JPS6034501A - Controlling method and device for hydraulic pressure actuator - Google Patents

Abstract

PURPOSE:To improve control accuracy by improving response of an actuator, by a method wherein a velocity arithmetic unit and an acceleration arithmetic unit are provided and a quantity of an opening of a control valve is controlled based on a deviation between an aimed acceleration signal and an actual acceleration signal. CONSTITUTION:A position detector 3 is connected with a cylinder 1 and the output of the position detector 3 is applied to a velocity signal generator 13, a velocity arithematic unit 11 and an acceleration arithmetic unit 12. Quantities of openings of control valves 2a, 2b are controlled based on a deviation between an aimed acceleration signal and an actual acceleration signal by putting out an aimed velocity signal corresponding to an operating position from the velocity signal generator 13, the actual velocity signal and the actual accelerating signal from the velocity airthmetic unit 11 and the acceleration arithmetic unit 12, and the aimed acceleration signal from an acceleration signal generator 15 respectively. With this construction, response of an actuator can be improved and driving in an arbitrary state becomes possible. Accuracy, therefore, of control can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a fluid pressure actuator used in industrial robots and the like, and an apparatus for implementing the method.

Traditionally, feedback control has been performed simply based on position signals to control the positioning of pneumatic cylinders or low reactuators, but such control is affected by the compressibility of the fluid (i.e., is bad,
Overshoot in the stop position and vibrations in the cylinder pressure occurred, making it difficult to perform proper control in some cases.

The present invention properly accelerates, decelerates, brakes, stops, etc. of the actuator regardless of the fluid used, operating pressure, load change, cylinder dimensions, stop position, etc. 1! ), and in order to achieve that objective, the present invention includes a position detection means for detecting the operating position of the fluid pressure actuator, and a position detecting means for detecting the operating position of the fluid pressure actuator, and detecting the actual speed and the a speed calculator and an acceleration calculator that calculate the actual acceleration; a speed signal generator that outputs a target speed signal corresponding to the operating position from the memory; and a control valve connected to the fluid pressure actuator, the opening amount of which is controlled based on the acceleration deviation between the target acceleration signal and the actual acceleration signal. generates a target acceleration based on the speed deviation between the actuator's actual speed and the target speed that is fed back, and adjusts the opening amount of the control valve based on the acceleration deviation between the target acceleration and the fed-back actual acceleration. This is characterized in that the drive of the fluid pressure actuator connected to the control yt is controlled.

According to the method and apparatus of the present invention, the drive of the actuator is controlled based on the deviation between the target speed and the fed-back actual speed, and the deviation between the target acceleration and the fed-back actual acceleration. , the responsiveness of the actuator can be significantly improved, making it possible to drive in any manner, regardless of external disturbances, fluid pressure fluctuations, control valve follow-up delays, fluid compressibility, load fluctuations, etc. First, control can be performed with extremely high precision.

Embodiments of the present invention will be described in detail below based on the drawings.

Fig. 1 is a control calculation block diagram showing the flow of signals in a fluid pressure cylinder device to which the present invention is applied.
is fed back and the speed signal generating device outputs a target speed signal U corresponding to the signal is subtracted, and the speed deviation signal V-? is obtained as the subtraction result. / is sent to the acceleration signal generator to generate a target acceleration signal a corresponding to the signal V-'+7, and the actual position signal obtained by processing this signal a and the actual position signal X with an acceleration calculator. By performing subtraction with the acceleration signal A and sending the acceleration deviation signal A-a as a result of the subtraction to the control operation calculation device, the control signal jA is generated by performing calculations such as PID control on the signal A-a. The signals S, , S2 obtained by processing the signal ΔA with the effective cross-sectional area setting signal generator in the next stage are applied to the control valves, thereby controlling the opening amount of the control valves, and controlling the opening amount of the control valves. The drive of the connected cylinders is controlled.

FIG. 2 shows a specific configuration of a device that performs the control calculations shown in FIG. This is a digital counter that counts device pulses, which is composed of the position detector. By controlling the switching and opening amounts of the control valves 2a and 2b, the rod chamber 5 and head chamber 8 in the cylinder 1 are switched and communicated with the air sources 7 and 8 and the atmosphere, and the driving direction of the cylinder 1 and The operating position of the cylinder 1 driven by the speed is detected by the position detector 3 and continuously outputted as a position pulse, and the position pulse is read by the digital counter 4 to generate the actual position signal of the cylinder. It outputs X.

The position detector 3 can be composed of a rotary pulse encoder, a linear pulse encoder, a potentiometer, etc., and the control valves 2a and 2b are pressure control valves, flow rate control valves, electropneumatic proportional valves, on-off valves, or P
It can be configured by a WM type control valve, or by connecting a plurality of on-off valves or PWM type control valves in series or in parallel.

When on-off valves are used as the control valves 2a and 2b, the function of the flow rate control valve can be approximated as follows. That is, the flow rate characteristic of the on-off valve is expressed as G=C@, 71F, where G is the flow rate when fully opened, ΔP is the supply differential pressure, and C is the flow coefficient.

Now, if the control valve is turned on and off during a sufficiently short time ΔT so that the total time of the control valve being fully open becomes Δt',
The average flow rate G' at that time ΔT is as follows.

Here, when Δt' is changed, the apparent flow rate coefficient C' changes accordingly, so G' also changes, thereby making it possible to perform the same function as a flow rate control valve.

In the signal processing circuit connected to the digital counter 4, 11 is a speed calculator, 12 is an acceleration calculator, and 13 is a speed calculator.
1 is a speed signal generator, 14 is a subtracter, 15 is an acceleration signal generator, 16 is a subtracter, 17 is a control operation calculation device, 1
Reference numeral 8 indicates an effective cross-sectional area setting signal generating device for the control valve.

