CN114609964A - Polishing control method and device for cooperative robot and computer readable storage medium - Google Patents

Polishing control method and device for cooperative robot and computer readable storage medium Download PDF

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CN114609964A
CN114609964A CN202011461525.7A CN202011461525A CN114609964A CN 114609964 A CN114609964 A CN 114609964A CN 202011461525 A CN202011461525 A CN 202011461525A CN 114609964 A CN114609964 A CN 114609964A
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curve
grinding
controller
robot
free motion
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梁亮
刘世昌
邹风山
赵彬
白宏生
何书龙
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Shandong Siasun Industrial Software Research Institute Co Ltd
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Shandong Siasun Industrial Software Research Institute Co Ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
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    • G05B2219/34148—Coons interpolation, patch

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Abstract

The invention belongs to the technical field of robot control, and provides a polishing control method and a polishing control device of a cooperative robot and a computer readable storage medium, wherein the method comprises the following steps: s1, acquiring parameters of a plurality of discrete grinding points on a ground plane by a controller; s2, the controller fits the parameters of the discrete grinding points into a free motion curve of the surface of the grinding object through a NURBS curve; and S3, the controller plans the movement of the robot through the free movement curve and the S-shaped speed curve. Compared with the prior art, the invention has the beneficial effects that: the method can realize the control of the comprehensive covering, laminating and polishing of the complex curved surface, can also avoid the impact influence caused by sudden changes of acceleration and the like, and can ensure the polishing precision.

