CN113341886B - Smooth feed speed planning method, device and computer readable storage medium - Google Patents
Smooth feed speed planning method, device and computer readable storage medium Download PDFInfo
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- CN113341886B CN113341886B CN202110569695.5A CN202110569695A CN113341886B CN 113341886 B CN113341886 B CN 113341886B CN 202110569695 A CN202110569695 A CN 202110569695A CN 113341886 B CN113341886 B CN 113341886B
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/416—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control of velocity, acceleration or deceleration
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- G—PHYSICS
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/34—Director, elements to supervisory
- G05B2219/34432—Speed and current control integrated into nc control system
Abstract
The embodiment of the invention provides a smooth feeding speed planning method, a device and a computer readable storage medium, wherein the method comprises the following steps: acquiring a processing path, wherein the processing path comprises a plurality of line segment tracks which are sequentially connected end to end; generating an approximate curve of the processing path, wherein the joint point of the approximate curve corresponds to the joint point of the line segment track; and generating the constraint speed of each joint point on the approximation curve, and taking the constraint speed of the joint point of the approximation curve as the constraint speed of the corresponding joint point of the line segment track. According to the embodiment of the invention, the problem of frequent acceleration and deceleration caused by a feeding speed constraint mode based on included angle deceleration can be avoided by constructing the approximation curve and obtaining the constraint speed of the corresponding connection point of the processing path according to the approximation curve, so that the processing efficiency and the processing quality of the control system are improved.
Description
Technical Field
The embodiment of the invention relates to the field of numerical control systems, in particular to a smooth feeding speed planning method, smooth feeding speed planning equipment and a computer readable storage medium.
Background
The general flow of numerical control machining is that a workpiece geometric model is obtained through CAD/CAM software through design or reverse engineering, a curved surface/plane is dispersed into a cutter path through the CAD/CAM software based on preset parameters, wherein the cutter path is a straight line, a circular arc, a smooth spline curve or a discrete point directly, and then the original cutter path is converted into a machining program meeting the grammatical requirements of a numerical control system program through a post-processing program.
Since the linear and circular interpolation is a common function of all numerical control systems, the machining path generated by the post-processing program is generally a discrete path to the original tool path within a certain tolerance range, that is, when the original path is a smooth spline curve, the original path is also discrete into small line segments. Sometimes, according to the process requirement, the original circular arc path is also scattered into small line segments, and the machining path finally input into the numerical control system is generally a line segment or a circular arc.
Because the machining path is essentially a discrete approximation to the original tool path, the approximation error is a discrete tolerance, if the original path is a smooth path, the discrete path is not smooth, an included angle is formed between adjacent paths, and the direction is suddenly changed when the feeding speed passes through a connecting point, so that the acceleration for changing the speed direction exists, and the larger the included angle is, the larger the feeding speed is, the larger the acceleration is needed to change the direction. For a fixed machining path, the included path angle is fixed, and for a general numerical control machine tool, the maximum acceleration of each axis is also fixed, so that in order to ensure machining stability, the numerical control system needs to reduce the feed speed at a track joint point to ensure that the acceleration does not exceed the limit of the system.
According to the characteristics of the workpiece, the smooth curved surface of the workpiece is processed at a higher feeding speed, so that curved surface processing defects are avoided. Due to the existence of discrete tracks, original smooth tracks are converted into discrete tracks with included angles, and the existing feeding speed constraint mode based on speed reduction of the included angles can often lead the feeding speed of the joint points of the tracks to be very low, so that frequent addition and subtraction of the feeding speed are caused, the processing efficiency is reduced, and the final processing quality is also influenced.
Disclosure of Invention
The embodiment of the invention provides a smooth feeding speed planning method, equipment and a computer readable storage medium, aiming at the problems that the feeding speed is frequently changed and the processing efficiency and the processing quality are reduced by the feeding speed constraint mode based on the included angle speed reduction.
