Robot coordinate system calibration system based on orthogonal ranging

Abstract

The invention discloses a robot coordinate system calibration system based on orthogonal ranging. Three positioners are adopted and installed in a user workpiece coordinate system where the robot can reach, and the three-dimensional coordinates of the positioners are known. A reflector is installed at the tail end of the robot, the reflector is moved to a detection area of the positioner, and three built-in orthogonal distance measuring sensors automatically obtain center coordinates of the reflector and feed back the center coordinates to the controller. And the controller obtains the position and angle deviation of the user workpiece coordinate system in the robot base coordinate system through data processing. According to the calibration system, when the reflector moves to the working area of the positioner, careful calibration is not needed, the distance measuring sensor automatically detects the deviation and automatically compensates and corrects the deviation, the precision is far higher than that of manual reading, and the calibration system is easy and convenient to operate, high in speed and high in efficiency. The positioner is small in size, free of limitation on the installation position, high in universality, capable of being suitable for any robot working airspace and high in cost performance.

Description

Technical Field

[0001] The invention relates to a robot coordinate system calibration system, in particular to a robot user workpiece coordinate system calibration system based on orthogonal ranging. Background Art

[0002] Industrial robot systems have multiple coordinate systems, each of which plays a different and important role and is indispensable.

[0003] (1) Base coordinate system: A coordinate system built with the center of the robot base as the origin. Its XYZ axis values ​​are the offset values ​​of the robot terminal (TCP) relative to the origin. The base coordinate system is also the basic coordinate system of the robot and the basis of all other coordinate systems.

[0004] (2) Tool coordinate system: This is a coordinate system built with the tool center point (TCP) of the robot as the origin. The XYZ axis values ​​are all offset values ​​of TCP relative to the origin. The tool coordinate system is used to adjust the robot to the desired posture. When changing tools, it only needs to recalibrate the TCP without recalibrating the robot.

[0005] (3) User workpiece coordinate system: Its origin position and direction are set by the user. The functions of user workpiece coordinates are: first, it is convenient for customers to move the robot according to the coordinate system they set; second, when the user's workbench and the robot move relative to each other, only the workpiece coordinate system needs to be updated, and there is no need to re-teach the robot trajectory.

[0006] Therefore, after the robot's own precision calibration meets the standard, the user's workpiece coordinate system must also be calibrated so that the robot can know where the user's workpiece coordinate system is and can accurately operate the user's workpiece. Conversely, if the user's workpiece coordinate system is not calibrated accurately, even if the robot's own precision is very high, it cannot guarantee that the robot's operation precision meets the standard, which may still lead to work failure or even scrapping.

[0007] At present, the workpiece coordinate system calibration of robot users at home and abroad mainly adopts the manual teaching method. The process is as follows: First, on the user's workpiece or fixture, at any position within the robot's motion range, set the X, Y, and Z axes of any angle. The origin is located on the workpiece grasped by the robot. The direction of the coordinate system is arbitrarily defined according to customer needs, and the three axes are determined by the right-hand rule.

[0008] Then, select three visible teaching points in the user workpiece coordinate system that the robot TCP can touch: the first teaching point is the origin of the user coordinate system; the second teaching point is on the X-axis, the line connecting the first teaching point to the second teaching point is the X-axis, and the pointing direction is the positive X direction; the third teaching point is in the positive direction area of ​​the Y-axis.

[0009] Afterwards, the robot arm (TCP) is moved to these three points one after another, and the values ​​of the robot encoders are recorded to calculate the vectors and their angles between adjacent points, thereby calculating the position and posture of the user workpiece coordinate system, thereby realizing the calibration of the user workpiece coordinate system.

