JPH11226884A - Accuracy evaluating method for robot track - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method evaluating in a short time accuracy of a robot track formed by an off-line without using a Jacobian matrix. SOLUTION: A circular arc-shaped wrist singular point locus S1 , S2 in a paint robot is obtained, and the shortest distance between this singular point locus and a robot track Pc Pi of horizontal paint work obtained relating to a workpiece is obtained. For obtaining the shortest distance by whether this shortest distance is within a permissible value or not, in the case of evaluating accuracy of the robot track, a projection point Piπ from a search point Pi on the robot track is obtained in a plane π including the wrist singular point locus. An intersection Sci of a straight line connecting this projection point and a center point C of the singular point locus and the plane π is obtained, a three square theorem is applied to these three points, a distance Pi Sci between the search point on the robot track and the intersection on the singular point locus is obtained, this procedure is repeatedly performed in a plurality of parts on the robot track, and the shortest is the shortest distance, in this method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the accuracy of a robot trajectory that can improve the work accuracy by avoiding work near a singular point.

[0002]

2. Description of the Related Art In recent years, robots have been widely put to practical use in the production process of various mass-produced products, and robots have also been put to practical use in large structures such as ships and bridges.

For example, most welding operations are performed by welding robots. However, even in painting operations in which economic effects are not sufficiently exhibited as compared with welding, there is still a problem of securing skilled workers and the like. Robotization is desired.

[0004] In general, painting robots are widely used in the automobile industry and their operation data (NC data).
Was obtained by manual teaching. By the way, teaching by hand to the robot can be performed relatively easily when the painting range is small and the movement of the robot is not complicated, such as in a car, but in the case of a large structure, Since the painting area is large and many stiffening members protrude from the painting surface, there is a problem that manual teaching requires time and effort.

For this reason, it is necessary to create operation data of the robot by programming offline.
When creating robot operation data offline, the robot reads the structure data, coating condition data, and painting method data of the object to be coated from the library, and generates robot operation data, that is, a robot trajectory based on these data. I was

[0006] With respect to the robot trajectory generated off-line, it is indispensable to secure the trajectory accuracy in order to perform a stable painting operation or to exhibit necessary work skills. That is, it is necessary to check whether or not the robot trajectory passes near a singular point where the work accuracy is deteriorated. Conventionally, as a check method, there is a Jacobian matrix.

[0007]

By the way, in the case of this Jacobian matrix, it is necessary to know the joint angles at each posture on the robot trajectory. Therefore, it is necessary to solve the inverse kinematics for each point on the robot trajectory. , It is necessary to use a Jacobi matrix. Therefore, there is a problem that a large amount of time is required for the calculation time. In particular, when the object to be painted is a large structure, a problem that the calculation amount becomes enormous occurs.

Therefore, the present invention provides an evaluation method capable of performing accuracy evaluation of a robot trajectory generated off-line in a short time without using a Jacobi matrix.
In particular, an object of the present invention is to provide a method for evaluating a wrist singular posture.

[0009]

In order to solve the above-mentioned problems, a first method for evaluating the accuracy of a robot trajectory according to the present invention provides a tool posture, a robot specification and a robot operation range when a predetermined operation is performed by a robot. Based on the wrist singular point trajectory of the robot, the shortest distance between the wrist singular point trajectory and the robot trajectory obtained according to the work target is determined, and whether or not the shortest distance is within an allowable value, This is a method for evaluating the accuracy of the robot trajectory.

A second method for evaluating the accuracy of a robot trajectory according to the present invention is based on a tool posture, a robot specification, and a robot operation range when a predetermined operation is performed by the robot. And the shortest distance between the wrist singularity trajectory and the robot trajectory in the horizontal operation determined according to the work object.The accuracy of the robot trajectory is determined by whether or not this shortest distance is within an allowable value. Is a method for evaluating the accuracy of a robot trajectory, in which a perpendicular is drawn from a predetermined point on the robot trajectory to a plane including an arc-shaped wrist singularity trajectory to obtain the shortest distance, and the first intersection point is determined. And a second intersection point between a straight line connecting the first intersection point and the center point of the arc-shaped wrist singular point locus and the plane is determined.
The distance between a predetermined point on the robot trajectory and the second intersection on the trajectory of the wrist singular point is determined by applying the three-square theorem to the first and second intersections. This is a method in which the shortest of the obtained distances is set as the shortest distance.