The technical solution for solving the above technical problem according to an embodiment of the present invention is to provide a method for planning a smooth feeding speed, including:
acquiring a processing path, wherein the processing path comprises a plurality of line segment tracks which are sequentially connected end to end;
generating an approximate curve of the processing path, wherein the joint point of the approximate curve corresponds to the joint point of the line segment track;
and generating the constraint speed of each connection point on the approximation curve, and taking the constraint speed of the connection point of the approximation curve as the constraint speed of the corresponding connection point of the line segment track.
As a further improvement of the present invention, the generating a constraint speed of each junction point on the approximation curve includes:
obtaining a first speed tangent vector of an approximation curve taking the joint point as an end point at the joint point, and obtaining a second speed tangent vector of the approximation curve taking the joint point as a starting point at the joint point;
acquiring a minimum curvature acceleration proportionality coefficient at the junction point when the first speed cut vector and the second speed cut vector coincide, and making a constraint speed of the junction point a command feed speed when the minimum curvature acceleration proportionality coefficient is greater than or equal to 1, and making a product of the minimum curvature acceleration proportionality coefficient and the command feed speed as a constraint speed of the junction point when the minimum curvature acceleration proportionality coefficient is less than 1;
when the first speed cut vector and the second speed cut vector do not coincide, respectively obtaining a minimum curvature acceleration proportional coefficient and a minimum corner acceleration proportional coefficient of the joint point, when the smaller one of the minimum curvature acceleration proportional coefficient and the minimum corner acceleration proportional coefficient is greater than or equal to 1, making the constraint speed of the joint point be a command feed speed, and when the smaller one of the minimum curvature acceleration proportional coefficient and the minimum corner acceleration proportional coefficient is less than 1, taking the product of the smaller one of the minimum curvature acceleration proportional coefficient and the minimum corner acceleration proportional coefficient and the command feed speed as the constraint speed of the joint point.
As a further improvement of the present invention, the minimum curvature acceleration proportionality coefficient is the smallest curvature acceleration proportionality coefficient of all the axes participating in the interpolation, and the curvature acceleration proportionality coefficient of the j-th axis is:
wherein, a max (j) Maximum allowable acceleration of j-th axis, a c (j) The curvature of the approximation curve causes the acceleration generated by the j-th axis when the feeding speed passes through the joint point;
the minimum corner acceleration proportionality coefficient is the smallest one of all the axes participating in interpolation, and the corner acceleration proportionality coefficient of the j-th axis is as follows:
wherein, a a (j) The corners of the approximation curve contribute to the acceleration generated in the j-th axis in order to move the feed speed through the junction.
As a further improvement of the present invention, the generating an approximation curve according to the processing path includes:
respectively obtaining unit tangent vectors of three adjacent line segment tracks;
respectively obtaining average unit tangent vectors of the three adjacent line segment tracks at two connecting points;
and constructing a cubic polynomial curve according to the two connecting points and the average unit tangent vectors of the two connecting points, and taking the cubic polynomial curve as an approximation curve.
As a further improvement of the invention, the cubic polynomial curve F i (s) satisfies:
F i (0)＝Q i ,F i (s i )＝Q i+1
F i ′(0)＝D i ,F i ′(s i )＝D i+1
wherein Q i 、Q i+1 Joining points for the three adjacent line segment trajectories, D i 、D i+1 Is the mean unit tangent vector, s, of the three adjacent line segment trajectories at two junction points i Is a line segment Q with two of the connection points as end points i Q i+1 Of the length of (c).
As a further improvement of the present invention, the generating an approximation curve according to the processing path further includes:
acquiring the maximum approximation error of a point on the approximation curve;
and when the maximum approximation error is larger than the maximum allowable approximation error, adjusting the approximation curve by using the maximum approximation error.
As a further improvement of the present invention, said adjusting said approximation curve using said maximum approximation error comprises:
adjusting the approximation curve by the following calculation:
H i (s)＝G i (s)+C i,f ·(F i (s)-G i (s))
wherein H i (s) is the approximation curve after adjustment, G i (s) is a line segment with two junctions as endpoints, F i (s) is the approximation curve before adjustment,
and e tol Maximum allowed approximation error, e max,i The maximum approximation error of the approximation curve before adjustment is obtained.