In such a signal processing circuit, when the digital counter 4 outputs the actual position signal X, the actual velocity signal V and the actual acceleration signal A are generated from the signal X in the velocity calculator 11 and the acceleration calculator 12. , are sent to respective subtractors 14.18. Actual speed signal V above
In order to generate the actual acceleration signal A, a speed meter such as a tachometer may be attached to the actuator, and an appropriate accelerometer may also be attached directly to the actuator.

On the other hand, the actual position signal X is transmitted directly to the speed signal generator 1.
Sent to 3. This speed signal generator 13 has a position memory 21 in which a large number of cylinder operating positions are stored as digital i at arbitrary minute intervals, and each operating position in the 1-position memory 21 is made to correspond with a predetermined functional relationship. A speed memory 22 in which speed is stored as a digital quantity is provided, and when the actual position signal X is input, a speed signal corresponding to the position signal in the position memory 21 is output as a target speed signal.

In the speed signal generating device 13, a large number of cylinder operating positions set at minute time intervals can be stored and these can be made to correspond to the speed memory.

The target speed signal is calculated from the actual speed signal V by a subtracter 14 at the next stage, and a speed deviation signal V-re based thereon is sent to the acceleration signal generator 15.

The acceleration signal generator 15 has an arbitrary increasing function 24, and in the functional relationship, an acceleration signal corresponding to the deviation signal V-υ is output as a target acceleration signal. The target acceleration signal is the actual acceleration signal A
is subtracted by the subtracter 16 at the next stage, and an acceleration deviation signal A-a based on the result is further sent to the control operation calculation device 17 at the next stage.

The control operation calculation device 17 performs proportional control, PID control, on-off control, or P
It performs nonlinear control such as WM control. For example, when performing PID control, in the frequency domain, Kp: Proportional gain of PID operation Td: Differential time of PID operation Ti 2 Integral time of PID operation S Nira plus operator We will perform calculations like this.

The deviation signal ΔA obtained in this way is sent to the next-stage effective cross-sectional area setting signal generator 18, where the effective cross-sectional area setting signals Sa and Sb are calculated as follows: Saj = 5ad-, -K *ΔA Sbj=Sbj- + (1-K)ΔA However, 0≦≦1 Saj-+, 5bj-i: Effective cross-sectional area J at operating position , those signals are respectively transmitted to the control valves 2a,
2b to control the opening amount, thereby accelerating or decelerating the cylinder 1. Further, such acceleration or deceleration is repeated every time a certain minute displacement of the cylinder 1 or every minute time, and the cylinder 1 finally stops at the target position. In this case, if the cylinder is provided with a braking device, it is possible to improve the stopping accuracy and the possibility of reliably holding the cylinder at the stopped position.

FIG. 3 shows the control process of the cylinder. In the control of the present invention, the target speed is set like a curve as a function of the operating position of the cylinder, and the actual speed and position are set as a function of the cylinder's operating position. For example, 1tX
At n, the cylinder speed Vn is the target speed u on the curve
If it deviates from n, the cylinder is accelerated or decelerated based on the acceleration signal corresponding to the speed difference, thereby bringing the actual position and speed closer to the above-mentioned curve. In particular, the above-mentioned acceleration feedback The looseness allows the cylinder to quickly approach the final target position and target speed.

In addition, the operating position and target speed of the cylinder are set arbitrarily before cylinder operation, but if an extremely large load change occurs, they can be changed during operation to deal with load disturbances. Alternatively, the same effect can be expected by changing the increasing function in the target acceleration signal generating device or the control operation in the control operation calculation device during the operation. It goes without saying that the above-mentioned increasing function and control operation can be arbitrarily set before the operation of the cylinder.

It goes without saying that the present invention can be applied to the control of a plurality of cylinders and further to the control of a row reactuator.

In addition, as shown in Fig. 4, in order to simplify the algorithm of computers, etc., the speed signal generator, acceleration signal generator, and control operation calculation device each output an increasing or decreasing function that changes in stages. In addition to being configured to generate signals, an on-off valve may be used as a control valve connected thereto, and the on-off valve may be controlled by a digital signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing a specific example thereof, FIG. 3 is an explanatory diagram of its control method, and FIG. 4 is a different embodiment of the present invention. FIG. 2 is an example block diagram. 2a, 2b...control valve, 13...speed signal generator,
15... Acceleration signal generator.

Claims (1)

[Claims] 1. The operating position of the fluid pressure actuator is fed back as an operating position signal to the speed signal generator, and an actual velocity signal and an actual acceleration signal are generated from the operation of the fluid pressure actuator, and the operating position signal is Determine the speed deviation between the target speed signal output by the speed signal generator and the above actual speed signal based on the speed deviation, and further calculate the acceleration between the target acceleration signal output by the acceleration signal generator and the above actual acceleration signal based on the speed deviation. A method for controlling a fluid pressure actuator, characterized in that the fluid pressure actuator to which pressure fluid is supplied through the control valve is controlled by determining the deviation and adjusting the opening amount of the control valve based on the acceleration deviation. . 2. Position detection means for detecting the operating position of the fluid pressure actuator; a speed calculator and an acceleration calculator that calculate the actual velocity and actual acceleration from the operation of the fluid pressure actuator; and a target speed corresponding to the operating position. a speed signal generator that outputs a signal from a memory; an acceleration signal generator that outputs a target acceleration signal based on a speed deviation between the target speed signal and the actual speed signal; and an acceleration signal between the target acceleration signal and the actual acceleration signal. A control device for a fluid pressure actuator, comprising: a control valve connected to the fluid pressure actuator, the opening amount of which is controlled based on the deviation;