Further, a third method for evaluating the accuracy of a robot trajectory according to the present invention is based on an arc-shaped wrist singular point trajectory of a robot based on a tool posture, a robot specification and a robot operation range when a predetermined operation is performed by the robot. And the shortest distance between the wrist singularity trajectory and the robot trajectory in the vertical work determined according to the work target.The accuracy of the robot trajectory is determined based on whether the shortest distance is within an allowable value. A robot trajectory is projected onto a plane including an arc-shaped wrist singular point trajectory to obtain a projected trajectory, and the arc-shaped wrist singular is obtained. A perpendicular is drawn on the projected trajectory from the center point of the point trajectory to determine a first intersection with the projected trajectory and a second intersection with the wrist singularity trajectory. Obtains corresponding points on the robot path corresponding to the point, the distance between the corresponding point and the second intersection is a method for the shortest distance.

According to each of the above accuracy evaluation methods, the shortest distance between the robot trajectory, for example, the robot trajectory in the horizontal operation or the robot trajectory in the vertical operation, and the trajectory of the wrist singular point is determined. That is, since the evaluation is performed by comparing the distance with which an error occurs near the singular point, the trajectory accuracy can be evaluated without using the Jacobi matrix.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for evaluating the accuracy of a robot trajectory on a workpiece according to an embodiment of the present invention will be described with reference to FIGS.
2 will be described.

In the present embodiment, the accuracy evaluation of the trajectory in a multi-joint type painting robot will be described.
The object to be painted (an example of an object to be worked, hereinafter simply referred to as a work) in the present embodiment is a hull block,
It is assembled by horizontal and vertical members and has a box shape.

For example, as shown in FIG. 1, this hull block 1 has a beam member 3 attached to the inner surface of a hull outer plate 2 as a stiffening member, and a partition wall member perpendicular to the hull outer plate 2. A case where the surface of the hull block 1 is automatically painted by a painting robot (hereinafter, referred to as a robot) will be described.

First, the trajectory, ie, operation data, of a robot having a painting gun (hereinafter, referred to as a tool) attached to a wrist is obtained by an operation data generation system (computer system).

That is, as shown in the flowchart of FIG. 2, in the trajectory generation system, the work structure data is read from the CAD data 11 and recognized, and the painting condition data from the painting library 12 and the painting work from the work library 13 are read. Based on these data, the robot trajectory, that is, the moving speed of the tool, the tool posture, the tool tip trajectory, etc. are obtained. After a predetermined check (described later) is performed, the NC data is offline. Is generated.

More specifically, the information given to the data generation system when generating the trajectory is the structural data of the workpiece and the specifications of the robot at the reference coordinates where the robot is installed. That is, when the work structure is numerically recognized based on the information from the CAD, the origin position of the robot is determined based on the operation range which is one of the specifications of the robot, and the recognized work structure and the determined robot are determined. A painting path and a movement path corresponding to each part of the work are generated as a robot trajectory according to the origin position and the tool posture.

Next, a check is made as to whether the generated robot trajectory is appropriate, that is, an interference check, a check (evaluation) of trajectory accuracy, and a correction are performed. Hereinafter, a method for evaluating the accuracy of the trajectory will be described. The interference check is naturally performed, and the check is easy.

The trajectory accuracy is evaluated based on whether or not the robot trajectory passes through the region of the singular posture in which the motion performance deteriorates. First, the robot trajectory in the generated trajectory is determined. The trajectory of the singular point, that is, the singular posture, is obtained by calculation.

The unique posture includes a wrist and a shoulder. Fig. 3
As shown in (a), when the wrist part 32 and the forearm part 33 of the robot 31 fixedly holding the tool 21 are in a straight line, that is, when the tool posture is constant (hereinafter referred to as a wrist singular posture), the shoulder part 3B, the rotation center point 34 of the wrist 32 of the robot 31 is
Is located on the turning center axis 36 of the first joint axis 35 of the robot 31 (hereinafter, referred to as a shoulder specific posture).

