JPH0391404A - Lifting and lowering controller - Google Patents

Abstract

PURPOSE:To smoothly control lifting and lowering by providing a controlled variable setting means for respectively converting data of positional deviation obtained by a positional deviation acquiring means and data for a positional change obtained by a positional change acquiring means into plural data based on a prescribed function, processing selected data according to prescribed conditions and regulating opening degree of a control valve. CONSTITUTION:When control is carried out so as to maintain a ground working device at a prescribed level set on the basis of the ground surface, a positional deviation is obtained from a difference between the target level and a present level by a positional deviation acquiring means (A). a positional deviation change within unit time is then determined on the basis of a level change in lifting or lowering of the ground working device by a positional change acquiring means (B). The opening degree of a control valve (V) is subsequently set on the basis of respective obtained results by a controlled variable setting means (C). The controlled variables set by the controlled variable setting means (C) are outputted after conversion based on a prescribed function, prescribed selection and prescribed processing without simply calculating two kinds of inputted data.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an elevation control device, and more particularly, to a control technique used when a hydraulic actuator raises and lowers a ground work device provided in an agricultural tractor or the like. .

[Prior Art] Taking agricultural tractors as an example, conventional lifting control devices control the lifting and lowering of a rotary tiller, etc. to maintain it at a predetermined ground level during work, and control the lifting and lowering of a rotary tiller, etc. to a predetermined level. Conventional control devices are configured to feed back the level of the rotary tiller relative to the ground or the vehicle body when performing any of the above-mentioned controls. (References not listed).

In addition, in conventional control devices, PI or PID is used as an operation when performing control based on feedback signals.
Control etc. are adopted.

[Problem to be solved by the invention]

However, if we consider PID control, for example, in this PID control, by performing preset calculations on the value of the signal fed back, that is, calculations on each element of proportional element, integral element, and differential element. and
The control amount is obtained by simply adding these calculation results, so for example, when performing position control, as long as there is a position deviation, control will continue even if this deviation is a small value. This may cause the actuator to operate more frequently or cause overshoot.

In particular, when raising and lowering ground work equipment by operating hydraulic cylinders, such as agricultural tractors, the temperature of the hydraulic oil supplied to the hydraulic cylinder increases, and the viscosity of the hydraulic oil decreases. Even if the opening degree is set to a predetermined value, the operating speed of the hydraulic actuator increases. Therefore, when the operating speed increases in this way, not only does the above-mentioned overshoot become more likely to occur, but also the shock may become large when stopping the hydraulic actuator, so there is room for improvement.

The first object of the present invention is to prevent overshoot from occurring even when the ground work equipment is raised and lowered using a hydraulic actuator, and the control target for this raising and lowering is set based on the ground. A second object of the present invention is to construct a device that performs lifting and lowering control smoothly without having to use a hydraulic actuator. Even if it is set based on the vehicle body,
The object of the present invention is to configure a device that smoothly performs elevation control without causing overshoot.

[Means to solve the problem]

A first feature of the present invention is a control valve for controlling a hydraulic actuator for lifting and lowering a ground work device; a position deviation acquisition means for determining a positional deviation between a current level and a target level of a ground work device with respect to the ground; A position change amount acquisition means for obtaining a change in position deviation within a unit time during operation, position deviation data obtained by the position deviation acquisition means, and position change amount data obtained by the position change amount acquisition means, respectively, into a predetermined function. the data is converted into a plurality of data based on the data, one of the plurality of data is selected according to predetermined conditions, the data selected in this way is processed according to predetermined conditions, and the processing results are controlled. Output as a value for adjusting the opening degree of the valve, or data of the position deviation,
and control that outputs a value equal to the processing result as a value for adjusting the opening degree of the control valve without going through the processing based on the map data by inputting the respective values of data for the position deviation change. A second feature of the present invention is that the present invention includes a control valve for controlling a hydraulic actuator for raising and lowering the ground work equipment, and a control valve that controls the current level and target level for the vehicle body of the ground work equipment. position deviation acquisition means for determining the position deviation of the ground work device; speed change acquisition means for determining the change in speed deviation between the lifting speed and the target speed during the lifting operation of the ground work equipment; and the position deviation acquisition means. The positional deviation data and the speed deviation change data obtained by the speed change acquisition means are each converted into a plurality of data based on a predetermined function, and any of the plurality of data is converted under a predetermined condition. Further, the data selected in this way is processed according to predetermined conditions, and the processing result is output as a value for adjusting the opening degree of the control valve, or the data of the position deviation, and Control amount setting that outputs a value equal to the processing result as a value for adjusting the opening degree of the control valve without going through the processing based on the map data by inputting each value of data for speed deviation change. The functions and effects are as follows.

