CN117301073A - Robot kinematics self-calibration device, method and system and electronic equipment - Google Patents
Robot kinematics self-calibration device, method and system and electronic equipment Download PDFInfo
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Abstract
The invention discloses a robot kinematics self-calibration device, a method, a system and electronic equipment, and relates to the field of robot calibration, wherein the device comprises: the contact probe comprises a base and a plurality of probes; the mounting surface of the base is fixedly connected with the mounting end surface of the first mechanical arm to be tested; one end of each probe is connected with the detection surface of the base; the mounting surface of the touch array sensor is connected with the mounting end surface of the second mechanical arm to be detected; when the other end of each probe is contacted with the detection surface of the touch array sensor, the touch array sensor collects the pressure applied by the probe and sends the pressure to the upper computer; the upper computer is used for determining the contact position of each probe and the detection surface of the touch array sensor according to the pressure, acquiring a plurality of groups of joint angle data and contact positions through multiple contact of a plurality of probes of the first mechanical arm to be detected and the touch array sensor of the second mechanical arm to be detected, and calculating kinematic parameter errors of the first mechanical arm to be detected and the second mechanical arm to be detected. The invention improves the calibration efficiency of the robot.
Description
Technical Field
The invention relates to the field of robot calibration, in particular to a robot kinematics self-calibration device, a method and a system and electronic equipment.
Background
Along with the development of intelligent manufacturing technology, the use scene of the robot is continuously developed to the fields with higher requirements on positioning accuracy, such as automobile assembly, electronic product assembly, medical auxiliary equipment and the like, and higher requirements are also put forward on the absolute positioning accuracy of the robot.
At present, a great deal of work research has been carried out on robot kinematics calibration, but most of work is still completed by means of external precise instruments, such as a laser tracker, a three-coordinate measuring machine and the like, and the method is high in cost and difficult to meet the requirement of calibrating multiple robots simultaneously for improving efficiency during mass production of robots. Another method that is more used is a robot self-calibration method based on point and plane constraints, which reduces the cost of robot kinematic calibration to a certain extent and improves the flexibility of calibration. However, this method puts a requirement on the use environment that a fixed point or a known plane is required to be attached, which definitely brings additional working requirements to the robot calibration, and does not solve the problem that multiple robots can be calibrated simultaneously. In addition, most of the works have the problem of considering only position calibration and not posture.
Disclosure of Invention
The invention aims to provide a robot kinematics self-calibration device, a robot kinematics self-calibration method, a robot kinematics self-calibration system and an electronic device, which can calibrate the position and the gesture of a robot at the same time, improve the calibration efficiency, can be performed at any time and place, and are simple to operate and low in cost.
In order to achieve the above object, the present invention provides the following solutions:
the robot kinematics self-calibration device comprises a touch array sensor, a contact probe and an upper computer;
the contact probe comprises a base and a plurality of probes; the mounting surface of the base is fixedly connected with the mounting end surface of the first mechanical arm to be tested; one end of each probe is fixedly connected with the detection surface of the base; the other end of each probe is used for contacting with the detection surface of the tactile array sensor;
the touch array sensor comprises a plurality of touch sensing units which are periodically arranged; the shape of the vertical projection of the touch sensing unit is square; the mounting surface of the touch array sensor is fixedly connected with the mounting end surface of the second mechanical arm to be detected; the detection surface of the touch array sensor is parallel to the mounting end surface of the second mechanical arm to be detected;
the first mechanical arm to be tested drives the contact probe to enable the other end of the probe to be in contact with a detection surface of the touch array sensor driven by the second mechanical arm to be tested;
the touch array sensor is connected with the upper computer; when the other end of each probe is in contact with the detection surface of the tactile array sensor, the tactile array sensor collects the pressure exerted by the probe and sends the pressure to the upper computer;
the upper computer is used for determining the contact position of each probe and the detection surface of the tactile array sensor according to the pressure, acquiring a plurality of groups of joint angle data and a plurality of corresponding groups of contact positions through a plurality of probes of the first mechanical arm to be detected and the tactile array sensor of the second mechanical arm to be detected, and calculating a first kinematic parameter error of the first mechanical arm to be detected and a second kinematic parameter error of the second mechanical arm to be detected according to each group of joint angle data and each corresponding group of contact positions; the joint angle data comprise a first joint angle of each shaft of the first mechanical arm to be tested and a second joint angle of each shaft of the corresponding second mechanical arm to be tested; the contact position is a touch sensing unit which is contacted with a plurality of probes.