Here, actually, the robot is operated,
FIG. 4 shows a case where the robot is given a trajectory passing through the singular point and its vicinity, and errors in the tool tip (TCP) and the tool posture at every moment are observed at a horizontal angle of 15 degrees and a depression angle of 30 degrees. The specified speed is
The speed required for heavy coating with a large film thickness is 300 mm /
s. From FIG. 4, in the trajectory passing near the singular point, especially as the wrist singular point _Sh is approached,
It can be seen that there is an error in the trajectory accuracy of the tool tip, tool posture, etc.

The relationship between the distance from the singular point and the trajectory accuracy was grasped by taking the amount of shift of the trajectory in the Y and Z directions from the trajectory including the singular point as a measurement parameter. The wrist singularity is shifted in the Y and Z directions, and the shoulder singularity is shifted in the Y direction.

FIG. 5 shows a measurement result of each trajectory error with respect to a shift amount from the singular point trajectory, that is, a spatial distance from the singular point. FIG. 5A shows a tool tip (TCP),
(B) represents the tool posture, and (c) represents the moving speed. From FIG. 5, it can be seen that the singular point orbit is shifted in the Y and Z directions from the singular point trajectory, and the shoulder singular point is shifted in the Y direction.
That is, for any accuracy item, it can be read that the error is inversely proportional to the distance from the singular point.

By the way, the path error ΔP at the tip of the tool and the tool attitude error Δψ are synergistic to become the target position error δ on the coating surface. The maximum value that the target position error δ of the coating surface can take is that the coating distance between the coating gun, which is a tool, and the coating surface is L.
Then, it is represented by the following equation (1).

Δ ≒ ΔP _max + L × Δψ (1) From the measurement result of the trajectory error shown in FIG. 5 and equation (1), the spatial distance from the singular point to the trajectory and the maximum value of the target position error of the coating surface. 6 is as shown in FIG. 6 if L = 300 mm. FIG. 6 shows that the error is again inversely proportional to the distance from the singular point.

As described above, since the trajectory accuracy depends on the distance from the singular point, in order to maintain the trajectory accuracy, a region having a radius around an allowable value centered on the singular point is provided. It can be seen that the trajectory accuracy should be evaluated based on whether or not the robot trajectory to be evaluated passes through this singular region.

For example, assuming that the allowable value of the target position error on the application surface is 30 mm, as shown in FIG. 6, it is understood that the trajectory needs to be separated from the singular point by 10 mm or more. As described above, the area in which the trajectory accuracy is degraded is regarded as a singular area, and whether the robot trajectory passes through this singular area can be evaluated very easily.

As shown in FIG. 7, if singular point trajectory 41 Sadamare as a set of singular points, the allowable value r _s from the singular point along the specific point trajectory 41 with a radius and a set of the radius r _s Is obtained.

Therefore, as a method of trajectory evaluation, if the shortest distance in space between the trajectory (line segment) of the robot and the singular point trajectory (line segment) is larger than the radius of the singular point region, the trajectory is determined. If it is acceptable, it can be determined that it is not possible if it is small. By the way, it is preferable that the value of the radius of this singular point region is determined based on actual work, and specifically,
This value is proportional to the moving speed specified in the painting operation.

Here, the evaluation method for the wrist part among the above singular points will be described in detail. First, a method of obtaining the locus of the wrist singularity will be described.

Generally, in order to obtain a painting trajectory, that is, a robot trajectory, a target point (target position of a tool which is a tool tip), a tool posture, and a linear velocity are designated. FIG. 8 illustrates a trajectory that draws a wrist singular point of a puma-type robot when a fixed tool posture is designated.
It is assumed that the tool axis and the wrist axis are arranged on the same axis.

As shown in FIG. 8, the trajectory of the singular point of the wrist corresponds to the vector * a [symbol *
Indicates that the character described thereafter is a vector (hereinafter the same), and in the following equation, the vector is shown in bold.] And the second joint axis (θ ₂ ) is movable while being kept parallel to This is a locus drawn by the tool tip (TCP) when moved within the range, and is an arc S ₁ S ₂ having a radius equal to the length (L ₁ ) of the upper arm. This arc is a vector *
lies on a plane π determined by a.

Hereinafter, a wrist singular point locus will be obtained. (1) First, Z- is given as a part of NC data.
A tool axis (wrist axis) direction vector * a = [x _a , ya _a , z _a ] ^T viewed from the reference coordinate system is obtained from the tool posture based on the YX Euler angles (α, β, γ).

The vector * a is obtained by the following equation (3) from a rotation transformation matrix up to the tool based on the robot joint angle [shown in the following equation (2)].

