WO2002033815A1

WO2002033815A1 - Method for controlling acceleration/deceleration of motor

Info

Publication number: WO2002033815A1
Application number: PCT/JP2000/007198
Authority: WO
Inventors: Tomoaki Hachiya; Masashi Nakayama; Yuuichi Komazawa
Original assignee: Technowave, Ltd.
Priority date: 2000-10-17
Filing date: 2000-10-17
Publication date: 2002-04-25

Abstract

A method for controlling acceleration/deceleration of a motor for mechanical operation is characterized by comprising the steps of receiving command variables including at least one of the target position, speed, trace shape, acceleration, calculating a step width (ΔT ) of an internal time using the received command variable, receiving a speed changing command from outside, calculating a variable internal step width (σTn), from the value of the speed changing command and the ΔT, calculating a step width (dTn) of the internal time which is smoothly varied by performing an internal time acceleration/deceleration processing using a filter based on the σTn, updating the internal time using the dTn, and calculating position data for every interpolation period applied to the motor based on the updated internal time. A software for realizing the same is also disclosed. By the method, even if the command speed is changed, no shock is applied to the motor, the acceleration/deceleration is smoothly performed, and thereby the precision of the trace can be improved.

Description

TECHNICAL FIELD The present invention relates to a method of controlling acceleration and deceleration of a motor for machine operation and software used for the method, and more particularly, to a method of performing smooth acceleration and deceleration without giving a shock to the motor. The present invention relates to a method for controlling acceleration and deceleration of a machine operation motor for improving trajectory accuracy and software used for the method. BACKGROUND ART The motor used to drive each axis, such as a multi-axis machine or an articulated robot, is subject to the weight of the operating axis and inertia. It does not operate on the same trajectory, so it is necessary to perform appropriate acceleration / deceleration control while reaching the target coordinate position from the starting coordinate position. FIG. 5 shows a general schematic flow of such a control method. When an operation command is issued by a machining program, an interpolation process is executed, whereby position data for each interpolation cycle is calculated, and The motor is driven via the single point processing system. Also, although not shown, the servo processing system always reads the feed nozzle position data using the encoder attached to the motor.

Machining program is provided by G code, teaching play back, etc. It indicates the target position, the moving speed, the shape of the trajectory such as a straight line or an arc, and the caro speed. Here, as shown in Fig. 6, an operation command for a trajectory shape orthogonal to the XY 2-axis (moving from? 0 to? 1 in the X direction first, then moving from P1 to P2 in the Y direction) The following describes an example of the speed and the trajectory operation when.

At this time, the simplest interpolation processing is as shown in Fig. 7. However, in practice, it is impossible to make the device have a constant speed V0 due to the weight of the mechanical system and the indignation during operation.

Therefore, it is necessary to perform acceleration / deceleration control so that the speed is continuous in the interpolation. Therefore, the acceleration / deceleration method before interpolation was devised.

This method is a method of calculating so that the speed is continuous at the stage of generating the data for interpolating the trajectory. As a calculation method for making the speed continuous, use of a spline function or the like can be mentioned.

Fig. 8 shows an example of the execution procedure by this method. In this example, the interpolation cycle is divided into fixed intervals T, and the concept of an internal time Tn that changes by this interval is used. The position data is given as a function of the internal time Tn.

Fig. 9 shows an example of control using this method.

The advantage of this method is that the trajectory can be kept unchanged even if the speed is changed. On the other hand, the disadvantage is that it is practically impossible to change the speed or make a temporary stop on the way. This is often a fatal problem in the field where machine tools are actually used. On the other hand, there is a system called a filter system that can change the speed or stop during the operation.

This method prepares a FIF buffer of a certain length, records the data obtained by interpolating the trajectory in the buffer while receiving it every moment, and averages the data in the buffer. This is a method of controlling the data of this, and is a method of performing so-called smoothing. That is, as shown in FIG. 10, a step of acceleration / deceleration processing is provided after the execution calculation processing for interpolation. An example of control by this method is shown in Fig. 11 (a). The case where the speed is 100% and the case where the speed is 50% are shown.