Optionally, the plurality of probes comprises a first probe, a second probe, and a third probe; the connecting lines of the vertical projections of the first probe, the second probe and the third probe are isosceles right triangles.
Optionally, the shape of the vertical projection of the tactile array sensor is square.
Optionally, the side length of the vertical projection of the tactile array sensor is greater than the side length of the vertical side of the isosceles right triangle.
Optionally, the other end of the probe is spherical in shape.
Optionally, the side length of the vertical projection of the tactile sensing unit is larger than the diameter of the cross section of the other end of the probe.
The robot kinematics self-calibration method is applied to the robot kinematics self-calibration device, and comprises the following steps:
acquiring pressure acquired by a touch array sensor, determining the contact position of a probe according to the pressure, and acquiring joint angle data of the first mechanical arm to be tested and the second mechanical arm to be tested;
multiple groups of joint angle data and corresponding multiple groups of contact positions are obtained through multiple contact between the multiple probes of the first mechanical arm to be tested and the touch array sensor of the second mechanical arm to be tested;
respectively constructing a first kinematic error model of a first mechanical arm to be tested and a second kinematic error model of a second mechanical arm to be tested based on an MDH method according to each set of joint angle data and each corresponding set of contact positions to obtain a first coordinate of the circle center of a circle where the contact positions are located under the base coordinate system of the second mechanical arm to be tested and a second coordinate of the circle center of a circle where the tail ends of a plurality of probes are located under the base coordinate system of the second mechanical arm to be tested;
constructing a first equation according to the first plane of the circle of the contact position and the second plane of the circle of the tail ends of the probes in parallel;
constructing a second equation according to the distance between the first coordinate and the second coordinate as a preset value;
and solving the first equation and the second equation to obtain the kinematic parameter error of the first mechanical arm to be tested and the kinematic parameter error of the second mechanical arm to be tested.
The robot kinematics self-calibration system applies the robot kinematics self-calibration method, and the calibration system comprises:
the first acquisition module is used for acquiring the pressure acquired by the touch array sensor, determining the contact position of the probe according to the pressure, and acquiring joint angle data of the first mechanical arm to be tested and the second mechanical arm to be tested;
the second acquisition module is used for acquiring a plurality of groups of joint angle data and a plurality of corresponding groups of contact positions through a plurality of probes of the first mechanical arm to be tested and the touch array sensor of the second mechanical arm to be tested;
the coordinate determining module is used for respectively constructing a first kinematic error model of a first mechanical arm to be tested and a second kinematic error model of a second mechanical arm to be tested based on an MDH method according to each group of joint angle data and each corresponding group of contact positions to obtain a first coordinate of the circle center of a circle where the contact positions are located under the base coordinate system of the second mechanical arm to be tested and a second coordinate of the circle center of a circle where the tail ends of a plurality of probes are located under the base coordinate system of the second mechanical arm to be tested;
the first construction module is used for constructing a first equation according to the parallel of a first plane where the circle of the contact position is located and a second plane where the circles of the tail ends of the plurality of probes are located;
the second construction module is used for constructing a second equation according to the distance between the first coordinate and the second coordinate as a preset value;
and the solving module is used for solving the first equation and the second equation to obtain the kinematic parameter error of the first mechanical arm to be tested and the kinematic parameter error of the second mechanical arm to be tested.
An electronic device comprising a memory and a processor, the memory being configured to store a computer program, the processor being configured to run the computer program to cause the electronic device to perform the robot kinematics self-calibration method described above.
Optionally, the memory is a readable storage medium.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
1. by controlling the movement of the first mechanical arm to be tested and the second mechanical arm to be tested, the contact collection of the angles of the joints of the two robots at the moment is realized, and the calculation of a large amount of inverse Jie Yake ratio matrix of the kinematics of the robots in the traditional method is avoided.
2. The two robot tail end contact probes are in contact with the touch array sensor to form a closed loop, high-cost equipment such as a laser tracker is not needed, the requirement that an attached fixed point or a known plane is needed in the environment is avoided, and the calibration tool is simple and can be implemented at any time and place.
