Precision decomposition method for multi-joint series robot

Abstract

The invention discloses a precision decomposition method for a multi-joint series robot, the multi-joint series robot is a robot composed of a base, nine movable joint assemblies connected in series and an end effector, and the method comprises the following steps: determining the relative position relationship among the nine movable joint assemblies connected in series; a D-H coordinate system of the multi-joint series robot is established, and structural parameters of the multi-joint series robot are obtained; according to the structure parameters, a D-H parameter table of the multi-joint series robot is determined; establishing a kinematic model of the multi-joint series robot, and determining a transformation matrix; the influence proportional relation of each movable joint assembly on the position of the end effector is determined; according to the influence proportion of the position of the end effector, the index precision is decomposed to each movable joint assembly, and the decomposition precision is determined; according to the precision decomposition method for the multi-joint series robot, the requirement for the precision of each stage of joint of the multi-joint series robot can be put forward through the method, and therefore the error of an end effector is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of robots, and in particular to a precision decomposition method for a multi-joint serial robot. Background Art

[0002] The serial robot is composed of multiple highly rigid rods connected by joints. By driving the movement of each joint, the connecting rods are driven to move relative to each other, so that the end effector reaches the predetermined position.

[0003] Different from parallel robots, the terminal error of serial robots is the superposition of the influence values ​​of errors at each level. Therefore, its terminal error value is often larger than the errors of each level. By analyzing the errors at each level separately, the total error value of the terminal can be obtained, so that the mechanism meets the motion index requirements. Summary of the invention

[0004] Purpose of the invention: To provide a precision decomposition method for a multi-joint serial robot, based on the DH coordinate system method and taking the extreme position as the constraint condition, to decompose the index and ensure that the position requirements of the end effector are met.

[0005] Technical solution:

[0006] A precision decomposition method for a multi-joint serial robot, wherein the multi-joint serial robot is a robot composed of a base, nine movable joint assemblies connected in series, and an end effector, wherein the nine movable joint assemblies include six rotating joint assemblies and three moving joint assemblies, and each of the movable joint assemblies includes a power part, a joint rod, and a joint shaft. The method comprises the following steps:

[0007] Step 1: Determine the relative position relationship between the six rotating joint assemblies and the three moving joint assemblies, establish the DH coordinate system of the multi-joint serial robot, and obtain the structural parameters of the multi-joint serial robot, wherein the structural parameters include the motion range of each active joint assembly and the relative position relationship between two adjacent active joint assemblies in the initial position;

[0008] Step 2: According to the structural parameters, determine the DH parameter table of the multi-joint serial robot, the DH parameter table includes the length L of the joint rod i , the torsion angle α of the joint rod i , the offset d of the joint rod i and the rotation angle θ of the joint member i ;

[0009] Step 3: Establish a kinematic model of the multi-joint serial robot according to the DH parameter table, and use a general formula to determine the transformation matrix of each active joint component, end effector and base;

[0010] Step 4: Based on the transformation matrix obtained by each active joint component, under the premise that the positions of other active joint components are fixed, a motion test is performed on each active joint component to determine the proportional relationship of the influence of each active joint component on the position of the end effector;

[0011] Step 5: Based on the preset accuracy indicators of the multi-joint serial robot in the x-axis, y-axis and z-axis, and the corresponding influence proportion relationship of each active joint component obtained above, determine the decomposition accuracy value of each active joint component in the x-axis, y-axis and z-axis respectively.

[0012] In a further embodiment, the nine movable joint assemblies are respectively a first joint rotation assembly, a second joint swing assembly, a third joint translation assembly, a fourth joint rotation assembly, a fifth joint rotation assembly, a sixth joint telescopic assembly, a seventh joint rotation assembly, an eighth joint rotation assembly and a ninth joint translation assembly connected in sequence, the first joint rotation assembly is mounted on the base, and the end effector is mounted on the ninth joint translation assembly;

[0013] The first joint rotation assembly, the second joint swing assembly, the fourth joint rotation assembly, the fifth joint rotation assembly, the seventh joint rotation assembly and the eighth joint rotation assembly are all the rotation joint assemblies, and the third joint translation assembly, the sixth joint telescopic assembly and the ninth joint translation assembly are all the moving joint assemblies.