Description

Polishing control method and device for cooperative robot and computer readable storage medium
Technical Field
The invention belongs to the technical field of robot control, and particularly relates to a polishing control method of a cooperative robot, a polishing control device of the cooperative robot and a computer readable storage medium.
Background
At present, with the rapid development of the robot field, the tide of 'robot changing' is being raised. In order to further improve the product quality and the work efficiency, robots are being widely used in production lines. The robot is particularly suitable for work types with severe working environments and high working strength, such as a grinding process and the like. However, when the robot is used for polishing a workpiece, certain defects exist, and the defects are as follows: the robot has the problems of insufficient position control precision, insufficient rigidity and the like, so that a complex comprehensive polishing task is difficult to complete.
Therefore, it is urgently needed to design a polishing control method and a polishing control device for a cooperative robot, which have high precision and can achieve comprehensive polishing of a complex curved surface.
Disclosure of Invention
In view of the above, in order to solve the problem that the conventional cooperative robot is difficult to complete a complicated overall polishing task, the present invention provides a polishing control method for a cooperative robot, which includes the steps of:
s1, acquiring parameters of a plurality of discrete grinding points on a ground plane by a controller;
s2, the controller fits the parameters of the discrete grinding points to a free motion curve of the surface of the grinding object through a NURBS curve;
and S3, the controller plans the movement of the robot through the free movement curve and the S-shaped speed curve.
Preferably, the fitting method of the free motion curve in step S2 is:
step S20, taking the discrete grinding points as nodes, parameterizing the nodes to form a node matrix equation, and solving control points by using an inverse solution method;
step S21, calculating a basis function;
step S22, calculating a physicochemical equation of the free motion curve;
and step S23, carrying out curve densification on the free motion curve through interpolation.
Preferably, the node matrix equation in step S20 is:
Figure BDA0002822566910000021
wherein d is a control point, u is a selected discrete grinding point, and a, b, c, e are matrix parameters obtained by node parameterization.
Preferably, the method for calculating the basis function in step S21 is as follows:
Figure BDA0002822566910000022
wherein k is more than or equal to 1, and u is the selected discrete grinding point.
Preferably, the physicochemical equation of the free motion curve in step S22 is:
Figure BDA0002822566910000023
where d is the control point, ω is the weight, and N (u) is the basis function.
Preferably, the functional expression of the S-shaped speed curve in step S3 is:
Figure BDA0002822566910000031
wherein v ismaxRepresents the maximum speed, amaxRepresents the maximum acceleration, JmaxFor jerking, t1To t7Representing the time of each part of the sigmoid curve plan.
Preferably, before executing step S1, the following steps are executed:
step S10, the controller establishes a kinematic model;
the kinematicsTransformation matrix of model
Figure BDA0002822566910000033
Comprises the following steps:
Figure BDA0002822566910000032
wherein alpha isi-1Angle of rotation of the Z axis about the X axis, diIs the distance the X-axis moves along the Z-axis, θiIs the angle of rotation of the Z axis about the Z axis.
The present invention also provides a sanding control device of a cooperative robot, comprising: the controller comprises a parameter acquisition module, a free motion curve generation module and a motion planning module, wherein the free motion curve generation module is respectively connected with the motion planning module and the parameter acquisition module;
the parameter acquisition module is used for acquiring parameters of a plurality of discrete polishing points on a polished plane;
the free motion curve generation module is used for fitting the parameters of the discrete grinding points into a free motion curve of the surface of the grinding object through a NURBS curve;
the motion planning module is used for planning the motion of the robot through a free motion curve and an S-shaped speed curve.
Preferably, the apparatus further comprises a pose sensor connected to the controller.
The invention also provides a computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the above-mentioned method.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
the method can realize the control of the comprehensive covering, laminating and polishing of the complex curved surface, can also avoid the impact influence caused by sudden changes of acceleration and the like, and can ensure the polishing precision.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a flowchart of a grinding control method of a cooperative robot according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for fitting a free-running curve according to a second embodiment of the present invention;
fig. 3 is a schematic structural diagram of a sanding control device of a cooperative robot according to a second embodiment of the present invention;
FIG. 4 is a graph of S-shaped velocity curves for a second embodiment of the present invention;
fig. 5 is a graph of acceleration in a second embodiment of the present invention.
Reference numerals:
the system comprises a controller 1, a parameter acquisition module 2, a free motion curve generation module 3, a motion planning module 4 and a pose sensor 5.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by functions and internal logic of the process, and should not limit the implementation process of the embodiments of the present invention in any way.
Example one
Fig. 1 is a flowchart of a grinding control method of a cooperative robot according to an embodiment of the present invention. As shown in fig. 1, a grinding control method of a cooperative robot according to a first embodiment of the present invention includes the following steps:
step S1, the controller 1 obtains parameters of a plurality of discrete grinding points on the ground plane;
step S2, the controller 1 fits the parameters of the discrete grinding points into a free motion curve of the surface of the grinding object through the NURBS curve;
in step S3, the controller 1 plans the movement of the robot by the free movement curve and the S-shaped speed curve.
The polishing control method of the cooperative robot provided by the embodiment of the invention has the beneficial effects that:
the method is characterized in that a NURBS curve (non-uniform rational B-spline curve) is used for fitting a free motion curve of the surface of a polished object, and then the free motion curve is combined with the trajectory planning of an S-shaped curve to realize the motion trajectory control of the polishing motion of the robot. The method can realize the control of the comprehensive covering, laminating and polishing of the complex curved surface, can also avoid the impact influence caused by sudden changes of acceleration and the like, and can ensure the polishing precision.
An embodiment of the present invention further provides a polishing control device for a cooperative robot, including: the controller 1, the controller 1 includes a parameter obtaining module 2, a free motion curve generating module 3 and a motion planning module 4. The free motion curve generation module 3 is respectively connected with the motion planning module 4 and the parameter acquisition module 2.