As a further improvement of the present invention, the method further comprises:
and when the minimum curvature acceleration proportionality coefficient of the non-connection point is less than 1, taking the product of the minimum curvature acceleration proportionality coefficient of the non-connection point and the command feed speed as the constraint speed of the non-connection point.
The embodiment of the invention also provides smooth feeding speed planning equipment, which comprises a processor and a memory, wherein the memory is in communication connection with the processor; wherein the memory stores instructions executable by the processor to enable the processor to perform the smooth feed speed planning method as described above.
Embodiments of the present invention also provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the smooth feed speed planning method as described above.
According to the smooth feeding speed planning method, the smooth feeding speed planning equipment and the computer readable storage medium, the approaching curve is constructed, and the constraint speed of the corresponding connection point of the processing path is obtained according to the approaching curve, so that the problem of frequent acceleration and deceleration caused by a feeding speed constraint mode based on included angle deceleration can be solved, and the processing efficiency and the processing quality of the control system are improved.
Drawings
FIG. 1 is a schematic flow chart diagram of a smooth feed rate planning method according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating the generation of constraint speed of a joint point in a smooth feed speed planning method according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a constraint speed for generating a junction point in a smooth feed speed planning method according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart illustrating the generation of an approximation curve in the smooth feed rate planning method according to the embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating the generation of an approximation curve in the smooth feed rate planning method according to an embodiment of the present invention;
FIG. 6 is a schematic illustration of a feed rate profile using a conventional corner constraint plan;
fig. 7 is a schematic diagram of a feed rate profile obtained using a smooth feed rate planning method provided by an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The invention uses the curvature of the connecting point to restrain the feeding speed of the connecting point of the track of the processing path, so that the feeding speed meets the acceleration limit of each axis through the acceleration generated by the connecting point, and simultaneously, the curvature of the track is used in the track to restrain the change of the feeding speed, thereby fully utilizing the continuous characteristic of the curvature of the original smooth track to ensure that the feeding speed is continuously and smoothly changed, so as to improve the processing flexibility and the processing quality.
Fig. 1 is a schematic flow chart of a smooth feed speed planning method according to an embodiment of the present invention, which can be applied to a numerical control system. The smooth feeding speed planning method of the embodiment can be executed by the control system, and can also be executed by a computer device independent of the numerical control system, and the method specifically comprises the following steps:
step S11: and acquiring a processing path which comprises a plurality of line segment tracks connected end to end in sequence. The processing path is a tool operation path when a workpiece is processed, and a plurality of line segment tracks can be obtained through smooth track dispersion.
Correspondingly, the step may specifically include: a series of line segment tracks are read in by a numerical control system, and the obtained end point sequence of the line segment tracks is Q 0 ，Q 1 ，…，Q m And m is an integer greater than or equal to 4, each end point is an n-dimensional track point, and n can be three, for example, so that three-dimensional linkage interpolation is represented.
Step S12: and generating an approximation curve of the processing path, wherein the joint points of the approximation curve correspond to the joint points of the line segment tracks.
In this step, the approximation curve may be a smooth curve (such as a spline curve or a circular arc), and specifically, the end point tangent vector of the approximation curve may be determined according to the tangent vectors of the front and rear line segment tracks at the junction point, so that the approximation curve of the line segment track may be constructed. And, can also calculate and get the approximation error by approximating curve and line segment orbit, if the approximation error is in preserving the tolerance range, think the approximation curve is similar to the line segment orbit in the cutter route, can approximate the geometric feature of the line segment orbit with the geometric feature of the approximation curve; if the approximation error is out of the preset tolerance range, the approximation error is just the preset tolerance by modifying the approximation curve, the modified approximation curve is considered to be similar to the original line segment track, and then the geometric characteristics of the modified approximation curve are used for approximating the geometric characteristics of the original line segment track.
