linear object gripping system.

8. a control device for controlling a robot according to claim 5, the robot, the laser displacement sensor, and a second robot; the control device instructs the second robot to grip the gripping position with the other hand provided to the second robot; Linear object gripping system.

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