3. And establishing an equation I by using the parallel relation between the plane of the contact sphere center of the probe tip and the plane of the tactile array sensor during contact, and establishing an equation II by using the circle center of the circle of the contact sphere centers of the three probe tips and the circle center distance d/2 of the circle of the three tactile sensing array units during contact, wherein the calibration is performed by using the position information and the gesture information.
4. The method can complete the calibration of the kinematic parameter errors of two robots at the same time, improves the calibration efficiency, and is suitable for occasions where a large number of robots need to be calibrated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a calibration site;
FIG. 2 is a schematic diagram of a tactile array sensor;
FIG. 3 is a schematic diagram of a three-point contact probe;
FIG. 4 is a schematic diagram of a three-point contact probe and tactile array sensor contact live;
FIG. 5 is a block diagram of the method of the present invention at the time of actual application;
fig. 6 is a flow chart of a robot kinematics self-calibration method of the present invention.
Reference numerals illustrate:
1. the touch sensing system comprises a touch array sensor, a touch probe, a first mechanical arm to be tested, a second mechanical arm to be tested, a first probe, a second probe, a third probe, a first touch sensing unit, a second touch sensing unit and a third touch sensing unit, wherein the touch array sensor is composed of the following components of the touch array sensor, the touch probe, the first mechanical arm to be tested, the second mechanical arm to be tested, the first probe, the second probe, the third probe, the first touch sensing unit, the second touch sensing unit and the third touch sensing unit.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a robot kinematics self-calibration device, a robot kinematics self-calibration method, a robot kinematics self-calibration system and an electronic device, which can calibrate the position and the gesture of a robot at the same time, improve the calibration efficiency, can be performed at any time and place, are simple to operate and have low cost, and the robot kinematics self-calibration device, the robot kinematics self-calibration system and the electronic device belong to a self-calibration method without using an external measuring instrument.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
As shown in fig. 1-4, the invention provides a robot kinematics self-calibration device, which comprises a touch array sensor, a contact probe and an upper computer.
The contact probe comprises a base and a plurality of probes; the mounting surface of the base is fixedly connected with the mounting end surface of the first mechanical arm to be tested; one end of each probe is fixedly connected with the detection surface of the base; the other end of each probe is used for contacting with the detection surface of the touch array sensor.
The touch array sensor comprises a plurality of touch sensing units which are periodically arranged; the shape of the vertical projection of the touch sensing unit is square; the mounting surface of the touch array sensor is fixedly connected with the mounting end surface of the second mechanical arm to be detected; and the detection surface of the touch array sensor is parallel to the mounting end surface of the second mechanical arm to be detected. In particular, the tactile sensing unit is a pressure sensor.
The first mechanical arm to be tested drives the contact probe to enable the other end of the probe to be in contact with the detection surface of the touch array sensor driven by the second mechanical arm to be tested.
The touch array sensor is connected with the upper computer; when the other end of each probe is in contact with the detection surface of the touch array sensor, the touch array sensor collects the pressure exerted by the probe and sends the pressure to the upper computer.
The upper computer is used for determining the contact position of each probe and the detection surface of the tactile array sensor according to the pressure, acquiring a plurality of groups of joint angle data and a plurality of corresponding groups of contact positions through a plurality of probes of the first mechanical arm to be detected and the tactile array sensor of the second mechanical arm to be detected, and calculating a first kinematic parameter error of the first mechanical arm to be detected and a second kinematic parameter error of the second mechanical arm to be detected according to each group of joint angle data and each corresponding group of contact positions; the joint angle data comprise a first joint angle of each shaft of the first mechanical arm to be tested and a second joint angle of each shaft of the corresponding second mechanical arm to be tested; the contact position is a touch sensing unit which is contacted with a plurality of probes.
As a specific embodiment, the plurality of probes includes a first probe, a second probe, and a third probe; the connecting lines of the vertical projections of the first probe, the second probe and the third probe are isosceles right triangles.
Specifically, the shape of the vertical projection of the tactile array sensor is square.
Further, the side length of the vertical projection of the touch array sensor is larger than the side length of the vertical side of the isosceles right triangle.
As a specific embodiment, the other end of the probe is spherical in shape. The other end of the probe is the tip contact of the probe; the tip contact of the probe is a small sphere with the diameter d, and the vertical projection is circular.
Specifically, the side length of the vertical projection of the touch sensing unit is larger than the diameter of the cross section of the other end of the probe.
