Method and system for detecting positioning error of linear movement mechanism

Abstract

A method and system for detecting a positioning error of a linear movement mechanism. The system comprises a linear movement mechanism (1), a moving element (2), a visual sensor (3), a calibration object (4), and a data processing system; the visual sensor (3) is fixed on the moving element (2) on the linear movement mechanism and is driven by the moving element (2) to move on the linear movement mechanism (1); the calibration object (4) is arranged in front of the line of sight of the visual sensor (3) and is used for calibrating an attitude of the visual sensor (3); the visual sensor (3) photographs the calibration object (4) at different movement position points on the linear movement mechanism (1); and the data processing system acquires photography results, calculates coordinate system transformation matrixes from a linear movement mechanism coordinate system at the movement position points to a preset linear movement mechanism coordinate system, and thus parses a positioning error of the linear movement mechanism. According to the solution, the structure is simple; assembly and disassembly are easy; and the present invention is applicable to repeated real-time detection-adjustment processes, error detection of dynamic motion scenarios, and various practical application scenarios, and is also applicable to repeated detection-adjustment processes of assembly / fitting errors.

Description

A method and system for detecting positioning error of a linear motion mechanism Technical Field

[0001] The present invention relates to the field of testing and detection technology, and in particular to a method and system for detecting positioning errors of a linear motion mechanism. Background Art

[0002] Linear motion mechanisms are one of the primary motion-carrying tools currently used in industrial automation and intelligent applications. While commercially available, these mechanisms are often customized or assembled in-house in current industrial automation and intelligent applications, such as factory automation and intelligent transformation.

[0003] During movement in actual application scenarios, linear motion mechanisms may generate geometric errors that are inconsistent with the presets, including but not limited to positioning, attitude (such as pitch angle, yaw angle and roll angle, etc.), trajectory and other geometric errors. Especially in the field of automated measurement and guided positioning, the angular degree of freedom errors of linear motion mechanisms during movement often have a significant impact on the measurement results.

[0004] There are multiple sources of positioning errors in linear motion mechanisms in practical applications, mainly including the following categories: 1) the manufacturing accuracy of the motion mechanism itself, such as the flatness / straightness and roughness of the mounting surface; 2) deformation errors, such as damage and deformation of the mechanism caused by careless transportation; 3) assembly / fitting / fixing errors, such as tightness, installation parallelism, splicing coplanarity, etc. This type of error is very susceptible to movement / vibration.

[0005] Traditional level / digital level measurement methods, flatbed micrometers, and coordinate measuring machines can measure the unevenness of the surface of processed objects, but these methods are time-consuming and labor-intensive, and can only detect the static processing state of the part, not the dynamic real-time deflection during the moving process.

[0006] At present, dynamic multi-degree-of-freedom geometric error measurement is mostly used for the detection of linear moving mechanisms. The measurement methods are mainly divided into contact measurement and non-contact measurement: 1) Contact measurement methods mostly use coordinate measuring machines for measurement, which are easily affected by the vibration of the moving mechanism itself during movement and the contact force during contact measurement, and the measurement accuracy is low; 2) Non-contact measurement methods are mainly divided into optical measurement, acoustic wave measurement and electromagnetic measurement. For operating mechanisms, the dynamic performance of optical measurement is significantly better than the other two measurement methods, but optical measurement methods (such as combined measurement methods based on laser interferometers and collimators and measurement methods based on laser tracking interferometers) generally contain complex lens groups, and the installation and measurement processes are complicated. The instruments are expensive and the cost is too high.

[0007] In industrial automation and intelligent applications, the error detection requirements for linear motion mechanisms have the following characteristics: 1) The size and structure of the mechanisms vary widely; 2) Most are custom-made and assembled, with a high proportion of errors originating from assembly. These errors are adjustable and require repeated real-time detection and adjustment; 3) The position of the mechanism in actual motion scenarios is inconsistent, potentially on the ground or in mid-air. Current non-contact detection methods for linear motion mechanisms are generally based on custom design of the mechanism's dimensions, and the assembly and disassembly process is complex, placing high demands on the operator. Coordinate measuring machines are suitable for ground-based measurements and are not suitable for the actual use of motion mechanisms. Summary of the Invention

[0008] The present invention aims to solve the above problems and provide a method for detecting positioning errors of a linear moving mechanism, which can quickly and accurately measure dynamic / static positioning errors, has a simple structure, high universality, fast and convenient disassembly and assembly, is suitable for practical application scenarios, and has high cost performance.

