JPS5914441A - Control system for travelling machine having backlash - Google Patents

Abstract

PURPOSE:To prevent a drive side travelling member and a load side travelling member from colliding with each other, in a method of controlling the movement of a linear control system having backlash, by making the drive side travelling member contact to the load side travelling member with a speed of zero, and by always judging whether the members are accelerated or decelerated during the travel thereof to their target. CONSTITUTION:In the case of a linear control, the existence of a gap is detected upon acceleration and control is made at first to reduce the gap to zero when the gap exists. The drive side travelling member A is made contact with the load side drive member at the acceleration side or deceleration side of the latter with a relative speed of zero. When the member B is moved to a target point from its arbitrary initial condition, computation is always made to judge whether acceleration or deceleration is necessary at its initial condition. In accordance with the result, the member is moved to the target point under linear control after the control of the above-mentioned gap by changing over from acceleration to deceleration To time before the ideal condition having no backlash, thereby the linear control to the target point can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method that allows smooth operation even when there is a shock, and enables highly accurate control.

As is well known, there are varying degrees of mechanical equipment, but
Nonotsu Crush exists.

This is due to the mechanical causes of movement of each part (for example, the incelute tooth shape of a gear, the thread shape of a feed screw rod, etc.)
This is due to the precision of workmanship, but due to the existence of this crush, the following points have become major problems.

1) Since the positioning accuracy cannot be made less than the width of the crush width, it has not been possible to realize a device with higher positioning accuracy.

2) Nonotsu crash is a factor that degrades stability in closed loop control, so the loop gain can only be set to a very small value, resulting in poor response and knocking. 3) Starting , a collision always occurs at the notch crash section when stopped, which significantly shortens the life of the power transmission section.

In addition to taking such countermeasures, the circus mechanism forms a foot-no-sec loop with only the actuator, which is outside the closed loop. A widely used method is to correct backlash in a static state by adding up the position command value only when the operating direction changes.

However, although such a method can avoid the above 2), it is not a solution to the problems 1) and 3).

In addition, as a control method for a control system that has a nototsu lash, especially a device that drives a moving body on the load side through a gear device, it is possible to control a device that drives a moving body on the load side through a gear device of the same type that does not have a nototsu lash. A control method was proposed in 1983, in which two drive systems were installed together, the difference in drive amount between the two drive systems was detected without contact, and the deviation was detected in the control circuit of the serze motor to eliminate backlash. It is known from the publication No. 1.0646.

However, this control method uses a positive/negative direction method of the target value.

Therefore, the present invention provides a driving side moving body A and a load side moving body 0.
In a linear control system moving device with a knot crash between them, a device R is provided to detect the position When making contact with the side or deceleration side at a relative speed of zero (e=o), that is, without shock, and when moving from an arbitrary initial state to the target point.

Determine whether acceleration or deceleration is necessary from the initial state,
Accordingly, after the above-mentioned gap control, the linear control is used to move to the target point, and if there is no backlash on the way, it is necessary to switch from acceleration to deceleration. This is a control method that performs deceleration switching to move to the target point without a collision due to a crash.

Normally, when building a control system, it is most often used and migrated.

The object of the present invention is to provide a control system that eliminates collisions caused by collisions and that can perform positioning regardless of the gap width.

In other words, in a linear control system, it is possible to provide conditions that clearly separate the conditions for gap control and load control, such as the deviation between the command value of the target position and the load position, and the information on speed, and to provide a method for configuring the control system. This is the object of the present invention.

For convenience of explanation, first consider a mobile machine with a linear control system when no backlash exists in the power transmission section.

A normal second-order linear control system is represented by a block diagram as shown in FIG.

In the figure, xLr is the load unit target position command signal -K21 +, 2x is each gain of the proportional controller 1.2, αt) is the operation amount applied to the drive unit motor, and JH, M are the load inertia moment JL and the motor The sum of the moments of inertia JM.

S represents a differential operator, XI represents the load section position, and the response of this system is given by the following equation.

JLM “KL+ to 22°XL + K21” K22
°XL=2t” Km 2・XLr・・・・・・
...(1) xL+ 2ζωnXL+ωn2XL=ωn2XLr
・・＋ +・+ ・++ (2) However, ωn is the natural frequency JLM ζ is the damping coefficient 2ωn If the command signal XLrk is a stellar step in the quadratic linear control system expressed by this equation (2), then ζ〉1 In the case of XL,
The intersection changes as shown in FIG.

In this figure, from an arbitrary initial state (XL I X et al.) =
(0,0), that is, the change when controlling with the origin as the target point.

occurs automatically, and the control device can move the load to the target position without special switching between acceleration and deceleration.