In practical application, the tactile array sensor is a square with a side length L, and N multiplied by N tactile sensing arrays are uniformly distributed inside the tactile array sensor, and each unit is a square with a side length m. The touch array sensor is mounted at the end of the robot A and parallel to the mounting end face.
The three-point contact probe, namely the contact probe in the invention, consists of three probes with the length of K, and is uniformly distributed in an isosceles right triangle shape, wherein the right-angle side length of the triangle is H, the diameter d of the tip contact of the probe is smaller than the side length m of the array unit, and H is smaller than L, namely the three-point contact probe is within the envelope range of the array sensor. The three-point contact probe is vertically installed at the end of the robot B.
The touch sense array sensor is used for detecting the contact of the three-point contact probe and displaying the position of the contacted touch sense array unit; the three-point contact probe is for contacting the tactile array sensor.
When the three-point contact probe and the touch array sensor are contacted, the data transmitted by the pressure of the touch array sensor can change (if the touch array sensor used in the invention is an 8×8 array, 64 data can be transmitted at a certain frequency, and the data can be enlarged when the array unit is stressed), and the three-point contact probe and the touch array sensor can be judged to be contacted according to the change of the transmitted data, and the specific positions of the contacted three array units can be judged according to the maximum of the transmitted 64 data. The tactile array sensor is utilized to sense both a contact and a non-contact condition. Each time contact is made, it is ensured that the three probe tip contacts make contact with three array elements on the tactile array sensor.
Example two
In order to realize the corresponding device of the first embodiment to achieve the corresponding functions and technical effects, a method for self-calibrating kinematics of a robot is provided below, as shown in fig. 5 and 6, where the calibrating method includes:
step S1: and acquiring pressure acquired by the touch array sensor, determining the contact position of the probe according to the pressure, and acquiring joint angle data of the first mechanical arm to be tested and the second mechanical arm to be tested.
Step S2: and multiple groups of joint angle data and corresponding multiple groups of contact positions are obtained through multiple contact between the multiple probes of the first mechanical arm to be tested and the touch array sensor of the second mechanical arm to be tested.
In practical application, joint angles of each axis and positions of three touch sense array units contacted by three-point contact type probes are collected when two robots are contacted each time, and movement of a robot A (a second mechanical arm to be tested) and a robot B (a first mechanical arm to be tested) is controlled to enable the touch sense array sensor to be contacted with the three-point contact type probes (the contact type probes) for a plurality of times, and joint angles of each axis of the robot A and the robot B when the two robots are contacted each time are recorded, wherein the corresponding positions of the three probes and the three touch sense array units contacted are recorded as follows: the first probe is in contact with the first tactile sensation unit, the second probe is in contact with the second tactile sensation unit, and the third probe is in contact with the third tactile sensation unit.
Further, for any N-axis robot, controlling the robot A and the robot B to contact in a common operation space, wherein the contact force is controlled within 0-1N, and the deformation of the sensor is ignored and is treated as a rigid body; recording the angle value of each joint of the robot A and the robot B during contact and the positions (1-1, 1-2 and 1-3) of the touch sensor array units contacted by the three probes (2-1, 2-2 and 2-3) respectively; changing the configuration of the robot, and repeating the steps to acquire multiple groups of joint axis angle data.
Step S3: and respectively constructing a first kinematic error model of the first mechanical arm to be tested and a second kinematic error model of the second mechanical arm to be tested based on the MDH method according to each set of joint angle data and each corresponding set of contact positions to obtain a first coordinate of the circle center of the circle where the contact positions are located under the base coordinate system of the second mechanical arm to be tested and a second coordinate of the circle centers of the circles where the tail ends of the plurality of probes are located under the base coordinate system of the second mechanical arm to be tested.
In practical application, a kinematic error model of a robot A and a robot B is respectively established based on an MDH method, a conversion matrix of a three-point contact probe tip contact sphere center relative to a robot B base coordinate system and a conversion matrix of three contacted array units relative to a robot A base coordinate system are obtained, and the robot B base coordinate system is converted under the robot A base coordinate system.
