Method and system for analyzing factors affecting robot trajectory accuracy

Abstract

The robot trajectory precision influencing factor analysis method and system, the robot motion control module planning, the robot joint servo module control and the robot body structure module follow three influencing links of the robot trajectory precision are proposed; the corresponding test straight line trajectory is obtained in each link, and then the corresponding test straight line trajectory obtained in each link is compared with the standard reference straight line trajectory L1, and the degree of influence of each link on the robot trajectory precision is determined. The robot trajectory precision influencing factor rapid analysis method based on the above influencing link is proposed, the factor link influencing the motion trajectory precision can be quickly positioned, the subsequent trajectory error compensation is provided with reference, and therefore the dynamic performance of the robot is further improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of robot detection and control, and particularly relates to a robot trajectory precision influencing factor analysis method and system. BACKGROUND

[0002] With the wide application of robots in high-precision machining and manufacturing, higher requirements are put forward for the motion trajectory precision of the robots. Generally, the main factors influencing the motion trajectory precision of the robots include robot body manufacturing and assembly tolerances, robot component elastic deformation and joint clearance, robot joint servo modules, and other changes such as environment and temperature. After the motion trajectory precision of a robot end effector is measured, it is generally known whether the trajectory precision of the whole robot meets the performance requirements, but it is difficult to determine whether the overall influence of the trajectory precision is caused by the above-mentioned multiple factors or a single factor, and the influence degree of each factor.

[0003] For example, in one prior art, a flexible robot model and a rigid robot model are used to control a target robot to run along a predetermined target trajectory, two running lines are obtained, and finally the deviation section between the two lines is calculated to determine the trajectory precision of the target robot, but this method only analyzes the influence of a single factor of flexible joint variation on the trajectory precision.

[0004] For another example, in another prior art, the kinematic model parameter error of an industrial robot is compensated from the perspective of kinematic analysis, the motion trajectory deviation is corrected, and the motion trajectory precision of the industrial robot is improved, but this system mainly compensates for the error for the problem of low motion trajectory precision of the industrial robot, and does not analyze the factors influencing the trajectory precision. SUMMARY

[0005] The application aims to provide a robot trajectory precision influencing factor analysis method and system, and solves the problem of difficulty in determining the robot trajectory precision influencing factors. The application is realized by the technical scheme described below.

[0006] A robot trajectory precision influencing factor analysis method, characterized in that it comprises:

[0007] Step 1: According to the control process of robot trajectory reproduction, factors influencing the robot trajectory precision are summarized into at least two links;

[0008] Step 2: A test starting point and an ending point are set, and a standard reference straight line trajectory L1 is determined according to the starting point and the ending point;

[0009] Step 3: Based on the starting point and the ending point, a corresponding test straight line trajectory is obtained at each link;

[0010] Step 4: respectively acquire the corresponding test straight line trajectory respectively compared with the standard reference straight line trajectory L1, determine the degree of influence of each link on the robot trajectory accuracy.

[0011] Specifically, the control flow of the robot trajectory reproduction includes: a, determining the start point and end point of the straight line trajectory; b, the motion control module completes the straight line trajectory planning based on the start point, end point and path motion parameter information of the straight line trajectory, and issues the planned joint angle position to the joint servo module; c, the joint servo module controls the servo motor based on the planned joint angle position; d, the robot body structure module realizes the straight line trajectory motion of the end effector based on the joint servo module control composite motion.

[0012] Specifically, in step 1, the at least two links include three links in the order of: motion planning link, joint servo control link and robot body structure execution link; in step 3, the planning test straight line trajectory L1-1 is acquired in the motion planning link, the control test straight line trajectory L1-2 is acquired in the joint servo control link, and the composite test straight line trajectory L1-3 is acquired in the robot body structure execution link; in step 4, the planning test straight line trajectory L1-1, the control test straight line trajectory L1-2 and the composite test straight line trajectory L1-3 are compared with the standard reference straight line trajectory L1 respectively, the degree of influence of each link on the robot trajectory accuracy is determined, and the degree of influence of the motion planning link, the joint servo control link and the robot body structure execution link on the robot trajectory accuracy is determined.

[0013] Specifically, in step 2, the start point and end point are provided by the laser tracker and the test system according to GB_T 12642-2013 "Industrial robot performance specification and test method", and the standard reference straight line trajectory L1 is determined.

