A robot fixture calibration method for simple geometric features

Abstract

The present invention provides a robot clamping calibration method for simple geometric features, comprising the following steps: Step 1: Select from six calibration modes according to the features of the calibration object; Step 2: Calibration data acquisition: Collect the position or posture of the object to be calibrated through a measuring device; Step 3: Simplest feature extraction: If the calibration object has plane, circular, spherical or cylindrical features, fit the actual data after acquisition to extract the simplest geometric features; Step 4: Create a calibration coordinate system: Create a calibration coordinate system based on the definition rules and simplest features of the six coordinate systems corresponding to the six different calibration modes selected in step 1. The method of the present invention takes into account features such as points, lines, planes, spheres, circular or cylindrical surfaces, and provides six clamping calibration modes for simple geometric features, which can be applied to most clamping calibration scenarios with simple geometric features. The calibration method is simple and suitable for fast and effective calibration of robot clamping.

Description

Technical Field

[0001] The invention belongs to the field of industrial robot clamping calibration, and in particular relates to a robot clamping calibration method oriented to simple geometric features. Background Art

[0002] The purpose of robot clamping calibration is to determine the position and posture relationship between the tool or workpiece and the robot body in the actual application scenario. In the robot offline programming software, the robot trajectory is generated through the theoretical clamping environment, and the relationship between the models is known; however, in actual application, the position and posture relationship between the actual tool or workpiece and the robot body is unknown. In order to be able to execute the robot offline programming trajectory, it is necessary to determine the clamping relationship between the actual tool or workpiece and the robot body in advance through clamping calibration.

[0003] At present, most robot controllers integrate simple clamping calibration functions, such as using the three-point method to determine the coordinate system of the workpiece outside the robot. This type of method is simple in theory, but has the following two disadvantages in practical applications: (1) limited scope of use, such as the three-point method is only applicable to workpieces with a cubic structure; (2) difficult to operate in practice, this type of method mainly relies on point features to specify the coordinate system, which is difficult to operate in practical applications.

[0004] The patent application with application number CN202111209743.6 proposes a calibration device and method for a robot tool coordinate system, which uses two cross-beams of light to calibrate the tool, but this method is only applicable to rotary tools. The paper "Quickrobot cell calibration for small part assembly" proposes a method for calibrating workpieces of simple geometric shapes using a calibrated contact measurement device, such as calibrating three orthogonal planes or a cylinder clamped on a spindle. The scope of use of this method is still limited.

[0005] To address the above problems, the present invention will expand the existing calibration method of the clamping coordinate system based on fixed features. In addition to relying on point features, it also considers features such as straight lines, planes, spheres, circular surfaces or cylindrical surfaces, and provides a clamping calibration method for simple geometric features, which can be applied to most clamping calibration scenarios with simple geometric features. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a robot clamping calibration method for simple geometric features, including six independent simple clamping calibration modes. The method can simply and quickly complete the robot clamping calibration by collecting a small amount of data, and is suitable for the calibration of the tool coordinate system and the workpiece coordinate system. The purpose of the robot clamping calibration is to determine the clamping relationship between the calibration object (tool or workpiece) and the robot. The present invention divides the robot clamping calibration problem into the robot clamping object calibration and the robot external object calibration. The robot clamping object includes the clamped tool or workpiece, and the coordinate system of the clamping object is recorded as TCS. The robot external object includes the workpiece or tool fixed outside the robot, and the coordinate system of the external object is recorded as WCS. The robot base coordinate system is recorded as RCS, and the flange coordinate system is recorded as ECS. The method proposed by the present invention is suitable for calibrating the relative relationship between TCS and ECS, and WCS and RCS.

[0007] The technical solution adopted by the present invention to solve the problems existing in the prior art is as follows:

[0008] A robot clamping calibration method for simple geometric features, characterized by comprising the following steps:

[0009] Step 1: According to the characteristics of the calibration object, select the calibration mode. The clamping calibration method includes six calibration modes: 1) three-plane method mode; 2) one point plus a straight line method mode; 3) one point plus two planes method mode; 4) two points plus one plane method mode; 5) three-point method mode; 6) two straight lines method mode;

[0010] Step 2: Calibration data acquisition: The position or posture of the object to be calibrated is collected by the measuring device. For external object calibration, the robot drives the measuring device to collect the position points of the points on the object to be calibrated in the robot coordinate system. For clamped object calibration, the robot drives the object to be calibrated to the fixed point to collect the posture of the flange.

