CN113146630A - Industrial robot milling error compensation method, system, device and medium - Google Patents
Industrial robot milling error compensation method, system, device and medium Download PDFInfo
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Abstract
The invention discloses a milling error compensation method, a system and a medium for an industrial robot, wherein the method comprises the following steps: acquiring milling force F in the robot machining process and acquiring a joint angle Q in the robot machining process; constructing a first relation between the milling force of the robot and the deformation error compensation value, and constructing a second relation between the joint angle of the robot and the positioning error compensation value; calculating the compensation quantity delta of the deformation error of the robot according to the milling force F and the first relation1Calculating the compensation quantity delta of the robot positioning error according to the joint angle Q and the second relation2(ii) a Will compensate for the quantity delta1And the compensation quantity delta2And (5) obtaining a total compensation value delta of the milling error of the robot through superposition, and feeding back the total compensation value delta to the robot. The invention simultaneously considers the deformation error of the robot under the action of milling force and the positioning error generated by the geometric parameters of the robot, and simultaneously compensates and supplements the two errorsThe compensation effect is stable, and the method can be widely applied to the technical field of robots.
Description
Technical Field
The invention relates to the technical field of robots, in particular to a milling error compensation method, a milling error compensation system, a milling error compensation device and a milling error compensation medium for an industrial robot.
Background
The robot is widely applied to the fields of stacking, painting, welding and the like due to the advantages of high flexibility, good flexibility, low price, high repeated positioning precision and the like, but the application in the field of cutting machining is limited due to the disadvantages of poor rigidity, low absolute positioning precision and the like, so that in order to improve the machining precision, a compensation system is introduced into a robot cutting machining unit, the production cost can be obviously reduced, the utilization rate of equipment and a machining space is improved, and the technical innovation speed and the enterprise competitiveness are effectively improved.
In the application of robot cutting machining, error prediction and compensation are always the hot problems of research. The robot error comprises the self positioning error of the robot and the deformation error generated by stress, the robot stress deformation comprises the robot connecting rod deformation and the joint deformation, and for most robots, the joint deformation is the main cause of the robot tail end deformation error.
Aiming at the compensation of the positioning error of the robot, most researchers adopt a robot geometric parameter calibration method to compensate, and the method is specifically divided into four steps of modeling, measuring, identifying and compensating, and is an off-line compensation method. For the compensation of deformation errors, most of the existing researches are based on measuring the terminal pose of the robot by a vision or optical measurement system, comparing the terminal pose with an ideal pose, and calculating the error value of the pose so as to compensate. The measurement accuracy of the vision or optical measurement system is easily affected by the chip, and the measurement range is limited, so that the measurement system has certain limitations. Most of the existing researches are to independently compensate the positioning error and the deformation error, and few students relate to the researches for online compensating the positioning error and the deformation error at present.
Disclosure of Invention
In order to solve at least one of the technical problems in the prior art to a certain extent, the invention aims to provide an industrial robot milling error online compensation method, system, device and medium based on force measurement feedback.
The technical scheme adopted by the invention is as follows:
an industrial robot milling error compensation method comprises the following steps:
acquiring milling force F in the robot machining process and acquiring a joint angle Q in the robot machining process;
constructing a first relation between the milling force of the robot and the deformation error compensation value, and constructing a second relation between the joint angle of the robot and the positioning error compensation value;
calculating the compensation quantity delta of the deformation error of the robot according to the milling force F and the first relation1Calculating the compensation quantity delta of the robot positioning error according to the joint angle Q and the second relation2；
Will compensate for the quantity delta1And the compensation quantity delta2And (5) obtaining a total compensation value delta of the milling error of the robot through superposition, and feeding back the total compensation value delta to the robot.