Further, respectively constructing Cartesian space coordinate systems at joints of the robot A and the robot B, respectively deriving actual conversion matrixes from the base coordinate systems of the robot A and the robot B to the flange coordinate system by utilizing forward kinematics of an MDH model, wherein nominal conversion matrixes from the adjacent coordinate systems i to i-1 are shown in a formula (1):
the deduction can be made as follows:
in the formula (2), c represents cos, s represents sin,representing the rotation of the adjacent link coordinate system, +.>Representing translation of adjacent link coordinate systems, where 0<i<N+1。
Due to the error of the geometric parameters of the connecting rod, the actual conversion relation from the adjacent coordinate system i to i-1 is shown in the formula (3):
Δα in equation (3) i-1 、Δa i-1 、Δθ i 、Δd i Representing the kinematic parameter error.
The actual conversion matrix from the base coordinate system of the robot A and the base coordinate system of the robot B to the flange coordinate system is shown in a formula (4):
in the formula (4)Representing the actual transformation matrix of the robot A-base coordinate system to the flange coordinate system, < >>The actual transformation matrix from the robot B-based coordinate system to the flange coordinate system is represented.
Establishing an actual transformation matrix from the robot A flange coordinate system to three contacted tactile sensing array unit coordinate systems, wherein the transformation matrix from the three contacted array unit coordinate systems to the robot A flange coordinate system is obtained through translation along the X, Y, Z three directions, as shown in a formula (5):
in the formula (5) (x 1-1 、y 1-1 、z 1-1 )、(x 1-2 、y 1-2 、z 1-2 )、(x 1-3 、y 1-3 、z 1-3 ) Representing the distance the origin of the 1-1, 1-2, 1-3 coordinate systems translates along the X, Y, Z axis, respectively.
Since the translation distances in the formula (5) are measured, a certain measurement error exists, and the tactile array sensor is installed at the tail end in an integral manner, the translation error of the origin of each array unit coordinate system relative to the robot A flange coordinate system is the same, namely the actual transformation matrix of the robot A flange coordinate system to the three contacted tactile sensing array unit coordinate systems is shown as the formula (6):
in the formula (6) (Deltax 1-1 、Δy 1-1 、Δz 1-1 ) Representing the distance error of translation of the origin of the 1-1, 1-2, 1-3 coordinate systems along the X, Y, Z axis.
Establishing an actual transformation matrix from the robot B flange coordinate system to the sphere centers of the three probe tip contacts, wherein the transformation matrix from the sphere center coordinate system of the three probe tip contacts to the robot B flange coordinate system is obtained through translation along the X, Y, Z three directions, as shown in a formula (7):
in the formula (7) (x 2-1 、y 2-1 、z 2-1 )、(x 2-2 、y 2-2 、z 2-2 )、(x 2-3 、y 2-3 、z 2-3 ) Representing the distance the origin of the 2-1, 2-2, 2-3 coordinate systems translates along the X, Y, Z axis, respectively.
Because the translation distances in the formula (7) are all obtained by measurement, and certain measurement errors exist, the actual transformation matrix from the robot B flange coordinate system to the three probe tip contact sphere center coordinate systems is shown as the formula (8):
in the formula (8) (. DELTA.x 2-1 、Δy 2-1 、Δz 2-1 )、(Δx 2-2 、Δy 2-2 、Δz 2-2 )、(Δx 2-3 、Δy 2-3 、Δz 2-3 ) The distance errors of the translation of the origin of the 2-1, 2-2, 2-3 coordinate systems along the X, Y, Z axis are shown, respectively.
Obtaining an actual transformation matrix from a robot A-based coordinate system to three contacted tactile sensing array unit coordinate systems and an actual transformation matrix from a robot B-based coordinate system to three probe tip contact sphere center coordinate systems, wherein the actual transformation matrix is shown in a formula (9):
step S4: and constructing a first equation according to the first plane of the circle of the contact position and the second plane of the circles of the tail ends of the plurality of probes.
Step S5: and constructing a second equation according to the distance between the first coordinate and the second coordinate as a preset value.
Step S6: and solving the first equation and the second equation to obtain the kinematic parameter error of the first mechanical arm to be tested and the kinematic parameter error of the second mechanical arm to be tested.
In practical application, an equation I is established according to the parallel relation between the plane where the sphere center of the tip contact of the three-point contact probe is positioned and the plane where the tactile array sensor is positioned in contact, and the equation I is used as a first equation in the invention; according to the circle center distance d/2 of the circle center of the sphere center of the three probe tip contacts and the circle center distance d/2 of the circle center of the three contacted array units, namely the preset value, establishing an equation II, wherein the equation II is used as a second equation in the invention; because the probe tip contact point is a small sphere, the diameter of the sphere is d, the first coordinate is the center of a circle where the sphere centers of the three probe tip contact points are located, and the second coordinate is the center of a circle where the three array units are contacted, the actual distance between the first coordinate and the second coordinate is half of the diameter of the small sphere of the probe tip contact point when the three array units are contacted. And solving the equation I and the equation II to obtain the kinematic parameter errors of the robot A and the robot B.