[0010] However, this method of manually teaching and calibrating the user workpiece coordinate system has insurmountable drawbacks: Poor accuracy: When moving the TCP to the three corner points, theoretically, it is accurate only when the TCP contacts the corner points. However, once the robot TCP contacts the corner points, it will inevitably cause the tool to deform, resulting in positioning deviation. If there is a certain gap between the two, it is also a positioning deviation. Therefore, the existence of positioning deviation is inevitable, and the calibration accuracy is low! Low efficiency: In order to minimize the positioning deviation, the operator needs to use the human eye to observe the relative distance and state between the TCP and the corner point, and adjust it repeatedly. Therefore, the speed is slow and the efficiency is low.

[0011] Unreliable: Long-term repeated observation and adjustment, the labor intensity of personnel is high, physically and mentally exhausted, and the calibration structure is very unreliable! In particular, when there are multiple robots working in the user's workpiece coordinate system at the same time, the coordinate system calibration workload is huge and time-consuming, and the problem becomes more prominent and serious.

[0012] Therefore, the current industrial robot application scenarios urgently need a user workpiece coordinate system calibration system that can balance accuracy and efficiency, greatly improve the coordinate system calibration accuracy, and significantly improve the calibration efficiency and reduce the labor intensity of operators to meet modern production needs. Summary of the invention

[0013] The present invention aims at the current situation that there is a lack of high-precision user workpiece coordinate system rapid calibration system in the field of industrial robots, and proposes a robot coordinate system calibration system based on orthogonal ranging. The calibration system adopts three locators, which are installed in the user workpiece coordinate system where the robot can reach, and its three-dimensional coordinates are known. A reflector is installed at the end of the robot. By teaching the pending reflector to reach the detection area of ​​the locator, the three orthogonal ranging sensors built into the locator automatically obtain the center coordinates of the reflector and feed it back to the controller. The controller can obtain the position and angle deviation of the user workpiece coordinate system in the robot base coordinate system through data processing, and then realize the calibration of the user workpiece coordinate system. When the calibration system controls the reflector to move to the working area of ​​the locator, it does not need to be carefully calibrated. The deviation is automatically detected by the three orthogonal ranging sensors built in, and the compensation and correction are performed by the executable. Not only is the accuracy much higher than the manual reading, but it is also easy to operate, fast and efficient, and realizes the high-precision rapid calibration of the user workpiece coordinate system. At the same time, the locator is small in size, has no restrictions on the installation position, is highly versatile, can be applied to any robot working space, and has high cost performance.

[0014] The present invention is achieved through the following technical solutions: The present invention provides a robot coordinate system calibration system based on orthogonal ranging. The calibration system comprises three parts: a positioner, a reflector and a controller. The positioner is equipped with three orthogonal ranging sensors, wherein: The positioner is an integrated small positioning measuring instrument, there are three of them, which are installed in the user's workpiece coordinate system and where the robot TCP can reach. Its position can be arbitrary and unlimited, and it does not have to be on the origin and coordinate axis. Its three-dimensional coordinates are known, and the direction of the positioner coordinate axis is parallel to the axis of the user's workpiece coordinate system; The distance measuring sensor is a non-contact absolute distance sensor. Each locator has three distance measuring sensors built in, and the three distance measuring sensors are orthogonal to each other at the same point. This intersection is the origin of the locator coordinate system, and the measuring axes of the three distance measuring sensors are the three coordinate axes of the locator. The front end of the reflector is square, and the rear end is installed on the robot end flange through a connecting rod. The center point of the square at the front end can be used to represent the robot end tool center (TCP); the size of the cube at the front end of the reflector depends on the range of the ranging sensor; the material of the reflector is light alloy to reduce weight; The controller is a portable industrial computer. On the one hand, it provides energy for the three positioners and obtains the measurement data of the ranging sensors from the three positioners; on the other hand, it processes the obtained data to obtain the origin coordinate position and coordinate axis inclination angle of the user workpiece coordinate system in the robot base coordinate system, and transmits them to the robot controller to realize coordinate system calibration.

[0015] The robot coordinate system calibration system based on orthogonal ranging of the present invention is also characterized in that the locator adopts a U-shaped structure, two of the three ranging sensors are independently installed on the locator base, and the third ranging sensor is placed inside the base, thereby ensuring that the reflector can be moved from multiple angles and orientations to the vicinity of the center position of the locator coordinate system, significantly improving the adaptability and convenience of user operation.