Further, the milling force is a three-dimensional force: f ═ F (fx, fy, fz)TThe joint angle is a six-degree-of-freedom joint angle: q ═ Q (Q)1,q2,q3,q4,q5,q6)T。
Further, the expression of the first relationship is:
when n > 2:
when n is less than or equal to 2:
wherein ,
robot joint stiffness matrix J corresponding to the nth tool location point for the robotnThe first three rows of the velocity jacobian matrix corresponding to the nth knife location point for the robot,
and JnAre all related to the pose of the robot; fnThe milling force corresponding to the nth tool location is provided for the robot,
and the PID adjustment proportion coefficient, the integral coefficient and the differential coefficient corresponding to the nth cutter position point of the robot are respectively used.
Further, the proportional coefficient, the integral coefficient and the differential coefficient are parameters for adaptive adjustment, and when n is greater than 2, the adaptive adjustment method is as follows:
wherein ,γnThe PID coefficient matrix corresponding to the nth cutter position point of the robot is obtained by correcting the PID coefficient matrix corresponding to the nth-1 cutter position point and the deformation error compensation value, E is an identity matrix, and X isnFor the input matrix, X, of PID corresponding to the nth knife location pointnIs the corresponding deformation error matrix.
Further, a PID coefficient matrix γnInput matrix XnAnd XnThe calculation method of (c) is as follows:
wherein ,γnIs a 3x1 coefficient matrix composed of proportional coefficient, integral coefficient and differential coefficient, gammanOnce the value of (A) is determined, a proportional coefficient, an integral coefficient and a differential coefficient are also determined; xnIs an input matrix of 3X3 related to the stiffness of the robot joint, the velocity Jacobian matrix and the milling force, XnIs an input matrix X corresponding to the first n cutter location points by the robotnForming an error matrix with 3n rows and 3 columns, ΔnA matrix of 3x 1.
Further, the expression of the second relationship is:
δ2＝f′(Q+ΔQ)-f(Q)
wherein f' (Q) is a forward kinematics equation of the robot after the calibration of the kinematics parameters,f (Q) is a forward kinematic equation of the robot without parameter calibration, and delta Q is a joint angle error and a positioning error delta after the kinematic parameter calibration2Is a 3x1 matrix representing the compensation values in the three directions xyz.
Further, the acquiring the milling force F in the robot machining process includes:
the method comprises the following steps of (1) measuring and acquiring a milling force F in the machining process of a robot on line by using a force sensor;
the joint angle Q in the robot machining process is obtained, and the method comprises the following steps:
and acquiring a joint angle Q in the machining process of the robot on line by adopting a robot communication interface.
The other technical scheme adopted by the invention is as follows:
an industrial robot milling error online compensation system, comprising:
the information acquisition module is used for acquiring the milling force F in the robot machining process and acquiring the joint angle Q in the robot machining process;
the relation building module is used for building a first relation between the milling force of the robot and the deformation error compensation value and building a second relation between the joint angle of the robot and the positioning error compensation value;
a compensation solving module for calculating the compensation quantity delta of the deformation error of the robot according to the milling force F and the first relation1Calculating the compensation quantity delta of the robot positioning error according to the joint angle Q and the second relation2；
A compensation feedback module for compensating the compensation quantity delta1And the compensation quantity delta2And (5) obtaining a total compensation value delta of the milling error of the robot through superposition, and feeding back the total compensation value delta to the robot.
The other technical scheme adopted by the invention is as follows:
an industrial robot mills online compensation arrangement of machining error, includes:
at least one processor;
at least one memory for storing at least one program;
when executed by the at least one processor, cause the at least one processor to implement the method described above.
The other technical scheme adopted by the invention is as follows:
a storage medium having stored therein a processor-executable program for performing the method as described above when executed by a processor.