[0009] The present invention solves the above problem and adopts the following technical solution: a method for detecting positioning errors of a linear motion mechanism, comprising a linear motion mechanism, a moving element, a visual sensor, a calibration object, and a data processing system; the visual sensor is rigidly fixed to the moving element on the linear motion mechanism directly or through a customized fixing structure, and the moving element drives the visual sensor to move on the linear motion mechanism; the calibration object is arranged in front of the line of sight of the visual sensor and is used to calibrate the posture of the visual sensor; the visual sensor is positioned at different moving position points P on the linear motion mechanism. i Photograph the calibration object and send the photographing result to the data processing system, where i≥1 and is an integer; the data processing system obtains the photographing result and calculates the value of the calibration object at the moving position point P based on formula (1) and formula (2). i The coordinate system conversion matrix H from the linear motion mechanism coordinate system to the preset linear motion mechanism coordinate system Line(i)2line(s) , through H Line(i)2line(s) Coordinate transformation matrix analyzes the positioning error of the linear motion mechanism;

[0010] H cam(r)2Line(s) ×H calib2cam(r) = H Line(i)2line(s) ×H cam(i)2Line(i) ×H calib2cam(i) (1)

[0011] H cam(i)2Line(i) = H cam(r)2Line(s) (2)

[0012] Among them, H cam(r)2Line(s)The coordinate system transformation matrix from the selected reference position of the visual sensor to the reference position of the linear motion mechanism is H calib2cam(r) H is the transformation matrix from the calibration object coordinate system to the coordinate system of the visual sensor at the selected reference position. calib2cam(i) The coordinate system of the calibration object is the moving position point P of the visual sensor. i The coordinate system transformation matrix, H cam(i)2Line(i) To move to the position point P of the linear motion mechanism i When the coordinate system of the visual sensor moves relative to the linear motion mechanism, P i Coordinate system transformation matrix between location point coordinate systems.

[0013] The positioning error of the linear motion mechanism includes a deflection angle error and a translation error relative to a preset linear motion mechanism coordinate system. The deflection angle error includes a roll angle error θx, a pitch angle error θy, and a yaw angle error θz. The data processing system is based on the principle of converting a rotation matrix to Euler angles, and analyzes the deflection angle error through a coordinate transformation matrix; the translation positioning error of the non-linear motion mechanism in the moving direction can be analyzed through the translation part of the coordinate transformation matrix.

[0014] The data processing system also uses H Line(i)2line(s) The set of coordinate transformation matrices is used to analyze the movement trajectory of the linear motion mechanism, and the source of the positioning error is analyzed based on the shape of the movement trajectory.

[0015] Said by H Line(i)2line(s) The coordinate transformation matrix analyzes the positioning error of the linear motion mechanism, including the H Line(i)2line(s) The set of coordinate transformation matrices is used to analyze the movement trajectory of the linear motion mechanism, perform spatial linear fitting on the movement trajectory of the linear motion mechanism, obtain the average movement direction of the linear motion mechanism, and correct the movement direction of the preset linear motion mechanism coordinate system to the average movement direction, and calculate the transformation matrix H from the preset linear motion mechanism coordinate system to the corrected linear motion mechanism coordinate system. Line(s)2line(r) , through H Line(s)2line(r) Calculate the moving position point P i The coordinate system conversion matrix H from the linear motion mechanism coordinate system to the corrected linear motion mechanism coordinate system Line(i)2line(r) , through H Line(i)2line(r) The coordinate transformation matrix analyzes the positioning error of the linear motion mechanism.