[0014] In a further embodiment, the power parts of the nine movable joint assemblies are respectively the first joint rotation hydraulic motor, the second joint swing hydraulic cylinder, the third joint translation hydraulic cylinder, the fourth joint rotation hydraulic motor, the fifth joint rotation hydraulic motor, the sixth joint telescopic hydraulic cylinder, the seventh joint rotation hydraulic motor, the eighth joint rotation hydraulic motor and the ninth joint translation hydraulic cylinder.

[0015] In a further embodiment, in step 1, a Cartesian coordinate system (x i ,y i ,z i ), (i=1,2,…,n), n is the number of degrees of freedom;

[0016] The coordinate system of the base is defined as the coordinate system 0 (x 0 ,y 0 ,z 0 ), the z 0 The axis of rotation coincides with the axis of rotation of the first joint rotary hydraulic motor;

[0017] The end effector coordinate system is the Nth coordinate system (x n ,y n ,z n ), the x n With the z n vertical.

[0018] In a further embodiment, in the revolute joint assembly, L i ,α i ,d i is a fixed value, θ i is a variable, in the mobile joint component, L i ,α i ,θ i is a fixed value, d i is a variable;

[0019] The power member drives the joint rod to move along the joint axis. Each joint axis A i At most, it is connected to two joint rods, which are A i-1 and A i+1 , the joint axis A of the i-th active joint component i Located at the connection between the two joint rods, the i-1 movable joint assembly and the i+1 movable joint assembly also have a joint axis A i-1 and A i+1 ;

[0020] The principle of establishing the DH coordinate system of the multi-joint serial robot in step 1 also includes the following steps:

[0021] Step 1-1: The origin Oi is set at the intersection of the Li and Ai+1 axes;

[0022] Step 1-2: The Zi axis coincides with the Ai+1 joint axis and points to any direction;

[0023] Step 1-3: The Xi axis coincides with the common normal line Li, and points along Li from the Ai axis to the Ai+1 axis;

[0024] Step 1-4: Use the right-hand rule for the first axis.

[0025] In a further embodiment, the specific steps of determining the DH parameters of the multi-joint serial robot in step 2 are as follows:

[0026] Step 2-1: Joint rod length L i Along x i Axis, z i-1 Axis and x i Axis intersection to 0 i distance;

[0027] Step 2-2: Joint rod torsion angle α i Around x i Axis, by z i-1 Turn to z i ;

[0028] Step 2-3: Joint member offset d i Along z i-1 Axis, z i-1 Axis and x i Intersection to ∑0 i–1 The distance from the origin of the coordinate system;

[0029] Step 2-4: Joint rod rotation angle θ i Around z i-1 Axis, by x i-1 Turn to x i .

[0030] In a further embodiment, the specific steps of determining the transformation matrix in step 3 are as follows:

[0031] The DH coordinate transformation matrix between the coordinate systems of two adjacent active joint components is as follows:

[0032]

[0033] Determine the transformation matrix of the coordinate system of each two adjacent active joint components 0 T 1 , 1 T 2 , 2 T 3 … n-1 T n

[0034] Get the final transformation matrix: 0 T n = 0 T 1 · 1 T 2 · 2 T 3 ··· n-1 T n .

[0035] In a further embodiment, the specific steps of determining the proportional relationship of the influence of each level of active joint components on the position of the end effector in step 4 are as follows:

[0036] Step 4-1: Test and run each level of active joint components, and collect data on the impact of the movement of each level of active joint components on the x, y, and z spatial coordinate positions of the end effector;

[0037] Step 4-2: Select any active joint component again to define as the verification joint, and move other active joint components to the limit position and then lock them;

[0038] Step 4-3: driving the verification joint, reading the motion parameters of the verification joint and the position change parameters of the end effector, and determining the proportional relationship;

[0039] Step 4-4: Repeat the above steps 4-2 and 4-3 to verify the remaining movable joint components and determine the proportional relationship.