The invention has the beneficial effects that: the invention simultaneously considers the deformation error of the robot under the action of milling force and the positioning error generated by the geometric parameters of the robot, compensates the two errors simultaneously, is not influenced by a processing angle, a processing space and processing chips, and has stable compensation effect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description is made on the drawings of the embodiments of the present invention or the related technical solutions in the prior art, and it should be understood that the drawings in the following description are only for convenience and clarity of describing some embodiments in the technical solutions of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of an industrial robot machining error online compensation method based on force measurement feedback in an embodiment of the invention;
FIG. 2 is a structural diagram of an online robot machining error compensation system based on force measurement feedback in an embodiment of the invention;
FIG. 3 is a comparison graph of position errors before and after compensation of positioning errors in an embodiment of the present invention;
FIG. 4 is a schematic diagram of a compensation strategy in an embodiment of the invention;
FIG. 5 is a schematic illustration of an industrial robot compensating for part errors before and after the embodiment of the invention;
FIG. 6 is a schematic diagram of the effects of the industrial robot before and after compensating the curved surface part in the embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. The step numbers in the following embodiments are provided only for convenience of illustration, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
Referring to the attached drawings 1 and 2, the embodiment provides a robot machining error online compensation method based on force measurement feedback, and a compensation system corresponding to the method is shown in the attached drawing 2 and comprises a six-degree-of-freedom industrial robot, an electric spindle, a force sensor, an upper computer, a robot control cabinet, a cutter and a workpiece.
The industrial robot machining error online compensation method based on force measurement feedback comprises the following steps:
s1, measuring the three-dimensional milling force F in the robot machining process on line through a force sensor arranged at the bottom of the workpiece, and acquiring the joint angle Q in the robot machining process on line through a robot communication interface;
s2, constructing a relation between the milling force of the robot and the deformation error compensation value, and constructing a relation between the joint angle of the robot and the positioning error compensation value;
s3, calculating the compensation quantity delta of the deformation error of the robot by using the milling force F obtained by on-line measurement1Calculating the compensation quantity delta of the robot positioning error by using the online acquired joint angle Q2；
S4, superposing the two compensation values to obtain a total compensation value delta-delta of the robot machining error1+δ2And then the total compensation value is fed back to the robot through the robot communication interface.
Specifically, in step S1, the milling force is three-dimensional force F ═ F (F)x,fy,fz)TThe joint angle is six-degree-of-freedom joint angle Q ═ Q (Q)1,q2,q3,q4,q5,q6)T. Since the milling force is obtained in the measurement coordinate system of the force sensor and the calculation of the deformation error compensation value is performed in the tool contact point coordinate system of the curved surface, the measured milling force needs to be converted into the tool contact point coordinate system.
As shown in fig. 4, in step S2, the relationship between the robot milling force and the deformation error compensation value is:
in the above-mentioned formula (1),
the rigidity matrix of the joint of the robot corresponding to the nth cutter position point is defined as6x6 Square matrix, JnThe first three rows of the velocity jacobian matrix for the robot at the nth tool location point, a 3x6 matrix,
and JnAre all related to the pose of the robot, and the calculation thereof uses the existing method. FnThe three-dimensional cutting force corresponding to the nth tool location point, which is a matrix of 3x1,
and the PID adjustment proportion coefficient, the integral coefficient and the differential coefficient corresponding to the nth cutter position point of the robot are respectively used. Distortion error compensation value delta1Is a 3x1 matrix representing the compensation values in the three directions xyz. The above formula is applicable to n being larger than 2, and for the first two tool positions, no PID regulation is added, and the calculation method of the deformation error compensation value is as follows:
in the formula (1), the proportional coefficient, the integral coefficient and the differential coefficient are parameters which can be adjusted in a self-adaptive manner, and when n is greater than 2, the adjusting method is as follows:
in the formula (3), gammanThe PID coefficient matrix corresponding to the nth cutter position point of the robot can be obtained by correcting the PID coefficient matrix corresponding to the nth-1 cutter position point and the deformation error compensation value, E is a unit matrix of 3X3, and X isnFor the input matrix, X, of PID corresponding to the nth knife location pointnFor the corresponding deformation error matrix, the specific calculation method is as follows:
in the formula (4), gammanIs formed byCoefficient matrix of 3x1 composed of proportional coefficient, integral coefficient and differential coefficient, gammanOnce the value of (c) is determined, the proportional, integral, and derivative coefficients are also determined. XnIs an input matrix of 3X3 related to the stiffness of the robot joint, the velocity Jacobian matrix and the milling force, XnIs an input matrix X corresponding to the first n cutter location points by the robotnForming an error matrix with 3n rows and 3 columns, ΔnA matrix of 3x 1. The initial value of γ can be taken to be 0, since the first two tool positions are not controlled by PID, γ is calculated from the third tool position, i.e. γ1＝γ2After the value of the coefficient matrix γ is determined, the scaling factor K can be calculated from equation (4) as 0PIntegral coefficient KIDifferential coefficient KDThe values of the three.