[0014] Specifically, the method for acquiring the planning test straight line trajectory L1-1 in the motion planning link is: the motion control module completes the straight line trajectory planning based on the test start point and end point and path motion parameter information, maps the straight line trajectory planning to the joint space based on the inverse kinematics model of the robot, and issues the planned joint angle position to the joint servo module. At the same time, the planned joint angle position is mapped to the Cartesian space through the forward kinematics model of the robot to form the planning test straight line trajectory L1-1.

[0015] Specifically, the method for obtaining the control test straight line trajectory L1-2 in the joint servo control link is: the joint servo module controls the servo motor based on the planned joint angle position issued by the motion control module, and returns the control joint angle position to the motion control module, and meanwhile, the control joint angle position is mapped to the Cartesian space through the robot kinematics forward solution model to form the control test straight line trajectory L1-2.

[0016] Specifically, the method for obtaining the compound test straight line trajectory L1-3 in the robot body structure execution link is: the robot body structure module controls the compound motion based on the joint servo module to realize the straight line trajectory motion of the end effector, and meanwhile, the compound test straight line trajectory L1-3 is obtained through laser tracker sampling.

[0017] An industrial robot trajectory precision influencing factor analysis system, characterized by comprising:

[0018] An influencing factor configuration module, which induces factors influencing the precision of the robot trajectory into at least two links according to a control process of the reproduction of the robot trajectory.

[0019] A standard setting module, which sets a test starting point and a test ending point, and determines a standard reference straight line trajectory L1 according to the starting point and the ending point.

[0020] A test module, which obtains a corresponding test straight line trajectory in each of the links based on the starting point and the ending point.

[0021] A comparison and analysis module, which compares each of the corresponding test straight line trajectories obtained in each of the links with the standard reference straight line trajectory L1 to determine the degree of influence of each of the links on the precision of the robot trajectory.

[0022] Specifically, the control process of the reproduction of the robot trajectory comprises: a, determining a starting point and an ending point of a straight line trajectory; b, the motion control module completes straight line trajectory planning and issues planned joint angle positions to the joint servo module based on the starting point, the ending point and path motion parameter information of the straight line trajectory; c, the joint servo module controls the servo motor based on the planned joint angle positions; d, the robot body structure module controls the compound motion based on the joint servo module to realize the straight line trajectory motion of the end effector.

[0023] Specifically, the at least two links include three links in sequence: a motion planning link, a joint servo control link and a robot body structure execution link; the test module includes: a first test unit that acquires a planning test straight line track L1-1 in the motion planning link; a second test unit that acquires a control test straight line track L1-2 in the joint servo control link; a third test unit that acquires a composite test straight line track L1-3 in the robot body structure execution link; and the analysis comparison unit compares the planning test straight line track L1-1, the control test straight line track L1-2 and the composite test straight line track L1-3 respectively with the standard reference straight line track L1 to determine the degree of influence of each link on the robot trajectory precision, and determine the degree of influence of the motion planning link, the joint servo control link and the robot body structure execution link on the robot trajectory precision.

[0024] The beneficial effects of the present application include: proposing three influence links of robot trajectory precision of a robot motion control module planning, a robot joint servo module control and a robot body structure module following; acquiring corresponding test straight line tracks in each link, and then comparing the test straight line tracks acquired in each link with the standard reference straight line track L1 to determine the degree of influence of each link on the robot trajectory precision. The present application proposes a robot trajectory precision influence factor rapid analysis method based on the above influence links, which can quickly locate the factor link that influences the motion trajectory precision, provide a reference for subsequent trajectory error compensation, and further improve the dynamic performance of the robot. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The robot trajectory precision influence factor analysis method provided for the embodiments of the present application divides the influence factors into multiple links and provides a comparison and analysis diagram of each link.

[0026] Figure 2 The error diagram of comparing the planning test straight line track L1-1 with the standard reference straight line track L1 in the robot trajectory precision influence factor analysis method provided for the embodiments of the present application.

[0027] Figure 3 The error diagram of comparing the control test straight line track L1-2 with the standard reference straight line track L1 in the robot trajectory precision influence factor analysis method provided for the embodiments of the present application.