[0016] When the vision sensor is rigidly fixed to the moving element of the linear motion mechanism directly or through a customized fixing structure, the setting method for maximizing the deflection angle error detection accuracy in a single or multiple directions is as follows:

[0017] When the optical axis direction of the visual sensor is set to be parallel to the moving direction X of the linear moving mechanism, the detection accuracy of the pitch angle θy and the yaw angle θz is maximized by the optical lever effect;

[0018] When the optical axis direction of the visual sensor is set to be parallel to the Y direction, the detection accuracy of the roll angle θx and the yaw angle θz is maximized through the optical lever effect;

[0019] When the optical axis direction of the visual sensor is set to be parallel to the Z direction, the detection accuracy of the roll angle θx and the pitch angle θy is maximized through the optical lever effect;

[0020] By setting two mutually perpendicular optical axis directions for the same vision sensor and repeating the detection steps or setting two mutually perpendicular vision sensors for detection at the same time, the maximum accuracy detection of the three deflection angles can be achieved; by setting a single vision sensor to a 45-degree direction, the detection accuracy of the roll angle θx, pitch angle θy and yaw angle θz can be evenly amplified.

[0021] The positioning geometric error detection resolution can be improved by increasing the resolution of the visual sensor.

[0022] The visual sensor is a 2D camera, and the calibration object is a plane with calibration features; or the visual sensor is a 3D camera, and the calibration object is a three-dimensional target or a planar target.

[0023] When the moving element drives the visual sensor to move on the linear motion mechanism, the visual sensor can be set to be soft-triggered by a timer or hard-triggered by a signal from a position sensor set on the linear motion mechanism.

[0024] The calibration object contains N complete calibration features, N≥1, and the pairwise posture conversion matrix set between each complete calibration feature has been pre-calibrated. The posture transformation matrix from any complete calibration feature to the selected reference complete calibration feature can be converted through the pairwise posture conversion matrix set.

[0025] A linear motion mechanism positioning error detection system applies the linear motion mechanism positioning error detection method.

[0026] Beneficial effects of the present invention:

[0027] 1. The structure is simple and easy to assemble and disassemble, which reduces the difficulty of installation and adjustment of the detection mechanism and the professional requirements for use by operators. It is also suitable for repeated real-time detection-adjustment processes, which makes it easy to adjust the assembly / assembly error and minimize the assembly / assembly error.

[0028] 2. High universality. It can be applied to positioning errors in static scenes, error detection in dynamic motion scenes, and various practical application scenarios. It can detect inherent processing errors and deformation errors within the accuracy range corresponding to the hardware selection, and can also be applied to the repeated detection-adjustment process of assembly / assembly errors. And simply changing the selection of visual sensors and calibration objects can be applied to mobile mechanisms of different sizes / structures.

[0029] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0031] FIG1 is a schematic structural diagram of a first embodiment of a linear motion mechanism positioning error detection system according to the present invention;

[0032] FIG2 is a schematic structural diagram of a second embodiment of a linear motion mechanism positioning error detection system according to the present invention;

[0033] FIG3 is a schematic structural diagram of a third embodiment of a linear motion mechanism positioning error detection system according to the present invention;

[0034] FIG4 is a schematic structural diagram of a fourth embodiment of a linear motion mechanism positioning error detection system according to the present invention;

[0035] FIG5 is a flow chart of a method for detecting positioning errors of a linear motion mechanism according to the present invention.

[0036] FIG6 is a schematic diagram showing the principle of amplifying the deflection angle error of a positioning error detection method for a linear motion mechanism according to the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0038] Figure 1 shows the specific structure of an embodiment of a positioning error detection system for a linear moving mechanism, which consists of a linear moving mechanism 1, a moving element 2, a visual sensor 3, a calibration object 4 and a data processing system; the visual sensor 3 is rigidly fixed to the moving element 2 on the linear moving mechanism 1 directly or through a customized fixed structure, and the moving element 2 drives the visual sensor 3 to move on the linear moving mechanism 1; the calibration object 4 is set in front of the line of sight of the visual sensor 3 and is used to calibrate the posture of the visual sensor 3; the visual sensor 3 shoots the calibration object 4 at different moving position points on the linear moving mechanism 1.

[0039] When moving element 2 drives visual sensor 3 along linear motion mechanism 1, visual sensor 3 can be set to soft-trigger using a timer. The real-time position of the linear motion mechanism in the direction of motion is calculated by multiplying the motion speed by the time. Alternatively, visual sensor 3 can be set to hard-trigger using a signal from a position sensor installed on the linear motion mechanism. The real-time position is then acquired by the position sensor. Based on the real-time position in the direction of motion, the error in the direction of motion can be determined.