[For production]

If the first feature is configured as shown in FIG. 1, for example, when controlling to maintain the ground work device (11) at a predetermined level set with reference to the ground (G), the third As shown in the flowchart in the figure, the positional deviation is calculated from the difference between the target level and the current level (positional deviation acquisition means
A)) Next, based on the level change when the ground work device (11) is raised and lowered, the position deviation change within a unit time is determined (position change acquisition means (B)), and then the determined result is determined. Based on each, the opening degree of the control valve (V) is set (controlled variable setting means (C)).

In addition, the control amount set by the control amount setting means (C) is not simply calculated from two types of input data, but after conversion based on a predetermined function, predetermined selection, and predetermined processing. (In the case of map data, the same value as the processing result is output), so by setting the movement suitable for this lifting work in the function, setting it in the selection condition, and setting it in the processing condition, If the deviation is small, it is possible to stop the control, or if the deviation is large, it is possible to suppress excessive speed increase, or to correct changes in the elevation speed due to increases in oil temperature.

Further, if the above-mentioned second feature is configured as shown in FIG. 2, for example, when performing control to raise and lower the ground work device (11) to a predetermined level set with the vehicle body (3) as a reference,
As shown in the flowchart of FIG. 4, the position deviation is calculated from the difference between the target level and the current level (position deviation acquisition means (L)), and the speed change within unit time when the ground work device (11) is raised and lowered is calculated. (Means for acquiring speed change amount (M)
), then the opening degree of the control valve (v) is set based on each of the obtained results (controlled variable setting means (N)).

Moreover, the control amount set by the control amount setting means (N) is not simply calculated from two types of input data, but after conversion based on a predetermined function, predetermined selection, and predetermined processing. (In the case of map data, the same value as the processing result is output), so by setting the movement suitable for this lifting work in the function, setting it in the selection condition, and setting it in the processing condition, If the deviation is small, it is possible to stop the control, or if the deviation is large, it is possible to suppress excessive speed increase, or to correct changes in the elevation speed due to increases in oil temperature.

〔Effect of the invention〕

Therefore, even if the ground work device is operated by a hydraulic actuator and the control target for raising and lowering is set based on the ground or the vehicle body, overshoot is unlikely to occur, and moreover, it can be raised and lowered smoothly. A control device was constructed.

〔Example〕

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

As shown in FIG. 11, an engine (4) is disposed at the front of a vehicle body (3) equipped with front and rear wheels (1) and (2), and
A transmission case (5) is arranged at the rear of the vehicle body (3), and a pair of left and right lift arms (6) are mounted on the upper part of this transmission case (5).
, and a lift cylinder (7) (an example of a hydraulic actuator) for driving the lift arm (6) up and down,
A driver's seat (9) is provided between the left and right rear fenders (8) at a position above the lift cylinder (7) to constitute an agricultural tractor.

A rotary tiller (11) (an example of a ground working device) is connected to the rear end of this agricultural tractor via a two-point linkage (lO), and the two-point linkage (lO) and the lift arm (6) and a pair of left and right glue rods (12)
By supporting the rotary tiller (11) in a suspended state, the rotary tiller (11) is raised and lowered by the drive of the lift cylinder (7), and furthermore, one of the pair of lift rods (12) is equipped with a double-acting rolling cylinder. (13), this rotary tilling device (11) is configured to roll hydraulic oil around the longitudinal axis by driving the rolling cylinder (13).