[0028] Figure 4 The error diagram of comparing the composite test straight line track L1-3 with the standard reference straight line track L1 in the robot trajectory precision influence factor analysis method provided for the embodiments of the present application. DETAILED DESCRIPTION

[0029] In combination withFigure 1 As shown, the robot trajectory precision influencing factor analysis method provided in the embodiment firstly induces and divides the factors influencing the robot trajectory precision. Generally, the general control flow of the robot to realize trajectory reproduction is as follows.

[0030] 1. The user uses the teaching box to teach the start point and the end point of the straight line trajectory;

[0031] 2. The straight line trajectory is planned based on the start point and the end point of the straight line trajectory, path motion parameters and other information;

[0032] 3. The joint servo module controls the servo motor based on the planned joint angle position issued by the motion control module;

[0033] 4. The robot body structure module controls the composite motion based on the joint servo module to realize the straight line trajectory motion of the end effector.

[0034] Therefore, without considering the environment and temperature changes, based on the influencing factors such as robot body manufacturing and assembly tolerances, robot component elastic deformation and joint clearance, and robot joint servo module, combined with the general robot system, the robot trajectory precision influencing factors can be divided into three links in sequence: motion planning link, joint servo control link and robot body structure execution link.

[0035] Based on the above analysis, the robot trajectory precision influencing factor analysis method of the embodiment is designed as shown in Table 1.

[0036]

[0037] Table 1

[0038] The embodiment aims to set the test start point and the test end point, and determine a straight line trajectory according to the start point and the end point. Then, based on the start point and the end point, the corresponding test straight line trajectory (planning test straight line trajectory L1-1, control test straight line trajectory L1-2, and composite test straight line trajectory L1-3) is obtained at each link. Finally, the corresponding test straight line trajectory (planning test straight line trajectory L1-1, control test straight line trajectory L1-2, and composite test straight line trajectory L1-3) obtained at each link is compared with the standard reference straight line trajectory L1, and the degree of influence of each link on the robot trajectory precision is determined.

[0039] The acquisition of the standard reference straight line trajectory L1, the planning test straight line trajectory L1-1, the control test straight line trajectory L1-2, and the composite test straight line trajectory L1-3 is described as follows.

[0040] (1) Standard reference straight line trajectory L1: The start point and the end point of the straight line trajectory are provided by the laser tracker according to GB_T 12642-2013 Industrial Robot Performance Specification and Test Method, and the standard reference straight line trajectory L1 can be determined.

[0041] (2) Planned test straight line trajectory L1-1: The motion control module completes straight line trajectory planning based on the start point and the end point of the straight line trajectory, path motion parameters and other information, maps the straight line to the joint space based on the inverse kinematics model of the robot, and issues the planned joint angle position to the joint servo module, and simultaneously remaps the position to the Cartesian space through the forward kinematics model of the robot to form the planned test straight line trajectory L1-1.

[0042] (3) Controlled test straight line trajectory L1-2: The joint servo module controls the servo motor based on the planned joint angle position issued by the motion control module, and returns the controlled joint angle position to the motion control module, and simultaneously remaps the position to the Cartesian space through the forward kinematics model of the robot to form the controlled test straight line trajectory L1-2.

[0043] (4) Compound test straight line trajectory L1-3: The robot body structure controls the compound motion based on the joint servo module to realize the straight line trajectory motion of the end effector, and the compound test straight line trajectory L1-3 can be obtained by sampling through the measurement system such as the laser tracker.

[0044] Finally, the planned test straight line trajectory L1-1, the controlled test straight line trajectory L1-2, the compound test straight line trajectory L1-3 and the standard reference straight line trajectory L1 are compared and analyzed as shown in Figure 1 , that is, the influence of each system module on the trajectory accuracy can be quickly analyzed and determined.

[0045] The following takes the analysis of the performance test trajectory accuracy influence factors of a six-axis industrial robot as an example to further illustrate the present application.

[0046] In this embodiment, the trajectory accuracy measurement device is a Leica AT960-MR type laser tracker, and the measurement accuracy of the device within a measurement range of 60m is ±(15um+6um / m). During the measurement of the pose of the robot end, the measurement distance between the laser tracker and the target ball is within 5m. The network listener is a BECKHOFF industrial Ethernet listener ET2000, which adds a high-precision timestamp of 1ns to the data frame based on hardware to ensure accurate analysis of network timing, and the time delay is less than 1us. The network monitoring software is Wireshark.

[0047] I. Determine the start and end points of the trajectory accuracy test procedure, RoboDyn (Leica laser tracker supporting test software) provides the start and end points of the performance test trajectory accuracy test procedure, as shown in Table 2.