The advantage of this method is that once the interpolated data stops, it stops completely and smoothly after a certain period of time according to the buffer length. Even if a pause is applied, acceleration / deceleration can be stopped smoothly.

However, as shown in Fig. 11 (b), changing the speed changes the motion trajectory.

Trajectory due to acceleration / deceleration; The degree of It becomes a problem when trying to control the position and orientation of the effect point (or the tool attached ahead) with more than two degrees of freedom. In the case of one degree of freedom, no matter what kind of acceleration or deceleration, the time of passing through a certain point only changes, and the trajectory does not change. In the case of two or more degrees of freedom, in order to control the effect point to a certain position and attitude, multiple axes must be coordinated and simultaneously and accurately controlled to the target position of each axis. Here, it is important to be at the same time.

In other words, if the time before or after each axis passes a certain point due to acceleration / deceleration, the effect point will not pass through the target point on the trajectory. For example, the goal of each tool In the case of a machine tool that performs machining in which the passing times for points must match, a time shift leads to a shift in the machining shape, which is a fatal drawback.

Another issue that must be addressed is that if the command speed is changed, the speed change curve due to acceleration / deceleration also changes, so that generally the way the track deviates from the calculated trajectory after acceleration / deceleration also changes. It is. For example, it means that the track force changes between when the robot program is operated at low speed to check the operation of the robot program and when it is operated at the highest speed for actual operation. In other words, confirming operation at low speed is not useful at all.

Therefore, countermeasures such as checking the operation in anticipation of the speed change by relying on intuition and programming a wasteful trajectory for safety are inevitable.

Also, in the case of a processing machine with one degree of freedom or a mouth pot program that moves only one axis at a time, if the operation direction is reversed, it stops at the target point on the outward path due to the acceleration and deceleration of the filter system If the axis movement of the return path is started before, a situation may occur in which the target position is not strictly reached.

—However, in order to prevent this, it is only necessary to wait until the axis operation completely stops once the axis operation on the return path is started, but the tact time, another problem, is sacrificed.

As described above, in the filter method, a decrease in trajectory accuracy or an increase in tact time has been a significant cost increase factor. As described above, the pre-interpolation acceleration / deceleration method is the only method that can accelerate / decelerate without changing the calculation trajectory, but cannot respond to the speed change or pause as described above. Conversely, with the Phil Evening method, how do you change the speed or pause It is possible to respond even if instructed, but the trajectory accuracy is poor.

Therefore, the present invention provides a method having both advantages, that is, a motor control method capable of improving the trajectory accuracy while performing smooth acceleration / deceleration without giving a shock to the motor even when the command speed is changed. The purpose is to provide. DISCLOSURE OF THE INVENTION In order to achieve the above object, the invention according to claim 1

In the interpolation of the coordinate position for acceleration / deceleration control of the machine operation mode, the method of performing continuous speed interpolation using a function that obtains the target position as an output when the elapsed time from the starting point is input,

A method for controlling acceleration and deceleration of motors, wherein the step size of the elapsed time is variable, and the variable step size is smoothed using a filter in the process of interpolation. The invention described in Claim 2 is

A procedure for receiving a command value including at least one of the target position, speed, trajectory shape, and acceleration,

A procedure for calculating an internal time interval T using the received command value, a procedure for receiving an external speed change command,

Variable internal step size based on the value of the speed change command and the T (the procedure for calculating 5 Tn,

Internal time acceleration / deceleration processing using fill time based on d T n:

Procedure to calculate the internal time step width d T n that changes smoothly A procedure for updating the internal time using the d T n; a procedure for calculating position data for each interpolation cycle given to the motor based on the updated internal time;

A method for controlling acceleration and deceleration of a motor for machine operation, characterized by having: The invention described in claim 3 is:

When interpolating the coordinate position for the acceleration / deceleration control of the machine operation motor, a method is used in which continuous time interpolation is performed using a function that can obtain the target position as an output when the elapsed time from the start point is input.