[0016] The present invention provides a robot TCP calibration method applicable to the above-mentioned robot coordinate system calibration system based on orthogonal ranging, which is as follows: (1) First, fix the reflector to the end of the robot and move it with it; (2) A positioner is reliably fixed at a certain position in the robot's workspace and connected to the controller; (3) Power on the controller and input the robot's DH model parameters; (4) Move the reflector to a position near the origin of the positioner coordinate system and stop. Make sure that the front cube surface of the reflector is facing the three distance measuring sensors of the positioner. At this time, the positioner obtains the readings of the three distance measuring sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (6) Move the reflector out of the positioner's workspace, rotate the reflector 90 degrees, and return to a position near the origin of the positioner's coordinate system and stop. Also ensure that the front cube surface of the reflector faces the three ranging sensors of the positioner. At this time, the positioner obtains the readings of the three ranging sensors when the reflector stops and sends them to the controller; the controller also obtains the angle values ​​of the encoders of each axis of the robot at this time; (7) Move the reflector out of the positioner's workspace again, rotate it 90 degrees, and return to a position near the origin of the positioner's coordinate system and stop. Also, ensure that the front cube surface of the reflector faces the three distance measuring sensors of the positioner. At this time, the positioner obtains the readings of the three distance measuring sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (8) The controller uses the readings of the three ranging sensors and the angle values ​​of each axis of the robot obtained when the reflector stops three times in the above process to obtain the three-dimensional coordinates of the center of the reflector (i.e., TCP) relative to the robot base coordinate system through inverse calculation, thereby realizing TCP calibration.