[0036]

(Equation 1)

(2) Next, when the joint angle θ ₁ (* a) of the first axis with respect to the plane π including the tool axis direction * a is obtained,
The following equation (4) is obtained. _{tanθ 1 (* a) = y} a / x a ··· (4) (3) Next, determine the singular point trajectory.

The singular point locus is, as shown in FIG. 8, an arc having a radius equal to the length L _{1 of the} upper arm, and the center c of the locus is shown in FIG.
In the robot coordinate system (x ₀ −y ₀ −z ₀ ) shown in (5), it is expressed by the following equation (5), and on the plane π, the following (6)
It is represented by the formula.

[0039]

(Equation 2)

The circle c is represented by the following equation (7) on a plane π by the parameter φ shown in FIG.
In the robot coordinate system, it is expressed by the following equation (8).

[0041]

(Equation 3)

(4) Next, the range of the singular point locus is determined. The range S ₁ S ₂ of the singular point set taking an arc is the range of each joint angle of the upper arm and the forearm and the specified tool axis direction vector *
a. Hereinafter, it is considered on the plane π.

The range of the joint angle between the upper arm and the forearm is set as follows in the direction shown in FIG. The range of motion of the forearm is for the upper arm. Brachial operating _{range: θ 2min ≦ θ 2 ≦ θ} 2max forearm operating _{range: θ 3min ≦ θ 3 ≦ θ} 3max S 1 is the upper arm articulation point q _2Cr1 satisfying the following equation (9) (*
Depending on the argument of a), the cases are classified as shown in the following equation (11). In addition, S ₂ satisfies the following equation (10): q
_{Depending on the declination of 2cr2} (* a), the cases are classified as shown in the following equation (12). Note that the equations (9) and (10)
The solution of Equation, selects the solution of _{z Q2 / x Q2> z a} / x a.

[0044]

(Equation 4)

The argument of the vector in complex number notation is represented by arg, and the value of the corresponding parameter φ is determined by equation (11) for S _{1 and} by equation (12) for S ₂ .

[0046]

(Equation 5)

After the trajectory of the wrist singular point is determined, it is necessary to determine the shortest distance between the trajectory of the wrist singular point and the robot trajectory. Hereinafter, a method of obtaining the shortest distance will be described.

By the way, the trajectory of the wrist singular point is an arc on an arbitrary vertical plane, and the robot trajectory is an arbitrary line segment in space, and it is difficult to directly determine the shortest distance between them.

The algorithm for calculating the shortest distance between the trajectory of the wrist singularity and the robot trajectory is considered in consideration of the practicality of incorporating it into a system for generating coating data of a structure.
Calculate under the following conditions.

The first condition is that, since most of the work is a box-shaped structure, the directions of the coating trajectory are all horizontal and vertical directions parallel to the robot reference coordinates. As a second condition, in consideration of the adhesion of the paint on the application surface, the attitude angle of the paint gun, which is a tool, with respect to the application surface is desirably 90 degrees. ) And the tool are up to 45 degrees.

In the following, the shortest distances in the horizontal coating and the vertical coating will be obtained in consideration of these conditions. Here, the tool tip trajectory P _c P _t is represented by the parameter t
Is expressed by the following equation (13).

[0052]

(Equation 6)

(A) Find the shortest distance in horizontal painting. First, a point closest to the shortest distance is obtained on the robot trajectory or the wrist singular point trajectory, and then the shortest distance is searched for at a constant interval by using this point as a starting point. by this,
The algorithm required for the driving data generation system is minimized by minimizing the time required for the search.

In this method, a point on the robot trajectory is searched to find the shortest distance from the trajectory of the wrist singularity, and a point on the trajectory of the wrist singularity is searched to determine the shortest distance from the robot trajectory. There is a way to find it.

The former can be reduced to the problem of finding the shortest distance between a point and a circle in space, and a search formula can be found geometrically in space. The latter can also be reduced to the problem of finding the shortest distance between a point and a straight line in space, and a search expression can be found using algebraic geometry.

