Industrial robot spatial pose accuracy testing device and method

Abstract

The application provides an industrial robot space pose precision testing device, comprising a sensor assembly and a pose measurement assembly connected with a master control end through wireless communication modules respectively; the sensor assembly comprises an execution block, a first gyroscope, a laser ranging sensor and a first wireless communication module, and the pose measurement assembly comprises a measurement support, a light receiving body, a second gyroscope and a second wireless communication module. The application adopts a special arrangement mode and a supporting data processing method of the laser ranging sensor, the arrangement and synchronous data processing of the double gyroscopes, the design of the high-precision measurement target ball and other technologies, can obtain the space absolute pose under the robot base coordinate system, can meet the space pose absolute precision testing requirements proposed in GB / T12642-2013, and is convenient for intuitively observing the robot precision condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spatial pose accuracy testing, in particular to an industrial robot spatial pose accuracy testing device and method. BACKGROUND

[0002] Spatial pose accuracy is one of the most important performance indicators of an industrial robot, mainly including spatial pose absolute accuracy and spatial pose repeatability. With the application of offline programming technology of industrial robots, the spatial pose absolute accuracy of robots is becoming more and more important. However, the measurement of spatial pose absolute accuracy is difficult, and generally requires the use of high-precision laser trackers, wire encoder testing devices or visual sensors for measurement.

[0003] High-precision laser trackers and wire encoder testing devices have high cost and complex operation, and additional sensors need to be purchased for measuring the posture, which increases the use cost.

[0004] The spatial pose absolute accuracy of a robot is measured using a visual sensor in Chinese patent CN 112917510 A, but due to the limited accuracy of general visual sensors, only the spatial pose absolute accuracy of the robot end can be measured, and the spatial pose repeatability cannot be measured, so the accuracy indicators of the robot cannot be completely evaluated. The cost of high-precision visual sensors is high, and the environmental adaptability is poor.

[0005] In addition, Chinese patents CN 105865341 A and CN 109341534 A respectively provide two devices and methods for measuring the spatial pose repeatability of the robot end using laser ranging sensors, but cannot measure the spatial pose absolute accuracy, and cannot completely evaluate the accuracy indicators of the robot. SUMMARY

[0006] The present application provides an industrial robot spatial pose accuracy testing device and method, which can obtain spatial absolute pose under the robot base coordinate system, has simple structure, high accuracy, shortens the required time, is easy to use, and has good adaptability to the test environment.

[0007] An industrial robot spatial pose accuracy testing device, characterized in that: it comprises a sensor assembly and a pose measurement assembly connected to a master control end through a wireless communication module respectively;

[0008] The sensor assembly comprises an execution block, a first gyroscope, a laser ranging sensor and a first wireless communication module, the execution block is installed at the end of the robot and moves with the end of the robot; the first gyroscope is installed inside the execution block to measure the motion posture of the execution block; a plurality of laser ranging sensors are installed around the execution block; the first wireless communication module is installed inside the execution block to transmit the data measured by the first gyroscope and the laser ranging sensor to the master control end;

[0009] The pose measurement assembly comprises a measurement support, a light receiving body, a second gyroscope and a second wireless communication module, the light receiving body is installed on the measurement support, the second gyroscope is installed inside the measurement support for measuring its attitude, and the second wireless communication module is installed inside the measurement support to transmit data of the second gyroscope to the host end.

[0010] Further improvement, the laser beams emitted by the plurality of laser ranging sensors are orthogonal to a point.

[0011] Further improvement, the light receiving body is a measurement target ball. The arrangement position of the measurement target ball is a test point of the largest cube in the robot workspace.

[0012] The application also provides an industrial robot space pose accuracy testing method, comprising the following steps:

[0013] 1) Install the execution block of the sensor assembly to the end of the robot, place the pose measurement assembly on a stable plane near the robot, and should be placed in the measurement area of the sensor assembly, and the second gyroscope on the pose measurement assembly transmits data to the host end through the second wireless communication module;

[0014] 2) Move the robot with the sensor assembly to a suitable position, so that the light emitted by the three laser sensors irradiates on the same measurement target ball, record the motion parameters of the robot, the laser ranging sensor and the first gyroscope transmit data to the host end through the first wireless communication module, and the relative relationship between the robot base coordinate system and the measurement coordinate system is solved;

[0015] 3) Control the robot to move to the remaining measurement target ball positions in turn, and repeat the movement until the test round is met, the laser ranging sensor and the first gyroscope will transmit data to the host end each time the robot moves to the specified position, and the absolute accuracy and the spatial pose repeatability of the robot space pose are obtained through calculation.