Step S13: and generating the constraint speed of each joint point on the approximation curve, and taking the constraint speed of the joint point of the approximation curve as the constraint speed of the corresponding joint point of the line segment track.
In this embodiment, the constraint speed approximating the junction on the curve may be a constraint speed formed by the curvature at the junction, and a constraint speed formed by the corner at the junction.
According to the smooth feeding speed planning method, the approximation curve is constructed, and the constraint speed of the corresponding connection point of the processing path is obtained according to the approximation curve, so that the feeding speed of the corresponding point on the processing path is constrained when a workpiece is processed, the problem of frequent acceleration and deceleration caused by the feeding speed constraint mode based on the included angle deceleration is solved, and the processing efficiency and the processing quality of the control system are improved.
In an embodiment of the present invention, as shown in fig. 2 to 3, the generating of the constraint speed of each connection point on the approximation curve in step S13 specifically includes:
step S131: obtaining to join point Q i+1 Approximation curve Q for the end point i Q i+1 First velocity tangent vector V at the junction e,i And obtaining the connection point Q i+1 Approximation curve Q as starting point i+1 Q i+2 At the connection point Q i+1 Second velocity tangent vector V of (d) s,i+1 。
In fig. 3, a straight line Q is assumed i Q i+1 And a straight line Q i+1 Q i+2 Adjacent line segment locus, curve Q, read in for numerical control system i Q i+1 And curve Q i+1 Q i+2 Are respectively a straight line Q i Q i+1 And a straight line Q i+1 Q i+2 Is approximated by a curve. In this step, the approximation curve Q may be calculated first i Q i+1 And Q i+1 Q i+2 Point A with upper command speed tangent parallel to original line segment track i And A i+1 And obtaining the speed tangent vector V of the two points i And V i+1 And the running time t of the two points from the end point of the line segment e,i And t s,i+1 (ii) a Then, an approximation curve Q is calculated i Q i+1 And Q i+1 Q i+2 At the track connection point Q i+1 First velocity tangent vector V of e,i And a second velocity tangent vector V s,i+1 。
Step S132: judging the first speed tangent vector V e,i And a second velocity tangent vector V s,i+1 Whether they coincide. If the first speed tangent vector V e,i And a second velocity tangent vector V s,i+1 If so, step S133 is executed, otherwise, step S134 is executed.
In general, the first velocity vector V is the first velocity vector if the approximation curve is not modified e,i And a second velocity tangent vector V s,i+1 Is equal to the commanded speed, and the first speed tangent vector V e,i And a second velocity tangent vector V s,i+1 Overlapping; if the approximation curve is modified, the first velocity vector V is e,i And a second velocity tangent vector V s,i+1 The length of the two lines is determined by the modified approximate curve, the two lines are not coincident, and an included angle exists between the two lines.
Step S133: obtaining the junction point Q i+1 Minimum curvature acceleration proportionality coefficient c min And at the minimum curvature acceleration proportionality coefficient c min Greater than or equal to 1 (i.e. c) min Not less than 1), making the connection point Q i+1 The constraint speed of (2) being a command feed speed V p I.e. without constraining the commanded feed rate; acceleration proportionality coefficient less than 1 at minimum curvature (i.e. c) min When < 1), the minimum curvature acceleration proportionality coefficient c min And a command feed speed V p Product of c min ×V p As a contact point Q i+1 The constraint speed of (2).
