WO2023013168A1

WO2023013168A1 - Control device, control method, and program

Info

Publication number: WO2023013168A1
Application number: PCT/JP2022/015553
Authority: WO
Inventors: 庸弘原田; 裕貴 ▲高▼▲崎▼
Original assignee: オムロン株式会社
Priority date: 2021-08-02
Filing date: 2022-03-29
Publication date: 2023-02-09
Also published as: JP2023021555A

Abstract

This control device controls a robot that has a plurality of axes and supports an object in a cantilever manner. The control device comprises: a generation unit that generates a motion command that defines the motion of the robot; and a robot control unit that controls the robot such that the object linearly moves, in accordance with input information including the motion command. The generation unit receives an input of a first parameter that defines the resonance cycle of the object, and generates a motion command such that the sum of the jerk time and constant acceleration time in linear movement of the object is a natural number multiple of the resonance cycle. This reduces the vibration of the object supported by the robot having the plurality of axes.

Description

Control device, control method and program

The present disclosure relates to a control device, control method and program.

In recent years, damping technology has been developed that suppresses the vibrations that occur in machines by satisfying conditions that do not excite vibrations due to the machine's natural frequency. For example, Japanese Patent Laying-Open No. 2017-84288 (Patent Document 1) discloses a command generation device that calculates a position command based on an input machine performance index and a damping conditional expression and outputs the calculated position command to a servo driver. is disclosed.

JP 2017-84288 A

　In order to suppress vibration, it is important to control the speed, acceleration and jerk (jerk) of the tip of the multi-axis robot. In general, a control device for controlling a multi-axis robot having multiple axes cannot specify a motion profile including these three parameters in detail. Therefore, the object supported by the multi-axis robot is likely to vibrate, and the development of vibration control technology for the multi-axis robot is desired. The technique described in Patent Literature 1 relates to generation of a position command to be output to a servo driver, and is difficult to apply to multi-axis robots.

The present disclosure has been made in view of the above problems, and its purpose is to provide a control device, control method, and program capable of suppressing vibration of an object supported by a robot having multiple axes.

According to an example of the present disclosure, a control device controls a robot that has multiple axes and supports an object in a cantilever manner. The control device includes a generation unit that generates a motion command that defines the motion of the robot, and a robot control unit that controls the robot so that an object linearly moves according to input information including the motion command. The generator receives an input of a first parameter that defines the resonance cycle of the object, and generates an operation command so that the sum of the jerk time and constant acceleration time in linear movement of the object is a natural number multiple of the resonance cycle.

According to this disclosure, the vibration generated at the point where the jerk changes is canceled by the vibration generated at the point shifted by N times the resonance period. Thereby, vibration of the workpiece 300 can be suppressed when the workpiece 300 supported in a cantilever shape is linearly moved by the robot 200 having a plurality of axes.

In the above disclosure, the motion command includes a second parameter that indicates the ratio to the maximum synthetic acceleration of the robot. The generation unit accelerates from a zero speed state to the maximum synthetic acceleration and acquires the standard time required to reach the speed limit. Further, the generator calculates a first ratio of the reciprocal of the natural number multiple of the resonance period to the reciprocal of the standard time, and determines the value of the second parameter based on the first ratio.

The inventors of the present invention have found that when the robot is controlled using the second parameter, the ratio of the reciprocal of the sum of the jerk time and constant acceleration time to the reciprocal of the standard time matches the value of the second parameter. rice field. Therefore, according to the above disclosure, it is possible to generate an operation command so that the sum of the jerk time and constant acceleration time in linear movement of the object is a natural number multiple of the resonance period.

In the above disclosure, the input information includes the second ratio. The robot controller operates the robot at a speed obtained by multiplying the speed determined according to the motion command by the second ratio. The second parameter indicates the value obtained by dividing the first ratio by the second ratio.

According to this disclosure, considering the second ratio for adjusting the speed, the motion command is generated so that the sum of the jerk time and constant acceleration time in the linear movement of the object is a natural number multiple of the resonance period. be able to.

In the above disclosure, the motion command includes a third parameter for defining the maximum velocity of the object in linear movement. The generation unit further receives an input of the moving distance of the object and the first speed, and divides the moving distance by the sum of the natural number times the resonance period and the jerk time to obtain the second speed and the first speed. compare. The generator generates a third parameter defining the second speed as a maximum speed in response to the second speed being less than the first speed, and a third parameter in response to the second speed being greater than the first speed. A third parameter is generated that defines 1 speed as the maximum speed.

As will be described later, when the second velocity is smaller than the first velocity, generating a third parameter that defines the first velocity as the maximum velocity will cause the sum of the jerk time and constant acceleration time to match the natural number times the resonance period. I can't let you. According to the above disclosure, responsive to the second velocity being less than the first velocity, generating a third parameter defining the second velocity as the maximum velocity. As a result, an operation command can be generated so that the sum of the jerk time and constant acceleration time in the linear movement of the object is a natural number multiple of the resonance period.

