JP2004137702A - Actuator controller of working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator controller securely reducing jerking motion generating in a rapid operation by a simple control to eliminate a shock. <P>SOLUTION: The working machine is provided with an actuator 6 driving the movable part of the working machine, an operation lever for operating the actuator 6, and a controller 9 controlling the actuator according to an operation instruction of the operation lever. The controller 9 is provided with a target speed calculator 9a calculating the target speed of the actuator based on the operation quantity of the operation lever and a jerk regulation processing part 9b calculating a jerk expectation figure by two-step differentiation of the calculated target speed and judging whether the calculated jerk expectation value exceeds a specified value and correcting the target speed so that the jerk expected value is not higher than the specified value when the jerk expectation value is judged to be higher than the specified value. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an actuator control device for a work machine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, many working machines that perform various operations by operating an operation lever by an operator use a hydraulic cylinder or a hydraulic motor as an actuator.
[0003]
In this type of work machine, a control valve connected to a hydraulic pump is switched by a pilot pressure from a remote control valve, and hydraulic oil whose flow and direction is controlled by the control valve is supplied to the actuator. When the operation lever is suddenly operated, a shock is generated, and there is a problem that work stability is impaired or operability is deteriorated. In addition, the machine may break down due to the vibration generated by the shock.
[0004]
Therefore, in order to reduce such a shock, a known technique such as a shockless relief valve has been introduced.
[0005]
On the other hand, the above-described hydraulic drive system has a problem in that energy efficiency is low due to resistance in the control valve, pressure loss in the supply / exhaust line, generation of excess flow rate, and the like. There is also a technique that improves the performance (see, for example, Patent Document 1).
[0006]
In the "swing drive device for construction machines" described in this publication, an electric motor is used as a swing motor for swinging the upper swing body.
[0007]
[Patent Document 1]
JP 2001-11897 A (page 3, FIG. 2)
[0008]
[Problems to be solved by the invention]
However, when an electric motor is used for the actuator, the energy efficiency is improved, but the response of the actuator to the lever operation tends to be too sensitive as compared with the hydraulic drive system. Naturally, the shock when the operation lever is suddenly operated also increases. Therefore, it is necessary to more reliably reduce the shock in the electric drive system than in the hydraulic drive system.
[0009]
In this electric drive system, there is a known technique that suppresses the maximum torque by using torque control in combination with speed control of the electric motor. However, even when this technique is used, when a sudden operation is performed, the fluctuation of the torque is large, and the fluctuation of the torque causes the fluctuation of the acceleration, that is, the jerk value to increase, causing a shock.
[0010]
It is to be noted that a known technique for reducing the shock by changing the speed of the actuator so as to draw an S-shaped curve is known. However, in a system in which the speed of the actuator is changed by operating the operation lever, when the operation lever is suddenly operated. Since the same S-shaped characteristic is provided when the operation is slow and the operation is slow, there is a problem that the shock reduction effect is insufficient at the time of sudden operation, and the responsiveness is deteriorated at the time of the slow operation.
[0011]
Further, if the control for reducing the shock is complicated, the actual jerk value may exceed the predicted jerk value due to a delay in the control system, and the purpose of reducing the jerk during a sudden operation cannot be fulfilled.
[0012]
The present invention has been made in consideration of the above-described problems in the conventional working machine, and can reliably reduce undesirable jerk generated at the time of sudden operation by simple control, and can reduce the shock accompanying jerk. An actuator control device is provided.
[0013]
[Means for Solving the Problems]
The present invention relates to a working machine including an actuator for driving a movable portion of a working machine, an operating body for operating the actuator, and a controller for controlling the actuator in accordance with an operation command of the operating body. A target speed calculator for calculating a target speed of the actuator in accordance with the operation amount of the operating body, a jerk predicted value calculator for calculating a jerk predicted value by differentiating the calculated target speed by the second order, A determination unit that determines whether the estimated jerk value exceeds a predetermined value; and a target speed that corrects the target speed so that the jerk prediction value becomes equal to or less than the predetermined value when the jerk prediction value is determined to exceed the predetermined value. An actuator control device for a work machine, comprising: a correction unit.
[0014]
According to the present invention, when the operating tool is operated, a target speed corresponding to the operation amount is calculated, a jerk value is predicted from the target speed, and if it is determined that the predicted jerk value exceeds a predetermined value, the jerk is determined. The target speed is corrected so that the value does not exceed the predetermined value. Thus, even when the operating tool is suddenly operated, the jerk value is always reduced to a predetermined value or less, and the shock is reduced.