Tangent at first speed V e,i And a second velocity tangent vector V s,i+1 At the time of coincidence, the feed speed passes through the junction point Q i+1 Only the curvature of the trajectory of the line segment causes a change in the direction of the feed speed. If approaching the curve Q i Q i+1 And Q i+1 Q i+2 The point where the upper command speed tangent is parallel to the original line segment track and the connecting point Q i+1 There are n axes participating in the interpolation, and accordingly, the speed tangent vector of each axis speed participating in the interpolation can be expressed as:
accordingly, considering the curvature factor, the acceleration generated by the j-th axis when the feeding speed passes through the trajectory engagement point is:
namely a c (j) The curvature of the approximation curve causes an acceleration in the j-th axis as the feed speed passes through the junction. If the maximum allowable acceleration of the j-th axis is a max (j) Then, the curvature acceleration proportionality coefficient of the j-th axis is:
accordingly, the minimum curvature acceleration proportionality coefficient is the smallest curvature acceleration proportionality coefficient of all the axes participating in the interpolation, namely:
step S134: separately obtain the connection points Q i+1 And at the minimum curvature acceleration proportionality coefficient c min And a minimum corner acceleration proportionality coefficient k min The smaller one is greater than or equal to 1, the connection point Q is connected i+1 Is the commanded feed speed, and at said minimum curvature acceleration proportionality coefficient c min And a minimum corner acceleration proportionality coefficient k min The smaller one is less than 1, the minimum curvature acceleration proportionality coefficient c is set min And a minimum corner acceleration proportionality coefficient k min The smaller of the two and the command feed speed V p The product of (a) is taken as a connecting point Q i+1 Speed of constraint, i.e. engagement point Q i+1 With a constraint speed of min(V p ×c min ，V p ×k min )。
Tangent at first speed V e,i And a second velocity tangent vector V s,i+1 At an included angle, the feed speed passes through the junction point Q i+1 In the process, the curvature of the line segment track not only causes the change of the direction of the feeding speed, but also causes the change of the direction of the feeding speed due to the included angle of the line segment track. Thus, in addition to the need to calculate the minimum curvature acceleration proportionality coefficient c min In addition to (by the method in step S133), the minimum corner acceleration proportionality coefficient k needs to be calculated min 。
Similarly, considering the angle factor, as the feed rate passes through the trajectory engagement point Q i+1 The acceleration generated by the j-th axis is:
namely a a (j) The corners of the approximation curve promote acceleration in the j-th axis when the feed speed passes through the junction, where T s Is an interpolation period. Accordingly, the corner acceleration proportionality coefficient for the j-th axis is:
the minimum corner acceleration proportionality coefficient is the smallest one of all the axes participating in interpolation, namely:
traversing all the joints as above can obtain a series of constrained velocities of the joints, where the velocities of the first and last joints are typically 0. After the splice point feed speed constraint, a look-ahead planning process of the numerical control system determines the final splice point speed.
Of course, in practical applications, other ways of generating the constraint speed for each of the engagement points on the approximation curve may be used. In the interpolation process, in order to ensure that the feeding speed continuously and smoothly changes in the track and avoid unnecessary acceleration and deceleration processes, the feeding speed is restrained by calculating the curvature speed of each point in the track, so that the change of the feeding speed conforms to the change rule of the curvature of the track. And because the curvature change of the smooth track is continuous and smooth, the change of the feeding speed constrained by the curvature speed is also continuous and smooth, thereby further improving the motion stability and the processing quality.
In an embodiment of the present invention, as shown in fig. 4 to 5, the generating an approximation curve according to the processing path in step S12 may specifically include the following steps:
step S121: and respectively acquiring unit tangent vectors of three adjacent line segment tracks.
The method comprises the following steps of obtaining four adjacent continuous vertexes Q in a line segment track endpoint sequence i-1 ，Q i ，Q i+1 ，Q i+2 I.e. obtaining three line segments Q i-1 Q i ，Q i Q i+1 ，Q i+1 Q i+2 。
Step S122: respectively obtaining three adjacent line segment tracks Q i-1 Q i ，Q i Q i+1 ，Q i+1 Q i+2 At two connecting points Q i 、Q i+1 The average unit tangent vector of (d).
In this step, first three line segments Q are calculated i-1 Q i ，Q i Q i+1 ，Q i+1 Q i+2 Unit tangent vector T of i-1 And T i+1 The method specifically comprises the following steps:
wherein "| | |" is a modulo operation.
