JPH083758B2 - Control device for multi-joint structure machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control device for a multi-joint structure machine including a multi-joint arm, and more specifically, a control suitable for suppressing vibration of a multi-joint arm of the multi-joint structure machine. Regarding the device.

[Conventional technology]

An example of an articulated structure machine is a robot equipped with an articulated arm. Although this type of robot arm has relatively high rigidity, the arm still vibrates, and various means for suppressing the vibration have been proposed.
(JP-A-54-31877 and JP-A-58-3001) On the other hand, as another example of the articulated structure machine, various machines having two or more arms have been proposed. In this type of multi-joint structure machine, as the number of arms increases, the capacity of the drive system also increases. Therefore, the weight of the arms is being reduced from the standpoint of downsizing drive actuators such as hydraulic cylinders and saving energy. . However, when the shape of the arm is made thin to reduce the weight, the rigidity of the arm becomes low and the natural frequency becomes low. Therefore, the low rigidity of the arm is added to the spring mass effect due to the arm mass and the compressibility of oil.
The damping characteristics of the system deteriorate. Therefore, the pulsation of low vibration generated at the time of starting or stopping the drive actuator was not attenuated in a short time, resulting in poor operability. As a measure for suppressing this vibration, there is one described in Japanese Patent Laid-Open No. 58-135388. This measure always connects the hydraulic actuator and the hydraulic pump that controls the speed of the hydraulic actuator.

[Problems to be solved by the invention]

In the hydraulic circuit of the multi-joint structure machine described above, in order to prevent the arm from dropping due to breakage of the pipeline, etc., the switching that connects and disconnects the hydraulic pipeline between the hydraulic actuator and the control valve that controls the speed of the hydraulic actuator. The valve is normally installed, and when the operating lever is in the neutral position, this switching valve separates the pipe line. Therefore, when the above conventional example is applied to a multi-joint structure machine having such a switching valve, the vibration of the arm at the time of start can be suppressed, but the operation at the time of stop can be performed. As soon as the lever is returned to the neutral position, the switching valve separates the conduit between the hydraulic actuator and the control valve, so that the vibration cannot be suppressed. Further, when the operation lever is neutral, even if vibration is generated for some reason, the vibration cannot be suppressed.

The present invention has been made based on the above-mentioned matters, and an object of the present invention is to provide a control device for a multi-joint structure machine capable of suppressing the vibration in any case when the arm vibrates. And

[Means for solving problems]

The above object of the present invention is to provide a drive control system for at least one arm with an actuator for driving the arm,
In a control device for a multi-joint structure machine composed of a control valve controlled by operating an operation lever and a switching valve for connecting and disconnecting a flow of pressure oil between the control valve and an actuator, a vibration for detecting a vibration of the arm. A detection means is provided, the control valve is connected to a vibration suppressing means for suppressing the vibration generated in the arm, and an acceleration check circuit that outputs an ON-OFF signal to the switching valve according to a signal from the vibration detecting means. This is achieved by connecting a switching valve control circuit that controls ON / OFF of the switching valve by the logical sum of the ON-OFF signal from this acceleration check circuit and the operation amount signal of the operating lever.

[Action]