The hydraulic system for performing this lifting and lowering operation and rolling operation is shown in FIG.
4), a flow priority valve (15) for flow rate control, an electromagnetic valve (16) that supplies the controlled flow from the flow priority valve (15) to the rolling cylinder (13), It is provided with an electromagnetic proportional control valve (V) for supplying the surplus flow of the flow priority valve (15) to the lift cylinder (7) or discharging the hydraulic oil from the lift cylinder (7),
Furthermore, this control valve (V) is a first valve (17) for upward control.
), a second valve (18) for pilot pressure control that opens and closes this first valve (17), a third valve (19) for downward control, and a pilot pressure that opens and closes this third valve (19). It consists of a fourth control valve (20) and a relief valve (21), and when controlling the rotary tiller (11) to the upward side, it is connected to the solenoid (18a) of the second valve (18>). By supplying current and adjusting this current value, the pilot pressure changes in accordance with this current value, resulting in a valve opening proportional to this current value.
) to the downward side, the fourth valve (
By adjusting the current value of the current supplied to the solenoid (20a) of 20), the opening degree of the valve can be obtained in proportion to this current value.

Further, in this agricultural tractor, the rotary tilling device (1
There are two types: position control that raises and lowers the rotary tiller (1) to a predetermined level based on the vehicle body (3), and automatic tillage depth control that raises and lowers the rotary tiller (11) to a predetermined level based on the tilled ground (G). The elevator is equipped with an elevation control device that controls the

This elevator control device is configured as shown in FIG. 9, and in this configuration, as shown in FIG. 11, a first potentiometer (23) and lift arm (
A position control setting system and a feedback system are configured with the second potentiometer (24) that detects the level of the rotary tiller (11) relative to the vehicle body from the amount of rocking of the rear fender (8). ) and a third potentiometer (27) that detects the setting position of the tilling depth setting dial (26) of the control box (25), and a swing type rear cover (lla) of the rotary tilling device (11). A setting system and a feedback system for automatic tillage depth control are constituted by a fourth potentiometer (28) that detects the level of the rotary tillage device (11) relative to the vehicle body from the amount of rocking.

Also, the signals from these four potentiometers are A/D
Via the converter (29), a control mechanism (30) equipped with a microprocessor (not shown) is powered, which outputs an intermittent pulse signal and outputs an intermittent pulse signal to the power transistors (31), ( 31), the solenoid (
18a), (20a).

Further, this control device controls the solenoids (18a), (20) by adjusting the duty cycle of the pulse signal.
a) by adjusting the current value of the current supplied to the control valve (
(2) The opening degree is adjusted, and the program is set so that this adjustment is performed according to the flowchart of FIG. 3 during the automatic plowing depth control and according to the flowchart of FIG. 4 during the position control.

In other words, when performing automatic plowing depth control, based on the signals from the third and fourth potentiometers (27) and (28),
The target level (Rx) and the current level (X) of the rotary tiller (11) are obtained, and the positional deviation (Ex) is obtained based on each value (#l step).

Next, the absolute value of the position error (Ex) is compared with the value (ε) set as the dead zone, and if it is smaller than this value, the data is cleared and no control is performed (Steps #2 and #3). ), conversely, if it is large, if this control is initial,
Duty cycle (Di) based on position deviation (Ex)
(Steps #4 and #5).

Next, after determining the control direction, the duty cycle (Di
) is output to operate the electromagnetic proportional control valve (■), and the third and fourth potentiometers (27), (2
Based on the signal from 8), the target level (Rx f+)
, obtain the current level (xtl) of the rotary tiller (11), and calculate the position deviation (EX (1)) based on each value.
(Step #6. #7. #8. #9).

Next, the change in positional deviation within unit time (△Ex,
. 〉 (Step #10), and further calculate this change (△
Ex. , ) and the positional deviation (EX +-+ ), the duty cycle (
Find the amount (ΔD) (unit: %) (Step #11).

This amount (△D) is determined by two types of input signals (△Ex fnl
) and (Ex (al)) are calculated in advance and given as map data,
It is set based on the so-called fuzzy theory (details will be described later).

Next, the amount of duty cycle to be adjusted (ΔD) (given as a positive or negative value) is added to the duty cycle of the currently output pulse signal, and the result of this addition is the limit. The duty cycle of the pulse signal that should be processed and output to a value smaller than
Di) is determined (steps #12 and #13), and this control continues until reset (step #14).

Furthermore, the configuration of the control system described above can be represented as shown in FIG. 1, and the position deviation acquisition means (A) in the same figure consists of steps #1 and #9 in the flowchart. The position change acquisition means (B) consists of step #10 in the flowchart, and the control amount setting means (C) consists of step #11 of the flowchart.

Next, an outline of the fuzzy theory used in the automatic plowing depth control will be explained.

