JPH0773831B2 - 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 an articulated robot. 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-54-3187
On the other hand, various other multi-joint structure 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, so drive arms, such as hydraulic cylinders, can be made smaller and energy saving can be achieved. It's starting. However, if the shape of the arm is made thinner and the weight is reduced, the rigidity of the arm becomes lower,
The natural frequency is also low. Therefore, low rigidity of the arm is added to the effect of the spring mass due to the mass of the arm portion and the compressibility of oil, and the damping characteristic of the system deteriorates. 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.

Japanese Patent Application Laid-Open No. 58-
There is a 135388 publication. This technology constantly connects a hydraulic actuator and a hydraulic pump that controls the speed of the hydraulic actuator. However, in a hydraulic circuit of an articulated structure machine, in order to prevent the arm from dropping due to damage to the pipeline, etc., a switching valve that connects and disconnects the hydraulic pipeline between the hydraulic actuator and a control valve that controls the speed of the hydraulic actuator. Is normally equipped, and when the operation lever is neutral, the switching valve separates the pipeline.

[Problems to be solved by the invention]

When the above-mentioned conventional technology is applied to a multi-joint structure machine having a switching valve, the vibration at the time of start can be suppressed, but the vibration at the time of stop can be immediately returned to the neutral position of the operating lever. In addition, since the switching valve separates the conduit between the hydraulic actuator and the control valve, 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 suppress vibration generated in the arm, a cylinder thrust check circuit that detects arm vibration, a lever operation amount operation signal, and an ON-OFF signal of the cylinder thrust check circuit. Turns suppression means on
This is achieved by providing a switching valve control circuit that turns off.

[Action]

The cylinder thrust check circuit always outputs an ON signal for a certain period of time if the cylinder thrust fluctuation exceeds a specified value. As a result, when the thrust of the cylinder fluctuates even when the operation lever is neutral, that is, when the arm is vibrating, the vibration suppressing unit operates, so that the arm vibration can be suppressed quickly. it can.

〔Example〕

 An embodiment 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.
The arm 7 is a third arm attached to the tip of the second arm 5. These first arm 3, second arm 5 and third arm
The arms 7 are driven 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 detectors 9 to 14. The detection values of the detectors 9 to 14 are transmitted to the cylinder thrust calculation circuit 16 by the detection circuit 15.

The cylinder thrust calculation circuit 16 calculates the thrust f ₁ of the first cylinder 4 based on the head side pressure P _1H and the rod side pressure P _{1R of} the first cylinder 4, and the head side area A _1H and the rod side area A _1R. , The thrust f ₂ of the second cylinder 6 is calculated based on 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 _2R , and the third cylinder 8
Head side pressure P _3H and rod side pressure P _3R and head side area
The thrust force f ₃ of the third cylinder 8 is calculated based on A _3H and the rod side area A _3R , and this is output to the comparison calculation control circuit 18 via the filter 1 circuit 17.

An input device 19 is installed in the driver's seat (not shown) of the articulated structure machine. This input device 19 is equipped with operating levers that give the velocities v ₁ , v ₂ , and v ₃ of the cylinders 4, 6, and 8. The input device 19 outputs a comparison speed instruction v ₁ of the first cylinder 4 to the arithmetic control circuit 18, the speed command v ₂ of the second cylinder 6, the 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 calculation 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, and an electrohydraulic servo valve whose output flow rate is proportional to the input current, so-called servo valves 21-23.
To drive. As a result, each cylinder 4, 6, 8 operates.

The outputs f _{1 to} f ₃ of the cylinder thrust calculation circuit 16 are one filter circuit.
It is input to 17 and is transmitted to the cylinder thrust check circuit 25 via the filter 2 circuit 24.

The cylinder thrust check circuit 25 turns on when the cylinder thrust fluctuates greatly (that is, when the arm is vibrating) based on the fluctuation value of each cylinder thrust and a certain specified value, and turns it off when it does not fluctuate. The signal is output to the switching valve control circuit 26.

The switching valve control circuit 26 controls the speed commands v _{1 to} v ₃ of each cylinder from the input device 19 and turns on and off from the cylinder thrust check circuit 25.
Based on the signals, switching signals of switching valves 28-30 provided between servo valves 21-23 and cylinders 4, 6, 8 are output to drive circuit 27.

First, the elements 16 and 1 for constituting the vibration suppression means of the arm
7,18 will be explained in detail. In this description, the state of the switching valves 28 to 30 is assumed to be the function on the right side of FIG.

