JPH01206404A - Acceleration/deceleration controller - Google Patents

Abstract

PURPOSE:To set the beginning of the rise of acceleration and that of the fall of deceleration to a large time constant so as to avoid the sudden change of acceleration at the time of acceleration and deceleration by switching the time constant of linear acceleration and deceleration from tau1 to tau2 which is smaller than tau1 is the middle of acceleration and deceleration. CONSTITUTION:At the time of acceleration, a feed rate F, a move quantity S and a sampling period T, which are necessary as a command, are given to a pulse distributor 1, and the pulse generator 1 executes pulse distributing operation based on the inputted move quantity S, generates the move quantity DELTAS of a one sample time so as to send it to a switching circuit 4. The switching circuit 4 selects a first direct acceleration deceleration circuit 2 so that the move quantity S is sent to the circuit 2 from the beginning of acceleration to a constant time t1. When t1 passes, the switching circuit 4 selects a second linear acceleration and deceleration circuit 3, sends the move quantity DELTAS and controls linear acceleration and deceleration with the time constant tau2 which is smaller than tau1. Consequently, an acceleration control characteristic turns into a tertiary curve approximate acceleration characteristic. The same occurs at the time of deceleration in the same way as an acceleration time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an acceleration/deceleration control device for a servo device that drives a movable part of a machine tool, for example, and in particular to a smooth drive at the start of acceleration/deceleration. .

[Prior Art] Conventionally, when controlling the axis movement of a machine tool, etc., acceleration and deceleration are generally performed in order to avoid applying a shock to the mechanical system at the time of starting or decelerating the axis movement.

Linear acceleration/deceleration control is adopted as this acceleration/deceleration control.

FIG. 5 is a block diagram showing a conventional linear acceleration/deceleration control device, in which (1) is a pulse distributor, (13) is a linear acceleration/deceleration circuit, and (5) is a servo circuit.

The servo circuit (5) includes a subtracter (6) and an amplifier (7). (8) is a servo motor driven by the output signal of the servo circuit (5), (9) is a servo motor (8)
This is the machine side drive system driven by.

In the linear acceleration/deceleration control device configured as described above,
The pulse distributor (1) is given a feed rate F, a movement amount S, and a sampling period T as commands. Pulse distributor (
1) performs a pulse distribution calculation based on the input movement amount s, generates a movement amount ΔS per one sampling time T, and sends this movement amount ΔS to the linear acceleration/deceleration circuit (13).

The linear acceleration/deceleration circuit (13) uses (G) and (J) in Figure 6 by the amount of movement ΔS per sampling time during acceleration and deceleration.
), linear acceleration/deceleration control is performed with a time constant τ to generate a moving port ΔS. The servo circuit (5) drives the servo motor (8) based on this movement amount ΔS to move the axis of the machine drive system (9).

When moving the axis of this machine side drive system (9), the machine side drive system (9)
The position of 9) is detected and the servo circuit (5) is activated based on this position.
is under feedback control. Therefore, during acceleration/deceleration, there is an exponential delay τP (τP
-1/position loop gain), the input (G) to the servo circuit (5) shown in FIG.

With respect to (J), the output of the servo circuit (5) is delayed (11
).

The curve becomes smooth as shown in (K), and the servo motor (8) is driven by this output.

[Problems to be Solved by the Invention] In the conventional acceleration/deceleration control device configured as described above, linear acceleration control is performed with a time constant τ during acceleration/deceleration, so that the initial acceleration at the rise of acceleration as shown in FIG. The acceleration of the servo motor (8) changes rapidly at the beginning of the fall of deceleration. This has caused a problem in that shocks and vibrations occur in the mechanical system during acceleration and deceleration.

In order to prevent shocks occurring in the mechanical system during acceleration/deceleration, if the time constant τ of linear acceleration/deceleration control is made excessively large, the acceleration/deceleration time becomes too long, and if the position loop gain of the servo circuit is made low, acceleration/deceleration is completed. There was a problem in that the speed change in the vicinity took too long.

This invention was made to solve these problems, and the object is to obtain an acceleration/deceleration control device that can smoothly drive a mechanical system without excessively lengthening the acceleration/deceleration time. It is something to do.

[Means for Solving the Problems] An acceleration/deceleration control device according to the present invention replaces a first linear acceleration/deceleration circuit that performs linear acceleration/deceleration with a time constant τ1 during acceleration/deceleration with a time constant τ2 smaller than the time constant τ1. It is characterized by switching to a second linear acceleration/deceleration circuit that performs linear acceleration/deceleration.

[Operation] In this invention, by switching between the first linear acceleration/deceleration circuit and the second linear acceleration/deceleration circuit during acceleration/deceleration, acceleration/deceleration is performed with a large time constant at the beginning of the rise of acceleration and the beginning of the fall of deceleration. Perform cubic curve approximation acceleration/deceleration control.