Further, an actual conversion matrix between the robot B base frame and the robot a is calculated. The conversion relationship between the robot B and the robot a base frames is obtained by rotational translation about three axes X, Y, Z, as shown in equation (10):
in the formula (10), phi, theta and phi respectively represent the rotation angles around X, Y, Z axis, a x 、a y 、a z Respectively, the distance translated along the X, Y, Z axis.
However, due to the error in the installation of the two robots, the actual conversion relationship between the base standard system of the robot B and the base standard system of the robot A is shown as the formula (11):
ζ in equation (11) x 、ξ y 、ξ z Respectively represent the rotation error delta around X, Y, Z axis x 、δ x 、δ z Respectively representing translational errors along the X, Y, Z axis.
The conversion relations between the three probe tip contact sphere center coordinate systems of the robot B and the three touch sense sensing array unit coordinate systems on the robot A and the base coordinate system of the robot A are shown as a formula (12):
the calculation results of the formulas are all 4 multiplied by 4 matrixes, only the fourth column vector representing the position is intercepted, and the fourth column vector is respectively and sequentially represented as
The plane equation of the tactile array sensor at the moment can be obtained by the positions of three tactile sensing array units contacted on the robot A at the moment of contact as shown in the following formula (13):
A 1 x+B 1 y+C 1 Z+D 1 ＝0 (13)
the plane equation of the sphere center of the three probe tip contacts on the robot B at the time of contact is shown in the following formula (14):
A 2 x+B 2 y+C 2 z+D 2 ＝0 (14)
equation one (15) can be obtained according to the parallel relation between the plane of the touch array sensor and the plane of the sphere center of the three-point contact probe tip contact point when in contact:
A 1 /A 2 ＝B 1 /B 2 ＝C 1 /C 2 (15)
the circle center position coordinates E of the circle where the three touch sense array units are positioned can be obtained according to the position coordinates of the three touch sense array units which are contacted during contact 1 The center position coordinate E of the circle where the three probe tips are positioned can be obtained according to the center position coordinates of the contact points of the three probes during contact 2 According to the contact time E 1 And E is 2 Establishing equation two (16) for distance d/2:
||E 1 -E 2 ||＝d/2 (16)
and solving equation one (15) and equation two (16) to obtain the kinematic parameter errors of the robot A and the robot B.
The above equation contains a total of 4×n×2+3+3×3+6 error parameters, where the error parameters (Δα) based on the MDH method i-1 、Δa i-1 、Δθ i 、Δd i ) There are N x 2 groups, 3 conversion relation error parameters between the three touch sense array unit coordinate systems contacted to the robot A flange coordinate system, 3 x 3 conversion relation error parameters between the three probe tip contact sphere centers to the robot B flange coordinate system, and 6 conversion relation error parameters between the robot B base standard system and the robot A base standard system. And solving the equation I and the equation II to obtain the kinematic parameter errors of the two robots A, B.
In the invention, when the three-point contact probe is contacted with the array sensor, the distance between the center of the circumscribed circle where the center of the contact point of the three probe is positioned and the center of the circumscribed circle where the center of the contacted three array units is positioned is d/2 of the radius of the contact point of the probe, so that the calibration by using the position information is realized, and the method corresponds to the formula (16); when the three-point contact probe is contacted with the array sensor, the plane where the sphere center of the tip contact point of the three probes is parallel to the plane where the center of the three array units is (the plane where the sensor is also) and calibration by using gesture information is realized by parallel normal vectors of the two planes, and the method corresponds to the formula (13), the formula (14) and the formula (15).