In the above disclosure, the generator may be implemented by defining instructions in the form of function blocks.

According to an example of the present disclosure, a control method for controlling a robot having a plurality of axes and supporting an object in a cantilever manner includes generating a motion command that defines motion of the robot; and controlling the robot to linearly move the object according to the input information. The step of generating includes the step of receiving input of parameters defining the resonance cycle of the object, and the step of generating the motion command so that the sum of the jerk time and constant acceleration time in linear movement of the object is a natural number multiple of the resonance cycle. and including.

According to one example of the present disclosure, the program causes the computer to execute the above control method. According to these disclosures as well, vibration of the work 300 can be suppressed when the work 300 supported in a cantilever shape is linearly moved by the robot 200 having a plurality of axes.

According to the present disclosure, vibration of an object supported by a robot having multiple axes can be suppressed.

It is a figure which shows an example of the system in which the control apparatus which concerns on embodiment is applied. FIG. 4 is a diagram showing an example of profiles of synthetic velocity and synthetic acceleration of a robot; FIG. 5 is a diagram showing an example of a profile (S-curve profile) of the synthetic velocity and synthetic acceleration of the robot when the jerk time is set; FIG. 4 is a diagram showing temporal changes in jerk (jerk) corresponding to the S-curve profile shown in FIG. 3; It is a schematic diagram which shows the hardware constitutions of a control apparatus. It is a schematic diagram which shows the functional structure of a control apparatus. FIG. 10 is a diagram showing an example of temporal change in composite speed when the speed adjustment ratio is changed; 4 is a flowchart showing the flow of processing by the control device; FIG. 9 is a flow chart showing an example of a flow of a subroutine of step S100 of FIG. 8. FIG. FIG. 10 is a diagram showing variables calculated in step S2 of FIG. 9; FIG. FIG. 8 is a diagram showing a speed profile with the value of variable H calculated in step S2 as the maximum value of the composite speed and a speed profile with the value of the left side of Equation (4) as the maximum value of the composite speed; FIG. 10 is a diagram showing a vibration waveform of a workpiece when using the control device according to the reference embodiment; FIG. 5 is a diagram showing vibration waveforms of a workpiece when using the control device according to the present embodiment;

Embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. Each modified example described below may be selectively combined as appropriate.

§1 Application Example An outline of the control device according to the present embodiment will be described. FIG. 1 is a diagram illustrating an example of a system to which a control device according to an embodiment is applied. A system 1 shown in FIG. 1 is installed, for example, in a production line. As shown in FIG. 1, the system 1 includes a control device 100 and a robot 200. As shown in FIG.

The robot 200 is a multi-axis robot having multiple axes 201 and an end effector 202 . For example, robot 200 is a vertical articulated robot. An end effector 202 of the robot 200 supports the workpiece 300 like a cantilever beam. Work 300 is, for example, a shaft.

The control device 100 controls the robot 200. When the workpiece 300, which is a shaft, is linearly moved in a direction crossing the axial direction, the workpiece 300 is likely to vibrate. If the workpiece 300 vibrates after it is moved, it is necessary to wait until the vibration falls within the allowable range. As a result, the tact time becomes longer. The control device 100 controls the robot 200 so as to suppress the vibration of the workpiece 300 in order to shorten the tact time.

The control device 100 includes an action command generation unit 10 that generates an action command that defines the action of the robot, a robot control unit 12 that controls the robot 200 so that the workpiece 300 moves linearly according to input information including the action command, Prepare.

In order to linearly move the workpiece 300, the robot 200 performs a linear interpolation operation so that the trajectory of the end effector 202 becomes a straight line. Since the trajectory of the end effector 202 is one-dimensional, the synthetic velocity and synthetic acceleration of the multiple axes 201 of the robot 200 are also one-dimensionally expressed.

FIG. 2 is a diagram showing an example of the profile of the synthetic velocity and synthetic acceleration of the robot. FIG. 2 shows a profile when the robot 200 exhibits its maximum capability. In FIG. 2, line 20 indicates the time change of the synthesized velocity, and line 21 indicates the time change of the synthesized acceleration. The workpiece 300 accelerates during acceleration time T10, performs uniform motion during constant velocity time T11, and decelerates during deceleration time T12.

A line 20 shown in FIG. 2 indicates a trapezoid. That is, FIG. 2 shows a so-called trapezoidal velocity profile. By using a trapezoidal velocity profile, the travel time can be minimized. However, the acceleration changes abruptly at the start and end of acceleration/deceleration. The robot 200 receives an impact due to a sudden change in acceleration. For the purpose of mitigating such impact, a time (jerk time) is set during which the acceleration is changed continuously.

FIG. 3 is a diagram showing an example of the profile (S-curve profile) of the synthetic velocity and synthetic acceleration of the robot when the jerk time is set. In FIG. 3 as well, line 20 indicates the time change of the synthesized velocity, and line 21 indicates the time change of the synthesized acceleration. In the S-curve profile, jerk time T1, constant acceleration time T2, jerk time T3, constant velocity time T4, jerk time T5, constant acceleration time T6, and jerk time T7 are set in this order.