The parameter acquisition module 2 is used for acquiring parameters of a plurality of discrete polishing points on a polished plane.
The free motion curve generation module 3 is used for fitting the parameters of the discrete grinding points to the free motion curve of the surface of the grinding object through the NURBS curve.
The motion planning module 4 is used to plan the motion of the robot by means of a free motion curve and an S-shaped velocity curve. For example, the movement velocity and acceleration of the robot tip are controlled by a free motion curve and an S-shaped velocity curve.
Example two
The difference between this embodiment and the first embodiment is:
before executing step S1:
step S10, the controller 1 builds a kinematic model.
Kinematics and workspace analysis are the basis for robot motion planning and control. Preferably, the controller 1 establishes a corresponding cartesian coordinate system for each joint of the robot according to a DH (Denavit-Hartenberg) modeling method in step S10.
Transformation matrix of the kinematic model
Figure BDA0002822566910000063
Comprises the following steps:
Figure BDA0002822566910000061
wherein alpha isi-1Angle of rotation of the Z axis about the X axis, diIs the distance the X-axis moves along the Z-axis, θiIs the angle of rotation of the Z axis about the Z axis.
Fig. 2 is a flowchart of a method for fitting a free motion curve according to a second embodiment of the present invention. As shown in fig. 2, the free motion curve in step S2 is fitted by:
step S20, taking the discrete grinding points as nodes, parameterizing the nodes to form a node matrix equation, and solving the control points by using an inverse solution method;
step S21, calculating a basis function N (u);
step S22, calculating a physicochemical equation of the free motion curve;
in step S23, the free motion curve is densified by interpolation.
The node matrix equation in step S20 is as follows:
Figure BDA0002822566910000062
d is a control point, u is a selected discrete grinding point, wherein a, b, c and e are matrix parameters obtained by node parameterization.
The method for calculating the basis function n (u) in step S21 is:
Figure BDA0002822566910000071
wherein k is more than or equal to 1.
The physicochemical equation representing the free motion curve by the NURBS curve in step S22 is:
Figure BDA0002822566910000072
where d is the control point, ω is the weight, and N (u) is the basis function.
The NURBS curve is a non-uniform rational B-spline, and the method provides mathematical representation for the accurate representation and design of elementary curve surfaces and free curve surfaces in a standard analytical form. A k-th order NURBS curve defined by n polygon control vertices can be represented as a rational vector function of 1 piece of the piecewise rational polynomial.
The requirement of a precision instrument on the continuity of the interpolation track of the industrial robot can be met by using S curve speed planning. The function expression of the S-shaped speed curve in step S3 is
Figure DEST_PATH_FDA0002822566900000022
Wherein v ismaxRepresents the maximum speed, amaxRepresents the maximum acceleration, JmaxFor jerk, t1To t7Representing the time of each part of the sigmoidal program. Fig. 4 is an S-shaped velocity profile. As shown in FIG. 4, S1To S7Representing the distance of movement of each segment. Fig. 5 is a sum acceleration graph.
The time of each stage of the S-shaped speed curve is t1To t7By velocityThe relationship with acceleration and jerk yields a functional expression of the S velocity curve.
It should be noted that, before the step S1, that is, the steps S2 and S3 are performed, the polishing control method of the cooperative robot according to the present invention further includes the steps of: and filtering the collected polishing curved surface motion data before polishing.
Fig. 3 is a schematic structural diagram of a sanding control apparatus of a cooperative robot according to a second embodiment of the present invention. As shown in fig. 3, the sanding control device of a cooperative robot according to the second embodiment of the present invention further includes a posture sensor 5, and the posture sensor 5 is connected to the controller 1. The pose sensor 5 is used for acquiring attitude and position data in real time.
It can be understood that the pose sensor 5 is responsible for acquiring the pose in real time; the position data and the grinding curved surface motion data collected before grinding are filtered and then are planned through NURBS and S-shaped speed to obtain a grinding track motion curved surface, so that the grinding path continuity of the cooperative robot is realized, and particularly when the cooperative robot is used for grinding curved surfaces with uneven shapes, small areas and large quantities, the cooperative robot can be ensured to have high grinding precision on each grinding curved surface.
The system adopts a TCP communication mode, acquires the information of the pose sensor, the position and the posture of the polishing device at the tail end of the cooperative robot and the data of the polished curved surface through the TCP communication mode.
It can be understood that the overall control flow when the grinding control device of the cooperative robot is applied to grinding of the cooperative robot is as follows: teaching a plurality of discrete grinding points on a grinding plane through a mechanical arm of the cooperative robot, and calculating the numerical values of the motion angle and the tail end posture of each axis of the robot through a kinematic model of the cooperative robot. Secondly, selecting the discrete grinding points as nodes u, fitting a free curve by using NURBS, parameterizing the nodes u to form a node matrix equation, solving control points by using a reverse solution as shown in the formula, solving a physicochemical equation of the curve according to the formula, and finally carrying out curve densification to carry out interpolation and point calculation. After the motion distance of the curve is determined, the motion speed and the acceleration of the tail end of the robot are controlled by using an S-shaped speed curve, so that the position, the speed and the acceleration of each interpolation point can be continuous, and the position, the speed and the acceleration are reversely deduced to a joint space, so that the angle, the angular speed and the angular acceleration of each joint can be obtained. The sensor is responsible for collecting data of postures and positions in real time, the grinding curved surface motion data collected before grinding are subjected to filtering processing, and then the grinding curved surface motion data are used for obtaining a grinding track motion curved surface through planning of a NURBS fitting free curve and an S-shaped speed curve, so that the continuity of the grinding path of the cooperative robot is realized, and the cooperative robot can finely grind curved surfaces with uneven shapes, small grinding areas and large quantity.
The polishing control method of the cooperative robot has the following beneficial effects:
1. planning the motion trail of the S-shaped speed curve by fitting a NURBS curve to a free motion curve;
2. collecting polishing position information through a sensor, and carrying out data collection and real-time monitoring on a polished curved surface;
3. by the control method, the precision of the grinding process of the cooperative robot is improved.
EXAMPLE III
The difference between the present embodiment and the first embodiment is:
the present embodiment provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the above-described method of controlling grinding by a cooperative robot.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein.