If the signal from the vibration detection means exceeds a certain specified value, the acceleration check circuit always outputs an ON signal for a certain period of time to a switching valve provided between the actuator and the control valve,
Since this switching valve is maintained in the ON state, the actuator is operated based on the control of the control valve controlled by the vibration suppressing means when the arm is vibrating even when the operation lever is in the neutral position. Therefore, the vibration of the arm can be quickly suppressed.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a multi-joint structure machine provided with an example of the control device of the present invention. In the figure, 1 is a revolving structure, 2 is a bracket provided on the revolving structure 1, and 3 is a bracket 2. The first arm 5 is a second arm attached to the tip of the first arm 3, and 7 is a third arm attached to the tip of the second arm. The first arm 3, the second arm 5 and the third arm 7 are operated by the first cylinder 4, the second cylinder 6 and the third cylinder 8, respectively. The pressures on the head side and the rod side of the first cylinder 4, the second cylinder 6, and the third cylinder 8 are detected by pressure detectors 9 to 14. The detection values of the pressure detectors 9 to 14 are transmitted to the thrust calculation circuit, that is, the cylinder thrust calculation circuit 16 by the detection circuit 15. The cylinder thrust calculation circuit 16 calculates the head side pressure P _1H , the rod side pressure P _1R, and the head side area A _{1H of} the first cylinder 4.
And the rod side area A _1R , the thrust f ₁ of the first cylinder 4 is calculated, and the head side pressure P _2H and the rod side pressure P _{2R of} the second cylinder 6 and the head side area A _2H and the rod side area A are calculated.
The thrust f ₂ of the second cylinder 6 is calculated based on _2R , and the third pressure is calculated based on the head side pressure P _3H and the rod side pressure P _{3R of} the third cylinder 8, and the head side area A _{3H and the} rod side area A _3R .
The thrust f _{3 of the} cylinder 8 is calculated, and this is calculated by the filter circuit 17
Is output to the comparison calculation control circuit 18 via. An input device 19 is installed in the driver's seat (not shown) of the articulated structure machine. This input device 19 has the speeds v ₁ , v ₂ ,
It has an operating lever that gives v ₃ . This input device 19 tells the comparison calculation control circuit 18 the speed command v ₁ of the first cylinder 4,
Speed command v ₂ of the second cylinder 6, and outputs a speed command v ₃ of the third cylinder 8. Based on the speed commands v _{1 to} v ₃ of each cylinder and the thrust forces f _{1 to} f ₃ of each cylinder, the comparison operation control circuit 18 controls each cylinder 4, 6 required to suppress the vibration of each arm 3, 5, 7. And outputs the flow rate to 8 to the servo amplifier 20 in the form of voltage. The servo amplifier 20 converts this voltage input into a current,
It drives electro-hydraulic servo valves whose output flow rate is proportional to the input current, so-called servo valves 21-23. As a result, each cylinder 4, 6, 8 operates. 24,25,26 are the first arm 3,
It is an acceleration detector provided on the second arm 5 and the third arm 7. The detected values of these acceleration detectors 24 to 26 are passed through a detection circuit 27 and a filter circuit 28 to an acceleration check circuit 29.
Is transmitted to. Acceleration check circuit 29 consists of arms 3, 5,
Based on the acceleration value of 7 and a specified value, an ON signal is output to the switching valve control circuit 30 if the arms 3, 5, 7 are vibrating, and an OFF signal is output if they are not vibrating. The switching valve control circuit 30 operates on the basis of the speed commands v _{1 to} v ₃ of each cylinder from the input device 19 and the ON / OFF signals from the acceleration check circuit 29 to determine the servo valves 21 to
The switching signals of the switching valves 32 to 34 provided between the 23 and the cylinders 4, 6, 8 are output to the drive circuit 31.

First, the elements for configuring the vibration suppression means of the arm,
That is, the cylinder thrust calculation circuit 16, the filter circuit 17,
The comparison calculation control circuit 18 will be described in detail. In this description, the state of the switching valves 32-34 is assumed to be the function on the right side of FIG.

FIG. 2 shows the configuration of the cylinder thrust calculation circuit 16. In this figure, first, the system of the first cylinder 4 will be described. The head side pressure signal P _1H from the detection circuit 15 to the head side pressure signal P _1H has a coefficient. In the unit 160, a value obtained by multiplying the head side area A _1H and the rod side pressure signal P _1R are _added to the coefficient unit 16
The difference from the value obtained by multiplying the area A _1R on the rod side at 1 is obtained by the comparator 162, and the value, that is, the cylinder thrust force f ₁ is output to the filter circuit 17. In this way, the same processing is performed for the system of the second cylinder 6 and the system of the third cylinder 8, and the cylinder thrusts f ₂ and f ₃ are output to the filter circuit 17.

FIG. 3 shows the frequency characteristics of the filter circuit 17 described above. In this figure, the horizontal axis represents the frequency ω and the vertical axis represents the amplitude ratio B of the input and the output in decibels. ω ₁ is a low cutoff frequency for removing the influence of the cylinder thrust due to gravitational acceleration, and ω ₂ is a high cutoff frequency. The filter circuit 17 is a bandpass filter, and has three filters having the same characteristics (the break frequencies may be different) corresponding to the first cylinder 4, the second cylinder 6 and the third cylinder 8. There is. The articulated structure machine has a complicated arm structure and has various vibration modes due to the interaction between the arm and the hydraulic pipeline or hydraulic cylinder. However, when trying to position the working device installed on the tip of the arm at a certain place by operating the machine,
The vibration component that the tip of the arm vibrates and feels difficult to operate is the primary mode or the secondary mode. The reason will be described below. Even if a large acceleration fluctuation occurs in the high-order mode, the position fluctuation of the arm tip is small because the frequency is high, but the position fluctuation of the arm tip is large because the frequency is low in the primary mode and the secondary mode. is there. Therefore, the vibration mode targeted for vibration suppression may be the primary mode or the secondary mode. Further, when a vibration suppression control device is processed in a digital system using a micro computer or the like, a problem of alias noise may occur. That is, although a microcomputer or the like performs arithmetic processing at a certain time interval, if a high frequency of 1/2 or less of this time interval is input, the input frequency component cannot be completely grasped, so the actual signal Will be processed as a signal that is completely different from the above, and an incorrect calculation result will be output.

For the above-mentioned two reasons, the frequency ω ₂ in the frequency characteristic shown in FIG. 3 is a high cutoff frequency for removing frequency components in the second-order mode or the third-order mode or higher.

Next, the configuration of the comparison operation control circuit 18 will be described with reference to FIG. First, the system of the first cylinder 4 will be described. The signal v ₁ from the operating lever 191 for speed input of the input device 19 and the first cylinder thrust signal f ₁ after passing through the filter circuit 17 are converted into a coefficient K in the coefficient unit 181. the difference between the value obtained by multiplying the _{1 ε 1}
And determined by the comparator 182, multiplied by the I connexion coefficient Kv ₁ to coefficient unit 183 to the difference epsilon _1, and outputs the value V1 to the servo amplifier 20. In this way, the same processing is applied to the system of the second cylinder 6 and the system of the third cylinder 8 to output V2 and V3. Further, the output of the switching valve control circuit 30 described later is OF
When F, the coefficients K _{1 to} K ₃ are set to zero.

FIG. 5 is a time chart for showing the operating condition by the conventional control circuit, and FIG. 6 is a time chart for showing the operating condition by the control device of the present invention.

FIG. 5 shows the first of the operating states by the conventional control device.
The signal of the system of the cylinder 4 is shown, (a) is the signal v ₁ from the operating lever 191 for speed input, (b) is the signal V ₁ from the comparative operation control circuit 18, and (c) is the first signal. This is the head side pressure signal P _1H of the cylinder 4. When the operating lever 191 is operated as shown in (a), the signal V1 becomes correspondingly as shown in (b). The pressure signal P _1H has a pressure P _1H0 corresponding to the weights of the first arm 3, the second arm 5, and the third arm 7 at time t ₀ . If a signal like (b) is input from this state,
As shown in (c), the transient vibration at start-up continues.

FIG. 6 shows signals of the system of the first cylinder 4 among the operating states by the control device of the present invention, and shows the same signals as in FIG. When the operating lever 191 is operated as shown in (a), the head side pressure P _1H rises as shown in (c), and therefore the signal V1 rises corresponding to (a) as shown in FIG. 5 (b). Since the pressure rises gently (A in the figure), the head side pressure P _1H rises gently. Also, the head side pressure P
When _1H decreases, the signal V1 rises (figure B), the drop in head-side pressure P _1H decreases. By repeating this operation, even if the operation lever 191 is operated as shown in (a), the transient vibration at the time of startup is quickly attenuated.

Next, control regarding ON-OFF of the switching valves 32-34 will be described.

The acceleration at the tip of each arm is detected by acceleration detectors 24 to 26, and the detected values α _{1 to} α ₃ are transmitted to a filter circuit 28 via a detection circuit 27. The filter circuit 28 removes the gravitational acceleration and allows only the acceleration generated by the vibration of the arms to pass through. The filter circuit 28 is a high-pass filter, and filters having the same characteristics (the break frequency may be different) are provided to each arm. Correspondingly, it has 3 circuits. Then, the acceleration values α ₁ ′ to α ₃ ′ passing through those filters are transmitted to the acceleration check circuit 29.

FIG. 7 is for explaining the configuration of the system of the first arm 3 in the acceleration check circuit 29. The acceleration check circuit 29 includes the system of the second arm 5 and the third arm 7 as shown in FIG. It has three circuits. The absolute value circuit 290 takes the absolute value | α ₁ ′ | of the acceleration signal α ₁ ′ from the filter circuit 28, and the comparator 291 compares the absolute value | α ₁ ′ | with the specified acceleration value α _10, and the specified acceleration value α ₁₀ <absolute of acceleration When the value is | α ₁ ′ |, an ON signal is output to the timer 292 and the OR circuit 293 otherwise. The timer 292 outputs an ON signal to the OR circuit 293 for a set time from the moment when the output of the comparator 291 is switched from ON to OFF, and an OFF signal in other cases. The OR circuit 293 is a comparator 291 and a timer 292.
The logical sum of these signals is output to the switching valve control circuit 30.