[0011] Step 3: Extract the simplest features: If the calibration object has plane, circular, spherical or cylindrical features, fit the actual data after collection to extract the simplest geometric features, where the simplest geometric features are point, straight line and plane features;

[0012] Step 4: Create a calibration coordinate system: According to the six different calibration modes selected in step 1, a calibration coordinate system is created based on the definition rules of the six coordinate systems corresponding to the six calibration modes and the simplest features extracted in step 3.

[0013] The step one is specifically as follows: observe the geometric features of the calibration object, select the calibration mode according to the features, and the calibration features should meet the following rules to create a calibration coordinate system, among which: 1) the three-plane method mode requires that the three planes can intersect at one point; 2) the one-point-plus-a-line method mode requires that the point is not on the straight line; 3) the one-point-plus-two-plane method mode requires that the two planes intersect and the point is not on the intersection line; 4) the two-point-plus-one-plane method mode requires that the straight line formed by the two points intersects with the plane; 5) the three-point method mode requires that the three points do not overlap with each other and are not collinear; 6) the two-line method mode requires that the two lines are not parallel.

[0014] The step two is specifically as follows: the robot drives the measuring device to collect data on the calibration object. When collecting plane data, three or more non-colinear points need to be collected, when collecting spherical data, four or more non-coplanar points need to be collected, when collecting cylindrical data, six or more non-coplanar points need to be collected, and when collecting circular surface data, three or more non-overlapping points on the circle need to be collected. For external object calibration, the robot clamps the measuring device to collect the position points of the points on the object to be calibrated in the robot coordinate system. For clamped object calibration, the robot clamps the object to be calibrated to a fixed point to collect the position and posture of the flange.

[0015] The step three is specifically as follows: fitting the collected plane, circular, spherical or cylindrical features into the simplest features: plane data can be fitted into a plane feature represented by a point and a normal, and the fitted points and vectors can also be used as straight line features; circular or spherical data can be fitted into a center of a circle or a center of a sphere for use as a point feature, and cylindrical data can be fitted into an axis for use as a straight line feature.

[0016] The specific process of creating the calibration coordinate system in step 4 is as follows: when the three-plane calibration mode is selected in step 1, the calibration method is applicable to the calibration of the coordinate system with the simplest feature of three plane features, and f1, f2, and f3 are three non-parallel planes on the object to be calibrated, and the planes are not required to be perpendicular to each other. The specific rules for establishing the coordinate system in this method are as follows: 1-1) The intersection of the three planes is used as the origin O of the coordinate system; 1-2) The normal of plane f1 is used as the Z axis; 1-3) The intersection line of planes f1 and f2 is used as the X axis;

[0017] The specific steps to express the coordinate system to be determined using mathematical expressions according to the above rules are as follows: i (i=1,2,3) respectively adopt the point method (P i , n i ) means: where P i Represents the plane f i Previous point, n i Represents the plane f i The normal of is calculated based on the above rules for a specific coordinate system: The calculation steps are as follows:

[0018] 1-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n1;

[0019] 1-b) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0020] 1-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0021] 1-d) Solve the intersection of the three planes as the origin of the coordinate system O: According to the points, establish the following equation system on the plane, and obtain the intersection of the three planes as the origin of the coordinate system by solving the following linear equation system;

[0022]

[0023] The specific process of creating the calibration coordinate system in step 4 is as follows: when the one-point plus straight line method calibration mode is selected in step 1, the calibration method is applicable to the coordinate system determination with the simplest feature having a point feature and a straight line feature. Assume that the straight line l1(Q1Q2) is the central axis extracted after cylindrical surface fitting or the straight line determined by two points, P l，1 For a point outside the line, the rules for establishing the coordinate system by this method are as follows: 2-1) Line l1 determines the Z axis of the coordinate system; 2-2) P l，1 Located on the X-axis of the coordinate system; 2-3)P l，1 The projection point onto the line l1 is taken as the origin O of the coordinate system;