In the formula (1), the compensation value of the deformation error has a direct relation with the milling force, the rigidity of the robot joint and the jacobian matrix of the speed of the robot, and the milling force, the rigidity of the joint and the jacobian matrix of the speed of the robot are closely related with the processing pose of the robot, so the method for compensating the deformation error has good pose adaptability. When the curvature of the surface of the machined workpiece changes suddenly, the machining pose of the robot is adjusted according to the curvature of the workpiece, the milling force, the rigidity of the robot joint and the jacobian matrix of the robot speed change correspondingly, and the compensation value is updated according to the milling force, the rigidity of the robot joint and the change of the jacobian matrix of the robot speed. Therefore, the compensation method has a good compensation effect on the complex curved surface. In addition, the PID coefficient at the nth cutter position can be obtained by correcting the PID coefficients of the n-1 cutter positions, and the deformation compensation value of the nth cutter position is related to the compensation values of the previous two cutter positions.
In step S2, the relationship between the joint angle and the positioning error compensation value is:
δ2＝f′(Q+ΔQ)-f(Q) (5)
in the formula (5), f' (Q) is a forward kinematics equation of the robot after the kinematics parameter calibration, and f (Q) is a forward kinematics equation of the robot without the kinematics parameter calibrationThe forward kinematic equation of the robot is calibrated by kinematic parameters, wherein delta Q is the joint angle error and the positioning error delta after the kinematic parameters are calibrated2Is a 3x1 matrix representing the compensation values in the three directions xyz. The method for calibrating kinematic parameters of the robot is an existing method and is not described herein. Wherein, fig. 3 is a comparison diagram of position errors before and after the positioning error compensation.
The method can calculate the compensation quantity delta of the deformation error of the robot through the milling force F obtained by on-line measurement1Meanwhile, the compensation quantity delta of the robot positioning error is calculated by utilizing the joint angle Q acquired on line2And superposing the two compensation values to obtain a total compensation value delta of the machining error of the robot1+δ2And finally, feeding back the total compensation value to the robot, namely completing the online compensation of the machining error of the robot. Fig. 5 is a schematic diagram of an industrial robot compensating for part errors before and after the industrial robot, as shown in fig. 5.
In the above method, the deformation error compensation value delta of the robot1Is obtained from the coordinate system of the contact point of the knife on the curved surface of the workpiece, and the positioning error compensation value delta of the robot2Is calculated in the robot base coordinate system and the final total compensation is achieved by superimposing the compensation values into the machining program of the robot, which is generated on the basis of the object coordinate system, and therefore the deformation error compensation value delta needs to be calculated1And a positioning error compensation value delta2And converting the coordinate system of the workpiece into a coordinate system of the workpiece and then overlapping.
In summary, in the embodiment, the milling force of the robot in the milling process is measured on line through the force sensor, and meanwhile, the joint angle of the robot in the milling process is acquired on line through the robot communication interface; constructing a relation between a milling acting force and a deformation error compensation value of the robot, and constructing a relation between a joint angle and a positioning error compensation value of the robot; and calculating a compensation value of the deformation error of the robot by using the measured milling acting force of the robot, calculating a compensation value of the positioning error by using the acquired joint angle of the robot, and superposing and feeding back the two compensation values to the robot, thereby improving the milling precision of the robot. As shown in fig. 6, fig. 6 is a schematic diagram of the effect of the industrial robot before and after compensating the curved surface part.