[0017] The present invention provides a robot user workpiece coordinate system calibration method applicable to the above-mentioned robot coordinate system calibration system based on orthogonal ranging, which is specifically as follows: (1) Place the reflector at the end of the robot and perform TCP calibration in advance; (2) Install the three positioners in the workpiece coordinate system and at a location that the robot TCP can reach. Their positions can be arbitrary and not limited, and do not have to be at the origin and coordinate axis. Their three-dimensional coordinates need to be known and determined, and the direction of the positioner coordinate axis must be parallel to the axis of the user's workpiece coordinate system. (3) Move the reflector to the positions near the origin of the coordinate system of the three positioners in turn. It is necessary to ensure that the front cube surface of the reflector faces the three distance measuring sensors of the positioner. At this time, the positioner obtains the readings of the three distance measuring sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (4) The controller calculates the three-dimensional coordinates of the reflector's three stopping points in the user's workpiece coordinate system based on the three-dimensional coordinates of the three positioners in the user's workpiece coordinate system and the distance sensor readings when the reflector stops three times; (5) The controller calculates the three-dimensional coordinates of the reflector's three stopping points in the robot's base coordinate system based on the encoder angle values ​​of each axis of the robot and the robot's own DH model parameters when the reflector stops three times; (6) Based on the three-dimensional coordinates of the reflector's three stopping points in the robot base coordinate system and the user workpiece coordinate system, the controller can obtain the origin coordinates and coordinate axis deflection angles of the user workpiece coordinate system in the robot base coordinate system through conventional matrix inverse operations, thereby realizing the calibration of the user workpiece coordinate system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the working principle of the user workpiece coordinate system calibration system of the present invention; Figure 2 A schematic diagram of the composition principle of a positioner of a user workpiece coordinate system calibration system of the present invention; Figure 3 A schematic diagram of the reflector structure of the user workpiece coordinate system calibration system of the present invention; Figure 4 A schematic diagram of the composition principle of a U-shaped positioner of a user workpiece coordinate system calibration system of the present invention; Figure 5 A schematic diagram of the TCP calibration method principle of the user workpiece coordinate system calibration system of the present invention; Figure 6 A schematic diagram of the TCP calibration method principle of the user workpiece coordinate system calibration system of the present invention; In the figure, 1-locator, 2-reflector, 3-controller, 4-robot, 5-robot controller, 6-distance sensor. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0020] The present invention is achieved through the following technical solutions: The present invention provides a robot coordinate system calibration system based on orthogonal ranging. The calibration system comprises three parts: a positioner, a reflector and a controller. The positioner has three orthogonal ranging sensors built in. Figure 1 and 2 As shown, where: The positioner 1 is an integrated small positioning and measuring instrument, and there are three of them, namely 1a, 1b and 1c, which are installed in the user workpiece coordinate system OwXwYwZw and where the TCP of the robot 4 can reach; the position of the positioner 1 can be arbitrary and unlimited, and does not have to be on the origin and the coordinate axis. Its three-dimensional coordinates are known, which are (xw1, yw1, zw1), (xw2, yw2, zw2), (xw3, yw3, zw3); the direction of the coordinate axis OpXpYpZp of the positioner 1 is parallel to the direction of the user workpiece coordinate axis OwXwYwZw; The distance sensor 6 is a non-contact absolute distance sensor, such as a laser distance sensor, an eddy current distance sensor, an ultrasonic distance sensor, etc.; each locator 1 is equipped with three distance sensors 6x, 6y and 6z, and the three distance sensors 6x, 6y and 6z are mutually orthogonal at the same point, and this intersection is the origin Op of the coordinate system OpXpYpZp of the locator 1, and the measuring axes of the three distance sensors 6x, 6y and 6z are the three coordinate axes XpYpZp of the locator; The front end of the reflector 2 is square, and the rear end is mounted on the end flange of the robot through a connecting rod. Figure 3 As shown; the center point of the square at the front end 2a of the reflector 2 can be used to represent the end tool center (TCP) of the robot 4; the size of the cube at the front end 2a of the reflector depends on the range of the distance sensor 6. For example, if the range of the distance sensor 6 is 10mm, the side length of the square at the front end 2a of the reflector can be 12-14mm; the material of the reflector 2 is a light alloy, such as an aluminum alloy, so as to reduce weight; The controller 3 is a portable industrial computer. On the one hand, it provides energy for the three positioners 1a, 1b and 1c, and obtains the measurement data of the distance sensors 6x, 6y and 6z from the three positioners 1a, 1b and 1c; on the other hand, it processes the obtained data to obtain the user workpiece coordinate system OwXwYwZw in the robot's base coordinate system O R X R Y R Z R The origin coordinate position (Xw, Yw, Zw) and the coordinate axis inclination angles α and β are transmitted to the robot controller 5 to realize the coordinate system calibration.

[0021] The robot coordinate system calibration system based on orthogonal ranging of the present invention is also characterized in that the positioner 1 adopts a U-shaped structure, such as Figure 4 As shown, two of the three ranging sensors 6x, 6y and 6z, 6x and 6y, are independently installed on the base of the locator 1, and the third ranging sensor 6z is placed inside the base. This ensures that the reflector 2 can be moved from multiple angles and orientations to the vicinity of the center position of the coordinate system of the locator 1, significantly improving the adaptability and convenience of user operation.