[0024] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0025] 2-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :

[0026] 2-b) Calculate P l，1 The projection point onto the straight line Q1Q2 is taken as the origin O of the coordinate system;

[0027] 2-c) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0028] 2-d) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0029] The specific process of creating the calibration coordinate system in step 4 is as follows: When the one-point plus two-plane method calibration mode is selected in step 1, the calibration method is suitable for determining the coordinate system with the simplest feature of one point and two plane features. Let P s，1 is a point or the center of a sphere, f s，1 and f s，2 are two non-parallel planes, plane f s，1 and plane f s，2 The normal directions are denoted as n s，2 and n s，2 The rules for establishing the coordinate system of this method are as follows: 3-1) The normal of the first plane determines the Z axis of the coordinate system; 3-2) f s，1 and f s，2 The intersection line of is taken as the X axis; 3-3)P s，1 As the origin of the coordinate system O;

[0030] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0031] 3-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n s，1 ;

[0032] 3-b) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0033] 3-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0034] 3-d)P s，1 As the origin O of the coordinate system.

[0035] The specific process of creating the calibration coordinate system in step 4 is as follows: When the two-point plus one-plane calibration mode is selected in step 1, the calibration method is applicable to the workpiece coordinate system determination with the simplest feature having two point features and one plane feature. Let P p，1 , P p，2 are two non-coincident points; f p，1 is a plane, and the straight line formed by the two points is not perpendicular to the plane. The rules for establishing the coordinate system of this method are as follows: 4-1) Plane f p，1 The normal direction determines the Z axis of the coordinate system; 4-2) The projection vectors of the two points on the plane determine the X axis; 4-3) P p，1 The projection point on the plane is taken as the origin O of the coordinate system;

[0036] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0037] 4-a) Calculate two points P p，1 , P p，2 In plane f p，2 Projection point on

[0038] 4-b) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0039] 4-c) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n, n is the plane f p，1 The normal direction of

[0040] 4-d) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0041] 4-e) Calculate the origin of the coordinate system:

[0042] The specific process of creating the calibration coordinate system in step 4 is as follows: When the three-point calibration mode is selected in step 1, the calibration method is suitable for determining the coordinate system with the simplest feature of three points. Let P c，1 , P c，2 , P c，3 For three points that are not coincident and not collinear, the rules for establishing the coordinate system by this method are as follows: 5-1) The first point P c，1 is the origin o of the coordinate system; 5-2) vector P c，1 P c，2 Determines the X-axis of the coordinate system; 5-3) The third point P c，3 Located on the XOY plane of the coordinate system (first quadrant);

[0043] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0044] 5-a) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0045] 5-b) Calculate the unit vector z of the Z axis of the coordinate system Dir :

[0046] 5-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0047] 5-d) Calculate the origin of the coordinate system: O = P c，1 .

[0048] The specific process of creating the calibration coordinate system in step 4 is as follows: When the two-line method calibration mode is selected in step 1, the calibration method is applicable to the workpiece with the simplest feature having two straight line features. l，1 , Q l，2 The straight line Q l，1 Two points on Q l，3 , Q l，4 For the straight line l l，2 The rules for establishing a coordinate system are as follows: 6-1) The direction perpendicular to both lines determines the Z axis; 6-2) The direction of the first line determines the X axis of the coordinate system; 6-3) If the two lines are coplanar, the intersection point is the origin of the coordinate system O; if the two lines are not coplanar, the intersection point of the common perpendicular line and the first line is the origin of the coordinate system;

[0049] Calculate the coordinate system based on the above rules: The calculation steps are as follows:

[0050] 6-a) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0051] 6-b) Calculate the unit vector z of the Z axis of the coordinate system Dir :

[0052] 6-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0053] 6-d) Use the method of finding the intersection point or common perpendicular line of two straight lines to calculate the origin O of the coordinate system.