　In the jerk time T1, the acceleration monotonically increases from 0 to the maximum acceleration. During the constant acceleration time T2, the acceleration is maintained at the maximum acceleration. During the jerk time T3, the acceleration monotonously decreases from the maximum acceleration to zero. The acceleration is maintained at 0 during the constant velocity time T4. At the jerk time T5, the acceleration monotonically decreases from 0 to the minimum acceleration (negative). During uniform acceleration time T6, the acceleration is maintained at the minimum acceleration. At the jerk time T7, the acceleration monotonically increases from the minimum acceleration to 0.

The jerk times T1, T3, T5 and T7 have the same length. Uniform acceleration times T2 and T6 have the same length.

The motion command generation unit 10 receives an input of a parameter (typically a resonance frequency) that defines the resonance period of the workpiece 300, and the sum of the jerk time T1 and the uniform acceleration time T2 in the linear movement of the workpiece 300 is the resonance period N An operation command is generated so as to double (N is a natural number). Vibration of the workpiece 300 is suppressed by generating an operation command so that the sum of the jerk time T1 and the constant acceleration time T2 is N times the resonance period. The mechanism will be described with reference to FIG.

FIG. 4 is a diagram showing temporal changes in jerk (jerk) corresponding to the S-curve profile shown in FIG. In FIG. 4, line 22 indicates the change in jerk over time. As shown in FIG. 4, the jerk changes at eight timings. That is, the jerk includes the start time t0 and end time t1 of the jerk time T1, the start time t2 and end time t3 of the jerk time T3, the start time t4 and end time t5 of the jerk time T5, and the start time t6 and end time of the jerk time T7. It changes at time t7.

The change in jerk at time t0 is in the positive direction, and the change in jerk at time t2 is in the negative direction. The time from time t0 to time t2, that is, the sum of the jerk time T1 and the constant acceleration time T2 is N times the resonance period. Therefore, the vibration generated at time t0 is canceled by the anti-phase vibration generated at time t2 after N times the resonance period. Similarly, the vibration generated at time t1 is canceled by the anti-phase vibration generated at time t3 after N times the resonance period. The vibration generated at time t4 is canceled by the anti-phase vibration generated at time t6 after N times the resonance period. The vibration generated at time t5 is canceled by the anti-phase vibration generated at time t7 after N times the resonance period. In this way, vibrations occurring at each of all points where the jerk changes are canceled by vibrations occurring at points shifted by N times the resonance period. Therefore, vibration of the workpiece 300 is suppressed.

Thus, according to the control device 100 according to the present embodiment, vibration of the work 300 can be suppressed when the work 300 supported in a cantilever shape by the robot 200 having a plurality of axes is linearly moved.

§2 Specific example <Hardware configuration of control device>
FIG. 5 is a schematic diagram showing the hardware configuration of the control device. As shown in FIG. 5 , control device 100 includes field network controller 102 , control processing circuitry 104 and input interface 106 .

The field network controller 102 exchanges data with an external device such as a PLC (Programmable Logic Controller) via the field network.

The control processing circuit 104 executes arithmetic processing necessary to drive the robot 200 . As an example, control processing circuitry 104 includes processor 110 , main memory 112 , storage 114 , and interface circuitry 116 .

The processor 110 executes control operations for driving the robot 200 . The main memory 112 is composed of, for example, a volatile storage device such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory). The storage 114 is composed of, for example, a non-volatile storage device such as an SSD (Solid State Drive) or HDD (Hard Disk Drive).

A control program 120 for realizing control for driving the robot 200 is stored in the storage 114 . The control program 120 includes commands for executing control operations related to the operation of the robot 200 and commands related to interfaces with the robot 200 . The control program 120 may contain one or more function blocks (FB). A function block is a block having input/output variables, and is executed by being read and instantiated at specified timing. A control program 120 shown in FIG. 5 includes a damping control function block 122 and a linear interpolation function block 124 . Note that the control program 120 may be installed from a recording medium such as a memory card, a distribution server, or the like.

Interface circuit 116 exchanges data with robot 200 .
The input interface 106 mediates data transmission between the control processing circuit 104 and an input device 400 such as a keyboard, mouse, touch panel, dedicated console, or the like. That is, input interface 106 accepts information given by the user operating input device 400 .

<Functional configuration of control device>
FIG. 6 is a schematic diagram showing the functional configuration of the control device. As shown in FIG. 6, the control device 100 includes an action command generator 10, a robot controller 12, and a profile selector . The motion command generation unit 10, the robot control unit 12, and the profile selection unit 14 are realized by executing the control program 120 by the processor 110 (see FIG. 5). More specifically, the motion command generator 10 and the robot controller 12 are implemented by the processor 110 executing a damping control function block 122 and a linear interpolation function block 124, respectively.