[0040] In a further embodiment, the specific steps of determining the decomposition accuracy values ​​of each movable joint component in the x-axis, y-axis and z-axis in step 5 are as follows:

[0041] Step 5-1: Determine the single-axis accuracy indicators of the x-axis, y-axis and z-axis;

[0042] Step 5-2: Determine the active joint components corresponding to the single-axis precision affecting the x-axis, y-axis and z-axis respectively, and distribute the precision of the active joint components affecting the x-axis, y-axis and z-axis respectively according to the corresponding influence proportion relationship of the active joint components;

[0043] Step 5-3: Select the minimum value among the precision distribution values ​​of the active joint component that simultaneously affects at least two axes among the x-axis, the y-axis and the z-axis as the decomposition precision value of the active joint component;

[0044] Step 5-4: Combining the accuracy allocation in step 5-2 and the minimum value selection in step 5-3, determine the final decomposition accuracy value of each active joint component.

[0045] In a further embodiment, the joints that affect the accuracy of the x-axis are the second joint swing assembly, the fourth joint rotation group, the fifth joint rotation assembly, the sixth joint telescopic assembly and the eighth joint rotation assembly, and the overall accuracy of the x-axis is required to be within 1 mm;

[0046] The joints that affect the accuracy of the y-axis are the third joint translation assembly, the fourth joint rotation assembly, the sixth joint telescopic assembly and the seventh joint rotation assembly. The overall accuracy of the y-axis is required to be within 1 mm.

[0047] The joints that affect the accuracy of the z-axis are the first joint rotation assembly, the second joint swing assembly, the fifth joint rotation assembly, the sixth joint telescopic assembly, the eighth joint rotation assembly and the ninth joint translation assembly. The overall accuracy of the z-axis is required to be within 5 mm.

[0048] Beneficial effects of the present invention: This method is based on the DH coordinate system method, takes the extreme position as the constraint condition, decomposes the index, and does not use advanced algorithms such as parameter optimization. The method has wide applicability and can meet the accuracy decomposition requirements of various serial robots. In order to ensure that the end effector can accurately reach the predetermined position, this method can make requirements on the accuracy of each level of the joint of the multi-joint serial robot, thereby reducing the error of the end effector. In order to meet the needs of replacing equipment parts under high temperature and high pressure environments, a multi-joint serial robot is designed. The serial robot has a large working space, flexible movements, and can work for a long time, solving the problem of replacing equipment parts in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a structural diagram of the multi-joint serial robot of the present invention.

[0050] Figure 2 Schematic diagram of the coordinate system of the multi-joint serial robot of the present invention.

[0051] Figure 3 This is an error analysis diagram of the second-stage swing hydraulic cylinder of the multi-joint serial robot of the present invention.

[0052] Figure 4 This is an analysis diagram of the impact of the fourth joint error of the multi-joint serial robot of the present invention on the terminal X-axis.

[0053] Figure 5 This is an analysis diagram of the impact of the fourth joint error of the multi-joint serial robot of the present invention on the terminal Y-axis.

[0054] Figure 6 This is an analysis diagram of the impact of the fifth joint error of the multi-joint serial robot of the present invention on the end.

[0055] Figure 7 This is an analysis diagram of the impact of the seventh joint error of the multi-joint serial robot of the present invention on the terminal Y-axis.

[0056] Figure 8 This is an analysis diagram of the impact of the eighth joint error of the multi-joint serial robot of the present invention on the end.

[0057] The figures are marked as: first joint rotation assembly 1, second joint swing assembly 2, third joint translation assembly 3, fourth joint rotation assembly 4, fifth joint rotation assembly 5, sixth joint telescopic assembly 6, seventh joint rotation assembly 7, eighth joint rotation assembly 8, ninth joint translation assembly 9, base 10, and end effector 11. DETAILED DESCRIPTION