[0048]

[0049]

[0050] Table 2

[0051] II. The error between the planning test straight line trajectory L1-1 and the RoboDyn standard reference straight line trajectory L1 of the motion control module link: the motion control module plans the straight line trajectory based on the start and end point data in Table 2, and sends the planned joint angle position to the joint servo module through the industrial Ethernet EtherCAT.

[0052] Wherein, ET2000 and Wireshark are used to capture the joint angle position, and the kinematics forward solution model of the motion control module is used to remap the position to the Cartesian space to form the planning test straight line trajectory L1-1, and compared with the RoboDyn standard reference straight line trajectory L1, as shown in Figure 2 The comparison trajectory error is 0.00037885mm.

[0053] III. The error between the control test straight line trajectory L1-2 and the RoboDyn standard reference straight line trajectory L1 of the joint servo module link: the joint servo module feedback control joint angle position is captured by ET2000 and Wireshark, and the kinematics forward solution model of the motion control module is used to remap the position to the Cartesian space to form the control test straight line trajectory L1-2, and compared with the RoboDyn standard reference straight line trajectory L1, as shown in Figure 3 The comparison trajectory error is 0.14217mm.

[0054] IV. The error between the composite test straight line trajectory L1-3 and the RoboDyn standard reference straight line trajectory L1 of the body structure module link: the Leica laser tracker is used as a measuring device to obtain the actual composite test straight line trajectory L1-3 of the robot end effector position coordinate point, and compared with the RoboDyn standard reference straight line trajectory L1, as shown in Figure Four The comparison trajectory error is 0.8147mm.

[0055] From the above, from the motion control module to the joint servo module, the trajectory error is amplified by nearly 1x10 3times; due to the joint servo module to the body structure module, the trajectory error amplification is nearly 10 times. Therefore, the main factors affecting the trajectory accuracy of the six-axis industrial robot can be quickly determined as the joint servo module and the body structure module. The above specific embodiments take the six-axis industrial robot as the experimental object, but are not limited to the six-axis industrial robot, and can be applied to SCARA, Delta and other industrial robots.

[0056] The embodiment also correspondingly provides an industrial robot trajectory accuracy influencing factor analysis system, comprising:

[0057] An influencing factor configuration module induces factors affecting the robot trajectory accuracy into three links in the order of a motion planning link, a joint servo control link and a robot body structure execution link according to a control flow of robot trajectory reproduction;

[0058] A standard setting module sets a test starting point and an ending point, and determines a standard reference straight line trajectory L1 according to the starting point and the ending point;

[0059] A test module acquires corresponding test straight line trajectories at each of the links based on the starting point and the ending point;

[0060] A comparison and analysis module compares each of the corresponding test straight line trajectories acquired at each of the links with the standard reference straight line trajectory L1 to determine the degree of influence of each of the links on the robot trajectory accuracy.

[0061] The test module includes a first test unit acquiring a planning test straight line trajectory L1-1 at the motion planning link, a second test unit acquiring a control test straight line trajectory L1-2 at the joint servo control link, and a third test unit acquiring a composite test straight line trajectory L1-3 at the robot body structure execution link. An analysis comparison unit compares the planning test straight line trajectory L1-1, the control test straight line trajectory L1-2 and the composite test straight line trajectory L1-3 with the standard reference straight line trajectory L1 to determine the degree of influence of each of the links on the robot trajectory accuracy and determine the degree of influence of the motion planning link, the joint servo control link and the robot body structure execution link on the robot trajectory accuracy.

[0062] The above embodiments are only for full disclosure and not to limit the present application, and any equivalent technical features obtained based on the creative spirit of the present application without creative labor should be considered as the disclosed range of the present application.