The control device 100 uses, as input variables, the resonance frequency (Hz) of the work 300, the movement distance (mm) of the work 300, and the maximum speed (mm/s) of the work 300 desired by the user (hereinafter referred to as "input speed"). ), speed adjustment ratio (%), jerk time (ms), adjustment constant (natural number), and robot specific parameters. The movement distance of the workpiece 300 is the distance from the current position of the tip of the robot 200 to the target position. Controller 100 receives these input variables from field network or input device 400 .

The resonance frequency of the workpiece 300 is measured in advance. For example, the resonance frequency of the work 300 is measured by analyzing an image obtained by imaging the work 300 when the robot 200 is operated. Alternatively, the resonance frequency of the workpiece 300 may be measured by visually confirming the vibration of the workpiece 300 when the robot 200 is operated. Alternatively, the resonance frequency of workpiece 300 may be measured using a sensor.

The speed adjustment ratio is used to adjust the synthetic speed of the robot 200 (that is, the speed of the workpiece 300). Adjustment constants (natural numbers) are used as multiples of the resonance period.

FIG. 7 is a diagram showing an example of temporal changes in composite speed when the speed adjustment ratio is changed. In FIG. 7, line 25 indicates the time change of the synthetic speed of robot 200 when the adjustment ratio is 100%. A line 26 indicates the time change of the synthetic speed of the robot 200 when the speed adjustment ratio is 50%. As shown in FIG. 7, the speed when the speed adjustment ratio is set to 50% is adjusted to 50% of the speed when the speed adjustment ratio is set to 100%. Therefore, acceleration time T20 and deceleration time T22 when the speed adjustment ratio is set to 50% are twice the acceleration time T10 and deceleration time T12 when the speed adjustment ratio is set to 100%. Thus, acceleration time T10 and deceleration time T12 are inversely proportional to the speed adjustment ratio.

The robot-specific parameters include standard time (ms), speed limit (mm/s) and limit ratio (%).

The speed limit is a composite speed when the robot 200 operates at its maximum capacity, and is a value unique to the robot 200.

The limit ratio is the upper limit value of the ratio (hereinafter referred to as "acceleration adjustment ratio") used for adjusting the synthetic acceleration of the robot 200 (that is, the acceleration of the workpiece 300), and is a value unique to the robot 200. is. The acceleration adjustment ratio is a ratio to the synthetic acceleration (maximum synthetic acceleration) when the robot operates at its maximum capacity. Specifically, the acceleration adjustment ratio indicates the ratio to the first reference acceleration (positive) when the robot operates at its maximum capability during acceleration, and indicates the ratio to the second reference acceleration (negative) during deceleration. . The value of the first reference acceleration matches the absolute value of the maximum synthesized acceleration. The absolute value of the second reference acceleration is the same as the value of the first reference acceleration.

The standard time is the acceleration/deceleration time when the jerk time is 0 ms. That is, the standard time is the time required to accelerate from the zero speed state to the first reference acceleration (that is, the maximum synthetic acceleration) and reach the speed limit. The standard time is a unique value for the robot 200, eg 180ms. With a jerk time of 0 ms, the velocity profile is represented by line 20 in FIG. Therefore, the standard time corresponds to acceleration time T10 (or deceleration time T12) in FIG.

As shown in FIG. 6, the profile selection unit 14 receives input of the jerk time. The profile selection unit 14 selects one S-curve speed profile corresponding to the input jerk time from among a plurality of speed profiles that the robot control unit 12 can accept. The profile selection unit 14 outputs variables indicating the selected speed profile to the robot control unit 12 . The multiple speed profiles have S-curves as shown in FIG. 3 and have different jerk times. Therefore, the profile selection unit 14 may select the speed profile having the input jerk time from among the plurality of speed profiles.

In each of the plurality of speed profiles that the robot control unit 12 can accept, the jerk times T1, T3, T5, and T7 (see FIG. 3) have the same length, and the constant acceleration times T2 and T6 have the same length. have a length.

The robot control unit 12 receives the current position and target position of the tip of the robot 200, speed adjustment ratio, speed profile, maximum combined speed and acceleration adjustment ratio, and controls the robot 200 so that the workpiece 300 moves linearly. The maximum combined speed indicates the maximum value of the combined speed of the robot 200 when the speed adjustment ratio is 100%.

The robot control unit 12 corrects the speed profile according to the movement distance, speed adjustment ratio, maximum combined speed, and acceleration adjustment ratio.

Specifically, the robot control unit 12 corrects the speed of the constant speed time T4 (see FIG. 3) in the speed profile to the maximum combined speed.