[0022] The present invention provides a robot TCP calibration method applicable to the above-mentioned robot coordinate system calibration system based on orthogonal ranging, such as Figure 5 As shown, the details are as follows: (1) First, fix the reflector 2 to the end of the robot 4 and move it together; (2) A positioner 1 is reliably fixed at a certain position in the working space of the robot 4 and connected to the controller 3; (3) The controller 3 is powered on and the DH model parameters of the robot 4 are input; (4) Move the reflector 2 to a position near the origin of the coordinate system of the positioner 1 and stop. It is necessary to ensure that the front end of the cube surface of the reflector 2 faces the three distance sensors 6x, 6y and 6z in the positioner 1. At this time, the positioner 1 obtains the readings Lx1, Ly1 and Lz1 of the three distance sensors 6x, 6y and 6z when the reflector 2 stops, and sends them to the controller 3; the controller 3 also obtains the angle value {θ11, θ12, θ13, θ14, θ15, θ16} of the encoder of each axis of the robot 4 at this time; (6) Move the reflector 2 out of the working space of the positioner 1, rotate the reflector 2 90 degrees, and return to the position near the origin of the coordinate system of the positioner 1a and stop. Similarly, ensure that the front end of the cube surface of the reflector 2 is facing the three distance sensors 6x, 6y and 6z in the positioner 1a. At this time, the positioner 1 obtains the readings Lx2, Ly2 and Lz2 of the three distance sensors 6x, 6y and 6z when the reflector 2 stops, and sends them to the controller 3; the controller 3 also obtains the angle value {θ21, θ22, θ23, θ24, θ25, θ26} of the encoder of each axis of the robot 4 at this time; (7) Move the reflector 2 out of the working space of the positioner 1 again, rotate the reflector 2 90 degrees, and return to the position near the origin of the coordinate system of the positioner 1 and stop. Similarly, ensure that the front end of the cube surface of the reflector 2 is facing the three distance sensors 6x, 6y and 6z in the positioner 1. At this time, the positioner 1 obtains the readings Lx3, Ly3 and Lz3 of the three distance sensors 6x, 6y and 6z when the reflector 2 stops, and sends them to the controller 3; the controller 3 also obtains the angle value {θ31, θ32, θ33, θ34, θ35, θ36} of the encoder of each axis of the robot 4 at this time; (8) The controller 3 uses the above process to obtain the readings of the three distance measuring sensors 6x, 6y and 6z {Lx1, Ly1, Lz1, Lx2, Ly2, Lz2 ， Lx3, Ly3, Lz3} and the angle values ​​of each axis of robot 4 {θ11, θ12, θ13, θ14, θ15, θ16; θ21, θ22, θ23, θ24, θ25, θ26; θ31, θ32, θ33, θ34, θ35, θ36}, the center of the front end cube of reflector 2 (i.e. TCP) relative to the base coordinate system O of robot 4 is obtained by inverse calculation R X R Y R Z R The origin coordinate position (Xw, Yw, Zw) is determined, thereby achieving TCP calibration.