[Example] FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, (1), (5) and (6) are exactly the same as the conventional example shown in FIG. (2) is (A
), the first linear acceleration/deceleration circuit performs linear acceleration/deceleration control with a time constant τ1, and (3) is the time constant τ of the first linear acceleration/deceleration circuit (2), as shown in FIG. 2 (B). This is a second linear acceleration/deceleration circuit that performs linear acceleration/deceleration control (2) with a smaller time constant τ2. (4) is the movement amount ΔS per sampling time calculated by the pulse distribution in the pulse distributor (1) into which the feed rate F and movement IJA S + sampling period T are input, and the movement amount ΔS per sampling time is calculated with the first linear acceleration/deceleration circuit (2). A switching circuit (11) that switches to and sends data to the second linear acceleration/deceleration circuit (3) accelerates and decelerates data by an acceleration/deceleration start signal sent from a control device (not shown) and a clock pulse sent from the clock pulse generation circuit (12). A certain period of time from the start (
tl) This is a counting circuit that sends a switching signal to the switching circuit (4) after the elapsed time.

In the acceleration/deceleration control device configured as described above, during acceleration, the necessary feed rate F, movement amount S, and sampling period T are given as commands to the pulse distributor (1), and the pulse distributor (1) receives input signals. A pulse distribution calculation is performed on the basis of the movement amount S, and a movement amount ΔS for one sampling time is generated and sent to the switching circuit (4). The switching circuit (4) selects the first linear acceleration/deceleration circuit (2) at the start of acceleration, and selects the second linear acceleration/deceleration circuit (2) according to the time count signal from the counting circuit (11) when a certain time (tl) has elapsed from the start of acceleration. (3) is configured to be selected. Therefore, the switching circuit (4
) to a certain time (tl) from the start of acceleration, the movement amount ΔS
is sent to the first linear acceleration/deceleration circuit (2).

The first linear acceleration/deceleration circuit (2) performs linear acceleration control using the input movement amount ΔS with a time constant τ1 shown in FIG. 2(A), and sends the movement amount ΔS to the servo circuit (5). When a certain period of time (tl) has elapsed from the start of acceleration, the switching circuit (4) selects the second linear acceleration/deceleration circuit (3) and sends the movement amount ΔS to the linear acceleration/deceleration circuit (3). The second linear acceleration/deceleration circuit (3) performs linear acceleration control using the input movement amount ΔS with a time constant τ2 shown in FIG. 2(B), and sends the movement amount ΔS to the servo circuit (5).

Therefore, the acceleration control characteristic input to the servo circuit (5) during acceleration becomes a cubic curve approximation acceleration characteristic with a small slope at the time of rise, as shown in FIG. 3(C).

When this signal is input to the servo circuit (5), the position loop gain of the servo circuit (5) causes an exponential delay factor, and the output characteristic of the servo circuit (5) changes to a smooth three-dimensional curve as shown in (D) in Figure 3. The acceleration control characteristic is the following curve, and the acceleration control of the servo motor (8) is performed according to this characteristic.

During deceleration, a certain period of time (t
l), the time constant τ1 is set by the first linear acceleration/deceleration circuit (2).
After a certain period of time (tl) has elapsed, the second linear acceleration/deceleration circuit (3) performs linear deceleration control with a time constant τ2. Therefore, the deceleration characteristic applied manually to the servo circuit (5) during deceleration also becomes the cubic curve approximation deceleration characteristic shown in (E) in Figure 3, and the output characteristic of the servo circuit (6) is shown in (P) in Figure 3. This results in a cubic curve deceleration control characteristic.

In addition, in the above embodiment, the first linear acceleration/deceleration circuit (2)
and the second linear acceleration/deceleration circuit (3) during acceleration/deceleration. Servo motor (
8), but as shown in Fig. 4, by providing an exponential acceleration/deceleration circuit (14) that performs exponential acceleration/deceleration control before the servo circuit (5), smoother third-order Curvilinear acceleration/deceleration characteristics can be obtained.

[Effects of the Invention] As explained above, the present invention includes a first linear acceleration/deceleration circuit that performs linear acceleration/deceleration with a time constant τ1 during acceleration/deceleration, and a linear acceleration/deceleration circuit that performs linear acceleration/deceleration with a time constant τ2 smaller than the time constant τ1. Second
By switching to a linear acceleration/deceleration circuit, a large time constant is used at the beginning of the rise of acceleration and the beginning of the fall of deceleration.Since the cubic curve approximation acceleration/deceleration control is performed, sudden changes in acceleration occur during acceleration and deceleration. It is possible to prevent shocks and vibrations from occurring in the mechanical system.

Furthermore, since it is not necessary to increase the overall time constant when performing acceleration/deceleration, there is an effect that the mechanical system can be driven smoothly without increasing the acceleration/deceleration time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG.
3 is an explanatory diagram of the operation of each of the above embodiments, FIG. 4 is a block diagram showing another embodiment of the present invention, FIG. 5 is a block diagram of a conventional example, and FIG. 6 is an explanatory diagram of the operation of the conventional example. It is. (1)... Pulse distributor, (2)... First linear acceleration/deceleration circuit, (3)... Second linear acceleration/deceleration circuit, (4)...
- Switching circuit, (5>... servo circuit, (8)... servo motor, (9)... machine side drive system. In addition, the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] In an acceleration/deceleration control device that accelerates or decelerates the feed speed of a servo device to a commanded speed, there is a pulse distributor that outputs position data every sampling period, and a time constant τ.
A first linear acceleration/deceleration circuit performs linear acceleration/deceleration of _1, a second linear acceleration/deceleration circuit performs linear acceleration/deceleration of time constant τ_2 smaller than the time constant τ_1, and the first
An acceleration/deceleration control device comprising: a switching circuit that switches a linear acceleration/deceleration circuit to a second linear acceleration/deceleration circuit.