All error parameters consist of the following four parts: (1) In the MDH-based modeling method, each joint has four kinematic parameters: alpha i-1 、a i-1 、θ i 、d i Respectively represent torsion angle, link length, joint angle and link offset parameter of ith joint, delta alpha i-1 、Δa i-1 、Δθ i 、Δd i For the corresponding error, corresponding to formula (3), there are 4×n×2 error parameters based on the MDH method for two N-degree-of-freedom robots, 4 representing 4 error parameters per joint, N representing N joints, 2 representing two robots; (2) The tactile array sensor is mounted at the end in an integral manner, so that the translational error of each array unit with respect to the robot a flange coordinate system is the same, i.e. there are 3 errors: Δx 1-1 、Δy 1-1 、Δz 1-1 Corresponding to equation (6); (3) The conversion error parameters between the sphere centers of the three probe tips and the robot B flange coordinate system are 3×3: the spherical center of the tip contact of each probe has translational error along the X, Y, Z axis relative to the flange coordinate system of the robot B, and 3 probes are totally arranged, which corresponds to the formula (8); (4) There are 6 conversion relation errors between the robot B base frame and the robot a base frame, including a rotation error about the X, Y, Z axis and a translation error along the X, Y, Z axis, corresponding to equation (11).
The error parameters are obtained, and the robot kinematics inverse operation can be performed according to the real kinematics parameters to realize compensation so as to improve the absolute positioning accuracy of the robot.
Example III
In order to execute the method corresponding to the second embodiment to achieve the corresponding functions and technical effects, a robot kinematic self-calibration system is provided below, where the calibration system includes:
the first acquisition module is used for acquiring the pressure acquired by the touch array sensor, determining the contact position of the probe according to the pressure, and acquiring joint angle data of the first mechanical arm to be tested and the second mechanical arm to be tested.
The second acquisition module is used for acquiring a plurality of groups of joint angle data and a plurality of corresponding groups of contact positions through a plurality of probes of the first mechanical arm to be tested and the touch array sensor of the second mechanical arm to be tested.
The coordinate determining module is used for respectively constructing a first kinematic error model of the first mechanical arm to be tested and a second kinematic error model of the second mechanical arm to be tested based on an MDH method according to each group of joint angle data and each corresponding group of contact positions to obtain a first coordinate of the circle center of the circle where the contact positions are located under the base coordinate system of the second mechanical arm to be tested and a second coordinate of the circle center of the circle where the tail ends of the plurality of probes are located under the base coordinate system of the second mechanical arm to be tested.
And the first construction module is used for constructing a first equation according to the first plane of the circle of the contact position and the second plane of the circles of the tail ends of the plurality of probes.
And the second construction module is used for constructing a second equation according to the distance between the first coordinate and the second coordinate as a preset value.
And the solving module is used for solving the first equation and the second equation to obtain the kinematic parameter error of the first mechanical arm to be tested and the kinematic parameter error of the second mechanical arm to be tested.
Example IV
The embodiment of the invention provides electronic equipment, which comprises a memory and a processor, wherein the memory is used for storing a computer program, and the processor runs the computer program to enable the electronic equipment to execute the robot kinematics self-calibration method in the first embodiment.
Alternatively, the electronic device may be a server.
In addition, the embodiment of the invention also provides a computer readable storage medium, which stores a computer program, and the computer program realizes the robot kinematics self-calibration method of the first embodiment when being executed by a processor.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (10)
1. The robot kinematics self-calibration device is characterized by comprising a touch array sensor, a contact probe and an upper computer;
the contact probe comprises a base and a plurality of probes; the mounting surface of the base is fixedly connected with the mounting end surface of the first mechanical arm to be tested; one end of each probe is fixedly connected with the detection surface of the base; the other end of each probe is used for contacting with the detection surface of the tactile array sensor;
the touch array sensor comprises a plurality of touch sensing units which are periodically arranged; the shape of the vertical projection of the touch sensing unit is square; the mounting surface of the touch array sensor is fixedly connected with the mounting end surface of the second mechanical arm to be detected; the detection surface of the touch array sensor is parallel to the mounting end surface of the second mechanical arm to be detected;
the first mechanical arm to be tested drives the contact probe to enable the other end of the probe to be in contact with a detection surface of the touch array sensor driven by the second mechanical arm to be tested;
the touch array sensor is connected with the upper computer; when the other end of each probe is in contact with the detection surface of the tactile array sensor, the tactile array sensor collects the pressure exerted by the probe and sends the pressure to the upper computer;
the upper computer is used for determining the contact position of each probe and the detection surface of the tactile array sensor according to the pressure, acquiring a plurality of groups of joint angle data and a plurality of corresponding groups of contact positions through a plurality of probes of the first mechanical arm to be detected and the tactile array sensor of the second mechanical arm to be detected, and calculating a first kinematic parameter error of the first mechanical arm to be detected and a second kinematic parameter error of the second mechanical arm to be detected according to each group of joint angle data and each corresponding group of contact positions; the joint angle data comprise a first joint angle of each shaft of the first mechanical arm to be tested and a second joint angle of each shaft of the corresponding second mechanical arm to be tested; the contact position is a touch sensing unit which is contacted with a plurality of probes.