A computer readable program recording program for controlling the acceleration / deceleration of the motor, characterized in that the step width of the elapsed time is variable and the variable step width is smoothed using a filter in the process of interpolation. Recording medium. The invention described in Claim 4 is

Receiving a command value including at least one of a target position, a speed, a trajectory shape, and an acceleration;

Calculating the internal time interval using the received command value; receiving an external speed change command;

A step for calculating a variable internal step width δTn based on the value of the speed change command and the T,

Calculating the internal time step width dTn that smoothly changes by performing the internal time acceleration / deceleration processing using a filter based on (5Tn) —the internal time update processing using the dTn; Based on the updated internal time, the step of calculating position data for each interpolation cycle given to the motor

A computer-readable recording medium storing a program for performing acceleration / deceleration control of a machine operation mode, comprising: The invention described in claim 5 is

Software for performing acceleration / deceleration control of a motor, wherein the step width of the elapsed time is variable, and the variable step width is smoothed using a filter in the process of interpolation. The invention described in claim 6

Using the received command value to calculate the internal time interval ^] T, receiving an external speed change command,

Calculate a variable internal step width δTn based on the value of the speed change command and the T. The internal time acceleration / deceleration processing using a filter based on the δTn is performed.

Calculates the internal time interval d T n that changes smoothly—

Using the above d T n to update the internal time

Based on the updated internal time, the position data for each interpolation cycle This is software for performing acceleration / deceleration control of a motor for machine operation, characterized by having: In the present invention, since one of the goals is to maintain the final trajectory shape, basically, while adopting the acceleration / deceleration method before interpolation, the internal time interval ^ 1 T has been improved to be variable, Furthermore, a filter method is introduced in the process of interpolation. The above-mentioned filter method is to prepare a FIFO buffer of a certain length, record the data with the trajectory interpolated every moment, record it in the buffer, and average the data in the buffer at this time. In this method, data after acceleration / deceleration is used. However, the filtering method adopted in the present invention, that is, the execution timing is different from that of the conventional filtering method. In contrast to the conventional filter method in which filtering is performed after interpolation, in the present invention, filtering is performed in the process of interpolation. In the present invention, in order to use the filter method in the interpolation process, the momentary calculation method using the acceleration / deceleration method before interpolation is converted into the following standard form. In other words, this is a calculation method that defines a function that can obtain the target position as an output when the elapsed time or the time from the start point is input. This method is hereinafter referred to as a variable internal time method.

This change is always feasible. If necessary, the instantaneous target position can be calculated in advance by simulation and stored in a table, and the function can be implemented by referring to the table.

Of course, if an appropriate formula can be found, the function can be defined without wasting storage space. Can be justified.

After such conversion, the input to the function for calculating the target position can be switched not to the actual elapsed time itself but to the smoothly changing internal time that has been subjected to acceleration and deceleration processing in the fill-in method. As described above, a method having both advantages of the acceleration / deceleration method before interpolation and the filter method is realized.

That is, it is possible to receive a speed change command from the outside, thereby enabling smooth acceleration / deceleration without giving a shock to the motor even when the command speed is changed, and improving the trajectory accuracy. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an interpolation processing method according to the present invention.

FIG. 2 is a graph showing an example of performing acceleration / deceleration with a trapezoidal speed change. FIG. 3 is a graph showing an interpolation method according to the present invention.

FIG. 4 is a graph showing an interpolation method according to the present invention.

FIG. 5 is an explanatory diagram showing a schematic execution procedure of a commonly used motor acceleration / deceleration control method.

FIG. 6 is a graph showing a target movement locus.

FIG. 7 is a graph showing the simplest form of interpolation.

FIG. 8 is a diagram showing a conventional interpolation processing method of the pre-interpolation acceleration / deceleration method.

FIG. 9 is a graph showing an interpolation method using a conventional acceleration / deceleration method before interpolation. FIG. 10 is a diagram showing a conventional filtering method interpolation method. FIG. 11 is a graph showing an interpolation method using a conventional filter method. BEST MODE FOR CARRYING OUT THE INVENTION A specific embodiment will be described below with reference to the drawings.