[0015]
Further, according to the present invention, in the work machine described above, the controller calculates a target speed of the actuator in accordance with an operation amount of the operating body, and a jerk prediction by performing second order differentiation of the calculated target speed. A jerk prediction value calculation unit for calculating a value, a determination unit for determining whether the calculated jerk prediction value exceeds a predetermined value, and a driving force of the actuator when it is determined that the jerk prediction value exceeds the predetermined value. An actuator control device for a working machine, comprising: a driving force limiting unit that limits a maximum value.
[0016]
According to the present invention, when it is determined that the predicted jerk value exceeds the predetermined value, the maximum value of the driving force of the actuator is limited so that the jerk value does not exceed the predetermined value. And the possibility that the actual jerk value becomes larger than the predetermined value can be eliminated. Also in this configuration, when the operating body is suddenly operated, the jerk value is always reduced to a predetermined value or less, and the shock is reduced.
[0017]
In the present invention, if a predetermined value changing means for changing the predetermined value is provided, the operator can adjust the jerk value to a desired value, and can cope with a case where agile responsiveness is required. become able to.
[0018]
In the present invention, the target speed calculating section is for giving a static speed characteristic to the operation amount of the operating body by a map or a function formula, and a delay adding section for giving a dynamic delay to the speed characteristic. Can be provided. If a delay is added to the speed characteristic, the jerk peak value at the beginning of the change in the operation amount of the operating tool can be reduced, and at the same time, the jerk peak value at the end of the change in the operation amount can be reduced. The accompanying shock can be reduced.
[0019]
In the present invention, the actuator can be constituted by an electric motor. The electric motor used as an actuator of the work machine includes, for example, a swing motor that swings an upper swing body of a construction machine, a winch motor that hoists and unwinds a winch, and a travel motor that serves as a drive source of a lower travel body. It is.
[0020]
ADVANTAGE OF THE INVENTION According to this invention, even if the responsiveness becomes sensitive compared with a hydraulic drive system by comprising an actuator with an electric motor, jerk can be reduced effectively and the accompanying shock can be reduced. .
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.
[0022]
FIG. 1 shows a hydraulic excavator to which the actuator control device of the present invention is applied.
[0023]
Referring to FIG. 1, the hydraulic excavator has an upper revolving unit 2 mounted on a lower traveling unit 1. It is configured to be able to turn around A.
[0024]
A front attachment 3 is provided at a front portion of the upper swing body 2. The front attachment 3 includes a boom 3a, a boom cylinder 3b for raising and lowering the boom 3a, an arm cylinder 3d for rotating the arm 3c and the arm 3c, and a bucket cylinder for rotating the bucket 3e and the bucket 3e. 3f.
[0025]
A cabin 4 is arranged on the left side of the front attachment 3. An engine, a hydraulic device, a tank, and the like (not shown) are arranged behind the cabin 4 and are covered with a device cover 5.
[0026]
FIG. 2 shows a first embodiment of an actuator control device mounted on the hydraulic excavator.
[0027]
A reduction gear 7 is connected to an output shaft of an electric motor 6 composed of an AC servomotor or a DC servomotor, and a rotation shaft of the reduction gear 7 has a load inertia (specifically, a rotating body as a rotating system, a winch, and a traveling system). , Etc.) 8 are connected.
[0028]
The controller 9 is adapted to impart rotational speed signals S ₁ to the inverter 10a, the motor 6 is controlled to rotate by the inverter 10a, the rotational speed of the electric motor 6 is detected by the encoder 11, the detected rotational speed is fed back as a signal _{S 2} to the controller 9.
[0029]
Reference numeral 12 denotes an operation lever (operating body) for the operator to operate the rotation speed of the electric motor 6.
[0030]
As a power supply source for driving the electric motor 6, a generator 13a driven by the engine 13, a battery 14, a capacitor 15, and the like are used in combination. 16a is a converter for converting AC into DC, and 16b and 16c are DC-DC converters for increasing or decreasing the voltage.
[0031]
In the present embodiment, the generator 13a is mounted on the hydraulic shovel and stored in the battery 14. However, the configuration is not limited to this, and power may be supplied from an external power supply.
[0032]
Reference numeral 3b denotes a boom cylinder, which is representatively shown as an actuator of the front attachment 3.
[0033]
Reference numeral 17 denotes a hydraulic pump for supplying pressure oil to the boom cylinder 3b, and reference numeral 18 denotes another electric motor for driving the hydraulic pump 17.
[0034]
19 is a hydraulic circuit for adjusting the speed and pressure of the boom cylinder 3b, and 10b is an inverter.
[0035]
The boom cylinder 3b is driven by pressure oil supplied from the hydraulic circuit 19. Therefore, this other electric motor 18 does not drive the rotating system.
[0036]
Next, a control flow in the controller 9 will be described with reference to FIG.
[0037]
The controller 9 receives the operation amount S of the operation lever 12 and provides a lever-speed map 9a that associates the operation amount S with the target speed ω _ref , in other words, gives a static speed characteristic that does not include a time element. Thereby, the target speed is calculated. Hereinafter, the calculated target speed is referred to as a target calculated speed value ω _ref .
[0038]
As a method of calculating the target speed, besides using the above-described map 9a, for example, the target calculation speed value ω _ref can be obtained by substituting the manipulated variable S into a function formula for calculating the target speed. . The map 9a and the function formula function as a target speed calculation unit.
[0039]
The target calculation speed value ω _ref is given to the jerk limit processing unit 9b, and the speed feedback control by the PID 9c is performed so that the speed of the electric motor 6 follows the corrected target speed ω _mref output from the jerk limit processing unit 9b. I do. The jerk limit processing unit 9b functions as a jerk prediction value calculation unit, a determination unit, and a target speed correction unit.
[0040]
Reference numeral 9d denotes a predetermined value setting unit (predetermined value changing means) for allowing an operator to change the setting of a predetermined value described later.
[0041]
The control flow of the jerk restriction processing section 9b will be described with reference to FIG.
[0042]
In the jerk limiting process, a jerk prediction value is calculated by differentiating the target speed by the second order. Specifically, a target velocity arithmetic value omega _ref given work within the pre-control samples once stored in the buffer target velocity omega ^i-1 and the two previous target velocity omega ^i-2 controller 9 Then, the jerk prediction value ω ′ is calculated using the following equation (step S1).
[0043]
ω ′ = (ω _ref −2ω ⁱ⁻¹ + ω ⁱ⁻² ) / dt ² (1)
Here, dt is a sampling time. Further, it is determined whether or not the calculated jerk predicted value exceeds a predetermined value ω ′ _lim (step S2), and if the lever operation amount is changed, that is, if the answer is yes in step S3, the corrected target speed is determined. ω _mref is calculated as in the following equation (step S4).
[0044]
ω _mref = ω ^i-1 + Δω (2)
Here, Δω is an increment from the target speed ω ⁱ⁻¹ one control sample before, and this value is _such that the jerk value when the corrected target speed ω _mref is used does not exceed the predetermined value ω ′ _lim. The value may be a value, for example, a value as shown in Expression (3).
[0045]
Δω = dt ² ω ′ _lim + ω ⁱ⁻¹ −ω ⁱ⁻² (3)
If No in step S2, that is, if the jerk prediction value does not exceed the predetermined value ω ' _lim , the target speed ω _ref is output as it is as the corrected target speed ω _mref (step S5).
[0046]
The predetermined value ω ′ _lim is set to a value equal to or less than the maximum jerk value of the hydraulic drive system, for example.
[0047]
Next, the response characteristics obtained by the above control will be described in comparison with those of the related art.
[0048]
FIG. 5A shows a conventional response characteristic, and FIG. 5B shows a response characteristic according to the present embodiment.
[0049]
In the conventional response characteristics, FIG. 5A shows a change in lever operation amount, FIG. 5A-2 shows a change in target speed when the lever is operated, and FIG. FIG. 5A-4 shows a change in acceleration when the lever is operated, and FIG. 5A-4 shows jerk generated when the lever is operated.
[0050]
As shown in FIGS. 5A and 5A, in the conventional lever operation, large jerk peaks ω ′ _max , ω ′ at the beginning of the lever operation change (time t1) and at the end of the lever operation change (time t2). _min has occurred, and a large shock has occurred with this.
[0051]
Obtains a target speed calculated value omega _ref with respect to the lever operation in the present invention, on the other hand, obtains a jerk predicted value by by (1) using the omega _ref, when jerk predicted value exceeds a predetermined value omega _'lim Since the modified target speed is calculated by the equation (2) and the jerk value is thereby limited to a predetermined value ω ′ _lim or less, as shown in FIG. The jerk value ω ′ _{max at} time t1) is greatly reduced as compared with the related art (see FIG. (A-4)), thereby making it possible to reduce the shock.
[0052]
FIG. 6 shows a modification of the actuator control device shown in FIG.
[0053]
The same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.
[0054]
In the actuator control device shown in FIG. 6, a delay element adding unit 9e is provided between the lever-speed map 9a and the jerk limiting processing unit 9b. FIG. 7 shows a response characteristic due to the provision of the delay element adding section 9e.
[0055]
FIG. 7A shows a change in lever operation amount, FIG. 7B shows a change in target speed when the lever is operated, and FIG. 7C shows a change in acceleration when the lever is operated. FIG. 3D shows jerk generated when the lever is operated.
[0056]
In each of FIGS. 7A and 7B, at the beginning of the lever operation change (time t1), the jerk is reduced to a predetermined value or less by the same effect as that described in FIG. 5B-4 of the first embodiment. .
[0057]
Also, assuming that there is no delay element, the jerk value at the end of the lever operation change (time t2) has a constant speed immediately as shown in FIG. 5 (b-2). As shown in (2), the acceleration immediately becomes zero (it instantaneously falls in the acceleration characteristic), so that the jerk which is a differential value of the acceleration becomes a large negative value at time t2.
[0058]
On the other hand, if a dynamic delay element including a time element is added by the delay element adding unit 9d, the speed does not immediately become constant at the time t2 as shown in FIG. As shown, the acceleration does not immediately become zero but gradually decreases. As a result, the jerk value, which is a differential value of the acceleration, does not become a large negative value at the time t2, and the effect of reducing the jerk value ω ′ _min is obtained (see FIG. 7D).
[0059]
By adding such a delay element, the jerk value at the beginning of the lever operation change (time t1) and at the end of the lever operation change (time t2) can both be reduced, so that the shock accompanying this can be more effectively reduced. Can be reduced.
[0060]
FIG. 8 shows an actuator control device according to a second embodiment of the present invention.
[0061]
This configuration differs from FIG. 3 in that the jerk restriction processing unit 9b of the controller 9 is replaced with a second jerk restriction processing unit 9f. Other configurations are the same as those in FIG.
[0062]
The second jerk processing unit 9f shown in FIG. 8 calculates the torque limit value τ _lim by the following equation when the predicted jerk value exceeds the predetermined value ω ′ _lim and the lever operation amount changes.
[0063]
τ _lim = τ ^i-1 + Δτ (4)
Here, τ ⁱ⁻¹ is the motor torque one time before the control sample, and Δτ is the torque increment.
[0064]
This torque increment is given, for example, by the following equation (5).
[0065]
Δτ = Jω ′ _lim dt (5)
Here, J is the moment of inertia.
[0066]
The control flow of the second jerk processing unit 9f will be described with reference to FIG.
[0067]
The controller 9 receives the operation amount S of the operation lever 12, and calculates a target speed ω _ref using a lever-speed map 9a that associates the operation amount S with the target speed ω _ref .
[0068]
The calculated target calculation speed value ω _ref is given to the second jerk restriction processing unit 9e, and the second jerk restriction processing unit 9e first calculates a jerk prediction value (step S6), and calculates the calculated jerk prediction value. It is determined whether or not the predetermined value ω ′ _lim is exceeded (step S7), and if the lever operation amount is changed, that is, if the answer is yes in step S8, the torque limit value τ is calculated using the above-described equation (4). _lim is calculated, and the inverter 10a is controlled using the calculated τ _lim .
[0069]
The torque limit value τ _lim is, specifically, a motor current maximum value limit signal output from the controller 9.
[0070]
If No in step S7, that is, if the jerk prediction value does not exceed the predetermined value, no torque limitation is applied to the inverter 10a.
[0071]
By limiting the maximum value of the driving force in this way, it is possible to reduce the jerk value when the operation lever is suddenly operated, thereby preventing the occurrence of a shock.
[0072]
In the configuration shown in FIG. 8, the second jerk limiting processing unit 9f and the inverter 10a function as a driving force limiting unit that limits the maximum value of the driving force of the actuator.
[0073]
Further, the operator can change the predetermined value by the predetermined value setting section 9d. For example, if the operator wants to give priority to the speed of the actuator even with a slight shock, setting the predetermined value to a high value makes the operator more agile. Operations can be performed.
[0074]
In the above embodiment, the configuration in which the actuator is an electric motor has been described. However, when the actuator is a hydraulic device such as a hydraulic cylinder, the hydraulic oil is supplied to the hydraulic device when the calculated jerk predicted value exceeds a predetermined value. By limiting the flow rate of the hydraulic pump to be operated, it is possible to indirectly control the actuator so as not to generate a shock at the time of sudden operation.
[0075]
【The invention's effect】
As is apparent from the above description, according to the first aspect of the present invention, the target speed is calculated according to the operation amount of the operating body, the jerk value is predicted from the target speed, and the predicted jerk value is calculated. The target speed is corrected so that the jerk value does not exceed the predetermined value if it is determined that the jerk value exceeds the predetermined value, so that the jerk value is always reduced to the predetermined value or less even when the operating tool is suddenly operated. As a result, the occurrence of shock can be prevented.
[0076]
According to the second aspect of the present invention, when it is determined that the predicted jerk value exceeds the predetermined value, the maximum value of the driving force of the actuator is limited so that the jerk value does not exceed the predetermined value. Even when the operating body is suddenly operated, the jerk value is always reduced to a predetermined value or less without being affected by the delay of the control system, and an effect of reducing shock is obtained.
[0077]
According to the third aspect of the present invention, the configuration is such that the predetermined value can be changed, so that the operator can adjust the jerk value to a desired value. Can also respond.
[0078]
According to the fourth aspect of the present invention, since the response delay is added to the calculated target speed, the jerk peak value at the beginning of the change in the operation amount of the operating body is reduced, and at the same time, the operation amount changes. The jerk peak value at the end of the operation can also be reduced, and the associated shock can be reduced.
[0079]
According to the fifth aspect of the present invention, even when the actuator is constituted by an electric motor, the response is more sensitive than in the hydraulic drive system, the jerk is effectively reduced, and the accompanying shock is reduced. Can be done.
[Brief description of the drawings]
FIG. 1 is an external view of a hydraulic shovel to which an actuator control device of the present invention is applied.
FIG. 2 is an explanatory diagram showing a configuration of an actuator control device of the present invention.
FIG. 3 is a block diagram showing a first embodiment of the actuator control device.
FIG. 4 is a flowchart showing control contents according to the first embodiment.
FIG. 5A is a characteristic diagram showing a response characteristic as a comparative example, and FIG. 5B is a characteristic diagram showing a response characteristic according to the first embodiment.
FIG. 6 is a block diagram showing a modification of the first embodiment.
FIG. 7 is a characteristic diagram showing response characteristics according to the modification shown in FIG. 6;
FIG. 8 is a block diagram showing a second embodiment of the actuator control device.
FIG. 9 is a flowchart showing control contents according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Undercarriage 2 Upper revolving superstructure 3 Front attachment 4 Cabin 5 Equipment cover 6 Motor 7 Reduction gear 8 Load inertia 9 Controller 9a Lever-speed map 9b Jerk limitation processing part 9c PID
9d Predetermined value setting section 9e Delay element adding section 9f Second jerk limiting processing section 10a Inverter 11 Encoder 12 Operating lever 13 Engine 13a Generator 14 Battery

Claims (5)

An actuator for driving a movable portion of a work machine, an operating body for operating the actuator, and a working machine including a controller for controlling the actuator in accordance with an operation command of the operating body,
A controller configured to calculate a target speed of the actuator according to an operation amount of the operating body; and a jerk prediction value calculator configured to calculate a jerk prediction value by performing second order differentiation of the calculated target speed. A determination unit that determines whether the calculated jerk predicted value exceeds a predetermined value, and a target speed such that the jerk predicted value becomes equal to or less than the predetermined value when it is determined that the jerk predicted value exceeds the predetermined value. An actuator control device for a work machine, comprising: a target speed correction unit that corrects the target speed. An actuator for driving a movable portion of a work machine, an operating body for operating the actuator, and a working machine including a controller for controlling the actuator in accordance with an operation command of the operating body,
A controller configured to calculate a target speed of the actuator according to an operation amount of the operating body; and a jerk prediction value calculator configured to calculate a jerk prediction value by performing second order differentiation of the calculated target speed. And a determining unit for determining whether the calculated predicted jerk value exceeds a predetermined value, and a driving force limit for restricting a maximum value of the driving force of the actuator when it is determined that the predicted jerk value exceeds the predetermined value. And an actuator control device for a work machine. 3. The actuator control device for a work machine according to claim 1, further comprising a predetermined value changing unit configured to change the predetermined value. The target speed calculating section is for giving a static speed characteristic to the operation amount of the operating body by a map or a function expression, and is provided with a delay adding section for giving a dynamic delay to the speed characteristic. An actuator control device for a work machine according to claim 1. The actuator control device for a working machine according to any one of claims 1 to 4, wherein the actuator is an electric motor.

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