[0023] The present invention provides a robot user workpiece coordinate system calibration method applicable to the above-mentioned robot coordinate system calibration system based on orthogonal ranging, such as Figure 6 As shown, the details are as follows: (1) Place the reflector 2 at the end of the robot 4 and perform TCP calibration in advance; (2) The three positioners 1a, 1b and 1c are installed in the workpiece coordinate system OwXwYwZw and at a location that the TCP of the robot 4 can reach. Their positions can be arbitrary and not limited, and do not have to be on the origin and coordinate axis. Their three-dimensional coordinates {(x W a, y W a,z W a),(xW b, y W b, z W b), (x W c, y W c, z W c)} needs to be known and determined, and the direction of the locator coordinate axis OpXpYpZp is parallel to the direction of the user workpiece coordinate axis OwXwYwZw; (3) Move the reflector 2 to the positions near the coordinate origins Owa, Owb and Owc of the three positioners 1a, 1b and 1c respectively. It is necessary to ensure that the front cube surface of the reflector 2 faces the three distance measuring sensors 6x, 6y and 6z inside the positioners 1a, 1b and 1c. At this time, the three positioners 1a, 1b and 1c respectively obtain the readings of the three distance measuring sensors 6x, 6y and 6z {Lxa, Lya, Lza, Lxb, Lyb, Lzb, Lxc, Lyc, Lzc} when the reflector 2 stops, and send them to the controller 3. The controller 3 also obtains the angle values ​​of the encoders of each axis of the robot 4 at this time {θa1, θa2, θa3, θa4, θa5, θa6; θb1, θb2, θb3, θb4, θb5, θb6; θc1, θc2, θc3, θc4, θc5, θc6}; (4) The controller 3 calculates the three-dimensional coordinates {(x W a, y W a, z W a),(x W b, y W b, z W b), (x W c, y W c, z W c)} and the readings of the distance measuring sensors 6x, 6y and 6z {Lxa, Lya, Lza, Lxb, Lyb, Lzb, Lxc, Lyc, Lzc} when the reflector 2 stops three times, and the three-dimensional coordinates {(xp W a, yp W a, zp W a), (xp W b, yp W b, zp W b) (xp W c, yp W c, zp W c)}; (5) The controller 3 calculates the three-dimensional coordinates of the three stopping points of the reflector 2 in the robot base coordinate system OrXrYrZr {(xpra, ypra, zpra), (xprb, yprb, zprb), (xprc, yprc, zprc)} according to the encoder angle values ​​of each axis of the robot 4 when the reflector 2 stops for three times {θa1, θa2, θa3, θa4, θa5, θa6; θb1, θb2, θb3, θb4, θb5, θb6; θc1, θc2, θc3, θc4, θc5, θc6} and the DH model parameters of the robot 4 itself; (6) The controller 3 obtains the three-dimensional coordinates of the reflector 2's three stopping points in the robot 4's base coordinate system OrXrYrZr and the user's workpiece coordinate system OwXwYwZw through conventional matrix inverse operations. The coordinates of the origin (Xw, Yw, Zw) and the coordinate axis deflection angles (αw, βw, γw) of the user's workpiece coordinate system OwXwYwZw in the robot's base coordinate system OrXrYrZr can then be used to calibrate the user's workpiece coordinate system. Compared with the prior art, the present invention has the following beneficial effects: (1) The robot coordinate system calibration system based on orthogonal ranging proposed in the present invention uses a non-contact ranging sensor to measure the position of the reflector. The center coordinate position of the reflector can be accurately obtained without human visual observation and repeated adjustment, which significantly improves the calibration work efficiency and reduces production costs.

[0024] (2) The robot coordinate system calibration system based on orthogonal ranging proposed in the present invention uses a non-contact ranging sensor to measure the position deviation of the reflector and automatically compensates and corrects it, thereby effectively overcoming the influence of positioning errors and greatly improving the three-dimensional coordinate measurement accuracy.

[0025] (3) The robot coordinate system calibration system based on orthogonal ranging proposed in the present invention adopts an integrated small-size positioner, which is directly fixed in the user's workpiece coordinate system. It has good rigidity, small deformation, and can work stably and reliably for a long time.

[0026] (4) The robot coordinate system calibration system based on orthogonal ranging proposed in the present invention uses a universal ranging sensor to realize the positioner function, which has a simple structure and low cost. The controller uses a universal portable industrial computer, which is easy to maintain and reduces daily maintenance costs.

[0027] (5) The robot coordinate system calibration system based on orthogonal ranging proposed by the present invention has no requirements or limitations on the installation position of the positioner. It does not need to be installed on the origin and coordinate axis of the user's workpiece coordinate system. It has strong versatility and good adaptability. The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A robot coordinate system calibration system based on orthogonal ranging, the calibration system comprises a positioner, a reflector and a controller, the positioner has three orthogonal ranging sensors built in, wherein: The positioner is an integrated small positioning measuring instrument, there are three of them, which are installed in the user's workpiece coordinate system and where the robot TCP can reach. Its position can be arbitrary and unlimited, and it does not have to be on the origin and coordinate axis. Its three-dimensional coordinates are known, and the direction of the positioner coordinate axis is parallel to the axis of the user's workpiece coordinate system; The distance measuring sensor is a non-contact absolute distance sensor. Each locator has three distance measuring sensors built in, and the three distance measuring sensors are orthogonal to each other at the same point. This intersection is the origin of the locator coordinate system, and the measuring axes of the three distance measuring sensors are the three coordinate axes of the locator. The front end of the reflector is square, and the rear end is installed on the robot end flange through a connecting rod. The center point of the square at the front end is used to represent the robot end tool center (TCP); the size of the cube at the front end of the reflector depends on the range of the ranging sensor; the material of the reflector is light alloy to reduce weight; The controller is a portable industrial computer. On the one hand, it provides energy for the three positioners and obtains the measurement data of the ranging sensors from the three positioners; on the other hand, it processes the obtained data to obtain the origin coordinate position and coordinate axis inclination angle of the user workpiece coordinate system in the robot base coordinate system, and transmits them to the robot controller to realize coordinate system calibration.