Next, the robot control unit 12 modifies the acceleration of the uniform acceleration time T2 (see FIG. 3) in the velocity profile to a value obtained by multiplying the first reference acceleration (positive) by the acceleration adjustment ratio. Similarly, the robot control unit 12 corrects the acceleration at constant acceleration time T6 (see FIG. 3) in the velocity profile to a value obtained by multiplying the second reference acceleration (negative) by the acceleration adjustment ratio. At this time, the robot control unit 12 also corrects the lengths of constant acceleration times T2 and T6 so that the speeds at the end of acceleration and the start of deceleration match the speed of constant speed time T4.

Next, the robot control unit 12 calculates a linear distance (that is, movement distance) connecting the current position of the tip of the robot 200 and the target position. The robot control unit 12 corrects the length of the constant velocity time T4 so that the integrated value of the velocity profile matches the movement distance.

Finally, the robot control unit 12 corrects the speed at each time of the speed profile in accordance with the speed adjustment ratio, and adjusts the jerk time T1, uniform acceleration time T2, jerk time T3, uniform velocity time T4, jerk time T5, uniform acceleration Modify the length of time T6 and jerk time T7.

The robot control unit 12 generates command values for each axis of the robot 200 and outputs the generated command values to the robot 200 so that a composite speed according to the speed profile corrected in this way is output.

The speed adjustment ratio, the maximum composite speed, and the acceleration adjustment ratio received by the robot control unit 12 are parameters that make it easy for the user to imagine the time change of the linear movement of the workpiece 300 . Therefore, a reference form is conceivable in which the robot control unit 12 directly acquires the speed adjustment ratio, the maximum combined speed, and the acceleration adjustment ratio from the input device 400 . Accordingly, the user can linearly move the workpiece 300 with a desired time change by appropriately adjusting the values of these parameters.

When the system 1 is installed in a production line, it is usually preferable to move the work 300 in as short a time as possible. Therefore, the user may input the maximum speed of the workpiece 300 when linearly moving the workpiece 300 in the shortest time as the maximum composite speed. However, if the work 300 is linearly moved in the shortest time, some problem may occur. In such a case, the user can adjust the speed of the workpiece 300 by adjusting the value of the speed adjustment ratio. Alternatively, the user can adjust the acceleration time and deceleration time by adjusting the acceleration adjustment ratio.

However, the speed adjustment ratio, maximum combined speed, and acceleration adjustment ratio do not directly define parameters related to damping of workpiece 300 (for example, the sum of jerk time and uniform acceleration time). In addition, the user determines how to adjust the speed adjustment ratio, the maximum combined speed, and the acceleration adjustment ratio to determine the conditions for suppressing the vibration of the workpiece 300 (for example, the sum of the jerk time and the constant acceleration time is a natural number of the resonance period). I do not know whether the condition that the Therefore, in the reference form in which the robot control unit 12 directly acquires the speed adjustment ratio, the maximum combined speed, and the acceleration adjustment ratio from the input device 400, it is difficult to suppress vibration when the work 300 is linearly moved.

Therefore, the control device 100 according to the present embodiment is characterized by including the operation command generation unit 10 .

The motion command generation unit 10 receives the resonance frequency, movement distance, input speed, speed adjustment ratio, jerk time, adjustment constant, and robot-specific parameters, and generates motion commands. The generated motion command is input to the robot controller 12 . The motion command includes the maximum combined speed and acceleration adjustment ratio.

As a result of comparing and verifying the acceleration adjustment ratio and the profile of the synthetic speed of the robot 200, the present inventor found that the ratio of the reciprocal of the sum of the jerk time and constant acceleration time to the reciprocal of the standard time matches the acceleration adjustment ratio. got Based on this knowledge, the motion command generator 10 generates a motion command so that the sum of the jerk time and constant acceleration time in the linear movement of the workpiece 300 is a natural number multiple of the resonance period. A method of generating an operation command will be described later.

<Processing flow of the control device>
FIG. 8 is a flow chart showing the flow of processing by the control device. As shown in FIG. 8, processor 110 uses the input variables to generate a motion command (step S100). Next, processor 110 controls robot 200 so that workpiece 300 linearly moves according to the generated input information including the motion command (step S200). Input information includes speed adjustment ratio and jerk time. As noted above, processor 110 selects a velocity profile that depends on the jerk time. Processor 110 controls robot 200 so that workpiece 300 moves linearly using the selected speed profile, speed adjustment ratio, and motion command (maximum combined speed and acceleration adjustment ratio).

<How to generate motion commands>
A method of generating an operation command will be described with reference to FIGS. 9 to 11. FIG. FIG. 9 is a flow chart showing an example of the subroutine flow of step S100 of FIG.

Processor 110 receives an input variable (step S1). Input variables include the following variables AN.
Variable A: moving distance (mm),
Variable B: input speed (mm/s),
Variable C: speed adjustment ratio (%),
Variable D: jerk time (ms),
Variable E: resonance frequency (Hz),
Variable F: adjustment constant,
Variable G: standard time (ms),
Variable M: speed limit (mm/s),
Variable N: limit ratio (%).

Processor 110 then calculates variables H, I, and J according to the following equations (1) to (3) (step S2).
H=B×C/100 Formula (1)
I=1000÷E×F Formula (2)
J=I+D Equation (3).