FIG. 2 is a diagram for explaining the configuration of the cylinder thrust calculation circuit 16. First, the system of the cylinder 4 shown in FIG. 1 will be described. In the coefficient unit 160 of the head side pressure signal P _1H of the first cylinder 4 from the detection circuit 15, a value obtained by multiplying the head side area A _1H and the rod side pressure signal. in the coefficient unit 161 to the P _1R the difference between the value obtained by multiplying the rod-side area a _1R, determined by the comparator 162, the value, i.e., the cylinder thrust f ₁ filter circuit
17 and the filter 2 circuit 24, respectively. In this way, the same processing is performed for the system of the second cylinder 6 and the system of the third cylinder 8 to output f ₂ and f ₃ .

FIG. 3 shows the frequency characteristic of the filter 1 circuit 17 described above. In this figure, the horizontal axis represents the frequency .omega. 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 1 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. ing.

In the articulated structure machine, the arm has a complicated structure, and due to the interaction between the hydraulic line and hydraulic cylinder and the arm,
It has various vibration modes. However, when trying to position the working device mounted on the tip of the arm at a certain place by operating the machine, the vibration component that the arm tip vibrates and feels difficult to operate is in the primary mode or the secondary mode. is there. The reason will be described below. Higher modes have high frequencies even if large acceleration fluctuations occur, so
This is because the position fluctuation of the arm tip is small, but the position fluctuation of the arm tip is large because the frequency is low in the primary mode and the secondary mode. 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 manner by using a microcomputer or the like, a problem of alias noise may occur. That is, although the microcomputer and the like perform 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 completely different signal, 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 coefficient v1 from the signal v ₁ from the speed input lever 191 of the input device 19 and the first cylinder thrust signal f ₁ after passing through the filter 1 circuit 17
The difference ε ₁ from the value multiplied by the coefficient K ₁ in 181 is calculated by the comparator 182
Then, the difference ε ₁ is multiplied by the coefficient K _v1 by the coefficient unit 183, and the value V1 is output to the servo amplifier 20. In this way, the same processing is performed for the system of the second cylinder 6 and the system of the third cylinder 8 to output V2 and V3.

FIG. 5 and FIG. 6 are time charts for showing the operating condition by the conventional control device and the operating condition by the control device of the present invention.

FIG. 5 shows signals of the system of the first cylinder 4 among the operating states by the conventional control device. (A) is a signal v ₁ from the speed input lever 191, (b) is a comparative calculation control signal V1 from the device 18, (c) is a head-side pressure signal P _IH of the first cylinder 4. When the speed input lever 191 is operated as shown in (a), the signal V1 correspondingly changes to (b).
become that way. 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 to. When a signal such as (b) is input from this state, the transient vibration at the time of startup continues as shown in (C).

FIG. 6 shows the first of the operating conditions by the control device of the present invention.
The signal of the system of the cylinder 4 is shown, and the same signal as FIG. 5 is shown. When the speed input lever 191 is operated as shown in (a), the head side pressure P _1H rises as shown in (c). Therefore, the signal V1 rises corresponding to (a) as shown in FIG. 5 (b). The head side pressure P _1H rises slowly because it rises gently (A in the figure) without doing so. When the head side pressure P _1H decreases, the signal V1 increases (B in the figure).
The head side pressure P _1H drops less. By repeating this operation, as shown in (a), the input speed lever 19
Even if 1 is operated, the transient vibration at start-up will be quickly attenuated.

Next, control regarding ON-OFF of the switching valves 28-30 will be described.

The outputs f _{1 to} f ₃ of the cylinder thrust calculation circuit 16 are one filter circuit.
It is input to 17 and transmitted to the filter 2 circuit 24.

The filter 2 circuit 24 removes the static cylinder thrust generated by the weight of the arm and passes only the fluctuation of the cylinder thrust generated by the vibration of the arm.
It is a high-pass filter, and has three circuits having the same characteristics (the breakpoint frequencies may be different) corresponding to each arm. And the cylinder thrust through those filters
The f ₁ ′ to f ₃ ′ are transmitted to the cylinder thrust check circuit 25.

FIG. 7 is for explaining the configuration of the system of the first arm 3 in the cylinder thrust check circuit 25. The cylinder thrust check circuit 25 includes the system of the second arm 5 and the third arm 7 in FIG. There are three circuits having the above structure.

The absolute value circuit 250 takes the absolute value | f ₁ ′ | of the cylinder thrust force f ₁ ′ from the filter 2 circuit 24, and the comparator 251 compares it with the specified cylinder thrust force value f _10, and f ₁₀ <| f ₁ ′ If the signal is ｜, the ON signal is output.
Output to OR circuit 253.

The timer 252 outputs an ON signal for the set time from the moment when the output of the comparator 251 switches from ON to OFF, and in other cases
The OFF signal is output to the OR circuit 253.

The OR circuit 253 takes the logical sum of the signals of the comparator 251 and the timer 252 and outputs it to the switching valve control circuit 26.

FIG. 8 shows the state of each signal in FIG. 7. (a) shows the cylinder thrust signal f ₁ ′, (b) shows the output signal | f ₁ ′ | of the absolute value circuit 250, ( 3C shows the output signal of the comparator 251, and FIG. 3D shows the output signal of the timer 252. The timer output signal of (d) is supposed to be turned on at time T ₁ and turned off at time t ₂ , but since it was turned on at time T ₂ before that, the timer continues to be in the on state. Repeating the same situation, the output signal of the timer until time t ₇ is
Turns on. It should be noted that the timer of the 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 for this is that if the fluctuation value of the cylinder thrust is smaller than the specified value for more than 1/2 cycle, the arm vibration can be regarded as small. (E) is an output signal of the OR circuit 253, which is the logical sum of (c) and (d).

FIG. 9 shows an algorithm when the cylinder thrust check circuit 25 is composed of a computer. First, in step 255, the cylinder thrust signal f ₁ ′ from the filter 2 circuit 24 is addressed. Next, in step 256, the absolute value of the cylinder thrust signal f ₁ ′ is obtained. Then, in step 257, it is compared with the specified value f _10, and if the absolute value | f ₁ ′ | is larger, the procedure is
The process proceeds to step 298, the counter C is set to 0, the ON output is performed in step 259, and the process returns to step 255. Absolute value | f ₁ ′ | in step 257
If it is determined that is smaller than, the procedure moves to step 260, and it is compared whether the value of the counter C is smaller than the specified value C _MAX ,
If the value of C is smaller, the procedure moves to step 261 and 1 is added to the counter C, the ON output is performed in step 259, and the procedure returns to step 255 again. If it is determined in step 260 that the counter C is larger, that is, the state of f ₁₀ | f ₁ ′ | is C
If it continues for _MAX × ΔT (ΔT is the sampling time of the program), go to step 262 and output OFF.
Return again to step 255. By performing the procedure described above, the same processing contents as the cylinder thrust check circuit 25 shown in FIG. 7 are obtained.

The switching valve control circuit 26 takes the logical sum of the signal due to the operation lever being pulled and the output signal of the cylinder thrust check circuit 25, and outputs the ON / OFF signal of the switching valve to the drive circuit 27.

FIG. 10 and FIG. 11 show the movement of each part when the conventional control device and the control device of the present invention are used.

First, the conventional control device shown in FIG. 10 will be described. (A) is the operation amount of the operating lever, (b) is the fluctuation waveform of the cylinder thrust, and (c) is the ON-OFF signal of the switching valve.
When the lever is operated at time to, the switching valve control circuit 26 outputs a signal for switching the switching valve ON, and the servo valve, for example, the first
Oil is supplied from the cylinder servo valve 21 to the first cylinder 4, and the first arm 3 is driven. When the arm is driven, the arm vibrates as described above, but the vibration is controlled by the cylinder thrust calculation circuit 16 or the like so as to be damped, and as shown in FIG. Cylinder thrust pulsation quickly attenuates. Since the start returning the operating lever at t ₁ decelerating force to the arm acts, the arm vibrates again, the cylinder thrust calculation circuit 16, etc., that the vibration is controlled to attenuate, operating at t ₂ At the same time as the lever becomes neutral, the switching valve is turned off from the switching valve control circuit 30.
Signal is output and the conduit between the servo valve 21 and the first cylinder 4 is separated, so that the vibration of the arm cannot be stopped.

Next, referring to FIG. 11, the case of using the control device of the present invention will be described. (A) is the operation amount of the operation lever,
(B) is the fluctuation waveform of the cylinder thrust, (c) is the ON-OFF command of the switching valve due to lever operation, (d) is the ON-OFF command of the switching valve by the cylinder thrust check circuit 25 (e) is the switching valve This is an ON-OFF signal. When the arm is activated, it is the same as (1). When the lever is neutralized at t ₂ when stopped, the signal (c) gives a switching valve OFF command, but the cylinder thrust check circuit 25 has a switching valve ON command, so the switching valve signal continues to be ON. The (time t ₃₎ the switching valve signal at the vibration of the arm has decreased small turned OFF.

FIG. 12 shows the movement of each part when the control device of the second embodiment of the present invention is used.

(A) is the operation amount of the operating lever, (b) is the fluctuation waveform of the cylinder thrust, (c) is the ON-OFF of the switching valve accompanying the lever operation.
Command, (d) ON-OFF command of switching valve by timer that turns on for a certain time from the time when the lever becomes neutral, (e)
Is ON / OFF of the switching valve by the cylinder thrust check circuit 25.
The command, (f), is an ON-OFF signal for the switching valve.

When the arm is activated, it is the same as in FIG. When the lever is suddenly neutralized at t ₁ when stopped, the signal (c) becomes a switching valve OFF command. At this time, the cylinder thrust check circuit 25 is a switching valve OFF command, but the timer output (d) switches Since it is a valve ON command, the switching valve signal continues to be ON. Here, if there is no timer output, the switching valve signal is turned off between t ₁ and t ₂ .

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 to operate the vibration suppressing means when the operation lever is neutral and the arm does not vibrate. It is safe because the switching valve is off.

In the above-described embodiment, the switching valves for each arm are turned on and off by using each cylinder thrust, but all the switching valves may be turned on and off by using one cylinder thrust.

Pressure may be used instead of cylinder thrust.

Further, in the above-described embodiment, the filter 1 circuit 17 and the filter 2 circuit 24 are used as the cylinder thruster filter circuit, but only one of them may be used.

Further, in the above-described embodiment, one embodiment of each control device and the like is shown by hardware, but all may be configured by a microcomputer or the like.

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.

〔The invention's effect〕

According to the present invention, if vibration occurs in the arm, the vibration can be suppressed in any case.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-joint structure machine equipped with an example of the control device of the present invention, FIG. 2 is a diagram for explaining the configuration of a cylinder thrust calculation circuit, and FIG. 3 is a frequency characteristic of a filter 1 circuit. FIG. 4, FIG. 4 is a diagram showing a configuration of a comparison operation device, FIG. 5 is an operation status diagram by a conventional control device, FIG. 6 is an operation status diagram by the control device of the present invention, and FIG. 7 is a cylinder thrust. FIG. 8 is a diagram showing the structure of a check circuit, FIG. 8 is a diagram showing the states of the signals in FIG. 7, FIG. 9 is a flow chart when the cylinder thrust check circuit is composed of a computer, and FIGS. 10 and 11 are Behavioral diagram of each part when the control device of the present invention is used for the conventional control device, respectively.
The drawings are diagrams showing the movement of each part in another embodiment of the control device of the present invention. 3,5,7 ... Arm, 4,6,8 ... Cylinder, 9-14 ... Pressure detector, 16 ... Cylinder thrust calculation circuit, 18 ... Comparison calculation control circuit, 20 ... Servo amplifier, 21-23 ... Servo valve, 25 ... Cylinder thrust check circuit, 26 ... Switching valve control circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G05B 19/18 (72) Inventor Hiroshi Inaman 650 Jinmachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura Plant (56) References JP-A-60-78101 (JP, A) JP-A-60-241503 (JP, A) Practical application Sho-57-169802 (JP, U)

Claims (3)

[Claims] 1. A switch for connecting and disconnecting at least one arm, a control valve and a hydraulic actuator that drive these arms by operating an operating lever, and a flow of pressure oil between the control valve and the hydraulic actuator. In a control device for a multi-joint structure machine having a valve, a vibration suppressing means for suppressing vibration generated in an arm and a check circuit for detecting the presence or absence of vibration generated in the arm from a pressure signal of the hydraulic actuator are provided, and the control lever of the operating lever is provided. A control device for an articulated structure machine, wherein the vibration suppressing means is operated by a logical sum of an operation signal and an ON-OFF signal of the check circuit, and the switching valve is turned ON-OFF. 2. A control device for an articulated structure machine according to claim 1, wherein a hydraulic cylinder is provided as the hydraulic actuator, and the vibration suppressing means detects the pressure of an input / output port of the hydraulic cylinder. A plurality of pressure detectors, a cylinder thrust calculation circuit that calculates thrust of a hydraulic cylinder from pressure values detected by these pressure detectors, an operation amount of the operation lever, and an output value of the cylinder thrust calculation circuit. A control device for a multi-joint structure machine, comprising: 3. A control device for an articulated structure machine according to claim 2, further comprising a band pass filter after the cylinder thrust calculation circuit. .