[0040] To improve the resolution of positioning geometric error detection, a higher-resolution vision sensor can be selected when building the system. Detection resolution is related to the field of view at the distance of the calibration object and the distance between two adjacent points in the vision sensor, calculated from the resolution of the vision sensor.

[0041] Preset linear motion mechanism coordinate system settings: if the moving direction is the X-axis, the vector parallel to the moving track plane is the Y-axis, and the vector perpendicular to the moving track plane is the Z-axis. The moving track plane is the plane that the linear motion mechanism travels when it moves.

[0042] The calibration object is a plane with calibration features: it can be a checkerboard calibration plate, a dot calibration plate, or a QR code calibration plate. The calibration object 4 is located in front of the line of sight of the visual sensor 3, with the feature surface facing the visual sensor 3; accordingly, the visual sensor should be a 2D camera.

[0043] The calibration object 4 and the visual sensor 3 are not limited to the above combination. The visual sensor may also use a 3D camera, and the calibration object may be a stereo target or a plane target.

[0044] The calibration object 4 contains one or more complete calibration features. The pairwise posture conversion matrix set between each complete calibration feature has been pre-calibrated. The posture transformation matrix from any complete calibration feature to the selected reference complete calibration feature can be converted through the pairwise posture conversion matrix set.

[0045] When the moving axis of the linear moving mechanism is too long, if the calibration object only contains one complete calibration feature, the visual sensor will not be able to fully capture the complete calibration feature after moving a certain distance. Therefore, in this case, it is necessary to set several calibration features along the line so that each shooting result can obtain complete calibration features that can be used to calculate the visual sensor posture; when the moving axis of the linear moving mechanism is short, the visual sensor can capture a single calibration feature during the movement process, and the calibration object can contain only one calibration feature.

[0046] Reference position of the vision sensor: the preferred starting position for movement.

[0047] Optical axis: The center line of the vision sensor lens is generally called the optical axis.

[0048] Vision sensor orientation: The coordinate system axes should be as parallel as possible to the preset linear motion mechanism coordinate system. This allows for quick acquisition of the conversion matrix from the reference vision sensor to the preset linear motion mechanism coordinate system and facilitates more intuitive subsequent observation and analysis. X-, Y-, and Z-axes do not necessarily need to correspond one to one. Depending on the requirements for detection accuracy and synchronization, the vision sensor orientation can also be set to be non-parallel to the preset linear motion mechanism orientation. For example, setting a single vision sensor to 45 degrees allows for simultaneous, high-precision detection of the coordinates of the three axes. The coordinate system conversion matrix can be obtained based on the posture between the vision sensor and the linear motion mechanism, as preset in the drawing when designing the custom fixed structure.

[0049] In the embodiment shown in Figure 1, the optical axis direction of the visual sensor 3 is parallel to the X-axis of the linear motion mechanism coordinate system. Figures 2, 3 and 4 respectively show three other embodiments of the linear motion mechanism positioning error detection system structure. The difference from the embodiment shown in Figure 1 is that, in the second embodiment shown in Figure 2, the optical axis direction of the visual sensor 3 is parallel to the Y-axis of the linear motion mechanism coordinate system. In the third embodiment shown in Figure 3, the optical axis direction of the visual sensor 3 is parallel to the Z-axis of the linear motion mechanism coordinate system. In the fourth embodiment shown in Figure 4, the optical axis direction of the visual sensor 3 is rotated 45° around the Z-axis of the linear motion mechanism coordinate system relative to Figure 2.

[0050] Using the above error detection system and configuration, the general calculation sequence of an embodiment of a method for detecting positioning errors of a linear motion mechanism is shown in FIG5 :

[0051] S1, set the moving starting position to the reference position of the visual sensor;

[0052] S2, based on the preset linear motion mechanism coordinate system and the installation posture of the visual sensor at the reference position, obtain the coordinate transformation matrix H from the visual sensor coordinate system at the reference position to the linear motion mechanism reference position coordinate system cam(r)2Line(s) , as shown in Figure 2 H cam(r)2Line(s) = ;

[0053] Δx, Δy, and Δz refer to the offset between the origin of the vision sensor coordinate system and the origin of the reference linear motion mechanism coordinate system. The origin of the 2D camera coordinate system is generally the center of the camera lens, while the origin of the 3D camera coordinate system is generally the center of the left camera lens.