In the present embodiment, referring to FIG. 10, the shortest distance between the search point on the robot trajectory and the arc-shaped wrist singular point trajectory is obtained spatially geometrically by the following procedure. (1) First, a projection point P _i π (first intersection) of the search point P _i (predetermined point) onto the plane π is obtained. (2) Next, the intersection S _ci ( _second ) of the arc S ₁ S ₂ with the line segment connecting the arc center C and P _i π of the wrist singular point locus (S ₁ S ₂ )
Intersection). (3) Then, the shortest distance h (P _i) with respect to P _i = P _i S
_ci is given by the following (14)
It is obtained by the formula.

[0057] ^{_{(P i S ci) 2 =}} (P i πS ci) 2 + (P i P i π) 2 ··· (14) When there is no intersection point S _ci is the arc end point S ₁ of S _2, and select a point near the intersection, directly determines the length of the line segment.

It is inefficient to perform the search in order from the end of the trajectory. Therefore, according to the preconditions of the algorithm, a near point that is almost the shortest distance is selected as the search starting point, and the search is performed on the left and right sides. , With the minimum number of search points.

[0059] That is, as the search starting point P _0, it is to choose the intersection Pπ the plane π containing the robot path P _c P _t and wrist singular point trajectory. If the intersection is not present among the orbital end point P _c and P _t, selecting a point closer to Ppai.
These are based on the condition that an extreme tool posture is not taken.

The comparison between the previous search point and the shortest distance is as follows.
Do it. h (P_i)> H (P_i-1): Shortest distance h = h (P_i-1) H (P_i) ≦ h (P_i-1): Continue search (i = i + 1) where P₀If is inside the orbit, it is shown in FIG.
So the starting point P₀Divided into right and left
, And finally, find their minimum value by the shortest distance h _minWhen
I do. Search point P here_iIs the starting point P₀Showing trajectory from
It is moved outward according to the equation (13).

When P ₀ is P _c or P _t , the search may be performed in one direction. Note that the interval between the search points is equal to the radius r used to define the singular region, as shown in the following equation (15).
_It is good to set to about 1/2 of _s .

[0062]

(Equation 7)

(B) Next, the shortest distance in vertical painting is determined. Under the condition that the painting trajectory is almost parallel to the robot reference coordinates, in vertical painting, the robot trajectory and the plane π including the wrist singularity trajectory are almost parallel, and thus the robot trajectory and the wrist singularity trajectory Can be obtained without using a search method.

In the following, the procedure to be determined will be described with reference to FIG. (1) First, the projection line P _c πP _t π onto the plane [pi robot trajectory P _c P _t. Note that the projected trajectory on the plane π *
pπ is the rotation transformation matrix ( ¹ R ₀ · *) of the robot trajectory * p
In p), the y component is set to zero. (2) Next, the projected line segment P _c πP _t from the point C on the plane π
The intersection S ₀ of the perpendicular CH ₀ down to π and the arc S ₁ S ₂ is determined. (3) Next, a point P ₀ on the robot trajectory corresponding to H ₀ (having the same vertical axis coordinates) is obtained. (4) Therefore, basically, the wrist singularity locus S ₁ S ₂
The shortest distance between the robot path P _c P _t is expressed by the following equation (16).

(S ₀ P ₀ ) ² = (S ₀ H ₀ ) ² + (H ₀ P ₀ ) ² (16) However, in detail, S and H are the wrist singular point trajectory and the projected trajectory, respectively. Is determined based on whether or not there is a difference between the cases described above. In addition, the case where the point in the space is on the line segment is represented by ⊆, and the case where it is not present is represented by ⊃.

[0066]

(Equation 8)

The shortest distance between the robot trajectory in the horizontal painting operation and the robot trajectory in the vertical painting operation thus determined and the trajectory of the wrist singular point is determined, and the shortest distance is compared with an allowable value. Then, the accuracy of the trajectory is evaluated.

Therefore, the accuracy of the robot trajectory can be evaluated very quickly and easily as compared with the case where the Jacobian matrix is used. According to the above evaluation, if the robot trajectory passes through the singular region, it can be corrected very easily by moving the robot origin so that the shortest distance exceeds the allowable value. it can.

[0069]

As described above, according to each accuracy evaluation method of the present invention, the shortest distance between the robot trajectory, for example, the robot trajectory in the horizontal operation or the robot trajectory in the vertical operation, and the wrist singular point trajectory is determined. Find the shortest distance and tolerance,
That is, since the evaluation is performed by comparing the distance with which an error occurs near the singular point, the trajectory accuracy can be evaluated very quickly and easily without using the Jacobi matrix. .