FIG. 8 shows the states of the signals in FIG. 7, where (a) shows the acceleration signal α ₁ ′ and (b) shows the absolute value circuit 2.
90 output signal | α ₁ ′ |, (c) output signal of comparator 291, (d) output signal of timer, (e) OR circuit
It is the output signal of 293, and shows the logical sum of (c) and (d). The output signal of the timer is O at time T ₁ .
It becomes N and turns off at time t ₂ , but before that at time T ₂ .
Since it is turned on, the timer continues to be on. The same situation is repeated, and the output signal of the timer is turned on until time t ₇ . Incidentally, the timer set time _{(t 2 -T 1, t 3} -T 2,
...) is set to 1/2 or more of the natural vibration period of the primary vibration mode. The reason is that if the acceleration value is smaller than the specified value for more than 1/2 cycle, the arm vibration can be regarded as small.

FIG. 9 shows a processing procedure when the acceleration check circuit 29 is composed of a computer. First, step 29
The acceleration signal α'from the filter circuit 28 is taken in at 5,
Next, in step 296, the absolute value of the acceleration signal α'is obtained. Then, compared with the specified value alpha ₁₀ in step 297, the absolute value | alpha '|
Is larger, the process proceeds to step 298, the counter C is set to O, the ON output is performed in step 299, and the process returns to step 295 again. If it is determined in step 297 that the absolute value | α '| is smaller, the _{process proceeds} to step 300, and it is compared whether or not the value of the counter C is smaller than the specified value C _mAX , and the value of C is smaller. In that case, the process proceeds to step 301, 1 is added to the counter C, ON output is performed in step 299, and the process returns to step 295 again. procedure
If it is determined in 300 that the counter C is larger, that is, if the state of α ₁₀ | α ′ | has continued for C _maX × ΔT (ΔT is the sampling time of the program), the procedure _proceeds to step 302. The output turns OFF and the process returns to step 295 again. By performing the procedure described above, the same processing contents as those of the acceleration check circuit 29 shown in FIG. 7 are obtained.

The switching valve control circuit 30 takes the logical sum of the signal and the output signal of the acceleration check circuit 29 when the operation lever is pulled, and outputs the ON / OFF signal of the switching valve to the drive circuit 31.

FIG. 10 shows the movement of each part when the conventional control device is used, and FIG. 11 shows the movement of each part when the control device of the present invention is used.
Explaining the conventional control device shown in FIG. 10, (a)
Is the amount of operation of the operating lever, (b) is the acceleration of the arm tip,
(C) is an ON-OFF signal of the switching valve. When the operating lever is operated at time t ₀ , the switching valve control circuit 30 outputs a signal for switching the switching valve ON, and at the same time, oil is supplied from the servo valve, for example, the servo valve 21 for the first cylinder to the first cylinder 4, 1
The arm 3 is driven. When the arm is driven, the arm vibrates as described above, but the cylinder thrust calculation circuit 16
As a result, the vibration is controlled to be damped, and the acceleration pulsation of the first arm 3 is quickly damped as shown in FIG. 10 (b). Then, when the operation lever is returned at time t ₁ , the damping force acts on the arm, so that the arm vibrates again, and the cylinder thrust calculation circuit 16 and the like control so that the vibration is damped. At the same time as the operation lever becomes neutral at ₂ , the switching valve control circuit 30 outputs a signal for switching the switching valve OFF, and the conduit between the servo valve 21 and the first cylinder 4 is separated, so the vibration of the arm is stopped. I can't.

On the other hand, the case of using the control device of the present invention will be described with reference to FIG. 11. (a) is the operation amount of the operation lever, (b) is the acceleration of the arm tip, and (c) is the lever operation. Switching valve ON-OFF signal command, (d) switching valve ON-OFF command by the acceleration check circuit 29 (e) switching valve ON
-OFF signal. When the arm is activated, it is the same as in FIG. When the operation lever is neutralized at time t ₂ when stopped, the signal (c) gives a switching valve OFF command, but the acceleration check circuit 29 gives a switching valve ON command, so the switching valve signal is ON.
To continue. The (time t ₃₎ the switching valve signal at the vibration of the arm has decreased small turned OFF.

