JPH1195826A - Acceleration-deceleration pattern producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceleration-deceleration pattern producing method for the speed control of a drive source by which the output performance of the drive source of the operation part of a robot is utilized as much as possible. SOLUTION: A function for indicating a linear acceleration-deceleration pattern P1 used for linear acceleration-deceleration is defined as F(t)1, the function for indicating a sine curve acceleration-deceleration pattern P5 used for sine curve acceleration-deceleration is defined as F(t)2, a coefficient determined so as not to make torque (maximum torque of G1-G5) required when acceleration is maximum exceed a torque upper limit value Trmax allowed in an acceleration-deceleration of a servo motor 1b is defined as K(0<K<1) and the function F(t)3 for indicating the acceleration-deceleration pattern is found by an equation F(t)3=K×(F(t)2-F(t)1)+F(t)1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for creating an acceleration / deceleration pattern used for controlling the speed of a drive source of an operating unit of a robot.

[0002]

2. Description of the Related Art Conventionally, as this kind of acceleration / deceleration pattern, a so-called linear acceleration / deceleration pattern (see FIG. 2A)
And, for example, a sinusoidal acceleration / deceleration pattern (see FIG. 2E).
Such a curve acceleration / deceleration pattern is known. By the way, in the speed control according to the linear acceleration / deceleration pattern, for example, the torque at the time of acceleration / deceleration of a drive source such as a servomotor is almost constant from the start to the end of acceleration / deceleration, and the torque changes instantaneously at the start and end of acceleration / deceleration. Therefore, at the start and end of acceleration / deceleration, a large shock is likely to be applied to the drive source, the robot, and the like, and vibration is likely to occur.
On the other hand, in the speed control according to the sinusoidal acceleration / deceleration pattern, the torque of the drive source is gradually increased or decreased from the start of acceleration / deceleration such as at the time of starting, and is changed back to the original value after reaching a predetermined extreme value. Therefore, the torque of the drive source is not instantaneously changed at the start and end of the acceleration / deceleration, so that the shock applied to the drive source and the operation unit can be reduced, and the generation of vibration can be advantageously suppressed.

[0003]

However, to perform speed control in accordance with a curve acceleration / deceleration pattern such as a sine curve acceleration / deceleration pattern, if the acceleration / deceleration time and the speed difference before and after acceleration / deceleration are the same, the speed is controlled in accordance with the linear acceleration / deceleration pattern. At the time of the maximum acceleration, a torque of about 1.57 times at the maximum is required as compared with the case where the control is performed. Therefore, a driving source capable of obtaining a larger torque is required, and the robot apparatus becomes large-sized or expensive. .

The present invention provides an acceleration / deceleration pattern in which the output performance of a drive source is utilized to the utmost, a shock applied to the drive source and an operation unit at the start and end of acceleration / deceleration is reduced as much as possible, and vibration is hardly generated. It is an object of the present invention to provide a method for creating a document.

[0005]

According to the present invention, there is provided a method for creating an acceleration / deceleration pattern used for controlling the speed of a drive source of an operating unit of a robot. The function representing the curve acceleration / deceleration pattern used is F (t) 1, and the function representing the curve acceleration / deceleration pattern used for curve acceleration / deceleration is F (t) 1.
(t) 2, a function F representing an acceleration / deceleration pattern, where K (0 <K <1) is a coefficient determined so that the torque required at the time of maximum acceleration does not exceed the torque upper limit allowed during acceleration / deceleration of the drive source. (t) 3 is expressed by the following equation: F (t) 3 = K × (F (t) 2-F (t) 1) + F
(t) Determined by 1.

The curve acceleration / deceleration pattern changes so that the rate of change in speed gradually increases from the speed change start point and decreases as approaching the speed change end point. And one inflection point between them, for example, a sinusoidal acceleration / deceleration pattern.