[0054] S3, the visual sensor starts to move from the starting position, obtains pictures at different moving positions Pi, and sends them to the data processing system;

[0055] S4, the data processing system calculates the conversion matrix H from the calibration object coordinate system to the reference visual sensor coordinate system based on the shooting results obtained at the reference position calib2cam(r);

[0056] The data processing system calculates the transformation matrix H between the visual sensor coordinate system and the coordinate system of the calibration object at different moving positions Pi calib2cam(i) ;

[0057] Since the visual sensor is rigidly fixed, the transformation matrix between the coordinate system of the linear motion mechanism and the coordinate system of the visual sensor remains unchanged after the movement;

[0058] S5, thus, the moving position point P is calculated by formula (1) and formula (2) i The coordinate system conversion matrix H from the linear motion mechanism coordinate system to the preset linear motion mechanism coordinate system Line(i)2line(s) :

[0059] H cam(r)2Line(s) ×H calib2cam(r) = H Line(i)2line(s) ×H cam(i)2Line(i) ×H calib2cam(i) (1)

[0060] H cam(i)2Line(i) = H cam(r)2Line(s) (2)

[0061] Where H cam(i)2Line(i) Move to the position point P of the linear motion mechanism i When the coordinate system of the visual sensor moves relative to the linear motion mechanism, P i Coordinate system transformation matrix between location point coordinate systems;

[0062] S6, by H Line(i)2line(s) Coordinate transformation matrix is ​​used to analyze the positioning error of linear motion mechanism.

[0063] Each H Line(i)2line(s) The coordinate transformation matrix obtains the information of a point, including the xyz position and attitude. The set of points at all Pi positions of the linear moving mechanism is summarized into a moving trajectory. Each point on the moving trajectory can also be marked with the attitude direction. Therefore, in addition to analyzing the positioning error, the data processing system can also use H Line(i)2line(s) A collection of coordinate transformation matrices is used to analyze the movement trajectory of the linear moving mechanism and analyze the source of positioning error based on the shape of the movement trajectory.

[0064] The positioning error of the linear motion mechanism calculated by the above processes S1 to S6 includes the deflection angle error and translation error relative to the preset linear motion mechanism coordinate system. The deflection angle error includes the roll angle error θx, the pitch angle error θy and the yaw angle error θz. The data processing system is based on the principle of converting the rotation matrix to Euler angle, and analyzes the deflection angle error relative to the preset linear motion mechanism coordinate system through the coordinate transformation matrix; the translation part of the coordinate transformation matrix can be used to analyze the translation positioning error in the moving direction of the non-linear motion mechanism.

[0065] If the direction deviation of the moving trajectory of the linear moving mechanism is found to be relatively large, and a more quantitative analysis is desired, further corrections can be made using the following steps: the data processing system performs spatial linear fitting on the moving trajectory of the linear moving mechanism to obtain H Line(s)2line(r) The average moving direction of the linear moving mechanism, and H Line(s)2line(r) The moving direction of the preset linear motion mechanism coordinate system is corrected to H Line(s)2line(r) The average moving direction is calculated from H Line(s)2line(r) The conversion matrix H from the preset linear motion mechanism coordinate system to the corrected linear motion mechanism coordinate system Line(s)2line(r) , through H Line(s)2line(r) Calculate the moving position point P i The coordinate system conversion matrix H from the linear motion mechanism coordinate system to the corrected linear motion mechanism coordinate system Line(i)2line(r) , through H Line(i)2line(r) Coordinate transformation matrix analysis H Line(s)2line(r) Positioning error of linear motion mechanism.

[0066] When the vision sensor is rigidly fixed to the moving element of the linear motion mechanism directly or through a customized fixing structure, the detection accuracy of deflection angle errors in single or multiple directions can be maximized through the following settings:

[0067] (1) When the optical axis of the vision sensor is set to be parallel to the moving direction X of the linear motion mechanism (as shown in Figure 1), the detection accuracy of the pitch angle θy and the yaw angle θz is maximized;

[0068] (2) When the optical axis of the vision sensor is set to be parallel to the Y direction (as shown in Figure 2), the magnification and detection accuracy of the roll angle θx and yaw angle θz are maximized;

[0069] (3) When the optical axis of the vision sensor is set to be parallel to the Z direction (as shown in Figure 3), the detection accuracy of the roll angle θx and pitch angle θy is maximized.