[0054] The present invention has the following advantages:

[0055] 1. The present invention provides a calibration method for a clamping coordinate system based on fixed features, taking into account features such as points, lines, planes, spheres, circular surfaces or cylindrical surfaces, and provides six clamping calibration modes for simple geometric features, which can be applied to most clamping calibration scenarios with simple geometric features. The calibration method is simple and suitable for fast and effective calibration of robot clamping. The six calibration coordinate system establishment methods proposed in the present invention are widely applicable and can cover most application scenarios.

[0056] 2. The method of the present invention has computational stability, can realize a closed-loop connection between the robot and the tool workpiece, and provide accuracy guarantee for the robot to execute any trajectory. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Schematic diagram of robot active processing in an embodiment of the present invention;

[0058] Figure 2Schematic diagram of passive processing by a robot in an embodiment of the present invention;

[0059] Figure 3 A schematic diagram of creating a coordinate system using the three-plane method in an embodiment of the present invention;

[0060] Figure 4 A schematic diagram of a coordinate system created by a point-plus-a-straight-line method in an embodiment of the present invention;

[0061] Figure 5 A schematic diagram of creating a coordinate system using a one-point-plus-two-planes method according to an embodiment of the present invention;

[0062] Figure 6 A schematic diagram of creating a coordinate system using the two-point plus one plane method in an embodiment of the present invention;

[0063] Figure 7 A schematic diagram of creating a coordinate system using the three-point method in an embodiment of the present invention;

[0064] Figure 8 A schematic diagram of a coordinate system created by the two-straight-line method in an embodiment of the present invention. DETAILED DESCRIPTION

[0065] The technical solution of the present invention is further described in detail below through embodiments and in conjunction with the accompanying drawings. Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram of a robot holding a tool to perform cutting on an external workpiece. Figure 2 It is a schematic diagram of a robot clamping a workpiece for processing on an external tool. In the present invention, the coordinate system of the clamped object is recorded as TCS, the coordinate system of the external object is recorded as WCS, the robot base coordinate system is recorded as RCS, and the flange coordinate system is recorded as ECS. The method proposed in the present invention is suitable for calibrating the relative relationship between TCS and ECS, and between WCS and RCS.

[0066] The present invention provides a robot clamping calibration method for simple geometric features, comprising the following steps:

[0067] Step 1: Select the calibration mode according to the characteristics of the calibration object. The clamping calibration method includes six calibration modes: 1) three-plane method mode; 2) one point plus a straight line method mode; 3) one point plus two planes method mode; 4) two points plus one plane method mode; 5) three-point method mode; 6) two straight lines method mode;

[0068] Step 1 is as follows: observe the geometric features of the calibration object, select the calibration mode according to the features, and the calibration features should meet the following rules to create a calibration coordinate system, among which: 1) The three-plane method mode requires that the three planes can intersect at one point; 2) The one-point-plus-a-line method mode requires that the point is not on the straight line; 3) The one-point-plus-two-plane method mode requires that the two planes intersect and the point is not on the intersection line; 4) The two-point-plus-one-plane method mode requires that the straight line formed by the two points intersects the plane; 5) The three-point method mode requires that the three points do not overlap or collinear with each other; 6) The two-line method mode requires that the two lines are not parallel.

[0069] Step 2: Calibration data acquisition: The position or posture of the object to be calibrated is collected through the measuring equipment. For external object calibration, the robot drives the measuring equipment to collect the position points of the points on the object to be calibrated in the robot coordinate system. For clamped object calibration, the robot drives the object to be calibrated to reach the fixed point to collect the posture of the flange. The measuring equipment is a generalized measuring equipment, which can be a measuring probe, a sharp point device or a line laser scanning device, etc.

[0070] Step 2 is as follows: the robot drives the measuring device to collect data on the calibration object. When collecting plane data, three or more non-collinear points need to be collected. When collecting spherical data, four or more non-coplanar points need to be collected. When collecting cylindrical data, six or more non-coplanar points need to be collected. When collecting circular data, three or more non-overlapping points on the circle need to be collected. For external object calibration, the robot clamps the measuring device to collect the position points of the points on the object to be calibrated in the robot coordinate system. For clamped object calibration, the robot clamps the object to be calibrated to a fixed point to collect the position and posture of the flange.