[0016] Further improvement, the calculation process of the relative relationship between the robot base coordinate system and the measurement coordinate system in step 2) is as follows:

[0017] 2.1) Obtain the actual position of the center point O of the measurement target ball through the three laser sensors;

[0018] 2.2) Set the coordinate system V as the robot end tool coordinate system, and the coordinate system W as the measurement coordinate system of the pose measurement assembly, record the position of point O in the coordinate system V as O_v, and the position of point O in the coordinate system W as O_w, according to the coordinate system transformation principle, it is easy to obtain:

[0019] V_org_w = O_w - R_v_w * O_v (1)

[0020] In the formula, V_org_w is the position of the origin of the coordinate system V in the coordinate system W, that is, the position of the robot end tool center in the measurement coordinate system; R_v_w is the rotation matrix of the coordinate system V to the coordinate system W, that is, the posture of the robot end tool in the measurement coordinate system;

[0021] R_v_w = R_v_T * R_w (2)

[0022] In the formula, R_v and R_w are respectively the rotation matrix of the first gyroscope and the first gyroscope output, and R_v_T is the transpose of R_v;

[0023] The pose of the robot end tool center in the measurement coordinate system is obtained after each measurement;

[0024] 2.3) According to the coordinate system transformation principle, formula 3 and formula 4 are obtained:

[0025] R_w_b = R_v_b * R_v_w_T (3)

[0026] In the formula, R_w_b is the rotation matrix of the coordinate system W to the coordinate system B, which is a constant; R_v_b is the posture of the robot end tool in the robot base coordinate system, that is, the robot command posture; R_v_w_T is the transpose of R_v_w, which is obtained by formula 2;

[0027] W_org_b = V_org_b - R_w_b * V_org_w (4)

[0028] In the formula, W_org_b is the position of the origin of the coordinate system W in the coordinate system B, which is a constant; V_org_b is the position of the origin of the coordinate system V in the coordinate system B, that is, the position of the robot end tool center in the robot base coordinate system; R_w_b is obtained by formula 3; V_org_w is obtained by formula 1.

[0029] 2.4) In the same test, since the relative relationship between the robot base coordinate system and the measurement coordinate system is unchanged, the pose of the robot end tool center in the robot base coordinate system [R_v_b, V_org_b] can be easily obtained according to the coordinate system transformation principle, as shown in formula 5 and formula 6;

[0030] R_v_b = R_w_b * R_v_w (5)

[0031] V_org_b = W_org_b + R_w_b * V_org_w (6)

[0032] The measurement target ball at the center of the pose measurement assembly is selected as the first measured point, and the relative relationship between the robot base coordinate system and the measurement coordinate system is solved.

[0033] Step 2.1) the actual position determination method of the ball center point O is as follows: the vector FG, the vector HG and the vector CG are laser beam directions, and the three laser beam directions are orthogonal to the point G; the points P, Q and R are the intersection points of the three laser beams and the measuring target ball surface, and the position coordinates of the points P, Q and R are obtained by calculating the size of the computing block and the data measured by the laser ranging sensor; the position of the measuring target ball center is calculated by knowing the coordinates of three points on the spherical surface and the radius of the measuring target ball.

[0034] The present application has the advantages of:

[0035] 1) The present application adopts a special arrangement mode and a supporting data processing method of a laser ranging sensor, a double-gyroscope arrangement and synchronous data processing, and a high-precision measuring target ball design, so that the absolute spatial pose under the robot base coordinate system can be obtained, the requirements of the absolute spatial pose accuracy test in GB / T 12642-2013 can be met, and the robot precision condition can be intuitively observed;

[0036] 2) The present application can simultaneously measure the absolute spatial pose accuracy and the spatial pose repeatability in GB / T 12642-2013, simplifies the test operation, and shortens the required time;

[0037] 3) The present application uses a high-precision laser ranging sensor for measurement, has high precision, and has low cost;

[0038] 4) The present application has simple structure, is convenient to use, and has good adaptability to the test environment;