FIG. 10 is a diagram showing variables calculated in step S2 of FIG. As shown in FIG. 10, variable H indicates the maximum composite speed of robot 200 when workpiece 300 is linearly moved. In step S2, the value of variable H is calculated by multiplying the input speed by the speed adjustment ratio. A variable I indicates a time that is an adjustment constant (natural number) times the resonance period of the workpiece 300 . In the present embodiment, the motion command is generated so that the sum of the jerk time and the constant acceleration time is an adjustment constant (natural number) times the resonance period (see FIG. 3). Therefore, the sum of the jerk time and constant acceleration time matches the value of variable I. The variable J indicates the sum of the adjustment constant (natural number) times the resonance period of the workpiece 300 and the jerk time. When an operation command is generated such that the sum of the jerk time and the constant acceleration time is an adjustment constant (natural number) times the resonance period, the variable J indicates the acceleration time.

Next, processor 110 determines whether B<M is satisfied (step S3). If YES in step S3, ie the input speed is less than the speed limit, processor 110 determines that a value for variable B is available and executes the next step S4.

At step S4, the processor 110 determines whether D<I is satisfied. As shown in FIG. 10, D<I must be satisfied in order for the sum of the jerk time and constant acceleration time to match the resonance period times the adjustment constant (natural number). Therefore, if YES in step S4, the processor 110 determines that the values of the variables D and I are available, and executes the next step S5.

At step S5, the processor 110 determines whether the following equation (4) is satisfied.
A÷J×1000<H Equation (4).

FIG. 11 is a diagram showing a speed profile in which the value of the variable H calculated in step S2 is the maximum value of the synthetic speed, and a speed profile in which the value of the left side of Equation (4) is the maximum value of the synthetic speed. . In FIG. 11, line 20a shows the velocity profile when the value of variable H calculated in step S2 is the maximum value of the combined velocity and the constant velocity time is zero. A line 20b indicates a velocity profile when the value of the left side of the equation (4) is the maximum value of the combined velocity and the constant velocity time is zero. Line 21 shows the acceleration profile corresponding to the velocity profile shown by line 20b.

When the acceleration time and deceleration time are the same and the same movement distance is linearly moved, the acceleration time is the longest when the constant velocity time is 0.

When formula (4) is satisfied (YES in step S5), the acceleration time of the velocity profile indicated by line 20a is shorter than the acceleration time of the velocity profile indicated by line 20b, as shown in FIG. A line 20b shows the velocity profile when the sum of the jerk time and the constant acceleration time coincides with the resonance period times the adjustment constant (natural number). Therefore, when the formula (4) is satisfied, in the velocity profile in which the value of the variable H calculated in step S2 is the maximum value of the combined velocity, the sum of the jerk time and the constant acceleration time is the adjustment constant (natural number ) times shorter. That is, when the equation (4) is satisfied, the motion command cannot be generated so that the sum of the jerk time and the constant acceleration time is the adjustment constant (natural number) times the resonance period. Therefore, if YES in step S5, processor 110 replaces the value of variable H with the calculated value of A÷J×1000 (step S6). After that, the processor 110 executes step S7.

On the other hand, if equation (4) is not satisfied (NO in step S5), the acceleration time of the speed profile indicated by line 20a is greater than or equal to the acceleration time of the speed profile indicated by line 20b. In this case, even if the value of the variable H calculated in step S2 is the maximum value of the combined speed, the sum of the jerk time and the constant acceleration time is multiplied by the adjustment constant (natural number) of the resonance cycle by adjusting the constant speed time. can be matched with Therefore, in the case of NO in step S5, the processor 110 executes the next step S7 without changing the value of the variable H.

In step S7, processor 110 calculates variable L according to the following equation (5).
L=100×H÷C Equation (5).

At the next step S8, the processor 110 calculates a variable K according to Equation (6) below.
K=(100×G)÷(1000÷E×F)×(100÷C) Formula (6)
That is, the processor 110 calculates the ratio of the reciprocal of the natural number multiple of the resonance period to the reciprocal of the standard time ((100×G)/(1000/E×F)), and calculates the value of the variable K based on the ratio. decide. Specifically, processor 110 calculates the value of variable K by dividing the ratio by the speed adjustment ratio.

At the next step S9, the processor 110 determines whether K<N is satisfied. If K<N is satisfied (YES in step S9), processor 110 determines that variable K calculated in step S8 can be used, and executes step S10.

At step S10, the processor 110 outputs variables L and K as the maximum combined speed and acceleration adjustment ratio, respectively. After step S10, processor 110 returns the process to step S200 of FIG.