[0071] Step 3: Simplest feature extraction: If the calibration object has plane, circular, spherical or cylindrical features, fit the actual data after collection to extract the simplest geometric features, where the simplest geometric features are point, straight line and plane features;

[0072] Step three is as follows: fit the collected plane, circular, spherical or cylindrical features into the simplest features: plane data can be fitted into a plane feature represented by a point and a normal, and the fitted points and vectors can also be used as straight line features; circular or spherical data can be fitted into a center of a circle or a center of a sphere for use as a point feature, and cylindrical data can be fitted into an axis for use as a straight line feature.

[0073] Step 4: Create a calibration coordinate system: According to the six different calibration modes selected in step 1, create a calibration coordinate system based on the definition rules of the six coordinate systems corresponding to the six calibration modes.

[0074] like Figure 3As shown, when the three-plane calibration mode is selected in step 1, the calibration method is suitable for the calibration of the coordinate system with the simplest feature of three plane features. Let f1, f2, and f3 be three non-parallel planes on the object to be calibrated, and it is not required that the planes are perpendicular to each other. The specific rules for establishing the coordinate system by this method are as follows: 1-1) The intersection of the three planes is used as the origin O of the coordinate system; 1-2) The normal of plane f1 is used as the Z axis; 1-3) The intersection line of planes f1 and f2 is used as the X axis;

[0075] The specific steps to express the coordinate system to be determined using mathematical expressions according to the above rules are as follows: i (i=1,2,3) respectively adopt the point method (P i , n i ) means: where P i Represents the plane f i Previous point, n i Represents the plane f i The normal direction of a specific coordinate system can be calculated based on the above rules: The calculation steps are as follows:

[0076] 1-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n1;

[0077] 1-b) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0078] 1-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0079] 1-d) Solve the intersection of the three planes as the origin of the coordinate system O: According to the points, establish the following equation system on the plane, and obtain the intersection of the three planes as the origin of the coordinate system by solving the following linear equation system;

[0080]

[0081] like Figure 4 As shown in the figure, when the one-point-plus-a-line calibration mode is selected in step 1, the calibration method is applicable to the coordinate system determination with the simplest feature having a point feature and a straight line feature. Assume that the straight line l1(Q1Q2) is the central axis extracted after cylindrical surface fitting or the straight line determined by two points, P l，1 For a point outside the line, the rules for establishing the coordinate system by this method are as follows: 2-1) Line l1 determines the Z axis of the coordinate system; 2-2) P l，1 Located on the X-axis of the coordinate system; 2-3)P l，1 The projection point onto the line l1 is taken as the origin O of the coordinate system;

[0082] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0083] 2-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :

[0084] 2-b) Calculate P l，1 The projection point onto the straight line Q1Q2 is taken as the origin O of the coordinate system;

[0085] 2-c) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0086] 2-d) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0087] like Figure 5 As shown in the figure, when the one-point plus two-plane calibration mode is selected in step 1, the calibration method is suitable for the coordinate system determination with the simplest feature of one point and two plane features. Let P s，1 is a point or the center of a sphere, f s，1 and f s，2 are two non-parallel planes, plane f s，1 and plane f s，2 The normal directions are denoted as n s，1 and n s，2 The rules for establishing the coordinate system of this method are as follows: 3-1) The normal of the first plane determines the Z-axis unit vector z of the coordinate system Dir ;3-2)f s，1 and f s，2 The intersection line of is taken as the X axis; 3-3)P s，1 As the origin of the coordinate system O;

[0088] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0089] 3-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n s，1 ;

[0090] 3-b) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0091] 3-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0092] 3-d)Ps，1 As the origin O of the coordinate system.