Basically, in the linear control system between the moving bodies 13 on the side, when accelerating the load, it is necessary to bring the driving side A4 into contact with the acceleration side end (the right end in Figure 3), and when decelerating the load, it is necessary to bring the drive side A4 into contact with the acceleration side end (the right end in Figure 3). Bring the drive side into contact with the left end of Figure 3) and set the gap to 0.
It is necessary to control the

Therefore, in the case of linear control, the presence or absence of a gap during acceleration is detected, and if there is a gap, the gap is first reduced to zero.
In the linear control that moves to the target point, it is necessary to clearly know the change point where the transition from acceleration to deceleration automatically occurs, and when the moving body A' on the driving side is moved slightly before this change point Q,
If gap control is performed in which the deceleration end of the moving body B on the load side is brought into contact with the deceleration end of the moving body B on the load side, the moving body A on the load side can be accurately stopped at the target position.

FIG. 4 is a block diagram of a control device for performing notch lash control of a power transmission mechanism having a notch lash, in which 5 is a drive unit that drives a load unit 7 via a feed screw rod 6;
Reference numeral 8 indicates a position and speed detector for the drive unit, 9 indicates a position and speed detection device for the load unit 7, and 10\1 an arithmetic unit that calculates and logically determines how to perform appropriate control based on the detection signal of the detector 8.9; 11 is an actuator control section that sends out a command signal based on the calculation result of the calculation section 10, and 12 is a minor loop.

The presence or absence of the aforementioned gap and the point of change are detected by the calculation unit 10.

The inflection point is the inflection point 01 * C2+ in Figure 2.
...04. In other words, it is a point corresponding to XL=0. Connecting these inflection points 01102...... forms a straight line, which will be referred to as the total inflection point straight line f2.When finding the inflection point of the linear control system shown by equation (2), x
When Lr'i step input is used, the following equation can be used: XL + 2ζωnXL +ωn''XL=0 -...
...(3) The solution to equation (3) is /(X
L + XL ), t = 0 as P = (Xo, 0)
(See Figure 5) (5) Equation XL t-calculation, = 0
If we eliminate t as , α17yl'jD"+2ζ
It shows the positive value of two real roots of ωnD+ωn = 0.

Therefore, when moving from point P in Figure 5 to the origin (target position), the operation it U(t) will be given in the form of XL in Figure 6 (C1) as (XL, XL) changes. .

Point C1 in XL in Figure 6(c) satisfies equation (6)<
XL,;a-) is reached, and at this time the load will enter a state of deceleration from acceleration.

Therefore, in order to eliminate collisions caused by backlash upon reaching the target position, it is necessary to bring the drive section into contact with the deceleration end (here, the left end) of the load section before reaching the 01 point. Bumper gap control must be performed.

Otherwise, when the moving body A on the driving side reaches the target position,
The moving body A on the load side has an inertia of 19 from the gap (point of inflection) to the time TO required for gap control.This time To can be determined as follows.

The response of the drive is r, x, ” K12XM + 1 + XM to Xt2
= 0--- It is found by solving (7), and if this linear control system is set as ζ>1, two real roots α' and β' can be found. TOTh(1/B') as a practical settling time
It may be set to 3 to 5 times. (However, 1/β'〉1/α') Here, To=-... (8) β
′.

That is, the target value for gap control (L/2.0).

(-L/2,0) can settle within at least 10 hours.

In other words, the change in (Xt, , XL) when no manipulated variable is applied to the load section on the (xL, XL) phase plane is XL=-kXL (9). However, k is determined experimentally. The above points can be summarized as follows.

Consider the case where (xL, XL>→(0°) transitions from a certain initial state. 4) 扛zu L(0'l1勺.

First, measure XL, XL w XM+
2,0).

After gap control to (L/2.0) is achieved, side shape control is performed as a unit of the drive section and load section.

Meanwhile, while increasing the amount of operation in the drive unit, XL + Xt,
Constantly measure IX, J, and XM.

And (X'L, xL) is the gear control start plane ifR
When the point on ft is reached, gap control is performed. The target value at this time is (-L/2.0). Hereinafter, f will be referred to as a first determination straight line, and f2 will be referred to as a second determination straight line.

<-L/2, 0) until the gap control is achieved. When the target value is reached, the gap control is immediately performed. .

The measured value of (Xt, , Xt, ) is the first judgment surface @f
If it is below 1O, it means acceleration, and if it is above, deceleration must be achieved.

Next, the embodiment shown in FIG. 8 will be explained.