2. The robotic kinematic self-calibration device of claim 1, wherein the plurality of probes comprises a first probe, a second probe, and a third probe; the connecting lines of the vertical projections of the first probe, the second probe and the third probe are isosceles right triangles.
3. The robotic kinematic self-calibration device of claim 2, wherein the vertical projection of the tactile array sensor is square in shape.
4. A robotic kinematic self-calibration device according to claim 3, in which the side length of the vertical projection of the tactile array sensor is greater than the side length of the vertical side of the isosceles right triangle.
5. The robot kinematic self-calibration device of claim 1, wherein the other end of the probe is spherical in shape.
6. The robot kinematic self-calibration device according to claim 5, characterized in that the side length of the vertical projection of the tactile sensing unit is greater than the diameter of the cross section of the other end of the probe.
7. A robot kinematic self-calibration method applied to the robot kinematic self-calibration device according to any one of claims 1 to 6, characterized in that the calibration method comprises:
acquiring pressure acquired by a touch array sensor, determining the contact position of a probe according to the pressure, and acquiring joint angle data of the first mechanical arm to be tested and the second mechanical arm to be tested;
multiple groups of joint angle data and corresponding multiple groups of contact positions are obtained through multiple contact between the multiple probes of the first mechanical arm to be tested and the touch array sensor of the second mechanical arm to be tested;
respectively constructing a first kinematic error model of a first mechanical arm to be tested and a second kinematic error model of a second mechanical arm to be tested based on an MDH method according to each set of joint angle data and each corresponding set of contact positions to obtain a first coordinate of the circle center of a circle where the contact positions are located under the base coordinate system of the second mechanical arm to be tested and a second coordinate of the circle center of a circle where the tail ends of a plurality of probes are located under the base coordinate system of the second mechanical arm to be tested;
constructing a first equation according to the first plane of the circle of the contact position and the second plane of the circle of the tail ends of the probes in parallel;
constructing a second equation according to the distance between the first coordinate and the second coordinate as a preset value;
and solving the first equation and the second equation to obtain the kinematic parameter error of the first mechanical arm to be tested and the kinematic parameter error of the second mechanical arm to be tested.
8. A robot kinematic self-calibration system applying the robot kinematic self-calibration method of claim 7, characterized in that the calibration system comprises:
the first acquisition module is used for acquiring the pressure acquired by the touch array sensor, determining the contact position of the probe according to the pressure, and acquiring joint angle data of the first mechanical arm to be tested and the second mechanical arm to be tested;
the second acquisition module is used for acquiring a plurality of groups of joint angle data and a plurality of corresponding groups of contact positions through a plurality of probes of the first mechanical arm to be tested and the touch array sensor of the second mechanical arm to be tested;
the coordinate determining module is used for respectively constructing a first kinematic error model of a first mechanical arm to be tested and a second kinematic error model of a second mechanical arm to be tested based on an MDH method according to each group of joint angle data and each corresponding group of contact positions to obtain a first coordinate of the circle center of a circle where the contact positions are located under the base coordinate system of the second mechanical arm to be tested and a second coordinate of the circle center of a circle where the tail ends of a plurality of probes are located under the base coordinate system of the second mechanical arm to be tested;
the first construction module is used for constructing a first equation according to the parallel of a first plane where the circle of the contact position is located and a second plane where the circles of the tail ends of the plurality of probes are located;
the second construction module is used for constructing a second equation according to the distance between the first coordinate and the second coordinate as a preset value;
and the solving module is used for solving the first equation and the second equation to obtain the kinematic parameter error of the first mechanical arm to be tested and the kinematic parameter error of the second mechanical arm to be tested.
9. An electronic device comprising a memory for storing a computer program and a processor that runs the computer program to cause the electronic device to perform the robot kinematics self calibration method according to claim 7.
10. The electronic device of claim 9, wherein the memory is a readable storage medium.
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