[0093] like Figure 6 As shown in the figure, when the two-point plus one-plane calibration mode is selected in step 1, the calibration method is applicable to the workpiece coordinate system determination with the simplest feature of two point features and one plane feature. Suppose P p，1 , P p，2 are two non-coincident points; f p，1 is a plane, and the straight line formed by the two points is not perpendicular to the plane. The rules for establishing the coordinate system of this method are as follows: 4-1) Plane f p，1 The normal direction determines the Z axis of the coordinate system; 4-2) The projection vectors of the two points on the plane determine the X axis; 4-3) P p，1 The projection point on the plane is taken as the origin O of the coordinate system;

[0094] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0095] 4-a) Calculate two points P p，1 , P p，2 In plane f p，1 Projection point on

[0096] 4-b) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0097] 4-c) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n, n is the plane f p，1 The normal direction of

[0098] 4-d) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0099] 4-e) Calculate the origin of the coordinate system:

[0100] like Figure 7 As shown in the figure, when the three-point calibration mode is selected in step 1, the calibration method is suitable for the coordinate system with the simplest feature of three points. Let P c，1 , P c，2 , P c，3 For three points that are not coincident and not collinear, the rules for establishing the coordinate system by this method are as follows: 5-1) The first point P c，1 is the origin of the coordinate system O; 5-2) vector P c，1 P c，2 Determines the X-axis of the coordinate system; 5-3) The third point P c，3Located on the XOY plane of the coordinate system (first quadrant);

[0101] Calculate the coordinate system based on the above rules The calculation steps are as follows:

[0102] 5-a) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0103] 5-b) Calculate the unit vector z of the Z axis of the coordinate system Dir :

[0104] 5-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0105] 5-d) Calculate the origin of the coordinate system: O = P c，1 .

[0106] like Figure 8 As shown in the figure, when the two-line calibration mode is selected in step 1, the calibration method is suitable for workpieces with two straight line features as the simplest feature. l，1 , Q l，2 For the straight line l l，1 Two points on Q l，3 , Q l，4 For the straight line l l，2 The rules for establishing a coordinate system are as follows: 6-1) The direction perpendicular to both lines determines the Z axis; 6-2) The direction of the first line determines the X axis of the coordinate system; 6-3) If the two lines are coplanar, the intersection point is the origin of the coordinate system O; if the two lines are not coplanar, the intersection point of the common perpendicular line and the first line is the origin of the coordinate system;

[0107] Calculate the coordinate system based on the above rules: The calculation steps are as follows:

[0108] 6-a) Calculate the unit vector x of the X axis of the coordinate system Dir :

[0109] 6-b) Calculate the unit vector z of the Z axis of the coordinate system Dir :

[0110] 6-c) Calculate the unit vector y of the Y axis of the coordinate system Dir :

[0111] 6-d) Use the method of finding the intersection point or common perpendicular line of two straight lines to calculate the origin O of the coordinate system.

[0112] The protection scope of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope and spirit of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and modifications.

Claims

1. A robot clamping calibration method for simple geometric features, characterized in that: The steps include: Step 1: According to the characteristics of the calibration object, select the calibration mode. The clamping calibration method includes six calibration modes: 1) three-plane method mode; 2) one point plus a straight line method mode; 3) one point plus two planes method mode; 4) two points plus one plane method mode; 5) three-point method mode; 6) two straight lines method mode; Step 2: Calibration data acquisition: The position or posture of the object to be calibrated is collected by the measuring device. For external object calibration, the robot drives the measuring device to collect the position points of the points on the object to be calibrated in the robot coordinate system. For clamped object calibration, the robot drives the object to be calibrated to the fixed point to collect the posture of the flange. Step 3: Simplest feature extraction: If the calibration object has plane, circular, spherical or cylindrical features, fit the actual data after collection to extract the simplest geometric features, where the simplest geometric features are point, straight line and plane features; Step 4: Create a calibration coordinate system: According to the six different calibration modes selected in step 1, create a calibration coordinate system based on the definition rules of the six coordinate systems corresponding to the six calibration modes and the simplest features extracted in step 3; The step one is specifically as follows: observe the geometric features of the calibration object, select the calibration mode according to the features, and the calibration features should meet the following rules to create a calibration coordinate system, among which: 1) the three-plane method mode requires that the three planes can intersect at one point; 2) the one-point-plus-a-line method mode requires that the point is not on the straight line; 3) the one-point-plus-two-plane method mode requires that the two planes intersect and the point is not on the intersection line; 4) the two-point-plus-one-plane method mode requires that the straight line formed by the two points intersects with the plane; 5) the three-point method mode requires that the three points do not overlap with each other and are not collinear; 6) the two-line method mode requires that the two lines are not parallel.