[Brief description of the drawings]

FIG. 1 is a bird's-eye view of a main part of an object to be painted in an embodiment of the present invention.

FIG. 2 is a flowchart showing a schematic procedure for generating a robot trajectory according to the embodiment;

FIG. 3 is a schematic diagram showing a unique posture of the robot according to the embodiment.

FIG. 4 is a diagram showing errors in the tool tip and tool posture when the robot passes near a singular point of the robot in the embodiment.

FIG. 5 is a graph showing a measurement result of a trajectory error in the robot according to the embodiment.

FIG. 6 is a graph showing a measurement result of a target position error on a coating surface in the robot according to the embodiment.

FIG. 7 is a graph showing a relationship between a robot trajectory and a unique region of the robot in the embodiment.

FIG. 8 is a graph showing a relationship between a robot posture and its unique region in the embodiment.

FIG. 9 is a schematic diagram showing a range of a trajectory of a singular point of a wrist of the robot in the embodiment.

FIG. 10 is a perspective view illustrating a procedure for obtaining the shortest distance between the robot trajectory and the wrist singularity trajectory in horizontal painting in the embodiment.

FIG. 11 is a perspective view illustrating a procedure for obtaining the shortest distance between the robot trajectory and the wrist singularity trajectory in the horizontal painting in the embodiment.

FIG. 12 is a perspective view illustrating a procedure for obtaining a shortest distance between a robot trajectory and a wrist singularity trajectory in vertical painting according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Hull block 2 Hull outer plate 3 Beam material 4 Partition material 21 Tool 31 Robot 32 Wrist part 33 Forearm part 34 Center of rotation 35 First joint axis 36 Center axis of rotation 41 Singular point locus 42 Singular area _{Pc Pt} robot trajectory S ₁ S ₂ Wrist singular point trajectory _Pi search point _Pi π Projection point (first intersection) S _ci intersection (second intersection) h Shortest distance r _s tolerance

Claims (3)

[Claims] 1. A wrist singular point trajectory of a robot is obtained based on a tool posture, a robot specification, and a robot operation range when a predetermined operation is performed by the robot, and the trajectory is obtained according to the wrist singular point trajectory and a work object. A method for evaluating the accuracy of a robot trajectory, comprising determining a shortest distance from an obtained robot trajectory and evaluating the accuracy of the robot trajectory based on whether the shortest distance is within an allowable value. 2. An arc-shaped wrist singular point trajectory of a robot is determined based on a tool posture, a robot specification, and a robot operation range when a predetermined operation is performed by the robot. A robot trajectory accuracy evaluation method for determining the shortest distance to the robot trajectory in the horizontal work determined in accordance with the above, and evaluating the accuracy of the robot trajectory based on whether the shortest distance is within an allowable value. To determine the shortest distance, a perpendicular line is drawn from a predetermined point on the robot trajectory on a plane including the arc-shaped wrist singular point trajectory, and the first intersection point is obtained. The first intersection point and the arc-shaped wrist singular point trajectory are determined. A second intersection point between a straight line connecting the center point of the above and the plane is obtained, and these predetermined points,
The distance between a predetermined point on the robot trajectory and the second intersection on the trajectory of the wrist singular point is determined by applying the three-square theorem to the first and second intersections. And a method for repeatedly evaluating the accuracy of the robot trajectory, wherein the shortest one of the obtained distances is set as the shortest distance. 3. An arc-shaped wrist singular point trajectory of the robot is determined based on a tool posture, a robot specification, and a robot operation range when a predetermined operation is performed by the robot. A robot trajectory accuracy evaluation method for determining the shortest distance from the robot trajectory in the vertical work determined in accordance with the above, and evaluating the accuracy of the robot trajectory by determining whether the shortest distance is within an allowable value. To determine the shortest distance, the robot trajectory is projected on a plane containing the arc-shaped wrist singular point trajectory to obtain a projected trajectory, and a perpendicular is drawn on the projected trajectory from the center point of the arc-shaped wrist singular point trajectory. A first intersection with the projected trajectory and a second intersection with the trajectory of the wrist singular point are determined, and a corresponding point on the robot trajectory corresponding to the first intersection is determined. And accuracy evaluation method robot path, characterized in that the distance between the second intersection point to the shortest distance.