Then, calculating the locus of the adjacent line segments at the joint point Q i 、Q i+1 Mean unit tangent vector D of i And D i+1 ：
Step S123: and constructing a cubic polynomial curve according to the two connecting points and the average unit tangent vectors of the two connecting points, and taking the cubic polynomial curve as an approximation curve.
In this step, the connection point Q can be determined according to the above i 、Q i+1 And mean unit tangent D at the junction i And D i+1 Constructing a cubic polynomial function curve F i (s) and a cubic polynomial function curve F i (s) satisfies:
where s is a curve parameter, s i Is a straight line segment Q with two connecting points as end points i Q i+1 I.e.:
s i ＝||Q i+1 -Q i || (11)
the cubic polynomial function curve can be obtained as follows:
wherein s is a curve parameter, s i Is a straight line segment Q i Q i+1 The length of (d) is represented by equation (11).
The above calculation formula (12) can be simplified as follows:
F i (s)＝c 3,i s 3 +c 2,i s 2 +c 1,i s+c 0,i (13)
wherein, c 2,i 、c 2,i 、c 1,i Respectively, a cubic polynomial function curve F i Cubic term, quadratic term, coefficient of primary term of(s), c 0,i As a curve F of a cubic polynomial function i A constant term for(s).
In one embodiment of the present invention, the approximation error may also be calculated from the approximation curve and the trajectory of the line segment. If the approximation error is within the preset tolerance range, the approximation curve is considered to be approximate to the original tool path, and the geometric characteristics of the approximation curve can be used for approximating the geometric characteristics of the original tool path; if the approximation error is out of the preset tolerance range, the approximation error is just equal to the preset tolerance by modifying the approximation curve, the modified approximation curve is considered to be approximate to the original tool path, and the geometric characteristics of the modified approximation curve can be used for approximating the geometric characteristics of the original tool path.
Accordingly, step S12 in fig. 1 may further include: and acquiring the maximum approximation error of a point on the approximation curve, and adjusting the approximation curve by using the maximum approximation error when the maximum approximation error is larger than the maximum allowable approximation error.
In particular, use is made of F i (s) approximating straight-line segment Q i Q i+1 Its approximation error vector can be calculated as:
E i (s)＝F i (s)-G i (s) (14)
wherein G is i (s) is a straight line segment Q i Q i+1 The vector description of (a), namely:
G i (s)＝Q i +T i ×s (15)
accordingly, curve F is approximated i The true approximation error of any point on(s) is:
e i (s)＝||E i (s)×T i ||＝||F i (s)-G i (s)×T i || (16)
the maximum approximation error can be found by analytical or numerical methods:
if the maximum allowable approximation error is e tol If e is max,i ≤e tol Then is approximated to curve F i (s) no modification is required; otherwise, the approximation curve is modified as:
H i (s)＝G i (s)+C i,f ·(F i (s)-G i (s)) (18)
wherein:
approximation curve F without modification for unification i (s) and modified curve H i The expression of(s) can be set as C when emax, i is less than or equal to etol f，i =1, then the approximation curve F without modification i (s) and modified Curve H i The expression of(s) can be uniformly expressed as:
of course, in practical application, other ways to generate the approximation curve of the line segment trajectory may be used.
In an embodiment of the present invention, the method further includes: the method comprises the steps of obtaining a minimum curvature acceleration proportionality coefficient at a non-connection point on a processing path, enabling a constraint speed of the non-connection point to be a command feed speed when the minimum curvature acceleration proportionality coefficient at the non-connection point is larger than or equal to 1, and enabling a product of the minimum curvature acceleration proportionality coefficient of the non-connection point and the command feed speed to be used as the constraint speed of the non-connection point when the minimum curvature acceleration proportionality coefficient of the non-connection point is smaller than 1.