[0070] By setting two mutually perpendicular optical axis directions for the same visual sensor to repeat the detection steps or setting two mutually perpendicular visual sensors to perform detection at the same time, the maximum accuracy detection of the three deflection angles can be achieved.

[0071] The above-mentioned principle of amplifying the deflection angle error and maximizing the deflection angle detection accuracy is as follows: the change of the deflection angle around the non-camera optical axis will drive the rotation of the camera optical axis, and the change of the deflection angle is converted into a displacement change through the camera optical axis. The magnitude of the displacement change value is related to the distance between the camera optical axis and the calibration object and the angle between the camera optical axis and the linear motion mechanism. Increasing the distance or increasing the perpendicularity of the optical axis to a certain axis of the linear motion mechanism can improve the detection accuracy of the deflection angle around the axis. The latter is because when the camera optical axis is perpendicular to a certain axis of the linear motion mechanism, the change of the deflection angle around the vertical axis is maximized and converted into a rotation of the camera optical axis, thereby maximizing the displacement change, thereby maximizing the detection accuracy of the deflection angle around the vertical axis. Figure 6 illustrates the change of the deflection angle around the Z axis (non-camera optical axis) of the linear motion mechanism coordinate system, that is, the yaw angle, which causes the rotation of the camera optical axis, which is then converted into a displacement change of the calibration object.

[0072] Compared with the existing technology, the system and method provided by the present invention have a simple structure and are easy to assemble and disassemble, reducing the difficulty of installation and adjustment of the detection mechanism by operators and the professional requirements for use, and are applicable to repeated real-time detection-adjustment processes, which facilitates the minimization of assembly / assembly errors by adjusting assembly / assembly errors; it has high universality and can be applied to positioning errors in static scenes, error detection in dynamic motion scenes, and various practical application scenarios; it can detect inherent processing errors and deformation errors within the accuracy range corresponding to the hardware selection, and can also be applied to the repeated detection-adjustment process of assembly / assembly errors; and simply by replacing the selection of the visual sensor and the calibration object, it can be applied to mobile mechanisms of different sizes / structures.

[0073] Furthermore, it should be understood that the above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present invention, and these variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for detecting positioning error of a linear motion mechanism, characterized in that: It includes a linear motion mechanism, a moving element, a visual sensor, a calibration object, and a data processing system; the visual sensor is rigidly fixed to the moving element on the linear motion mechanism directly or through a customized fixing structure, and the moving element drives the visual sensor to move on the linear motion mechanism; the calibration object is arranged in front of the line of sight of the visual sensor and is used to calibrate the posture of the visual sensor; The different moving position points P of the visual sensor on the linear moving mechanism i Photograph the calibration object and send the photographing result to the data processing system, where i≥1 and is an integer; the data processing system obtains the photographing result and calculates the moving position point P based on formula (1) and formula (2). i The coordinate system conversion matrix H from the linear motion mechanism coordinate system to the preset linear motion mechanism coordinate system Line(i)2line(s) , through H Line(i)2line(s) Coordinate transformation matrix analyzes the positioning error of the linear motion mechanism; H cam(r)2Line(s) ×H calib2cam(r) = H Line(i)2line(s) ×H cam(i)2Line(i) ×H calib2cam(i) (1) H cam(i)2Line(i) = H cam(r)2Line(s) (2) Among them, H cam(r)2Line(s) The coordinate system transformation matrix from the coordinate system of the visual sensor at the selected reference position to the coordinate system of the reference position of the linear motion mechanism, H calib2cam(r) is the transformation matrix from the coordinate system of the calibration object to the coordinate system of the visual sensor at the selected reference position, H calib2cam(i) The coordinate system of the calibration object to the visual sensor at the moving position point P i The coordinate system transformation matrix, H cam(i)2Line(i) To move to the position point P of the linear motion mechanism i When the coordinate system of the visual sensor moves relative to the linear motion mechanism, P i Coordinate system transformation matrix between location point coordinate systems.