In this control, the value of the position deviation (Ex) mentioned above and the position change amount (△Ex) within a unit time of the position deviation is N
It is determined whether it is included in the seven types of fuzzy labels: B, NM, NS, ZOlPS, PM, and PB, and the position deviation (Ex
) and the amount of change (ΔEx) are given as fuzzy labels.

Further, each of the fuzzy labels given in this way includes a plurality of control amounts, and these control amounts are obtained as follows.

In other words, as shown in Figure 6 (a) and (0), the positional deviation (
A membership value function is defined that converts the respective values of Ex) and change (ΔEx) into membership values within the range of 0 to 1. For example, if the value of positional deviation (Ex) is (a)
If the value of the position change (△Ex) is (b), the values of (a) and (b) can be calculated from the membership value (ax ), (ax), (
bt), (b2).

Also, the membership values (a, ), Cat) are each a function N
51zOte is given, membership value (b+), (
bz) are given by functions NM and NB. Next, according to the fuzzy rules shown in Figure 6 (c), the values of (a,) and (b2) are compared, and (az), (b+ ), and the smaller value (b2) of the comparison result and (a
2) is selected, and furthermore, as shown in FIG. 6(d), the region of the function NH is cut off from the membership value (b,) according to the fuzzy rule for the function defined in the conclusion part. (Ul) and the region (U2) of the function NM whose upper part is cut off from the membership value (a2) are obtained, and the centroid positions ( c) is obtained as the value of the control amount (ΔD).

In addition, the above-mentioned fuzzy rule is ``Mamdani''
ni) method.

Incidentally, in the automatic plowing depth control, the above-mentioned calculations based on fuzzy theory are performed in advance, and as described above (step #11 in the flowchart), the values of the position deviation (Ex) and the variation (△Ex) are Once determined, the control amount (ΔD) is quickly determined based on the map data.

In addition, the operation when performing position control is as shown in the flowchart in Figure 4, using the first and second potentiometers (23
), target level (Rx) based on the signals from (24)
, obtain the current level (X) of the rotary tiller (11), and obtain the position deviation (Ex) based on each value (#
l step).

Next, the absolute value of the positional deviation (Ex) is compared with the value (ε) set as the dead zone, and if it is smaller than this value (ε), the data is cleared and no control is performed (#2. #3
conversely, if this control is in the initial stage, the duty cycle (step) is large based on the position deviation (Ex).
Di) (step #4 and #5).

Next, after determining the control direction, the target speed (Rv) is set based on the positional deviation (Ex), and the duty cycle (D
Output the pulse signal of i) to operate the electromagnetic proportional control valve (v) (steps #6, #7, and #8).

It should be noted that the target speed (Rv) set in step #7 is set to a higher value as the value of the positional deviation (Ex) is larger, and in step #5, initial steps are taken to obtain this speed. The duty cycle (Di) required for this is set to an appropriate value.

In addition, from step #8 onwards, the rotary tiller (11) is raised and lowered, and the value of the second potentiometer (24) is input again to obtain the operating speed (■) during this raising and lowering, and the calculation is performed. is carried out (#9.#10 steps).

Next, the value of the first potentiometer (23) is input again (this value matches the value in step #l if the position lever (22) is not operated),
Water the positional deviation (Ex) again (#11 step).

Next, the speed deviation (Ev) is calculated from the target speed (Rv) and the operating speed (V), and by performing the same process, the time change (△Ev) of the speed deviation (Ev) is calculated. and calculate the amount (ΔD) of the duty cycle (unit: %) that should be adjusted based on each value (#12. #13
．． #14 step).

This amount (△D) is determined by two types of input signals (Ev) and (△Ev
) is obtained in advance and given as map data, which is the so-called fuzzy theory (F
Uzzy Theory) (details will be described later).

Next, the amount of duty cycle to be adjusted (△D) (
A pulse signal that should be output by adding the value (given as a positive or negative value) to the duty cycle of the currently output pulse signal, and processing the addition result so that it falls within a predetermined value range. The duty cycle (Di) is determined (steps #15 and #16), and this control continues until reset (step #17).

Furthermore, the control system described above can be represented in its configuration as shown in FIG. 2, and the position deviation acquisition means (L) in the same figure is shown in #1 of the flowchart. The speed change acquisition means (M) consists of step #13 in the flowchart, and the control amount setting means (N) consists of step #14 of the flowchart.