[0058] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0059] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0060] Reference Figure 1-8 , is a precision decomposition method of a multi-joint serial robot disclosed in the present invention, wherein the multi-joint serial robot is a robot composed of a base, nine active joint assemblies connected in series, and an end effector, wherein the nine active joint assemblies include six rotating joints and three moving joints, each of the active joint assemblies includes a power part, a joint rod, and a joint shaft, and the nine active joint assemblies are respectively a first joint rotating assembly 1, a second joint swinging assembly 2, a third joint translation assembly 3, a fourth joint rotating assembly 4, a fifth joint rotating assembly 5, a sixth joint telescopic assembly 6, a seventh joint rotating assembly 7, an eighth joint rotating assembly 8, and a ninth joint translation assembly 9, which are connected in sequence, wherein the first joint rotating assembly 1 is installed on the base 10, and the end effector 1 1 is installed on the ninth joint translation assembly 9; the first joint rotation assembly 1, the second joint swing assembly 2, the fourth joint rotation assembly 4, the fifth joint rotation assembly 5, the seventh joint rotation assembly 7 and the eighth joint rotation assembly 8 are all the rotation joint assemblies, the third joint translation assembly 3, the sixth joint telescopic assembly 6 and the ninth joint translation assembly 9 are all the mobile joint assemblies, and the power parts of the nine movable joint assemblies are respectively the first joint rotation hydraulic motor, the second joint swing hydraulic cylinder, the third joint translation hydraulic cylinder, the fourth joint rotation hydraulic motor, the fifth joint rotation hydraulic motor, the sixth joint telescopic hydraulic cylinder, the seventh joint rotation hydraulic motor, the eighth joint rotation hydraulic motor and the ninth joint translation hydraulic cylinder, wherein, Figure 1As shown, it is a structural schematic diagram of a multi-joint serial robot, in which the base 10 of the multi-joint serial robot is fixed on the ground to provide fixed support for the moving parts of the robot; the first joint rotates the hydraulic motor, and the motor drives the gear to mesh with the rack, driving the robot end to move horizontally and linearly along the z-axis of the base 10; the second joint swings the hydraulic cylinder, and the lower hinge ear of the hydraulic cylinder moves synchronously along the z-axis of the base 10 with the movement of the first joint, and the upper hinge ear is connected to the hinge point on the parallelogram frame, and the hydraulic cylinder is telescopic, which can drive the movement of the robot end in the x-axis and z-axis directions; the third joint translation hydraulic cylinder affects the position of the robot end in the y-axis direction; the fourth joint rotary hydraulic motor can drive the subsequent joints to rotate along the z-axis; the fifth joint rotary hydraulic motor, the sixth joint telescopic hydraulic cylinder, the seventh joint rotary hydraulic motor, and the eighth joint rotary hydraulic motor have an impact on the robot end that is affected by the motion positions of the previous joints and need to be analyzed in detail, and the ninth joint translation hydraulic cylinder affects the displacement of the robot end in the z-axis direction, wherein the second joint swing assembly 2 composed of the connecting rod mechanism is decomposed into two rotations and one translation motion, and the angle of the rotating joint can be obtained by the geometric method.

[0061] The method comprises the following steps:

[0062] Step 1: Determine the relative position relationship between the six rotating joints and the three moving joints, establish the DH coordinate system of the multi-joint serial robot, obtain the structural parameters of the multi-joint serial robot, the structural parameters include the motion range of each active joint component and the relative position relationship of two adjacent active joint components in the initial position, and establish the overall coordinate system according to the DH coordinate system principle as follows: Figure 2 As shown;

[0063] In step 1, a Cartesian coordinate system (x i ,y i ,z i ), (i=1,2,…,n), n is the number of degrees of freedom;

[0064] The coordinate system of the base is defined as the coordinate system 0 (x 0 ,y 0 ,z 0 ), the z 0 The axis of the rotary motor coincides with the axis of rotation of the first joint rotary hydraulic motor, and the position and direction are optional;

[0065] The end effector coordinate system is the Nth coordinate system (x n ,y n ,z n ), the x n With the z n vertical;

[0066] In the revolute joint assembly, L i ,α i ,d i is a fixed value, θ i is a variable, in the mobile joint component, L i ,α i ,θ i is a fixed value, d i is a variable;

[0067] The power member drives the joint rod to move along the joint axis. Each joint axis A i At most, it is connected to two joint rods, which are A i-1 and A i+1 , the joint axis A of the i-th active joint component i Located at the connection between the two joint rods, the i-1 movable joint assembly and the i+1 movable joint assembly also have a joint axis A i-1 and A i+1 ;

[0068] The principle of establishing the DH coordinate system of the multi-joint serial robot in step 1 also includes the following steps:

[0069] Step 1-1: The origin Oi is set at the intersection of the Li and Ai+1 axes;

[0070] Step 1-2: The Zi axis coincides with the Ai+1 joint axis and points to any direction;

[0071] Step 1-3: The Xi axis coincides with the common normal line Li, and points along Li from the Ai axis to the Ai+1 axis;

[0072] Step 1-4: Use the right-hand rule for the first axis.