Claims (10)

1. A grinding control method of a cooperative robot is characterized by comprising the following steps:
s1, acquiring parameters of a plurality of discrete grinding points on a ground plane by a controller;
s2, the controller fits the parameters of the discrete grinding points to a free motion curve of the surface of the grinding object through a NURBS curve;
and S3, the controller plans the motion of the robot through the free motion curve and the S-shaped speed curve.
2. A dressing control method according to claim 1, wherein said free movement curve in step S2 is fitted by:
step S20, taking the discrete grinding points as nodes, parameterizing the nodes to form a node matrix equation, and solving control points by using an inverse solution method;
step S21, calculating a basis function;
step S22, calculating a physicochemical equation of the free motion curve;
and step S23, performing curve densification on the free motion curve by interpolation.
3. A dressing control method according to claim 2, wherein the node matrix equation in step S20 is:
Figure FDA0002822566900000011
wherein d is a control point, u is a selected discrete grinding point, and a, b, c, e are matrix parameters obtained by node parameterization.
4. A dressing control method according to claim 2, wherein said calculation method of the basis function in step S21 is:
Figure FDA0002822566900000012
wherein k is more than or equal to 1, and u is the selected discrete grinding point.
5. A dressing control method of a cooperative robot according to claim 2, wherein the physicochemical equation of the free motion curve in the step S22 is:
Figure FDA0002822566900000021
where d is the control point, ω is the weight, and N (u) is the basis function.
6. A dressing control method according to claim 1, wherein said S-shaped velocity profile in step S3 is functionally expressed as:
Figure FDA0002822566900000022
wherein v ismaxRepresents the maximum speed, amaxRepresents the maximum acceleration, JmaxFor jerking, t1To t7Representing the time of each part of the sigmoid curve plan.
7. A dressing control method of a cooperative robot according to claim 1, wherein before performing step S1:
step S10, the controller establishes a kinematic model;
transformation matrix of the kinematic model
Figure FDA0002822566900000023
Comprises the following steps:
Figure FDA0002822566900000024
wherein alpha isi-1Angle of rotation of the Z axis about the X axis, diIs the distance the X-axis moves along the Z-axis, θiIs the angle of rotation of the Z axis about the Z axis.
8. Sanding control device of cooperative robot, its characterized in that, it includes: the controller comprises a parameter acquisition module, a free motion curve generation module and a motion planning module, wherein the free motion curve generation module is respectively connected with the motion planning module and the parameter acquisition module;
the parameter acquisition module is used for acquiring parameters of a plurality of discrete polishing points on a polished plane;
the free motion curve generation module is used for fitting the parameters of the discrete grinding points into a free motion curve of the surface of the grinding object through a NURBS curve;
the motion planning module is used for planning the motion of the robot through a free motion curve and an S-shaped speed curve.
9. A sanding control device as claimed in claim 8, further comprising a pose sensor coupled to the controller.
10. Computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.
CN202011461525.7A 2020-12-08 2020-12-08 Polishing control method and device for cooperative robot and computer readable storage medium Pending CN114609964A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101493687A (en) * 2009-03-02 2009-07-29 广西大学 Real time forward looking whole-process acceleration and deceleration controlled NURBS curve self-adapting subsection interpolation method
CN107283422A (en) * 2016-04-11 2017-10-24 南京埃斯顿自动化股份有限公司 Robot based on off-line programing accommodates the method for planning track of grinding workpieces
CN107436592A (en) * 2017-07-28 2017-12-05 珞石（山东）智能科技有限公司 Accurate polishing orbit generation method based on B-spline
CN111975545A (en) * 2020-08-11 2020-11-24 武汉万邦德新科技有限公司 Complex curved surface workpiece polishing track generation method based on inverse control point algorithm

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101493687A (en) * 2009-03-02 2009-07-29 广西大学 Real time forward looking whole-process acceleration and deceleration controlled NURBS curve self-adapting subsection interpolation method
CN107283422A (en) * 2016-04-11 2017-10-24 南京埃斯顿自动化股份有限公司 Robot based on off-line programing accommodates the method for planning track of grinding workpieces
CN107436592A (en) * 2017-07-28 2017-12-05 珞石（山东）智能科技有限公司 Accurate polishing orbit generation method based on B-spline
CN111975545A (en) * 2020-08-11 2020-11-24 武汉万邦德新科技有限公司 Complex curved surface workpiece polishing track generation method based on inverse control point algorithm

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