When the same machining program and the same set of machining parameters are used, the traditional corner constraint method and the smooth feeding speed planning method are respectively used for machining, the line segment track speed planned by the traditional corner constraint method is shown in fig. 6, and as can be seen from the figure, the feeding speed has great fluctuation, frequent acceleration and deceleration processes are realized, and the whole machining time is 1466 milliseconds; fig. 7 shows the line segment trajectory speed planned by the smooth feeding speed planning method of the present invention, and it can be seen from the figure that the feeding speed has almost no fluctuation, has a smooth change process, and has no frequent acceleration and deceleration processes, the overall feeding speed is improved compared with the conventional method, and the whole processing time is 1225 milliseconds. Compared with the traditional method, the smooth feeding speed planning method reduces the processing time by 16.4 percent, thereby greatly improving the processing efficiency; from the viewpoint of feed speed smoothness, the method of the present invention has better speed smoothness than the conventional method, and therefore the final processing quality can be improved.
The embodiment of the invention also provides smooth feeding speed planning equipment which can be composed of a data system and computer equipment independent of a numerical control system, and comprises a processor and a memory in communication connection with the processor; wherein the memory stores instructions executable by the processor to enable the processor to perform a smooth feed rate planning method as described in the corresponding embodiments of fig. 1-5.
The smooth feed rate planning apparatus in this embodiment and the smooth feed rate planning method in the embodiment corresponding to fig. 1 to 5 belong to the same concept, and specific implementation processes thereof are detailed in the corresponding method embodiments, and technical features in the method embodiments are applicable in the apparatus embodiments, and are not described again here.
Embodiments of the present invention further provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform a smooth feed speed planning method according to embodiments corresponding to fig. 1 to 5.
The computer readable storage medium in this embodiment and the smooth feed speed planning method in the embodiment corresponding to fig. 1 to 5 belong to the same concept, and the specific implementation process thereof is detailed in the corresponding method embodiment, and the technical features in the method embodiment are all correspondingly applicable in this apparatus embodiment, which is not described again here.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
It is obvious to those skilled in the art that, for convenience and simplicity of description, the foregoing functional units and modules are merely illustrated in terms of division, and in practical applications, the foregoing functions may be distributed as needed by different functional units and modules. Each functional unit and module in the embodiments may be integrated in one processor, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only used for distinguishing one functional unit from another, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the description of each embodiment has its own emphasis, and reference may be made to the related description of other embodiments for parts that are not described or recited in any embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed smooth feed speed planning method, apparatus and storage medium may be implemented in other ways. For example, the smooth feed rate planner apparatus embodiments described above are merely illustrative.
In addition, functional units in the embodiments of the present application may be integrated into one processor, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated module/unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method of the embodiments described above can be realized by a computer program, which can be stored in a computer-readable storage medium and can realize the steps of the embodiments of the methods described above when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any physical or interface switching device, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signal, telecommunication signal, software distribution medium or the like capable of carrying said computer program code. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media which may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (10)
1. A smooth feed speed planning method, comprising:
acquiring a processing path, wherein the processing path comprises a plurality of line segment tracks which are sequentially connected end to end;
generating an approximation curve of the processing path, wherein a joint point of the approximation curve corresponds to a joint point of the line segment tracks, and an end point tangent vector of the approximation curve is determined according to tangent vectors of the front line segment track and the rear line segment track at the joint point;
generating a constraint speed of each connection point on the approximation curve, and taking the constraint speed of the connection point of the approximation curve as the constraint speed of the corresponding connection point of the line segment track; the constraint speed of the joining point on the approximation curve is a constraint speed formed by the curvature of the joining point or a constraint speed formed by the corner of the joining point.