[0073] Step 2: According to the structural parameters, determine the DH parameter table of the multi-joint serial robot, the DH parameter table includes the length L of the joint rod i , the torsion angle α of the joint rod i , the offset d of the joint rod i and the rotation angle θ of the joint member i , the specific steps of determining the DH parameters of the multi-joint serial robot are as follows:

[0074] Step 2-1: Joint rod length L i Along x i Axis, z i-1 Axis and x i Axis intersection to 0 i distance;

[0075] Step 2-2: Joint rod torsion angle α i Around x i Axis, by z i-1 Turn to z i ;

[0076] Step 2-3: Joint member offset d i Along z i-1 Axis, z i-1 Axis and x i Intersection to ∑0 i–1 The distance from the origin of the coordinate system;

[0077] Step 2-4: Joint rod rotation angle θ i Around z i-1 Axis, by x i-1 Turn to x i ;

[0078] based on Figure 2 Coordinate system and nine-joint robot structural parameters, determine the parameters in DH parameter table 1 as follows:

[0079] Table 1

[0080]

[0081] Step 3: Establish the kinematic model of the multi-joint serial robot according to the DH parameter table, and use the general formula to determine the transformation matrix of each active joint component, end effector and base. The specific steps of determining the transformation matrix are as follows:

[0082] The DH coordinate transformation matrix between the coordinate systems of two adjacent active joint components is as follows:

[0083]

[0084] The transformation matrix between the coordinate systems of two adjacent active joint components can be calculated by the parameters in Table 1. The calculation formula is shown in Formula 2. The DH coordinate transformation matrix between the coordinate systems of two adjacent active joint components is shown in Formula 3. The transformation matrix of the end of the multi-joint serial robot relative to the fixed coordinate system is shown in Formula 4.

[0085]

[0086]

[0087] Step 4: Based on the transformation matrix obtained for each active joint component, and under the premise that the positions of other active joint components are fixed, a motion test is performed on each active joint component to determine the proportional relationship of the influence of each active joint component on the position of the end effector. The specific steps are as follows:

[0088] Step 4-1: Test and run each level of active joint components, and collect data on the impact of the movement of each level of active joint components on the x, y, and z spatial coordinate positions of the end effector;

[0089] Step 4-2: Select any active joint component again to define as the verification joint, and move other active joint components to the limit position and then lock them;

[0090] Step 4-3: driving the verification joint, reading the motion parameters of the verification joint and the position change parameters of the end effector, and determining the proportional relationship;

[0091] Step 4-4: Repeat the above steps 4-2 and 4-3 to verify the remaining movable joint components and determine the proportional relationship;

[0092] The maximum parameter values ​​of the motion of the active joint components of each level of the multi-joint tandem joint robot are shown in Table 2:

[0093] Table 2

[0094]

[0095] Step 5: According to the preset accuracy indexes of the multi-joint serial robot in the x-axis, y-axis and z-axis, and the corresponding influence proportion relationship of each active joint component obtained above, determine the decomposition accuracy value of each active joint component in the x-axis, y-axis and z-axis respectively;

[0096] The specific steps of determining the decomposition accuracy values ​​of each movable joint component in the x-axis, y-axis and z-axis in step 5 are as follows:

[0097] Step 5-1: Determine the single-axis accuracy indicators of the x-axis, y-axis and z-axis;

[0098] Step 5-2: Determine the active joint components corresponding to the single-axis precision affecting the x-axis, y-axis and z-axis respectively, and distribute the precision of the active joint components corresponding to the x-axis, y-axis and z-axis respectively according to the corresponding influence proportion relationship of the active joint components, preferably distribute evenly;

[0099] Step 5-3: Select the minimum value among the precision distribution values ​​of the active joint component that simultaneously affects at least two axes among the x-axis, the y-axis and the z-axis as the decomposition precision value of the active joint component;

[0100] Step 5-4: Combining the accuracy allocation in step 5-2 and the minimum value selection in step 5-3, determine the final decomposition accuracy value of each active joint component.

[0101] Analyze the motion at each level:

[0102] The first joint rotation component 1 is a first joint rotation hydraulic motor that drives the entire mechanism to translate along the z-axis. The joint movement accuracy will only affect the accuracy of the z-axis at the end of the robot, and the impact ratio is 1:1.