2. A method for detecting positioning errors of a linear motion mechanism according to claim 1, characterized in that: The positioning error of the linear moving mechanism includes a deflection angle error and a translation error relative to a preset linear moving mechanism coordinate system. The deflection angle error includes a roll angle error θx, a pitch angle error θy and a yaw angle error θz. The data processing system is based on the principle of converting a rotation matrix to Euler angles and analyzes the deflection angle error through a coordinate transformation matrix. The translation positioning error of the non-linear moving mechanism in the moving direction can be analyzed through the translation part of the coordinate transformation matrix.

3. A method for detecting positioning errors of a linear motion mechanism according to claim 1, characterized in that: The data processing system also passes H Line(i)2line(s) The set of coordinate transformation matrices analyzes the moving trajectory of the linear moving mechanism, and the source of positioning error is analyzed according to the shape of the moving trajectory.

4. A method for detecting positioning errors of a linear motion mechanism according to claim 1, characterized in that: Said by H Line(i)2line(s) The coordinate transformation matrix analyzes the positioning error of the linear motion mechanism, including Line(i)2line(s) The set of coordinate transformation matrices is used to analyze the moving trajectory of the linear motion mechanism, perform spatial linear fitting on the moving trajectory of the linear motion mechanism, obtain the average moving direction of the linear motion mechanism, and correct the moving direction of the preset linear motion mechanism coordinate system to the average moving direction, and calculate the transformation matrix H from the preset linear motion mechanism coordinate system to the corrected linear motion mechanism coordinate system. Line(s)2line(r) , through H Line(s)2line(r) Calculate at the moving position point P i The coordinate transformation matrix H from the linear motion mechanism coordinate system to the corrected linear motion mechanism coordinate system Line(i)2line(r) , through H Line(i)2line(r) The coordinate transformation matrix analyzes the positioning error of the linear motion mechanism.

5. A method for detecting positioning errors of a linear motion mechanism according to claim 2, characterized in that: When the visual sensor is rigidly fixed to the moving element of the linear moving mechanism directly or through a customized fixing structure, the setting method for maximizing the deflection angle error detection accuracy in a single or multiple directions is as follows: When the optical axis direction of the visual sensor is set to be parallel to the moving direction X of the linear moving mechanism, the detection accuracy of the pitch angle θy and the yaw angle θz is maximized through the optical lever effect; When the optical axis direction of the visual sensor is set to be parallel to the Y direction, the detection accuracy of the roll angle θx and the yaw angle θz is maximized through the optical lever effect; When the optical axis direction of the visual sensor is set to be parallel to the Z direction, the detection accuracy of the roll angle θx and the pitch angle θy is maximized through the optical lever effect; By setting two mutually perpendicular optical axis directions for the same visual sensor to repeat the detection steps or setting two mutually perpendicular visual sensors for detection at the same time, the maximum accuracy detection of the three deflection angles can be achieved; by setting a single visual sensor to a 45-degree direction, the detection accuracy of the roll angle θx, pitch angle θy and yaw angle θz can be evenly amplified.

6. A method for detecting positioning errors of a linear motion mechanism according to claim 1, characterized in that: The positioning geometric error detection resolution can be improved by improving the resolution of the visual sensor.

7. A method for detecting positioning errors of a linear motion mechanism according to claim 1, characterized in that: The visual sensor is a 2D camera, and the calibration object is a plane with calibration features; or the visual sensor is a 3D camera, and the calibration object is a three-dimensional target or a plane target.

8. A method for detecting positioning errors of a linear motion mechanism according to claim 1, characterized in that: When the moving element drives the visual sensor to move on the linear moving mechanism, the visual sensor can be set to be soft-triggered by a timer or hard-triggered by a position sensor signal set on the linear moving mechanism.

9. According to the method for detecting positioning errors of a linear moving mechanism as described in claim 1, the calibration object contains N complete calibration features, N≥1, and the set of pairwise posture conversion matrices between each complete calibration feature has been pre-calibrated, and the posture transformation matrix from any complete calibration feature to the selected reference complete calibration feature can be converted through the pairwise posture conversion matrix set.

10. A linear motion mechanism positioning error detection system, characterized in that: A method for detecting positioning errors of a linear motion mechanism according to any one of claims 1 to 9.

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