In addition, in this position control, the control amount is determined based on the same fuzzy theory as described above, and as shown in Figs. 5 and 6.
By applying the data written in parentheses in the figure,
The control amount is determined using the same process as described above.

Furthermore, in this position control, calculations based on fuzzy theory are performed in advance as described above, and the speed deviation (Ev
) and the change (ΔEx) in the speed deviation (Ev) are determined, the control amount (ΔD) is quickly determined based on the map data.

Incidentally, when raising and lowering the rotary tiller (11), characteristics such as speed changes during raising and lowering differ depending on the effect of the weight of the rotary tiller (11), so it is necessary to use either automatic tillage depth control or position control. Also, when doing
Two types of map data are used for each control so that a difference is set in the control amount during ascending control and descending control so that no overshoot or shock occurs in either control.

Incidentally, a block diagram of a control system that performs automatic plowing depth control and position control based on fuzzy theory is shown in FIGS. 7 and 8.

[Another example]

In addition to the embodiments described above, the present invention can be implemented by configuring a program to determine the control amount by calculation without using map data, or by using a microprocessor dedicated to fuzzy control. Various implementations are possible, such as configuring the flow with steps other than those shown in the flowchart, and setting the characteristics of the membership function to be represented by an arbitrary curve.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the elevation control device according to the present invention, and the first embodiment
The figure is a claim correspondence diagram showing the structure of the first invention, FIG. 2 is a claim correspondence diagram showing the structure of the second invention, FIG. 3 is a flowchart showing the operation of the first invention, and FIG. 4 is the operation of the second invention. Figure 5 is a table representing the set of fuzzy coefficients, Figure 6 is (A), (0), (C), (D).
Figure 7 is a block diagram of the system that performs automatic plowing depth control, Figure 8 is a block diagram of the system that performs position control, and Figure 9 shows the process of determining the control amount from the membership function and fuzzy rule table. 10 is a block circuit diagram of the control device, FIG. 10 is a hydraulic circuit diagram, and FIG. 11 is an overall side view of the agricultural tractor. (3)...Vehicle body, (7)...Hydraulic actuator, (11>...Ground work device, (A
), (L)...Position deviation acquisition means, (B)...
...Position change acquisition means, (C), (N)...
... Controlled amount setting means, (G) ... Ground, (M
)... Speed change acquisition means, (v>...
・Control valve.

Claims (1)

[Claims] 1. A control valve (V) that controls the hydraulic actuator (7) for raising and lowering the ground work device, and a positional deviation between the current level and the target level of the ground work device (11) with respect to the ground (G). Position deviation acquisition means (
A) Position change acquisition means (B) for determining the change in position deviation within a unit time during the lifting and lowering operation of the ground work device (11)
, converting the position deviation data obtained by the position deviation acquisition means (A) and the position change data obtained by the position change amount acquisition means (B) into a plurality of data based on a predetermined function, and
Select one of the plurality of data according to predetermined conditions, further process the selected data according to predetermined conditions, and use this processing result to adjust the opening degree of the control valve (V). Alternatively, by inputting the respective values of the positional deviation data and positional deviation change data, a value equal to the processing result can be obtained based on the map data without going through the processing. An elevator control device comprising: control amount setting means (C) that outputs a value for adjusting the opening degree of a control valve. 2. A control valve (V) for controlling the hydraulic actuator (7) for raising and lowering the ground work equipment; a position deviation acquisition means for determining the positional deviation between the current level and the target level of the ground work equipment (11) with respect to the vehicle body (3); (
L), Speed change acquisition means (M) for determining the change in speed deviation between the lifting speed and the target speed during the lifting operation of the ground work device (11) and the target speed; Position deviation acquisition means (L) Converting the positional deviation data obtained by the step and the speed deviation change data obtained by the speed change obtaining means (M) into a plurality of data based on a predetermined function,
Then, any one of the plurality of data is selected according to a predetermined condition, the data thus selected is further processed according to a predetermined condition, and the processing result is applied to a control valve (V
), or by inputting the respective values of the position deviation data and the speed deviation change data, based on the map data without going through the above processing, control amount setting means (for outputting a value equal to the processing result as a value for adjusting the opening degree of the control valve;
N), an elevation control device comprising each of the above.