FIG. 1 shows an example of a control method according to the present invention.

First, the target position, moving speed, trajectory shape, and acceleration are input as command values as in the conventional machining program, and the initial time is calculated based on the input command values to calculate the internal time interval T. (S101). Here, among the intermediate data appearing in the calculation process of the subsequent execution calculation process (S105), the one that takes a constant value every time is obtained in the initial calculation process stage. These values are stored in a table consisting of several variables.

Specifically, for example, when performing acceleration / deceleration with a trapezoidal speed change as shown in Fig. 2,

K 1 = -A

Two

K2 = -AT a ² + V _n + T a

K3 = 5-ATa ² + V ₀ -f-Ta + Vj (Tb-Ta)

K 4 =-| A

K5 = (T c-T b) ²

Is calculated, and K 1 to Κ 5 are stored in a variable table. this is, As described later, it is used in execution calculation processing. A in the above equation is the acceleration.

Next, when an external speed change command Wn is instructed by an operator or the like, the speed change processing is performed based on the obtained internal time interval T.

δ Tn = WnT

Is performed (S102). The suffix n changes one by one every interpolation cycle, and all data with n is data that changes every moment. The speed change command input from the outside is the ratio (%) of the actual speed to the original speed, and the sign Wn in the equation is its override (weight), and Wn = 0 when stopped. That is, in the speed changing process, the step width T obtained as a result of the initial calculation process is multiplied by the weight Wn, and the variable internal time step width δTn is obtained by changing the speed every moment.

Next, acceleration / deceleration processing is performed based on the internal time step width changed by the speed change processing (5 Tn).

dTn = filter (<5 Tn)

Is performed (S103). In this acceleration / deceleration processing, the output dTn of this filter is obtained by applying acceleration / deceleration to the step width Τη in the same manner as in the filter method. The internal time update processing power S is performed based on this data (S104). That is, Tn = Tn-i + dTn

Is performed. This process is a process for advancing the internal time using the internal time interval after acceleration / deceleration.

Next, based on the updated internal time Tn and the variable table based on the result of the initial calculation, the execution calculation

Pn = f (Tn) (S105).

f (Tn) is, in the example of FIG.

f (Tn) = L (Tn) + P.

Where L (Tn) is

(1) When Ta is 0≤Tn

-ATn ² + V ₀ T n

2 ⁰

(2) When Ta≤Tn <Tb

^ AT a ² + V ₀ T a + V.CTn-T a)

(3) When Tb≤Tn <Tc

^ AT a ² + V ₀ T a + V Tb-T a)

2. ¹

+ i | A | {; Tc-Tb) ^2- (Tc-Tn) ² }

2 "

(4) When Tc≤Tn

Becomes P above. Is the start position of the step, and PL is the final target position of the step. The sign of A is V. Depending on the size of and.

At this time, if the variable tables (K1 to K5) calculated in advance in the initial calculation process (S101) are used, (1) to (3) in the above formulas are simplified as follows. You.

(1) (K1 · Tn + V 0) Tn

(2) K 2 + V, (Tn-Ta) (3) K3 + K4 (K 5-(Tc— Tn) ² )

The position data P n for each interpolation cycle based on the result of the execution calculation processing is given to the motor via the servo processing system in the same manner as in the past, and the motor is driven. According to this method, the filter processing is performed based on the internal time based on the speed change command, and the execution calculation processing is performed based on this. Therefore, even if there is a speed change, smooth acceleration / deceleration is performed, and at the same time, the output of the execution calculation is Since the output of the function f () is the same as that of the conventional acceleration / deceleration before interpolation, the output exists on the same trajectory, so that the trajectory accuracy is constant. FIG. 3 is an example in which the operation of the present invention is interpolated to output the operation of FIG.