[0103] The second joint swing assembly 2 is driven by the second joint swing hydraulic cylinder. According to the structural analysis, its movement will cause the movement of the x-axis and z-axis of the robot end. When the second joint swing hydraulic cylinder has a 1mm error in movement, the error of the x-axis and z-axis of the end is affected by the extension of the second joint swing hydraulic cylinder. Figure 3 As shown in the figure, due to the high precision requirements of the overall x and y axes of the multi-joint robot, the main focus is on the impact of its error on the x axis, and the impact ratio is approximately 1:1.

[0104] The third joint translation assembly 3 is driven by the third joint translation hydraulic cylinder, and its movement will bring about the y-axis movement of the end of the multi-joint robot, and the influence ratio is 1:1.

[0105] The fourth joint swivel assembly 4 is a rotational motion around the z-axis, and its error will cause coupling errors in the x- and y-axes. The magnitude of the error is affected by the amount of motion of the subsequent joints. Taking the extreme case as an example, when the joint 6 is extended 1492mm, the error of the fourth joint affects the x- and y-axes at the end as follows: Figure 4 , Figure 5 As shown in the figure, when the rotation accuracy of the fourth joint is higher than 0.01°, the influence of its error on the x-axis can be ignored. When the accuracy is lower than 0.01°, the influence ratio is 10:1, and the influence of the error on the y-axis is 25:1.

[0106] The fifth joint swivel assembly 5 is a rotational motion around the y-axis. Its error will cause coupling errors of the x-, y-, and z-axes. The magnitude of the error is affected by the movement of the fourth joint and subsequent joints. Similarly, when the sixth joint is extended by 1492mm, the fifth joint error affects the end as follows. Figure 6 As shown, the impact ratio on the x-axis is 20:1, and the impact ratio on the z-axis is 50:1.

[0107] The sixth joint telescopic assembly 6 is a telescopic movement of a multi-stage cylinder. As the movement amounts of the fourth, fifth, seventh and eighth joints are different, the effects on the end are also different, but they can be considered according to the maximum impact, and the impact ratio of their errors on the x, y, and z axes is 1:1.

[0108] The seventh joint rotation component 7 will affect the y-axis accuracy and the impact on the end is as follows Figure 7 As shown, the impact ratio on the y-axis is 4.7:1.

[0109] The eighth joint rotation component 8 will affect the accuracy of the x and z axes, and the impact on the end is as follows: Figure 8 As shown, the impact ratio on the x-axis is 3.6:1, and the impact ratio on the z-axis is 7.6:1.

[0110] The ninth joint translation assembly 9 is the translation movement of the multi-stage cylinder. According to the analysis of the multi-joint robotic arm, it will only affect the accuracy of the z-axis, and the influence ratio is 1:1.

[0111] In summary, the joints that affect the accuracy of the x-axis are the second joint swing assembly 2, the fourth joint rotation assembly 4, the fifth joint rotation assembly 5, the sixth joint telescopic assembly 6 and the eighth joint rotation assembly 8. The total accuracy of the x-axis is required to be within 1 mm, so the accuracy of each level is allocated according to the influence ratio. The influence ratio of the second joint swing assembly 2 and the sixth joint telescopic assembly 6 is 1:1, and the comprehensive accuracy of each joint is required to be within 0.05 mm. The influence of the fourth joint rotation assembly 4 and the fifth joint rotation assembly 5 will be multiplied, requiring the comprehensive accuracy of these two sections to be within 0.02°, and the comprehensive accuracy of the eighth joint rotation assembly 8 to be within 0.04°, in order to meet the overall accuracy requirement of 1 mm.

[0112] The joints that affect the accuracy of the y-axis are the third joint translation assembly 3, the fourth joint rotation assembly 4, the sixth joint telescopic assembly 6 and the seventh joint rotation assembly 7. The total accuracy of the y-axis is required to be within 1 mm, so the accuracy of each level is allocated according to the influence ratio. The influence ratio of the third joint translation assembly 3 and the sixth joint telescopic assembly 6 is 1:1, and the comprehensive accuracy of each joint is required to be within 0.1 mm. The influence of the fourth joint rotation assembly 4 will be multiplied, requiring the comprehensive accuracy of this section to be within 0.02°. The influence of the seventh joint rotation assembly 7 will be multiplied, requiring the comprehensive accuracy of this section to be within 0.04°, in order to meet the overall accuracy requirement of 1 mm.