The maximum composite speed represented by the variable L indicates the maximum value of the composite speed of the robot 200 at a speed adjustment ratio of 100%. The maximum speed in linear movement of the workpiece 300 is represented by the product of the maximum combined speed and the input speed adjustment ratio. Therefore, the variable L (maximum composite speed) is a parameter that defines the maximum speed of linear movement of the workpiece 300 . As described above, if equation (4) is satisfied, i.e., if the speed represented by A÷J×1000 is less than the speed represented by the product of variables B and C, processor 110 outputs A Create a variable L that defines the speed represented by ÷J×1000 as the maximum speed in linear motion. On the other hand, if the speed represented by A÷J×1000 is greater than the speed represented by the product of variables B and C, then processor 110 converts the speed represented by the product of variables B and C into a straight line. Create a variable L that defines the maximum speed in movement.

If NO in any of steps S3, S4, and S9, processor 110 generates an error code and outputs the generated error code (step S11). After step S10, processor 110 terminates the process.

The processor 110 operating as the robot control unit 12 controls the robot 200 so that the workpiece 300 moves linearly using the variables L and K received as the maximum combined speed and acceleration adjustment ratio.

Specifically, the processor 110 modifies the speed of the constant speed time T4 (see FIG. 3) in the speed profile to the value of the variable L (maximum composite speed). Processor 110 then modifies the acceleration at each of uniform acceleration times T2 and T6 in the velocity profile according to the value of variable K (acceleration adjustment ratio). At this time, processor 110 also corrects the lengths of constant acceleration times T2 and T6 so that the speeds at the end of acceleration and the start of deceleration match the speed of constant speed time T4. Next, processor 110 modifies the length of constant velocity time T4 so that the integrated value of the velocity profile matches the movement distance. Finally, the processor 110 corrects the speed at each time of the speed profile according to the speed adjustment ratio, and jerk time T1, constant acceleration time T2, jerk time T3, constant speed time T4, jerk time T5, constant acceleration time T6. , and the length of the jerk time T7.

As described above, the inventors have found that "the ratio of the reciprocal of the sum of the jerk time and the constant acceleration time to the reciprocal of the standard time matches the acceleration adjustment ratio." Also, as shown in FIG. 7, the acceleration time and deceleration time are inversely proportional to the speed adjustment ratio. Therefore, in the speed profile modified according to the acceleration adjustment ratio and the speed adjustment ratio, the sum of the jerk time and the acceleration time is represented by the following equation (7).
Sum of jerk time and acceleration time = G/(K/100) x (100/C) Equation (7)
By substituting equation (6) for K in equation (7), the sum of the jerk time and the acceleration time is (1000÷E×F), that is, the resonance period [ms] multiplied by the adjustment constant (natural number). Become.

In this way, by receiving the variables L and K as the maximum combined speed and the acceleration adjustment ratio, respectively, the sum of the jerk time and the uniform acceleration time follows the speed profile that matches the adjustment constant (natural number) times the resonance period of the workpiece 300. , the robot 200 is controlled. Thereby, the vibration of the workpiece 300 is suppressed.

<Effect of suppressing vibration>
The effect of suppressing the vibration of the workpiece 300 by the control device 100 according to the present embodiment was confirmed. FIG. 12 is a diagram showing vibration waveforms of a workpiece when using the control device according to the reference embodiment. FIG. 13 is a diagram showing vibration waveforms of a workpiece when using the control device according to the present embodiment.

12 and 13 show vibration waveforms when a wire having a resonance frequency of 31.05 Hz and a diameter of 0.55 mm is used as the workpiece 300. FIG. Note that the control device according to the reference embodiment differs from the control device 100 in that it does not include the operation command generation unit 10 . In the control device according to the reference embodiment, an acceleration adjustment ratio of 100% was input to the robot control unit 12, and an input speed was input as the maximum combined speed.

As shown in FIG. 12, when the robot 200 was controlled by the control device according to the reference embodiment, the tip of the workpiece 300 vibrated with an amplitude of approximately 1.0 mm. The vibration convergence time was 6 seconds or longer. In contrast, when the robot 200 was controlled by the control device 100 according to the present embodiment, the tip of the workpiece 300 vibrated with an amplitude of approximately 0.35 mm. The oscillation convergence time was 0.5 seconds. Vibration of the workpiece 300 is thus suppressed by using the control device 100 according to the present embodiment.

<Modification>
If the body of the robot 200 supports the end effector 202 in a cantilevered manner, the end effector 202 itself may vibrate. In this case, the user may input the resonant frequency of the end effector 202 or the overall resonant frequency of the end effector 202 and the workpiece 300 into the control device 100 .

§3 Supplementary Note As described above, the present embodiment includes the following disclosures.

(Configuration 1)
A control device (100) for controlling a robot (200) having a plurality of axes (201) and supporting objects (300, 202) in a cantilever manner,
a generator (10, 110) for generating a motion command that defines the motion of the robot (200);
a robot control unit (12, 110) that controls the robot (200) so that the object (300, 202) linearly moves according to input information including the operation command;
The generator (10, 110) receives an input of a first parameter defining a resonance period of the object (300, 202), and calculates the sum of the jerk time and constant acceleration time in the linear movement of the object (300, 202). is a natural number multiple of the resonance period.