In the function F (t) 3, a part of the torque of the driving source is changed according to a curve acceleration / deceleration pattern. The control according to the curve acceleration / deceleration pattern is not a control in which the magnitude of the torque of the drive source changes instantaneously at the start and end of the acceleration / deceleration, but a control in which the magnitude of the torque of the drive source gradually increases or decreases. It is. Therefore, if the acceleration / deceleration pattern created by the function F (t) 3 is used, the magnitude of the change in torque at the start and end of acceleration / deceleration is reduced by the torque changed according to the curve acceleration / deceleration pattern, Shock applied to the drive source and the operating unit is reduced, and vibration is less likely to occur. Also, if desired performance is obtained by using the acceleration / deceleration pattern created by using the function F (t) 3, there is no need to use a drive source capable of obtaining a larger torque, which increases the size and cost of the robot apparatus. Can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a robot controlled by a control unit 2, which has an arm 1a which performs a turning operation as an operation unit. The arm 1a is turned by a servomotor (hereinafter simply referred to as a motor) 1b as a drive source and is moved to a predetermined position.
b is rotated by the power output from the amplifier 3 based on the signal output from the control unit 2.

The control unit 2 includes a CPU, a storage means 4 for storing acceleration / deceleration patterns used for acceleration / deceleration control of the rotation speed of the motor 1b, an input means (not shown) such as a keyboard and a teaching box, and a CRT and the like. Interface 5 used to exchange signals with output means
And a servo interface 6 used for exchanging signals with the motor 1b. The storage means 4 stores a linear acceleration / deceleration pattern in which the speed increases / decreases in proportion to the elapsed time (see FIG. 2 (a)), and a curve acceleration / deceleration in which the speed increases / decreases as time elapses in a sine curve. A sine curve acceleration / deceleration pattern as a pattern (see FIG. 2E) is stored.

Assuming that the speed before acceleration is V1, the speed after acceleration is V2, and the acceleration time is T, for example, a linear acceleration pattern or a sinusoidal acceleration pattern has the following function F (t) using time t as a parameter. ) 1 ', F (t) 2' F (t) 1 '= V1 + (V2-V1) .times.t / T Linear acceleration pattern F (t) 2' = V1 + ((V2-V1) / 2 ) × sin ((t / T) −1/2) π... Sinusoidal acceleration pattern

In the control unit 2 configured as described above, the CP
At U, a command speed is obtained according to a predetermined acceleration / deceleration pattern read from the storage means 4, and a command speed signal indicating the command speed is output to the servo interface 6. In addition to the command speed signal, an actual speed signal indicating the actual speed detected by the motor 1b and an actual current signal indicating the actual current value of the motor 1b detected by a current sensor (not shown) are input to the servo interface 6. The servo interface 6 compares the command speed with the actual speed, and a signal (command current signal) indicating a current value (command current value) that causes the motor 1b to generate a torque such that the actual speed becomes the command speed. And a voltage value (command voltage value) that compares the command current value with the actual current value so that the actual current value becomes the command current value.
(Command voltage signal), and outputs both of the generated signals to the amplifier 3. Based on these signals, predetermined power is supplied from the amplifier 3 to the motor 1b. Such an operation is repeated until the arm 1a moves to a predetermined turning position.

In the case of controlling the rotation speed of the motor 1b by acceleration / deceleration, as described above, it is more advantageous to follow a sine curve acceleration / deceleration pattern than to follow a linear acceleration / deceleration pattern, since shock and vibration are less likely to occur. If the time and the speed difference before and after the acceleration / deceleration are the same, a torque of about 1.57 times at the maximum is required at the maximum acceleration rather than according to the linear acceleration / deceleration pattern. I do.

Therefore, in the present embodiment, a function indicating a linear acceleration / deceleration pattern is F (t) 1, a function indicating a sine curve acceleration / deceleration pattern is F (t) 2, and the torque required at the time of maximum acceleration is applied to the acceleration of the drive source. A function F (t) 3 = K ×, where K (0 <K <1) is a coefficient determined so as not to exceed the torque upper limit value allowed during deceleration.
An acceleration / deceleration pattern is created from (F (t) 2−F (t) 1) + F (t) 1 and stored in the storage unit 4.
U is caused to read the acceleration / deceleration pattern created by the function F (t) 3 to determine the command speed value. The above functions F (t) 1, F (t) 2, and F (t) 3 are functions using time t as a parameter. The coefficient K is set from input means such as a keyboard connected to the interface 5. When the coefficient K is set, an acceleration / deceleration pattern is created and stored in the storage means 4.