2. A robot clamping calibration method for simple geometric features as described in claim 1, characterized in that: The step two is specifically as follows: the robot drives the measuring device to collect data on the calibration object. When collecting plane data, three or more non-colinear points need to be collected, when collecting spherical data, four or more non-coplanar points need to be collected, when collecting cylindrical data, six or more non-coplanar points need to be collected, and when collecting circular surface data, three or more non-overlapping points on the circle need to be collected. For external object calibration, the robot clamps the measuring device to collect the position points of the points on the object to be calibrated in the robot coordinate system. For clamped object calibration, the robot clamps the object to be calibrated to a fixed point to collect the position and posture of the flange.

3. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The step three is specifically as follows: fitting the collected plane, circular, spherical or cylindrical features into the simplest features: fitting the plane data into a plane feature represented by a point and a normal, and the fitted point and vector are also used as straight line features; fitting the circular or spherical data into a center of a circle or a center of a sphere as a point feature, and fitting the cylindrical data into an axis as a straight line feature.

4. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The specific process of creating the calibration coordinate system in step 4 is as follows: when the three-plane calibration mode is selected in step 1, the calibration method is applicable to the calibration of the coordinate system with the simplest feature of three plane features, and f1, f2, and f3 are three non-parallel planes on the object to be calibrated, and the planes are not required to be perpendicular to each other. The specific rules for establishing the coordinate system in this method are as follows: 1-1) The intersection of the three planes is used as the origin o of the coordinate system; 1-2) The normal of plane f1 is used as the Z axis; 1-3) The intersection line of planes f1 and f2 is used as the X axis; The specific steps to express the coordinate system to be determined using mathematical expressions according to the above rules are as follows: i (i=1,2,3) respectively adopt the point method (P i , n i ) means: where P i Represents the plane f i Previous point, n i Represents the plane f i The normal of is calculated based on the above rules for a specific coordinate system: Where RCS is the robot base coordinate system, and the calculation steps are as follows: 1-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n1; 1-b) Calculate the unit vector x of the X axis of the coordinate system Dir : 1-c) Calculate the unit vector y of the Y axis of the coordinate system Dir : 1-d) Solve the intersection of the three planes as the origin of the coordinate system O: According to the points, establish the following equation system on the plane, and obtain the intersection of the three planes as the origin of the coordinate system by solving the following linear equation system; 5. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The specific process of creating the calibration coordinate system in step 4 is as follows: when the one-point plus straight line method calibration mode is selected in step 1, the calibration method is applicable to the coordinate system determination with the simplest feature having a point feature and a straight line feature. Assume that the straight line l1(Q1Q2) is the central axis extracted after cylindrical surface fitting or the straight line determined by two points, P l，1 For a point outside the line, the rules for establishing the coordinate system by this method are as follows: 2-1) Line l1 determines the Z axis of the coordinate system; 2-2) P l，1 Located on the X-axis of the coordinate system; 2-3)P l，1 The projection point onto the line l1 is taken as the origin O of the coordinate system; Calculate the coordinate system based on the above rules The calculation steps are as follows: 2-a) Calculate the unit vector z of the Z axis of the coordinate system Dir : 2-b) Calculate P l，1 The projection point onto the straight line Q1Q2 is taken as the origin O of the coordinate system; 2-c) Calculate the unit vector x of the X axis of the coordinate system Dir : 2-d) Calculate the unit vector y of the Y axis of the coordinate system Dir :

6. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The specific process of creating the calibration coordinate system in step 4 is as follows: When the one-point plus two-plane method calibration mode is selected in step 1, the calibration method is suitable for determining the coordinate system with the simplest feature of one point and two plane features. Let P s，1 is a point or the center of a sphere, f s，1 and f s，2 are two non-parallel planes, plane f s，1 and plane f s，2 The normal directions are denoted as n s，1 and n s，2 The rules for establishing the coordinate system of this method are as follows: 3-1) The normal of the first plane determines the Z axis of the coordinate system; 3-2) f s，1 and f s，2 The intersection line of is taken as the X axis; 3-3)P s，1 As the origin of the coordinate system O; Calculate the coordinate system based on the above rules The calculation steps are as follows: 3-a) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n s，1 ; 3-b) Calculate the unit vector x of the X axis of the coordinate system Dir : 3-c) Calculate the unit vector y of the Y axis of the coordinate system Dir : 3-d)P s，1 As the origin O of the coordinate system.

7. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The specific process of creating the calibration coordinate system in step 4 is as follows: When the two-point plus one-plane calibration mode is selected in step 1, the calibration method is applicable to the workpiece coordinate system determination with the simplest feature having two point features and one plane feature. Let P p，1 , P p，2 are two non-coincident points; f p，1 is a plane, and the straight line formed by the two points is not perpendicular to the plane. The rules for establishing the coordinate system of this method are as follows: 4-1) Plane f p，1 The normal direction determines the unit vector z of the Z axis of the coordinate system Dir ; 4-2) The projection vector of two points on the plane determines the X axis; 4-3) P p，1 The projection point on the plane is taken as the origin O of the coordinate system; Calculate the coordinate system based on the above rules The calculation steps are as follows: 4-a) Calculate two points P p，1 , P p，2 In plane f p，1 Projection point on 4-b) Calculate the unit vector x of the X axis of the coordinate system Dir : 4-c) Calculate the unit vector z of the Z axis of the coordinate system Dir :z Dir =n, n is the plane f p，1 The normal direction of 4-d) Calculate the unit vector y of the Y axis of the coordinate system Dir : 4-e) Calculate the origin of the coordinate system:

8. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The specific process of creating the calibration coordinate system in step 4 is as follows: When the three-point calibration mode is selected in step 1, the calibration method is suitable for determining the coordinate system with the simplest feature of three points. Let P c，1 , P c，2 , P c，3 For three points that are not coincident and not collinear, the rules for establishing the coordinate system by this method are as follows: 5-1) The first point P c，1 is the origin o of the coordinate system; 5-2) vector P c，1 P c，2 Determines the X-axis of the coordinate system; 5-3) The third point P c，3 Located on the XOY plane of the coordinate system; Calculate the coordinate system based on the above rules The calculation steps are as follows: 5-a) Calculate the unit vector x of the X axis of the coordinate system Dir : 5-b) Calculate the unit vector z of the Z axis of the coordinate system Dir : 5-c) Calculate the unit vector y of the Y axis of the coordinate system Dir : 5-d) Calculate the origin of the coordinate system: O = P c，1 .

9. A robot clamping calibration method for simple geometric features as claimed in claim 1, characterized in that: The specific process of creating the calibration coordinate system in step 4 is as follows: When the two-line method calibration mode is selected in step 1, the calibration method is applicable to the workpiece with the simplest feature having two straight line features. l，1 , Q l，2 For the straight line l l，1 Two points on Q l，3 , Q l，4 For the straight line l l，2 The rules for establishing the coordinate system for two points on are as follows: 6-1) The direction perpendicular to both lines determines the Z axis; 6-2) The direction of the first line determines the X axis of the coordinate system; 6-3) If the two lines are coplanar, the point of intersection is the origin of the coordinate system O; if the two lines are not coplanar, the point of intersection of the common perpendicular line and the first line is the origin of the coordinate system; Calculate the coordinate system based on the above rules: The calculation steps are as follows: 6-a) Calculate the unit vector x of the X axis of the coordinate system Dir : 6-b) Calculate the unit vector z of the Z axis of the coordinate system Dir : 6-c) Calculate the unit vector y of the Y axis of the coordinate system Dir : 6-d) Use the method of finding the intersection point or common perpendicular line of two straight lines to calculate the origin O of the coordinate system.

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