[0039] 5) The arrangement mode of the laser ranging sensor can use a smaller light receiver (measuring target ball), so that the volume of the whole test device is greatly reduced, and the test device is convenient to carry;

[0040] 6) The gyroscope is used on the pose measurement assembly of the present application, so that the leveling operation is no longer needed in the measurement process, different direction measurements can be supported, the operation is more convenient, and the application range is wider. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 is a structural schematic diagram of a sensor assembly;

[0043] Figure 2 is a structural schematic diagram of a pose measurement assembly;

[0044] Figure 3 This is a schematic diagram showing the relative positions of the light ray and the target ball during actual measurement;

[0045] Figure 4 This is a schematic diagram showing the relative positions of the industrial robot, sensor components, and pose measurement components during actual measurement.

[0046] Figure 5 This is a flowchart of the method of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] This invention provides an industrial robot spatial pose accuracy testing system. The system includes a sensor assembly, a pose measurement assembly, and a main control terminal, which is a computer. The sensor assembly includes, for example, a sensor component... Figure 1 As shown, the pose measurement component is as follows Figure 2 As shown.

[0049] like Figure 1 As shown, the sensor assembly includes an actuator block 1, a gyroscope 2, a laser rangefinder 3, and a wireless communication module 4. In use, the actuator block 1 is mounted on the robot's end effector and moves with it; the gyroscope 2 is installed inside the actuator block 1 and measures its attitude as it moves; three laser rangefinders 3 are mounted around the actuator block 1, and the laser beams emitted by the three laser rangefinders 3 are orthogonal to a single point; the wireless communication module 4 is installed inside the actuator block 1 and transmits the data measured by the gyroscope 2 and the laser rangefinders 3 to a computer.

[0050] like Figure 2 As shown, the pose measurement component includes a measurement bracket 5, a measurement target ball 6, a gyroscope 7, and a wireless communication module 8. The measurement target ball 6 is mounted on the measurement bracket 5, and its arrangement references the test points of the largest cube in the robot's workspace as specified in GB / T12642-2013. The gyroscope 7 is installed inside the measurement bracket 5, allowing for pose measurement once the bracket is in place. The wireless communication module 8 is also installed inside the measurement bracket 5, transmitting data from the gyroscope 7 to the computer.

[0051] By using the end effector of a mobile robot, the laser beam emitted by the laser rangefinder 3 can be directed onto the same measuring target sphere 6. For example... Figure 3As shown, vectors FG, HG, and CG represent the directions of the laser beams, which are orthogonal at point G. Point O is the center of the target sphere 6, and points P, Q, and R are the intersections of the three laser beams with the surface of the target sphere 6. The coordinates of points P, Q, and R can be obtained by calculating the dimensions of the execution block 1 and the data measured by the laser rangefinder 3. Given the coordinates of the three points (P, Q, and R) on the sphere and the radius of the target sphere 6, the position of the center of the target sphere 6 can be easily calculated, yielding two solutions (…). Figure 3 Points O and O' in the diagram. However, in reality, if the center of the target ball 6 is point O', the laser beam will be blocked and will not be able to illuminate points P, Q, or R. Therefore, the case where the center of the target ball 6 is point O' can be ruled out. Combining the direction of the laser beam and the relative positions of points O and O', the actual position of the center point O of the target ball 6 can be obtained.

[0052] like Figure 4 As shown, point O is the center of the measurement target sphere 6 illuminated by the laser beam, coordinate system V is the robot end effector coordinate system, and coordinate system W is the measurement coordinate system of the pose measurement component. The position of point O in coordinate system V is denoted as O_v, and the value of O_v can be obtained using the aforementioned... Figure 3 The method described in the instructions yields a unique solution. Let the position of point O in coordinate system W be O_w. The value of O_w can be obtained through calibration measurement after the tooling is machined. Based on the principle of coordinate system transformation, it is easy to obtain:

[0053] V_org_w=O_w-R_v_w·O_v (1)

[0054] In Equation 1, V_org_w is the position of the origin of coordinate system V in coordinate system W, that is, the position of the center of the robot end effector in the measurement coordinate system; R_v_w is the rotation matrix from coordinate system V to coordinate system W, that is, the attitude of the robot end effector in the measurement coordinate system, which can be calculated from the data of gyroscope 2 and gyroscope 7, as described in Equation 2.