As shown by the dashed line, it rises slightly behind the ideal trapezoid by the time constant, and the fall time during deceleration shifts accordingly (Fig. 3 (a)). However, it is possible to change the speed on the way, and the trajectory accuracy in that case is the same (Fig. 3 (b)). In the method of the present invention shown in FIG. 4 (a), the overlap point is determined by the area of the trapezoid, and the next axial force acceleration is performed before the first axial direction decelerates. Compared to the method shown in Fig. 3, it is possible to shorten the tact time.

In addition, as shown by the broken line in Fig. 4 (b), it is possible to draw the same trajectory at either 100% or 50% speed, and to secure a constant trajectory regardless of the speed. it can. As is apparent from the above description, in the motor acceleration / deceleration control method according to the present invention, the locus accuracy is improved while performing smooth acceleration / deceleration without giving a shock to the motor even when the commanded speed is changed. it can. Industrial applicability From the above characteristics, the control method of the present invention can be applied to acceleration / deceleration processed for each axis unit. For example, like a panel molding machine and other plastic working machines, It can be applied to general multi-axis processing machines that use a lot of rotating shafts and cam shafts, and whose speed must be changed during operation of the machine.

Also, the present invention can be applied to a drawing device such as an XY plotter. In this case, a shift or deformation of a figure due to a change in drawing speed can be prevented.

Claims

The scope of the claims

1. When interpolating the coordinate position for acceleration / deceleration control of the machine operation motor, in the method of performing continuous speed interpolation using a function that obtains the target position as an output when the elapsed time from the starting point is input,

A method of controlling the acceleration and deceleration of a motor, wherein the step width of the elapsed time is variable, and the variable step width is smoothed by using a filter in an interpolation process.

2. A procedure for receiving a command value including at least one of the target position, speed, trajectory shape, and acceleration;

A procedure for calculating the internal time interval ^ IT using the received command value, a procedure for receiving an external speed change command,

Calculating a variable internal step width δTn based on the value of the speed change command and the ^ T,

A procedure of calculating an internal time step width dTn that changes smoothly by performing internal time acceleration / deceleration processing using a filter based on the δTn;

A procedure for performing an internal time update process using the d T n,

A procedure for calculating position data for each interpolation cycle given to the motor based on the updated internal time,

And a method for controlling acceleration and deceleration of a motor for machine operation.

3. When interpolating the coordinate position for acceleration / deceleration control of the machine operation motor, use a function that can obtain the target position as an output by inputting the elapsed time from the start point. Using the method of interpolating continuously with speed

Recording a program for performing acceleration / deceleration control of the motor, wherein the step width of the elapsed time is variable, and the variable step width is smoothed by using a filter during interpolation. Computer-readable recording medium.

4. receiving a command including at least one of a target position, a speed, a trajectory shape, and an acceleration;

Calculating the internal time interval T using the received command value, receiving an external speed change command,

A step for calculating a variable internal step width <5 Tn based on the value of the speed change command and the T,

Calculating the internal time step width dTn that smoothly changes by performing the internal time acceleration / deceleration processing using a filter based on (5Tn)-updating the internal time using the dTn;

Based on the updated internal time, a step of calculating position data for each interpolation cycle given to the motor

A computer-readable recording medium on which a program for performing acceleration / deceleration control of a motor for mechanical operation is recorded.

5. When interpolating the coordinate position for acceleration / deceleration control of the machine operation motor, a method is used in which interpolation is performed at continuous speed using a function that can obtain the target position as an output when the elapsed time from the start point is input. ,

The step size of the elapsed time is variable, and in the process of interpolation Software for performing acceleration / deceleration control of motors and / or motors, wherein the variable step width is smoothed. Receiving a command value including at least one of a target position, a speed, a trajectory shape, and an acceleration;

A step of calculating an internal time interval T using the received command value; a step of receiving an external speed change command;

Calculates a variable internal step width δTn based on the value of the speed change command and the ^] T. An internal time step width d that smoothly changes by performing internal time acceleration / deceleration processing using a filter based on the δTn. Calculate T n-update the internal time using d T n

Software for performing acceleration / deceleration control of a motor for machine operation, characterized by having position data for each interpolation cycle given to the motor based on the updated internal time.