The embodiment also provides an industrial robot mills online compensating system of machining error, includes:
the information acquisition module is used for acquiring the milling force F in the robot machining process and acquiring the joint angle Q in the robot machining process;
the relation building module is used for building a first relation between the milling force of the robot and the deformation error compensation value and building a second relation between the joint angle of the robot and the positioning error compensation value;
a compensation solving module for calculating the compensation quantity delta of the deformation error of the robot according to the milling force F and the first relation1Calculating the compensation quantity delta of the robot positioning error according to the joint angle Q and the second relation2；
A compensation feedback module for compensating the compensation quantity delta1And the compensation quantity delta2And (5) obtaining a total compensation value delta of the milling error of the robot through superposition, and feeding back the total compensation value delta to the robot.
The online milling error compensation system for the industrial robot can execute the online milling error compensation method for the industrial robot provided by the method embodiment of the invention, can execute any combination of the implementation steps of the method embodiment, and has corresponding functions and beneficial effects of the method.
This embodiment still provides an industrial robot mills online compensation arrangement of machining error, includes:
at least one processor;
at least one memory for storing at least one program;
when executed by the at least one processor, cause the at least one processor to implement the method shown in fig. 1.
The device for online compensation of milling errors of the industrial robot can execute the method for online compensation of milling errors of the industrial robot provided by the method embodiment of the invention, can execute any combination of implementation steps of the method embodiment, and has corresponding functions and beneficial effects of the method.
The embodiment of the application also discloses a computer program product or a computer program, which comprises computer instructions, and the computer instructions are stored in a computer readable storage medium. The computer instructions may be read by a processor of a computer device from a computer-readable storage medium, and executed by the processor to cause the computer device to perform the method illustrated in fig. 1.
The embodiment also provides a storage medium, which stores instructions or a program capable of executing the method for online compensating the milling error of the industrial robot provided by the embodiment of the method of the invention, and when the instructions or the program are run, the method can execute any combination of the embodiment of the method to implement steps, and has corresponding functions and beneficial effects of the method.
In alternative embodiments, the functions/acts noted in the block diagrams may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Furthermore, the embodiments presented and described in the flow charts of the present invention are provided by way of example in order to provide a more thorough understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed and in which sub-operations described as part of larger operations are performed independently.
Furthermore, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise stated to the contrary, one or more of the described functions and/or features may be integrated in a single physical device and/or software module, or one or more functions and/or features may be implemented in a separate physical device or software module. It will also be appreciated that a detailed discussion of the actual implementation of each module is not necessary for an understanding of the present invention. Rather, the actual implementation of the various functional modules in the apparatus disclosed herein will be understood within the ordinary skill of an engineer, given the nature, function, and internal relationship of the modules. Accordingly, those skilled in the art can, using ordinary skill, practice the invention as set forth in the claims without undue experimentation. It is also to be understood that the specific concepts disclosed are merely illustrative of and not intended to limit the scope of the invention, which is defined by the appended claims and their full scope of equivalents.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
In the foregoing description of the specification, reference to the description of "one embodiment/example," "another embodiment/example," or "certain embodiments/examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A milling error compensation method for an industrial robot is characterized by comprising the following steps:
acquiring milling force F in the robot machining process and acquiring a joint angle Q in the robot machining process;
constructing a first relation between the milling force of the robot and the deformation error compensation value, and constructing a second relation between the joint angle of the robot and the positioning error compensation value;
calculating the compensation quantity delta of the deformation error of the robot according to the milling force F and the first relation1Calculating the compensation quantity delta of the robot positioning error according to the joint angle Q and the second relation2；
Will compensate for the quantity delta1And the compensation quantity delta2And (5) obtaining a total compensation value delta of the milling error of the robot through superposition, and feeding back the total compensation value delta to the robot.