[0113] The joints that affect the accuracy of the z-axis are the first joint rotation component 1, the second joint swing component 2, the fifth joint rotation component 5, the sixth joint telescopic component 6, the eighth joint rotation component 8 and the ninth joint translation component 9. The total accuracy of the z-axis is required to be within 5mm, so the accuracy of each level is allocated according to the impact ratio. The x and y axes determine the accuracy requirements of the second joint swing component 2, the fifth joint rotation component 5, the sixth joint telescopic component 6, and the eighth joint rotation component 8. The total error of the above four sections is 1.4mm. The first joint rotation component 1 and the ninth joint translation component 9 only affect the z-axis, and the total error must be less than 3.6mm.

[0114] Therefore, the accuracy requirements of each level of the nine-joint robot are broken down as follows:

[0115] Table 3

[0116]

[0117] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0118] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical scheme of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A precision decomposition method for a multi-joint serial robot, characterized in that: The multi-joint serial robot is a robot composed of a base, nine movable joint assemblies connected in series, and an end effector, wherein the nine movable joint assemblies include six rotating joint assemblies and three moving joint assemblies, and each of the movable joint assemblies includes a power part, a joint rod, and a joint shaft. The method comprises the following steps: Step 1: Determine the relative position relationship between the six rotating joint assemblies and the three moving joint assemblies, establish the DH coordinate system of the multi-joint serial robot, and obtain the structural parameters of the multi-joint serial robot, wherein the structural parameters include the motion range of each active joint assembly and the relative position relationship between two adjacent active joint assemblies in the initial position; Step 2: According to the structural parameters, determine the DH parameter table of the multi-joint serial robot, the DH parameter table includes the length L of the joint rod i , the torsion angle α of the joint rod i , the offset d of the joint rod i and the rotation angle θ of the joint member i ; Step 3: Establish a kinematic model of the multi-joint serial robot according to the DH parameter table, and use a general formula to determine the transformation matrix of each active joint component, end effector and base; Step 4: Based on the transformation matrix obtained by each active joint component, under the premise that the positions of other active joint components are fixed, a motion test is performed on each active joint component to determine the proportional relationship of the influence of each active joint component on the position of the end effector; Step 5: Based on the preset accuracy indicators of the multi-joint serial robot in the x-axis, y-axis and z-axis, and the corresponding influence proportion relationship of each active joint component obtained above, determine the decomposition accuracy value of each active joint component in the x-axis, y-axis and z-axis respectively.

2. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: The nine movable joint components are respectively a first joint rotation component, a second joint swing component, a third joint translation component, a fourth joint rotation component, a fifth joint rotation component, a sixth joint telescopic component, a seventh joint rotation component, an eighth joint rotation component and a ninth joint translation component which are connected in sequence, the first joint rotation component is mounted on the base, and the end effector is mounted on the ninth joint translation component; The first joint rotation assembly, the second joint swing assembly, the fourth joint rotation assembly, the fifth joint rotation assembly, the seventh joint rotation assembly and the eighth joint rotation assembly are all the rotation joint assemblies, and the third joint translation assembly, the sixth joint telescopic assembly and the ninth joint translation assembly are all the moving joint assemblies.

3. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: The power parts of the nine movable joint assemblies are respectively the first joint rotary hydraulic motor, the second joint swing hydraulic cylinder, the third joint translation hydraulic cylinder, the fourth joint rotary hydraulic motor, the fifth joint rotary hydraulic motor, the sixth joint telescopic hydraulic cylinder, the seventh joint rotary hydraulic motor, the eighth joint rotary hydraulic motor and the ninth joint translation hydraulic cylinder.

4. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: In step 1, a Cartesian coordinate system (x i ,y i ,z i ), (i=1,2,…,n), n is the number of degrees of freedom; The coordinate system of the base is defined as coordinate system No. 0 (x0, y0, z0), and the axis of z0 coincides with the axis of rotation of the first joint rotary hydraulic motor; The end effector coordinate system is the Nth coordinate system (x n ,y n ,z n ), the x n With the z n vertical.

5. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: In the revolute joint assembly, L i ,α i ,d i is a fixed value, θ i is a variable, in the mobile joint component, L i ,α i ,θ i is a fixed value, d i is a variable; The power member drives the joint rod to move along the joint axis. Each joint axis A i At most, it is connected to two joint rods, which are A i-1 and A i+1 , the joint axis A of the i-th active joint component i Located at the connection between the two joint rods, the i-1 movable joint assembly and the i+1 movable joint assembly also have a joint axis A i-1 and A i+1 ; The principle of establishing the DH coordinate system of the multi-joint serial robot in step 1 also includes the following steps: Step 1-1: The origin Oi is set at the intersection of the Li and Ai+1 axes; Step 1-2: The Zi axis coincides with the Ai+1 joint axis and points to any direction; Step 1-3: The Xi axis coincides with the common normal line Li, and points along Li from the Ai axis to the Ai+1 axis; Step 1-4: Use the right-hand rule for the first axis.

6. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: The specific steps of determining the DH parameters of the multi-joint serial robot in step 2 are as follows: Step 2-1: Joint rod length L i Along x i Axis, z i-1 Axis and x i Axis intersection to 0 i distance; Step 2-2: Joint member torsion angle α i Around x i Axis, by z i-1 Turn to z i ; Step 2-3: Joint member offset d i Along z i-1 Axis, z i-1 Axis and x i Intersection to ∑0 i–1 The distance from the origin of the coordinate system; Step 2-4: Joint rod rotation angle θ i Around z i-1 Axis, by x i-1 Turn to x i .

7. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: The specific steps of determining the transformation matrix in step 3 are as follows: The DH coordinate transformation matrix between the coordinate systems of two adjacent active joint components is as follows: Determine the transformation matrix of the coordinate system of each two adjacent active joint components 0 T1, 1 T2, 2 T3… n-1 T n Get the final transformation matrix: 0 T n = 0 T1 1 T2 2 T3··· n-1 T n .

8. The precision decomposition method of a multi-joint serial robot according to claim 1, characterized in that: The specific steps for determining the proportional relationship of the influence of each level of active joint components on the position of the end effector in step 4 are as follows: Step 4-1: Test and run each level of active joint components, and collect data on the impact of the movement of each level of active joint components on the x, y, and z spatial coordinate positions of the end effector; Step 4-2: Select any active joint component again to define as the verification joint, and move other active joint components to the limit position and then lock them; Step 4-3: driving the verification joint, reading the motion parameters of the verification joint and the position change parameters of the end effector, and determining the proportional relationship; Step 4-4: Repeat the above steps 4-2 and 4-3 to verify the remaining movable joint components and determine the proportional relationship.

9. The precision decomposition method of a multi-joint serial robot according to claim 2, characterized in that: The specific steps of determining the decomposition accuracy values ​​of each movable joint component in the x-axis, y-axis and z-axis in step 5 are as follows: Step 5-1: Determine the single-axis accuracy indicators of the x-axis, y-axis and z-axis; Step 5-2: Determine the active joint components corresponding to the single-axis precision affecting the x-axis, y-axis and z-axis respectively, and distribute the precision of the active joint components affecting the x-axis, y-axis and z-axis respectively according to the corresponding influence proportion relationship of the active joint components (preferably evenly distribute, and place the instruction manual); Step 5-3: Select the minimum value among the precision distribution values ​​of the active joint component that simultaneously affects at least two axes among the x-axis, the y-axis and the z-axis as the decomposition precision value of the active joint component; Step 5-4: Combining the accuracy allocation in step 5-2 and the minimum value selection in step 5-3, determine the final decomposition accuracy value of each active joint component.

10. The precision decomposition method of a multi-joint serial robot according to claim 9, characterized in that: The joints that affect the accuracy of the x-axis are the second joint swing assembly, the fourth joint rotation assembly, the fifth joint rotation assembly, the sixth joint telescopic assembly and the eighth joint rotation assembly. The overall accuracy of the x-axis is required to be within 1 mm. The joints that affect the accuracy of the y-axis are the third joint translation assembly, the fourth joint rotation assembly, the sixth joint telescopic assembly and the seventh joint rotation assembly. The overall accuracy of the y-axis is required to be within 1 mm. The joints that affect the accuracy of the z-axis are the first joint rotation assembly, the second joint swing assembly, the fifth joint rotation assembly, the sixth joint telescopic assembly, the eighth joint rotation assembly and the ninth joint translation assembly. The overall accuracy of the z-axis is required to be within 5 mm.

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