2. The robot coordinate system calibration system based on orthogonal ranging according to claim 1, further characterized by: The locator adopts a U-shaped structure, two of the three distance measuring sensors are independently installed on the locator base, and the third distance measuring sensor is placed inside the base, ensuring that the reflector can move to the vicinity of the center position of the locator coordinate system from multiple angles and orientations.

3. The present invention provides a robot TCP calibration method applicable to the above-mentioned robot coordinate system calibration system based on orthogonal ranging, which is as follows: (1) First, fix the reflector to the end of the robot and move it with it; (2) A positioner is reliably fixed at a certain position in the robot's workspace and connected to the controller; (3) Power on the controller and input the robot's DH model parameters; (4) Move the reflector to a position near the origin of the positioner coordinate system and stop. Make sure that the front cube surface of the reflector is facing the three distance measuring sensors of the positioner. At this time, the positioner obtains the readings of the three distance measuring sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (6) Move the reflector out of the positioner's workspace, rotate the reflector 90 degrees, and return to a position near the origin of the positioner's coordinate system and stop. Also ensure that the front cube surface of the reflector faces the three ranging sensors of the positioner. At this time, the positioner obtains the readings of the three ranging sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (7) Move the reflector out of the positioner's workspace again, rotate it 90 degrees, and return to a position near the origin of the positioner's coordinate system and stop. Also ensure that the front cube surface of the reflector faces the three ranging sensors of the positioner. At this time, the positioner obtains the readings of the three ranging sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (8) The controller uses the readings of the three ranging sensors and the angle values ​​of each axis of the robot obtained when the reflector stops three times in the above process to obtain the three-dimensional coordinates of the center of the reflector (i.e., TCP) relative to the robot base coordinate system through inverse calculation, thereby realizing TCP calibration.

4. The present invention provides a robot user workpiece coordinate system calibration method applicable to the above-mentioned robot coordinate system calibration system based on orthogonal ranging, which is as follows: (1) First, place the reflector at the end of the robot and perform TCP calibration in advance. (2) Install the three positioners in the workpiece coordinate system and at a location that the robot TCP can reach. Their positions can be arbitrary and not limited, and do not have to be at the origin and coordinate axis. Their three-dimensional coordinates need to be known and determined, and the direction of the positioner coordinate axis must be parallel to the axis of the user's workpiece coordinate system. (3) Move the reflector to the positions near the origin of the coordinate system of the three positioners in turn. It is necessary to ensure that the front cube surface of the reflector is facing the three ranging sensors of the positioner. At this time, the positioner obtains the readings of the three ranging sensors when the reflector stops and sends them to the controller. The controller also obtains the angle values ​​of the encoders of each axis of the robot at this time. (4) The controller calculates the three-dimensional coordinates of the reflector's three stopping points in the user's workpiece coordinate system based on the three-dimensional coordinates of the three positioners in the user's workpiece coordinate system and the distance sensor readings when the reflector stops three times; (5) The controller calculates the three-dimensional coordinates of the reflector's three stopping points in the robot's base coordinate system based on the encoder angle values ​​of each axis of the robot and the robot's own DH model parameters when the reflector stops three times; (6) Based on the three-dimensional coordinates of the reflector’s three stopping points in the robot base coordinate system and the user workpiece coordinate system, the controller obtains the origin coordinates and coordinate axis deflection angles of the user workpiece coordinate system in the robot base coordinate system through conventional matrix inverse operations, thereby realizing the calibration of the user workpiece coordinate system.

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