2. An industrial robot milling machining error compensation method according to claim 1, characterized in that the milling force is a three-dimensional force: f ═ F (fx, fy, fz)TThe joint angle is a six-degree-of-freedom joint angle: q ═ Q (Q)1,q2,q3，q4，q5，q6)T。
3. An industrial robot milling error compensation method according to claim 1, characterized in that the expression of the first relation is:
when n > 2:
when n is less than or equal to 2:
wherein ,
robot joint stiffness matrix J corresponding to the nth tool location point for the robotnThe first three rows of the velocity jacobian matrix corresponding to the nth knife location point for the robot,
and JnAre all related to the pose of the robot; fnThe milling force corresponding to the nth tool location is provided for the robot,
and the PID adjustment proportion coefficient, the integral coefficient and the differential coefficient corresponding to the nth cutter position point of the robot are respectively used.
4. The milling error compensation method for the industrial robot according to claim 3, wherein the proportional coefficient, the integral coefficient and the differential coefficient are adaptive parameters, and when n is larger than 2, the adaptive parameters are as follows:
wherein ,γnCompensating the PID coefficient matrix corresponding to the nth cutter position point for the robot through the PID coefficient matrix corresponding to the nth-1 cutter position point and the deformation errorValue correction is obtained, E is an identity matrix, XnFor the input matrix, X, of PID corresponding to the nth knife location pointnIs the corresponding deformation error matrix.
5. An industrial robot milling error compensation method according to claim 4, characterized in that PID coefficient matrix γnInput matrix XnAnd XnThe calculation method of (c) is as follows:
wherein ,γnIs a 3x1 coefficient matrix composed of proportional coefficient, integral coefficient and differential coefficient, gammanOnce the value of (A) is determined, a proportional coefficient, an integral coefficient and a differential coefficient are also determined; xnIs an input matrix of 3X3 related to the stiffness of the robot joint, the velocity Jacobian matrix and the milling force, XnIs an input matrix X corresponding to the first n cutter location points by the robotnForming an error matrix with 3n rows and 3 columns, ΔnA matrix of 3x 1.
6. An industrial robot milling error compensation method according to claim 1, characterized in that the second relation is expressed by:
δ2＝f′(Q+ΔQ)-f(Q)
wherein f' (Q) is a forward kinematics equation of the robot after being calibrated by kinematics parameters, f (Q) is a forward kinematics equation of the robot without being calibrated by parameters, delta Q is a joint angle error and a positioning error delta Q after being calibrated by the kinematics parameters2Is a 3x1 matrix representing the compensation values in the three directions xyz.
7. The method for compensating milling errors of an industrial robot according to claim 1, wherein the obtaining of the milling force F during the robot machining process comprises:
the method comprises the following steps of (1) measuring and acquiring a milling force F in the machining process of a robot on line by using a force sensor;
the joint angle Q in the robot machining process is obtained, and the method comprises the following steps:
and acquiring a joint angle Q in the machining process of the robot on line by adopting a robot communication interface.
8. An industrial robot milling error online compensation system, comprising:
the information acquisition module is used for acquiring the milling force F in the robot machining process and acquiring the joint angle Q in the robot machining process;
the relation building module is used for building a first relation between the milling force of the robot and the deformation error compensation value and building a second relation between the joint angle of the robot and the positioning error compensation value;
a compensation solving module for calculating the compensation quantity delta of the deformation error of the robot according to the milling force F and the first relation1Calculating the compensation quantity delta of the robot positioning error according to the joint angle Q and the second relation2；
A compensation feedback module for compensating the compensation quantity delta1And the compensation quantity delta2And (5) obtaining a total compensation value delta of the milling error of the robot through superposition, and feeding back the total compensation value delta to the robot.
9. The utility model provides an industrial robot mills online compensation arrangement of machining error which characterized in that includes:
at least one processor;
at least one memory for storing at least one program;
when executed by the at least one processor, cause the at least one processor to implement the method of any one of claims 1-7.
10. A storage medium having stored therein a program executable by a processor, wherein the program executable by the processor is adapted to perform the method of any one of claims 1-7 when executed by the processor.
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