(Configuration 2)
the motion command includes a second parameter indicating a ratio to the maximum synthetic acceleration of the robot (200);
The generating unit (10, 110)
Accelerate from a state of zero speed to the maximum synthetic acceleration, acquire the standard time to reach the speed limit,
calculating a first ratio of the reciprocal of the natural number multiple of the resonance period to the reciprocal of the standard time;
The controller (100) of arrangement 1, wherein the value of said second parameter is determined based on said first ratio.

(Composition 3)
the input information includes a second ratio;
The robot control unit (12, 110) operates the robot (200) at a speed obtained by multiplying the speed determined according to the operation command by the second ratio,
3. The controller (100) of configuration 2, wherein said second parameter represents a value obtained by dividing said first ratio by said second ratio.

(Composition 4)
said motion command includes a third parameter for defining a maximum velocity of said object (300, 202) in said linear movement;
The generating unit (10, 110)
further receiving an input of a moving distance of the object (300, 202) and a first speed;
comparing the first speed with a second speed obtained by dividing the movement distance by the sum of the natural number times the resonance period and the jerk time;
responsive to the second velocity being less than the first velocity, generating the third parameter defining the second velocity as the maximum velocity;
4. The controller (100) of any of the arrangements 1-3, responsive to the second speed being greater than the first speed, generating the third parameter defining the first speed as the maximum speed. .

(Composition 5)
5. The control device (100) according to any one of configurations 1 to 4, wherein the generator (10, 110) is implemented by defining an instruction in the form of a function block (122).

(Composition 6)
A control method for controlling a robot (200) having a plurality of axes (201) and supporting objects (300, 202) in a cantilever manner, comprising:
generating a motion command that defines the motion of the robot (200);
and controlling the robot so that the object (300, 202) moves linearly according to the input information including the operation command;
The generating step includes:
receiving input of parameters defining a resonance period of said object (300, 202);
and generating the operation command so that the sum of the jerk time and constant acceleration time in the linear movement of the object (300, 202) is a natural number multiple of the resonance period.

(Composition 7)
A program (120) for causing a computer (100, 110) to execute the control method according to configuration 6.

Although the embodiment of the present invention has been described, it should be considered that the embodiment disclosed this time is illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, and is intended to include all changes within the meaning and range of equivalents to the claims.

1 system, 10 motion command generator, 12 robot controller, 14 profile generator, 100 controller, 102 field network controller, 104 control processing circuit, 106 input interface, 110 processor, 112 main memory, 114 storage, 116 interface circuit , 120 control program, 122 damping control function block, 124 linear interpolation function block, 200 robot, 201 axis, 202 end effector, 300 workpiece, 400 input device.

Claims

A control device for controlling a robot having a plurality of axes and supporting an object in a cantilever manner,
a generation unit that generates a motion command that defines the motion of the robot;
a robot control unit that controls the robot so that the object moves linearly according to input information including the operation command;
The generator receives an input of a first parameter that defines a resonance period of the object, and generates the operation command so that the sum of the jerk time and constant acceleration time in linear movement of the object is a natural number multiple of the resonance period. A control device that generates
The motion command includes a second parameter indicating a ratio to the maximum synthetic acceleration of the robot,
The generating unit
Accelerate from a state of zero speed to the maximum synthetic acceleration, acquire the standard time to reach the speed limit,
calculating a first ratio of the reciprocal of the natural number multiple of the resonance period to the reciprocal of the standard time;
2. The controller of claim 1, wherein the value of said second parameter is determined based on said first ratio.
the input information includes a second ratio;
The robot control unit operates the robot at a speed obtained by multiplying the speed determined according to the operation command by the second ratio,
3. The control device according to claim 2, wherein said second parameter indicates a value obtained by dividing said first ratio by said second ratio.
said motion command includes a third parameter for defining a maximum velocity of said object in said linear movement;
The generating unit
further receiving an input of a moving distance of the object and a first speed;
comparing the first speed with a second speed obtained by dividing the movement distance by the sum of the natural number times the resonance period and the jerk time;
responsive to the second velocity being less than the first velocity, generating the third parameter defining the second velocity as the maximum velocity;
4. A controller as claimed in any one of the preceding claims, responsive to the second speed being greater than the first speed to generate the third parameter defining the first speed as the maximum speed. .
The control device according to any one of claims 1 to 4, wherein the generator is implemented by defining commands in the form of function blocks.
A control method for controlling a robot having a plurality of axes and supporting an object in a cantilever manner, comprising:
generating a motion command that defines the motion of the robot;
and controlling the robot so that the object moves linearly according to the input information including the operation command;
The generating step includes:
receiving input of parameters defining a resonance period of the object;
and generating the operation command so that the sum of the jerk time and constant acceleration time in the linear movement of the object is a natural number multiple of the resonance period.
A program that causes a computer to execute the control method according to claim 6.