FIGS. 2A to 2E show acceleration / deceleration patterns P1 to P5 created when the value of the coefficient K is set to the value displayed above each table. Graphs G1 to G5 displayed in accordance with the respective tables show changes in torque. As shown, the acceleration / deceleration pattern P created with the coefficient K set to 0
1 corresponds to the linear acceleration / deceleration pattern, and the acceleration / deceleration pattern P5 created by setting the coefficient K to 1 matches the sine curve acceleration / deceleration pattern.

That is, the acceleration / deceleration pattern created by the function F (t) 3 approaches the sinusoidal acceleration / deceleration pattern as the coefficient K is increased, as shown in FIG. The coefficient K matches the ratio of the torque of the motor 1b that is changed according to the sinusoidal curve acceleration / deceleration pattern. As shown in FIG. 3B, the larger the coefficient K is, the more the torque change amounts E1 to E5 at the start and end of the acceleration are.
And shock and vibration at the start and end of acceleration are reduced. From these points, it is preferable that the coefficient K is as large as possible. However, as the coefficient K is increased, as shown in FIG. 3B, the torque required at the time of the maximum acceleration is increased. The torque can only be increased within a range where the torque does not exceed the torque upper limit.

Therefore, if the acceleration / deceleration pattern created by defining the coefficient K so that the torque of the motor required at the time of the maximum acceleration matches the torque upper limit allowable at the time of acceleration / deceleration as the performance of the motor is used, The output performance is maximized, the amount of torque change at the start and end of acceleration / deceleration can be made as small as possible, and the motor can be used at the start and end of acceleration / deceleration without using a motor that can obtain a larger torque. And the shock and vibration applied to the robot arm can be reduced.

The maximum torque required when the linear acceleration / deceleration pattern is used is Tr1, the maximum torque required when the sine curve acceleration / deceleration pattern is used is Tr2, and the upper limit of the torque allowed during acceleration / deceleration as the performance of the motor is Tr2. Using the following equation as Trmax, K = (Trmax−Tr1) / (Tr2−Tr1), it is possible to determine the coefficient K at which the output performance of the motor is maximally used. For example, these torques Tr1,
If Tr2 and Trmax are the values shown in FIG.
The coefficient K is determined to be 0.5.

In FIGS. 3A and 3B, for the sake of explanation,
Since the pattern shape indicating the change in speed and torque is exaggerated, the pattern shape does not always match the actually used pattern shape. In FIG. 3B, a graph shape excluding a so-called overshoot appearing when the torque fluctuates. Are compared.

[0019]

As described above, according to the present invention, the shock applied to the drive source and the operation unit at the start and end of acceleration / deceleration is reduced by making full use of the output of the drive source, and vibration is generated more. A difficult acceleration / deceleration pattern can be created.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a robot to which the present invention is applied.

FIGS. 2A to 2E are diagrams showing an acceleration / deceleration pattern shape created by the method of the present invention by changing the value of a coefficient K, and a graph shape showing a change in torque.

3A is a diagram showing a main part of the acceleration / deceleration pattern shape shown in FIG. 2 which is superimposed, and FIG.
The figure which shows the principal part of what superimposed the graph shape which shows the change of torque which is shown in

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot 1a Arm (operation part) 1b Servomotor (drive source) 2 Control part 3 Amplifier G1-G5 Torque pattern P1 Linear acceleration / deceleration pattern P5 Sine curve acceleration / deceleration pattern (curve acceleration / deceleration pattern)

Claims (1)

[Claims] 1. A method for creating an acceleration / deceleration pattern used for controlling the speed of a drive source of an operating unit of a robot, wherein a function representing a linear acceleration / deceleration pattern used for linear acceleration / deceleration is represented by F (t) 1,
A function representing a curve acceleration / deceleration pattern used for curve acceleration / deceleration is represented by F (t) 2, and a coefficient K (K () is defined so that the torque required at the time of maximum acceleration does not exceed the torque upper limit allowed at the time of acceleration / deceleration of the drive source. Assuming that 0 <K <1), a function F (t) 3 representing the acceleration / deceleration pattern is obtained by the following equation: F (t) 3 = K × (F (t) 2−F (t) 1) + F (t) 1 A method for creating an acceleration / deceleration pattern, characterized in that: