JPS6234788A - Flexible structure working machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a beam structure 2411 used, for example, as a cargo handling machine having a low-rigidity multi-joint structure.

[Prior art]

In general, construction machines such as cargo handling machines have multiple long arms connected to each other to handle large and heavy objects, and the whole structure consists of 20 to 30 islands. Each arm of construction machinery has become larger and heavier, leading to a rise in manufacturing costs.

In order to improve these drawbacks, a working machine is known in which the drive actuator is made smaller and the arm is made lighter and warmer, and the overall structure is made flexible, in order to save energy.

Now, a flexible structure work machine according to the prior art will be explained with reference to FIG.

In the figure, 1 is a revolving body that constitutes a part of the working machine main body, 2 is a bracket that is attached to the revolving body l, and
3 is an arm body rotatably provided on the bracket 2, and the arm body 3 is rotatable on the bracket 2 around 01.
It consists of a first arm 4 that is pin-coupled to the TI function, and a second arm 5 that is rotatably coupled to the tip of the first arm 4 with a pin, and each of the arms 4, 5 Because it has a long length and is lightweight, it can be elastically deformed. 6 is a hydraulic cylinder that operates the first arm 4, and 7 is a hydraulic cylinder that operates the second arm 5.

The flexible structure work machine configured in this way has a second arm 5.
By providing a working device such as a gripping device or a hook at the tip of the hoist, the suspended load can be lifted and cargo handling operations can be performed.

In addition, since each arm 4, 5 is made into a light J-type, the hydraulic cylinder 6.7 that operates each arm 4, 5 can be downsized, manufacturing cost can be reduced, and energy saving can be achieved. can be achieved.

However, in such a low-rigid multi-joint construction work machine, the flexible construction work machine has flexure, low-frequency natural vibration, and each arm 4, 5 itself has no damping effect. The natural vibration has the disadvantage that it becomes a sustained vibration that is not easily attenuated. Therefore, in the conventional flexible structure work machine, as a method of suppressing the sustained vibration, arm 4. Or an acceleration detector (not shown) is provided near the tip of 5,
It is considered effective to control the amount of working fluid (or electric flow) to each hydraulic cylinder 6.7 in accordance with the acceleration signal from the acceleration sensor. However, in reality, among the frequency components of the vibrations occurring in arm 4.5, the frequencies of the low-order mode and high-order mode are very close to each other, and the frequency of each of these modes varies depending on the attitude of arm 4.5. Change? It is difficult to substantially suppress vibrations simply by controlling the amount of oil (or amount of electric IA) to each actuator according to the acceleration signal.

[Problem that the invention seeks to solve]

The present invention has been made by focusing on the drawbacks and problems of the prior art.

Therefore, when we look at the low frequency natural vibrations of each of the above-mentioned 7-1.4.5, the characteristics are as shown in FIG. That is, FIG. 5 shows the time response waveform of the acceleration generated at the tip of the arm when the first arm 4 is operated in the upward or downward direction. In the figure, 8 is the primary mode waveform, and 9 is the secondary mode waveform .

10 is the acceleration waveform actually generated in the arm 4, which is a combination of the primary mode waveform 8 and the secondary mode waveform 9 (however, 3
As can be seen from the figure, the primary mode and secondary mode of a flexible structure work machine are often very close to each other (for example, the primary mode). If the frequency of the vibration is 1 to 3Hz, then the vibration of the second mode! hgI is 3 to 5H2. The reason why there is a range in the vibration mode is that the natural frequency changes depending on the posture of each arm 4, 5. The reason for this will be described later. In addition, in Fig. 5, the secondary mode waveform 9 is relatively large compared to the primary mode waveform 8, but the primary mode is noticeable in the \ group, and the secondary mode is almost invisible in comparison. Each hydraulic cylinder is so small that it can be ignored.6.
The reason why the natural frequency of the first mode changes depending on the displacement of the arms 4 and 5, that is, the posture of each arm 4 and 5, will be discussed. 6th
The figure is, for example, an analytical model diagram for determining the natural frequency of the first arm 4, and FIG. 7 is an explanatory diagram of the vicinity of the first arm 4 and the bracket 2, showing the dimensional relationship necessary for the analytical model. For simple CP, the first arm 4 is a linear motion model, and the motion characteristics of the arm 4 are expressed by a spring K and an inertial mass m2, where ml is the inertial mass of the hydraulic cylinder 6, and W is the weight of the arm 4. , x is the displacement of the hydraulic cylinder 6, Y is the arm 4
The displacement position at the tip, QH, and Qll are the inflow and outflow flow rates to the hydraulic cylinder 6. In this model, ignoring higher-order modes, the hydraulic cylinder 6 is a spring with a spring constant Kv, and mI
(Considering rn7, the natural frequency ω of arm 4.

The result is the first-order equation (1).

Here, the tfj property W quantity m 2 is defined as the moment of inertia of the arm 4 to the equivalent mass of the hydraulic cylinder 6 i! This value can be obtained using FIG. That is, in Fig. 7, G is the center of gravity position of arm 4, and ■ is the center of gravity position mG.
The moment of inertia of the arm 4 at , r is the distance between the mounting position of the hydraulic cylinder 6 and the connection point 01 of the arm 4, and the intersection is the distance from the connection point 01 to the center of gravity G. ;Lo is the distance between the connection point O1 and the connection point between the arm 4 and the hydraulic cylinder;
φ indicates the angle formed by the arm 4 and the hydraulic cylinder 6, and using these values, the inertial property Nm2 is expressed as follows.

Further, the angle φ is geometrically expressed as in equation (3).

18X Furthermore, the spring constant 1aK of the arm 4 is the same as the inertia constant m2, and the spring constant of the arm 4 is the equivalent spring constant for the hydraulic cylinder 6, and in reality, the rotational spring obtained from the deflection of the arm 4 is Assuming that, find the rotational spring constant,
It is necessary to find a linear spring constant K that is a function of the cylinder displacement X. If this rotational spring constant is θ, then the linear spring constant is expressed by the following equation (4).

Therefore, from equation (3), the inertial mass m2 and spring constant of equations (2), , and (4) are functions of cylinder displacement X, and the natural frequency ω of equation (1) is a function of cylinder displacement x, m Chi,
It can be seen that it changes depending on the attitude of the arm 4.

The present invention focuses on the fact that, as mentioned above, when looking at the frequency components of the natural vibration generated in the arm, the low-order mode and the high-order mode are very close to each other, and the frequency of each mode changes depending on the posture of the arm. However, among the natural vibrations generated in the arm, all higher-order mode components higher than the second mode are cut regardless of the posture of the arm, and by suppressing the frequency component of the first mode, the vibration of the arm can be quickly suppressed. It has good damping characteristics.

The purpose is to provide a flexible construction work machine with excellent operability.

[Means for solving problems]

In order to achieve the L2 objective, the working machine of the present invention adopts an acceleration detecting means for detecting acceleration near the tip of the arm, frequency-analyzing the acceleration signal from the acceleration detecting means, and detecting the primary mode. frequency analysis means for outputting a first-order mode signal corresponding to the waveform; variable band-pass filter means for changing the frequency band through which the acceleration signal passes based on the first-order mode signal from the frequency analysis means; It consists of a calculation means that calculates the difference between the operation signal of the operation lever that operates the actuator to be rotated and the signal that has passed through the variable bad pass filter means, and outputs the signal that should actuate the actuator.

〔Example〕

Embodiments of the present invention will be described in detail below based on the embodiments shown in FIGS. 1 to 3. Components that are the same as those of the prior art shown in FIG. 4 are given the same reference numerals, and their explanations will be omitted.

However, 11 is a tank, 12 is a pump that supplies hydraulic oil from the tank 11 to the first hydraulic cylinder 6, 13 is a relief valve that controls the discharge pressure of the pump 12, and 14 is pressure oil from the pump 12. As the servo valve 14, an electro-hydraulic servo valve whose output flow rate is proportional to the input current is used. Further, reference numeral 15 denotes an operating lever provided in the operator's cab (not shown) of the upper revolving structure 1, and the operating lever 15 is operated at a tilt angle corresponding to the tilting angle of the hydraulic cylinder 6 in order to operate the hydraulic cylinder 6 in the extending or contracting direction. Outputs speed command signal VQ.

Reference numeral 16 denotes an acceleration detector provided near the tip of the first arm 4. The acceleration detector 16 detects the acceleration generated at the tip of the arm and outputs an acceleration signal α.

Reference numeral 17 denotes a frequency analyzer, which frequency-analyzes the signal component of the acceleration signal α from the acceleration detector 16, and generates a first-order mode signal M corresponding to the value of the first-order mode.
1 to a variable bandpass filter 18, which will be described later.

18 indicates a variable bandpass filter, and the filter 18
is the first mode signal M! outputted from the frequency analyzer 17. Based on this, the frequency band through which the acceleration signal α output from the acceleration detector 16 is passed can be changed.

Here, before discussing the above-mentioned variable bandpass filter 18, in order to filter only a signal in a predetermined frequency band, for example, the frequency of the first mode, with a normal bandpass filter, it is necessary to filter the signal from the minimum value of the first mode. It is sufficient to set a passband characteristic that has a maximum value of #1. However, as mentioned above, in flexible structure work equipment, the primary mode and secondary mode are very close to each other (see Figure 5). ), as a result, if the passband characteristic is set too thick as in the normal bandpass filter mentioned above, the value of the second mode will be smaller than the maximum value (wide cutoff frequency), A secondary mode signal may pass through this filter, and in such a case, the secondary mode may be excited and the arm may oscillate.

On the other hand, the variable bandpass filter 18 in this embodiment uses the first-order mode signal M1 from the frequency analyzer 17.
The pass frequency band is configured to be variable depending on the center frequency. To explain this more specifically with reference to FIG. 3, the center frequency of the first mode signal M1 is set to ω0. Assuming that the low cutoff frequency is ω, 1n and the wide cutoff frequency is ω□×, the center frequency of the pass frequency band of the variable bandpass filter 18 is variably set to be equal to the center frequency ω0, and the Therefore, each cutoff frequency ωs10 and ωx are also changed. Suppose that the primary mode signal M! If the center frequency ω0 of is 1.5H1,
The low cutoff frequency ω1n is set to 1, OHl, and the wide cutoff frequency is set so that (a) -4y becomes 2-OH2. Therefore, according to the variable bandpass filter 18 of this embodiment, no matter what state the first arm 4 is in, when the acceleration signal α from the acceleration detector 16 passes through the filter 18, Frequencies higher than the second mode are reliably blocked, and only the first mode acceleration signal α1 can be obtained.

Further, numeral 19 indicates a calculation device, into which the speed command signal VO from the operating lever 15 and the first-order mode acceleration signal α1 passed through the variable bandpass filter 18 are input, and the difference between these signals is calculated. Compare and calculate, servo valve 1
It has a function of outputting a servo valve current signal i3 to operate the servo valve 4. Therefore, as shown in FIG. 2, the metering characteristic conversion circuit M19 includes a metering characteristic conversion circuit 19A that converts the speed command signal VQ from the operating lever 15 into a corresponding current signal io, and a variable bandpass filter. The first-order mode acceleration signal α1 from 18 is multiplied by a predetermined feedback gain Fg as a coefficient, and the feedback signal iI is obtained as il =Fg·α.

The coefficient multiplication circuit 19B obtained as
and the feedback signal 11, is = io −
f+, and send the servo valve current signal i to the servo valve 14.
The comparator circuit 19C outputs 5.

The flexible structure working machine according to this embodiment is constructed as described above, and its operation will be described first.

First, in order to lift a load and perform cargo handling work using a work machine that is in a stopped state, the operating lever 15 for the hydraulic cylinder 6 is
, or by starting to operate the operating lever (not shown) for the hydraulic cylinder 7 and operating the first and second arms 4.5 of the arm body 3 in the upward and downward directions. That is, when the operation lever 15 starts operating, the operation lever 15 outputs a speed command signal VO corresponding to its tilt angle.
is the result of calculation! ? 19 is output. At this time, arm body 3
Since is still in a stationary state, the acceleration signal α from the acceleration detector 16 is zero. As a result, in the arithmetic unit 19, the speed command signal VQ is converted into a current signal i by the metering characteristic conversion circuit 19A.

The servo valve current signal is is output to the servo valve 14 via the comparison circuit 19G. As a result, the servo valve 14 supplies the hydraulic cylinder 6 with an amount of oil proportional to the servo valve current signal i;
It also operates in the contraction direction to move the arm 4 and start lifting the suspended load.

In this manner, the arm 4 starts to operate, and the acceleration when the arm 4 operates is detected by the acceleration detector 16 and output as an acceleration signal α. Then, this acceleration signal α is input to the frequency analyzer 17, the value of the first-order mode is determined, and the first-order mode signal Ml is output to the variable bandpass filter 18 at the next stage. The variable bandpass filter 18 is set so that the pass frequency band is variable according to the center frequency ω0 of the first-order mode signal Ml. As a result, when the acceleration signal α from the acceleration detector 16 passes through the variable bandpass filter 18, high-order mode frequencies higher than the second-order mode are blocked regardless of the posture of the arm 4, and only the first-order mode frequency is reliably filtered to form the first-order mode acceleration signal α1, which is output to the next-stage arithmetic unit 19.

In this way, the primary mode acceleration signal αl input to the arithmetic bag at19 is multiplied by the feedback gain Fg by the coefficient multiplication circuit 19B, and outputted as the feedback signal i to the comparison circuit 19C. However, since the current signal i6 is inputted from the metering characteristic conversion circuit 19A to the comparison circuit 19C, the feedback signal i1 is inputted thereto.

A comparison calculation is performed on the difference i@-1I=i5, and the servo valve 1 is set using the servo valve current signal ts as a feedback signal.
Output to 4. In this way, it is possible to remove the primary mode of the natural vibrations generated in the arm body 3, and the vibrations of the arm body 3 can be suppressed.

The present embodiment is as described above, and the arm body 3 has various vibration modes, and when the working device provided at the tip of the arm body 3 is positioned at a predetermined position, there are vibration components that impede operability. 1 The low frequency affects the fluctuation of the tip position 1
(Because higher-order modes higher than the second-order mode have high frequencies.

However, according to this embodiment, it is possible to derive only the vibration component of the first mode from the acceleration signal and remove the vibration component of the first mode. The vibration of the first arm 4 can be well damped, the vibration suppressing effect of the arm body 3 as a whole can be enhanced, and the operability can be improved.

In the embodiment of the present invention, the arm body 3 is composed of the wSl arm 4 and the second arm 5, but the arm body may be composed of one or three or more arms. It can be applied not only to machines but also to other working machines with flexible structures, such as hydraulic cranes.

Further, although the hydraulic cylinder 6.7 is used as the actuator, a hydraulic motor, an electric motor, etc. may also be used.On the other hand, the control valve for controlling the hydraulic cylinder 6.7 is not limited to the servo valve 14. An electromagnetic proportional valve or the like may also be used.

Furthermore, in the embodiment, the acceleration detector 16 is connected to the first arm 4.
Although it has been described that an acceleration detector is provided near the tip of the second arm and the first hydraulic cylinder 6 is feedback-controlled, an acceleration detector may be provided near the tip of the second arm to control the hydraulic cylinder 7 of the 5S2.

Furthermore, the arithmetic unit 19 may be an analog circuit, a digital circuit, a hybrid circuit, or the like, and may of course be realized within a microcomputer or the like.

[Effects of the Invention] The flexible structure working machine according to the present invention is as described in detail above, and has a structure that eliminates the vibration under the first-order motor, which affects the positioning accuracy the most among the vibrations generated in the arm body. Therefore, the vibration damping characteristics of the arm body can be improved, and the operability can be improved.

[Brief explanation of the drawing]

1 to 3 relate to embodiments of the present invention. Fig. 1 is an overall configuration diagram showing the flexible structure work machine and circuit configuration according to this embodiment, Fig. 2 is a circuit configuration diagram showing the arithmetic unit in Fig. 1, and Fig. 3 is a gain adjustment diagram of the variable bandpass filter. Time characteristic diagram, Figure 4 is a configuration diagram of a flexible structure work machine according to the conventional technology, Figure 5 is an acceleration-time characteristic diagram showing the acceleration waveform generated at the tip of the arm, and Figure 6 is to determine the natural frequency of the arm. FIG. 7 is an explanatory diagram showing the dimensional relationship in the vicinity of the arm and bracket necessary for the analytical model shown in FIG. 6. l... Upper revolving body, 2... Bracket, 3... Arm body, 4... First arm, 5... Second arm, 6.7... Hydraulic sill, 14... ...Servo valve, 1
5... Operation lever, 16... Acceleration detector, 17.
...Frequency analyzer, 18...Variable band pass filter, 19...Arithmetic unit, α...Acceleration signal, vo...
・Speed command signal, Ml...primary mode signal, i3...
・Servo valve current signal. Patent Applicant Hitachi Construction Machinery Co., Ltd. Agent Patent Attorney Kazuhiko Hirose
Naoki Nakamura Figure 1 Figure 2 Figure 3 Round 1 rest (w) Figure 4 Figure 5 Hyoma

Claims (1)

[Claims] A flexible construction work machine comprising an arm body consisting of at least one flexible arm and an actuator for rotating the arm of the arm body, an acceleration detection means for detecting acceleration near the tip of the arm; Frequency analysis means for frequency-analyzing the acceleration signal from the acceleration detection means and outputting a first-order mode signal corresponding to the first-order mode waveform, and passing the acceleration signal based on the first-order mode signal from the frequency analysis means. A variable bandpass filter means for changing a frequency band, and a difference between an operating signal of an operating lever for operating the actuator and a signal passed through the variable bandpass filter means is calculated, and a signal for operating the actuator is output. A flexible structure work machine characterized by comprising a calculation means.