Claims

1. A method for analyzing factors affecting robot trajectory accuracy, characterized by, Comprise: Step 1: according to the control flow of robot trajectory reproduction, the factors affecting the robot trajectory accuracy are sequentially summarized as motion planning link, joint servo control link and robot body structure execution link; Step 2: set the test starting point and end point, and determine a standard reference straight line trajectory L1 according to the starting point and end point; Step 3: based on the starting point and end point, the following operations are performed: In the motion planning link, the planning test straight line trajectory L1-1 is obtained, and the specific method is: the motion control module completes the straight line trajectory planning based on the test starting point and end point and path motion parameter information, maps the straight line trajectory planning to the joint space based on the inverse kinematics model of the robot, and issues the planning joint angle position to the joint servo module, and at the same time, the planning joint angle position is mapped to the Cartesian space through the forward kinematics model of the robot to form the planning test straight line trajectory L1-1; In the joint servo control link, the control test straight line trajectory L1-2 is obtained, and the specific method is: the joint servo module controls the servo motor based on the planning joint angle position issued by the motion control module, and returns the control joint angle position to the motion control module, and at the same time, the control joint angle position is mapped to the Cartesian space through the forward kinematics model of the robot to form the control test straight line trajectory L1-2; In the robot body structure execution link, the composite test straight line trajectory L1-3 is obtained, and the specific method is: the robot body structure module controls the composite motion based on the joint servo module, realizes the straight line trajectory motion of the end effector, and at the same time, the composite test straight line trajectory L1-3 is obtained by sampling through the laser tracker; Step 4: compare the planning test straight line trajectory L1-1, the control test straight line trajectory L1-2 and the composite test straight line trajectory L1-3 with the standard reference straight line trajectory L1 respectively, and determine the degree of influence of each link on the robot trajectory accuracy.

2. The robot trajectory accuracy influence factor analysis method according to claim 1, characterized in that, The control flow of robot trajectory reproduction comprises: a, determining the starting point and end point of the straight line trajectory; b, the motion control module completes the straight line trajectory planning based on the starting point, end point and path motion parameter information of the straight line trajectory, and issues the planning joint angle position to the joint servo module; c, the joint servo module controls the servo motor based on the planning joint angle position; d, the robot body structure module controls the composite motion based on the joint servo module, and realizes the straight line trajectory motion of the end effector.

3. The robot trajectory accuracy influence factor analysis method according to claim 1, characterized in that, In step 2, the starting point and end point are provided by the laser tracker and the test system according to GB_T 12642-2013 "Industrial robot performance specification and test method", and the standard reference straight line trajectory L1 is determined.

4. An industrial robot trajectory accuracy influencing factor analysis system, characterized by, Comprise: Influence factor configuration module, according to the control flow of robot trajectory reproduction, the factors affecting the robot trajectory accuracy are sequentially summarized as motion planning link, joint servo control link and robot body structure execution link; Standard setting module, set the test starting point and end point, and determine a standard reference straight line trajectory L1 according to the starting point and end point; Test module, based on the starting point and end point, respectively obtains the corresponding test straight line trajectory in each link; specifically including: The first test unit obtains a planned test straight line track L1-1 at the motion planning link, specifically: a motion control module completes straight line track planning based on test start point and end point and path motion parameter information, maps the straight line track planning to joint space based on a robot kinematics inverse solution model, and issues a planned joint angle position to a joint servo module, while the planned joint angle position is mapped to Cartesian space by a robot kinematics direct solution model to form the planned test straight line track L1-1; The second test unit obtains a control test straight line track L1-2 at the joint servo control link, specifically: a joint servo module controls a servo motor based on the planned joint angle position issued by the motion control module, and returns a control joint angle position to the motion control module, while the control joint angle position is mapped to Cartesian space by a robot kinematics direct solution model to form the control test straight line track L1-2; The third test unit obtains a composite test straight line track L1-3 at the robot body structure execution link, specifically: a robot body structure module controls composite motion based on the joint servo module to realize straight line track motion of an end effector, while the composite test straight line track L1-3 is obtained by sampling with a laser tracker; The comparison and analysis module compares the planned test straight line track L1-1, the control test straight line track L1-2, and the composite test straight line track L1-3 with the standard reference straight line track L1 respectively to determine the degree of influence of each link on robot track precision, determine the degree of influence of the motion planning link, the joint servo control link, and the robot body structure execution link on robot track precision, and determine the degree of influence of each link on robot track precision.

5. The robot trajectory accuracy influence factor analysis system of claim 4, wherein, The control process of the robot track reproduction includes: a, determining the start point and end point of the straight line track; b, the motion control module completes straight line track planning based on the start point, end point and path motion parameter information of the straight line track and issues a planned joint angle position to the joint servo module; c, the joint servo module controls the servo motor based on the planned joint angle position; d, the robot body structure module controls composite motion based on the joint servo module to realize straight line track motion of the end effector.

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