2. The smooth feed speed planning method according to claim 1, wherein the generating a constraint speed for each junction point on the approximation curve comprises:
obtaining a first speed tangent vector of an approximation curve taking the joint point as an end point at the joint point, and obtaining a second speed tangent vector of the approximation curve taking the joint point as a starting point at the joint point;
acquiring a minimum curvature acceleration proportionality coefficient at the junction point when the first speed cut vector and the second speed cut vector coincide, and making a constraint speed of the junction point a command feed speed when the minimum curvature acceleration proportionality coefficient is greater than or equal to 1, and making a product of the minimum curvature acceleration proportionality coefficient and the command feed speed as a constraint speed of the junction point when the minimum curvature acceleration proportionality coefficient is less than 1;
when the first speed cut vector and the second speed cut vector do not coincide, respectively obtaining a minimum curvature acceleration proportionality coefficient and a minimum corner acceleration proportionality coefficient of the joint point, when the smaller one of the minimum curvature acceleration proportionality coefficient and the minimum corner acceleration proportionality coefficient is larger than or equal to 1, enabling the constraint speed of the joint point to be a command feed speed, and when the smaller one of the minimum curvature acceleration proportionality coefficient and the minimum corner acceleration proportionality coefficient is smaller than 1, enabling the product of the smaller one of the minimum curvature acceleration proportionality coefficient and the minimum corner acceleration proportionality coefficient and the command feed speed to be used as the constraint speed of the joint point.
3. The smooth feed rate planning method according to claim 2, wherein the minimum curvature acceleration scaling factor is the smallest curvature acceleration scaling factor among all the axes participating in the interpolation, and the curvature acceleration scaling factor of the j-th axis is:
wherein, a max (j) Is the maximum allowable acceleration of the j-th axis, a c (j) The curvature of the approximation curve causes the acceleration generated by the j-th axis when the feeding speed passes through the joint point;
the minimum corner acceleration proportionality coefficient is the smallest one of all the axes participating in interpolation, and the corner acceleration proportionality coefficient of the j-th axis is as follows:
wherein, a a (j) The corners of the approximation curve contribute to the acceleration generated in the j-th axis in order to move the feed speed through the junction.
4. The smooth feed rate planning method of any of claims 1-3 wherein the generating an approximation of the machine path comprises:
respectively obtaining unit tangent vectors of three adjacent line segment tracks;
respectively obtaining average unit tangent vectors of the three adjacent line segment tracks at two connecting points;
and constructing a cubic polynomial curve according to the two connecting points and the average unit tangent vectors of the two connecting points, and taking the cubic polynomial curve as an approximation curve.
5. The smooth feed speed planning method according to claim 4, characterised in that the cubic polynomial curve F i (s) satisfies:
F i (0)＝Q i ,F i (s i )＝Q i+1
F i ′(0)＝D i ,F i ′(s i )＝D i+1
wherein Q is i 、Q i+1 Joining points for the three adjacent line segment trajectories, D i 、D i+1 Is the mean unit tangent vector, s, of the three adjacent line segment trajectories at two junction points i Is a line segment Q with two of the connection points as end points i Q i+1 Length of (d).
6. The smooth feed rate planning method of claim 5 wherein generating an approximation of the tool path further comprises:
acquiring the maximum approximation error of a point on the approximation curve;
and when the maximum approximation error is larger than the maximum allowable approximation error, adjusting the approximation curve by using the maximum approximation error.
7. The smooth feed rate planning method of claim 6 wherein said adjusting the approximation curve using the maximum approximation error comprises:
adjusting the approximation curve by:
H i (s)＝G i (s)+C i,f ·(F i (s)-G i (s))
wherein H i (s) is the approximation curve after adjustment, G i (s) is a line segment with two junctions as endpoints, F i (s) is the approximation curve before adjustment,
and e tol Maximum allowed approximation error, e max,i The maximum approximation error of the approximation curve before adjustment is obtained.
8. The smooth feed speed planning method according to claim 1, further comprising:
and when the minimum curvature acceleration proportionality coefficient of the non-connection point is less than 1, taking the product of the minimum curvature acceleration proportionality coefficient of the non-connection point and the command feed speed as the constraint speed of the non-connection point.
9. A smooth feed speed planner comprising a processor and a memory communicatively coupled to the processor; wherein the memory stores instructions executable by the processor to enable the processor to perform the smooth feed speed planning method of any one of claims 1 to 8.
10. A computer-readable storage medium having computer-executable instructions stored thereon for causing a computer to perform the smooth feed speed planning method of any one of claims 1 to 8.
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