This embodiment shows an example in which the present invention is applied when a load 14 is driven by a motor M via a power transmission mechanism 13 with a notch crash, and 15 is connected to the motor M. The detection signals of the speed detector TG1 and the position detector PG using a nosolus generator, the detection signals of the speed detector To2 connected to the load 14 and the position detector PG2 using a pulse 7 generator, The first and second judgment straight lines fl + selected based on the settings or those detection signals
18 is an L/2 command value setting device for performing gap control on the acceleration side, and 19 is for performing gap control on the deceleration side. L/2 command value setting device for, 20 is a gear tooth width setting device, 21 to 24 are ratios,
If there is a gap due to backlash on the acceleration side at the time of startup, first, the switching devices 11fi and 17 select the switching command value setter 1B to the 16b and 17a sides by the judgment device [15, and control the acceleration of the motor Mi to set the gap to 0. Then, control is performed to switch the switching device 16 by 16aK and move to the target position.

This operation control determining device 15 operates, and the determination straight line fs
, f, and the measured values XL, XL to determine whether or not deceleration is required.

XL * When XL exceeds the value on the first judgment straight line fl, the gap control on the deceleration side must be performed immediately in order to accurately stop the load side at the target position. 16b also has a switching device 17
17b and select the command value setter 19f to perform gap control.

When the gap control is completed, the judgment device #15 switches to the switching device 16 f 16 m, and automatic control is performed to stop all the loads at the target positions.

In addition, each gain Kl 1 + K of the proportional controllers 21 and 22
If the JLM of the control system is known, l t + can be changed to 2 in equation (2).
1 + K22 and the gains of the ωn proportional controllers 23 and 24, 21 + KH2, are determined by calculation if JM is known. The calculation formula is the same as formula (2).

Preferably, To is four times the slowest time constant of the drive system.

In practical use, if a large Coulomb friction force acts on the load part, if no operation amount is applied to the drive part when the load speed is below a certain value (XL), the load part will come to a standstill due to the friction force. The speed of the load will drop during the gap control period of , and when performing gap control from the information of (XL, xt, ), it may be started later by a time corresponding to this speed drop.

Figure 10 (r!, fs + (<K) shows the trajectory when a frictional force is applied and vXL, XL becomes stationary.

kLo can be known from actual measurements, and this X. .

-Shift fl to the left and right so that it touches f3+f4 at -xLC. f(obtained in this way) becomes a new gear control determination curve.

At this time, it is determined that 1xLl≦XLOyk, and no operation amount is applied to the drive unit.

I can.

゛: As mentioned above, according to the water valve a8, even if the crash is caused by the AI, there will be no collision at the crush part,
Therefore, it is possible to extend the overall life of the machine, and there is also a manufacturing advantage in that there is no need to require unreasonable precision in machine assembly, and the control system is stable even if a crash occurs in a closed loop. Coupled with the fact that the invention is fully guaranteed, it is an industrially excellent invention.

The present invention clarifies the method of specifying the switching point between gap control and load control when controlling a mobile machine that is prone to backlash control using linear control, thereby expanding the scope of application of backlash control. The fact that we were able to spread this out across the country is of great value to the prefecture.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the linear control system, Figure 2 is a diagram showing the relationship between the position and speed of the load (driven part) in the linear control system, and Figure 3 is a model diagram of the Nonotsu crush section. Fig. 4 is a block diagram of a control device for a power transmission mechanism with a crush, Fig. 5 is a modified diagram, Fig. 9 is a judgment flowchart in the judgment device, and Fig. 10 shows a large Chloron friction force acting on the load section. FIG. 3 is an explanatory diagram of first and second determination straight lines when M... Drive motor, 13... Power transmission mechanism with knot crash, TGl, T(h... Speed detector, PG,, PG,... Position detector, 14...
Load, 15... Judgment device, 16.17... Switching device, 18.19... Gap control command value setting device, 20
...Gear width setting device, 21-24...Proportional controller, 25...Power amplifier. Patent applicant Makoto Ishizaka, Director of the Agency of Industrial Science and Technology - 4th eye, 3rd circle, 6th Oka [10th fight. 914th

Claims (1)

[Claims] When a gap exists between the movable body A on the drive side and the movable body 8 on the load side, gap control is performed to adjust the relative speed of the movable body A on the drive side to the acceleration side or deceleration side of the movable body B on the load side. When making contact at zero (e = 0) and moving from an arbitrary initial state to a target point, it is determined from that initial state whether acceleration or deceleration is necessary, and linear control is performed after the gap control described above accordingly. to move to the target point,
On the way, the acceleration ← deceleration switching is performed earlier than the point at which the acceleration ← deceleration switching would be required when there is no crash by the time To required for the crash control, and linear control is performed until the target point is reached. A control method for mobile machines with a characteristic backlash.