[0055] R_v_w=R_v_T·R_w (2)

[0056] In Equation 2, R_v and R_w are the rotation matrices output by gyroscope 2 and gyroscope 7, respectively, and R_v_T is the transpose of R_v.

[0057] According to Equations 1 and 2, the pose of the robot end effector center in the measurement coordinate system (coordinate system W) can be obtained after each measurement.

[0058] like Figure 4 As shown, based on the principle of coordinate system transformation, equations 3 and 4 are easily obtained:

[0059] R_w_b=R_v_b·R_v_w_T (3)

[0060] In formula 3, R_w_b is a rotation matrix from the coordinate system W to the coordinate system B, which is constant in the same test because the relative relationship between the robot base coordinate system and the measurement coordinate system is unchanged; R_v_b is the pose of the robot end tool in the robot base coordinate system, that is, the robot instruction pose, which can be obtained by reading the robot instruction pose by a computer; R_v_w_T is the transpose of R_v_w, and R_v_w is obtained by formula 2.

[0061] W_org_b = V_org_b - R_w_b · V_org_w (4)

[0062] In formula 4, W_org_b is the position of the origin of the coordinate system W in the coordinate system B, which is constant in the same test because the relative relationship between the robot base coordinate system and the measurement coordinate system is unchanged; V_org_b is the position of the origin of the coordinate system V in the coordinate system B, that is, the position of the robot end tool center in the robot base coordinate system, which can be obtained by reading the robot instruction position by a computer; R_w_b is obtained by formula 3; V_org_w is obtained by formula 1.

[0063] In the same test, because the relative relationship between the robot base coordinate system and the measurement coordinate system is unchanged, the pose [R_v_b, V_org_b] of the robot end tool center in the robot base coordinate system can be easily obtained according to the coordinate system transformation principle, as shown in formula 5 and formula 6.

[0064] R_v_b = R_w_b · R_v_w (5)

[0065] V_org_b = W_org_b + R_w_b · V_org_w (6)

[0066] Generally, the measurement target ball 6 at the center of the pose measurement assembly can be selected as the first measured point to solve the relative relationship between the robot base coordinate system and the measurement coordinate system.

[0067] According to the above method, the position and pose information of the robot end tool center in the robot base coordinate system (coordinate system B) can be calculated each time. According to the same method, the measurement is measured to meet the measurement times, and the robot instruction pose is recorded, and then the computer is processed, and the method specified in chapter 7.2 of standard GB / T 12642 is calculated, so that the absolute accuracy and the spatial pose repeatability of the robot space pose can be obtained.

[0068] As shown in Figure 5 , an industrial robot space pose accuracy test method comprises the following steps:

[0069] 1) Install the execution block 1 of the sensor assembly to the robot end, place the pose measurement assembly on a stable plane near the robot, and should be placed within the measurement area of the sensor assembly, the gyroscope 7 on the pose measurement assembly will transmit data to the computer through the wireless communication module 8;

[0070] 2) The robot moves to the appropriate position with the sensor assembly, so that the light emitted by the three laser sensors 3 shines on the same measurement target ball 6, records the robot motion parameters, and the laser ranging sensor 3 and the gyroscope 2 transmit data to the computer through the wireless communication module 4;

[0071] 3) Control the robot to move to the remaining four measurement target ball 6 positions in turn, and repeat the movement until the test wheel number is met, and the laser ranging sensor 3 and the gyroscope 2 will transmit data to the computer every time the robot moves to the specified position;

[0072] 4) Use the algorithm provided in the specific embodiment to calculate the data in the computer to obtain the absolute accuracy of the pose and the repeat accuracy of the pose.