As described above, by using the control device of the present invention, it is possible to reliably suppress the vibration that occurs when the arm is stopped, and the vibration suppressing unit operates when the operation lever is neutral and the arm does not vibrate. And the switching valve
It is safe because it is off.

In the above embodiment, the acceleration detector attached to the tip of each arm is used to turn on the switching valve for each arm.
-Although it was turned off, one acceleration detector may be used to turn all switching valves on and off. On the contrary, a plurality of acceleration detectors may be attached to each arm, and the switching valve of each arm may be turned on and off based on those signals. Furthermore, instead of the acceleration detector, the rod side of the cylinder that drives the arm, or
It may be possible to detect whether or not the arm is vibrating based on a signal from a pressure detector that detects a pressure fluctuation on the head side.

In the above-described embodiment, one example of each control device and the like is shown by an analog circuit, but a digital circuit such as a micro computer may be used.

Further, in the above-described embodiment, the cylinder thrust calculation circuit or the like is used to suppress the vibration of the arm, but other vibration suppression methods, such as the acceleration feedback method, may be used.

According to the embodiments of the present invention described above, since the vibration of the arm can be suppressed, the positioning accuracy of the arm can be improved, the stability of the arm can be improved, and the structure of the arm can be lightweight. Can be realized.

[Effects of the Invention] According to the present invention, if vibration occurs in the arm, the vibration can be suppressed in any case, so that the positioning accuracy of the arm can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an articulated structure machine including an example of a control device of the present invention, FIG. 2 is a diagram showing a configuration of a cylinder thrust calculation circuit configuring the control device of the present invention, and FIG. Showing frequency characteristics of a filter circuit that constitutes the control device of
FIG. 4 is a diagram showing a configuration of a comparison circuit constituting the device of the present invention, FIG. 5 is an explanatory diagram showing an operating condition by the conventional control device, and FIG. 6 is an explanatory diagram showing an operating condition by the control device of the present invention. FIG. 7 is a diagram showing the configuration of an acceleration check circuit which constitutes the device of the present invention, FIG. 8 is a diagram showing the state of each signal in the acceleration check circuit shown in FIG. 7, and FIG. 9 is an acceleration check circuit. FIG. 10, FIG. 10 and FIG. 11 are diagrams illustrating the behavior of each part when the conventional control device and the control device of the present invention are used. 3,5,7 …… arm, 4,6,8 …… cylinder, 9 to 14 …… pressure detector, 16 …… cylinder thrust calculation circuit, 18 …… comparison calculation control circuit, 20 …… servo amplifier, 21 ~ 23 …… Servo valve,
24-26 ... Acceleration detector, 29 ... Acceleration check circuit,
30 ... Switching valve control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Inaman, 650 Jinritsucho, Tsuchiura, Ibaraki Prefecture, Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. (56) References JP-A 61-23212 (JP, A) JP-A Sho 52-101569 (JP, A)

Claims (5)

[Claims] 1. A drive control system for at least one arm, comprising: an actuator for driving the arm; a control valve controlled by operating an operating lever; and a flow of pressure oil between the control valve and the actuator. In a control device for a multi-joint structure machine configured with a switching valve in contact with each other, a vibration detecting means for detecting vibration of the arm is provided, and a vibration suppressing means for suppressing vibration occurring in the arm is connected to the control valve, and the switching is performed. An acceleration check circuit that outputs an ON-OFF signal to the valve in response to a signal from the vibration detection means, and a switching valve by the logical sum of the ON-OFF signal from this acceleration check circuit and the operation amount signal of the operating lever. A control device for an articulated structure machine, which is connected to a switching valve control circuit for controlling ON / OFF of the engine. 2. The control device for a multi-joint structure machine according to claim 1, wherein the vibration detecting means is an acceleration detector provided on the arm. apparatus. 3. The control device for a multi-joint structure machine according to claim 1, wherein the vibration detecting means is a pressure detector for detecting a pressure at an input / output port of the actuator. Control device for multi-joint structure machine. 4. The control device for a multi-joint structure machine according to claim 1, wherein the vibration suppressing means includes a pressure detector for detecting the pressure of the input / output port of the actuator, and the pressure detector. A thrust force calculation circuit that calculates the thrust force or torque of the actuator based on the pressure signal, and a comparison calculation control device that calculates the difference between the operation amount of the operation lever and the output value of the thrust calculation circuit. Control device for multi-joint structure machine. 5. The control device for an articulated structure machine according to claim 4, wherein a band pass filter is provided at a stage subsequent to the thrust calculation circuit.