[0073] Each embodiment in the specification is described in a progressive manner, and the same and similar parts between each embodiment can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, for the device embodiment, the above description is only the preferred embodiment of the present application, and since it is basically similar to the method embodiment, it is described more simply. The relevant part can refer to the part of the method embodiment. The above description is only the specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, and the changes or replacements within the technical range disclosed by the present application, without departing from the principle of the present application, should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An industrial robot space pose accuracy testing method, using an industrial robot space pose accuracy testing device, comprising a sensor assembly and a pose measurement assembly connected to a host end through a wireless communication module respectively; the sensor assembly comprises an execution block, a first gyroscope, a laser ranging sensor and a first wireless communication module, the execution block is installed at the end of the robot and moves with the end of the robot; the first gyroscope is installed inside the execution block to measure the motion posture of the execution block; a plurality of laser ranging sensors are installed around the execution block; the first wireless communication module is installed inside the execution block to transmit the data measured by the first gyroscope and the laser ranging sensors to the host end; the pose measurement assembly comprises a measurement support, a light receiver, a second gyroscope and a second wireless communication module, the light receiver is installed on the measurement support, the second gyroscope is installed inside the measurement support to measure its posture, and the second wireless communication module is installed inside the measurement support to transmit the data of the second gyroscope to the host end, characterized in that, The method comprises the following steps: 1) installing the execution block of the sensor assembly to the robot end, placing the pose measurement assembly on a stable plane near the robot, and placing the pose measurement assembly within the measurement area of the sensor assembly, and the second gyroscope on the pose measurement assembly transmits data to the host end through the second wireless communication module; 2) moving the robot with the sensor assembly to a suitable position so that the light emitted by the three laser sensors is irradiated on the same measurement target ball, recording the robot motion parameters, and the laser ranging sensor and the first gyroscope transmit data to the host end through the first wireless communication module, and the relative relationship between the robot base coordinate system and the measurement coordinate system is solved; The calculation process of the relative relationship between the robot base coordinate system and the measurement coordinate system is as follows: 2.1) obtaining the actual position of the ball center point O of the measurement target ball through the three laser sensors; the actual position of the ball center point O is determined as follows: vectors FG, HG and CG are the directions of the laser beams, and the three laser beam directions are orthogonal to point G; points P, Q and R are the intersection points of the three laser beams and the surface of the measurement target ball 6, and the position coordinates of points P, Q and R are obtained through the calculation of the size of the execution block and the data measured by the laser ranging sensor; the position of the ball center of the measurement target ball is calculated according to the known coordinates of three points on the spherical surface and the radius of the measurement target ball; 2.2) assuming that coordinate system V is the robot end tool coordinate system, coordinate system W is the measurement coordinate system of the pose measurement assembly, the position of point O in coordinate system V is O_v, and the position of point O in coordinate system W is O_w; according to the coordinate system transformation principle, it is easy to obtain: V_org_w = O_w-R_v_w·O_v (1) In the formula, V_org_w is the position of the origin of coordinate system V in coordinate system W, that is, the position of the robot end tool center in the measurement coordinate system; R_v_w is the rotation matrix of coordinate system V to coordinate system W, that is, the attitude of the robot end tool in the measurement coordinate system; R_v_w = R_v_T·R_w (2) In the formula, R_v and R_w are the rotation matrices output by the first gyroscope and the first gyroscope respectively, and R_v_T is the transpose of R_v; The pose of the robot end tool center in the measurement coordinate system is obtained after each measurement; 2.3) according to the coordinate system transformation principle, formula 3 and formula 4 are obtained: R_w_b = R_v_b · R_v_w_T (3) In the formula, R_w_b is the rotation matrix of coordinate system W to coordinate system B, which is a constant; R_v_b is the attitude of the robot end tool in the robot base coordinate system, that is, the robot command attitude; R_v_w_T is the transpose of R_v_w, which is obtained through formula 2; W_org_b = V_org_b -R_w_b · V_org_w (4) In the formula, W_org_b is the position of the origin of the coordinate system W in the coordinate system B, which is a constant; V_org_b is the position of the origin of the coordinate system V in the coordinate system B, that is, the position of the robot end tool center in the robot base coordinate system; R_w_b is obtained by formula 3; V_org_w is obtained by formula 1; 2.4) In the same test, since the relative relationship between the robot base coordinate system and the measurement coordinate system is unchanged, the pose of the robot end tool center in the robot base coordinate system [R_v_b, V_org_b] can be easily obtained according to the coordinate transformation principle, as shown in formula 5 and formula 6; R_v_b = R_w_b · R_v_w (5) V_org_b = W_org_b + R_w_b · V_org_w (6) The measurement target ball at the center of the pose measurement assembly is selected as the first measured point, and the relative relationship between the robot base coordinate system and the measurement coordinate system is solved; 3) Control the robot to move to the positions of the remaining measurement target balls in turn, and repeat the movement until the test round is met. Each time the robot moves to the specified position, the laser ranging sensor and the first gyroscope will transmit data to the host end, and the absolute accuracy and the spatial pose repeatability of the robot are obtained by calculation.

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