JPH0191702A - Positioning controller to the ground for working machine - Google Patents

Abstract

PURPOSE:To prevent accidental start of inclination of the working machine to the left or right, by releasing the means for inhibiting the inclination operation, after the actual stroke value becomes almost equal to the target value in case that the engine stops during controlling the inclination operation and is allowed to restart. CONSTITUTION:The horizontal sensor 12 detects the inclination of the machine 1, and the hydraulic cylinder 13 is driven to control the inclination according to its extent, as the stroke value is monitored with the sensor 14. When the engine stop, while the inclination of the working machine 3 is controlled, the inclination control is not allowed to start, until the engine restarts, and the machine is allowed to run a little to recover the inclination so that the target value of stroke is coincided to the actual value or the target value is changed by turning the dial so that it is coincided with the actual value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a ground-based work machine (hereinafter simply referred to as a "vehicle") such as a rotary tiller that is attached to the rear of a traveling vehicle (hereinafter simply referred to as a "vehicle") such as a tractor. The invention relates to a position control device for a work machine (referred to as a work machine), and in particular, the position control of the work machine
The present invention relates to a ground work equipment position control device that performs control to prevent unexpected lifting and tilting operations when an engine is started in an automatic control state.

(Prior Art) Generally, in a traveling work vehicle in which a work implement is attached to a vehicle such as a tractor, the work implement can be moved up and down between a work position and a non-work position, and can be moved left and right with respect to the vehicle. It is connected to the tractor side via a connecting mechanism so that it can be tilted. The starting/stopping of the lifting/lowering and tilting operations of the work equipment and the control of the position are often automatically controlled.

If the engine of such a mobile work vehicle is started at the start of work, or if the engine stalls during work and then the engine is restarted, if the control of the lifting and tilting of the work equipment remains in the automatic control state. There is a possibility that the automatic control is activated at the same time as the engine starts, causing the lifted work equipment to unexpectedly start lowering or tilting from side to side.

To address this problem, Japanese Patent Publication No. 58-26926 proposes the following device.

In this device, when the engine is started while the lifting control of the work equipment is in the automatic control state, the safety lock circuit is set to operate, and the safety lock circuit is activated by switching the switching mechanism to the neutral state of lifting. , is configured to be reset.

Therefore, until the switching mechanism is reset and the automatic control state is canceled, the automatic control for raising and lowering the working machine is not performed.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

When using an automatically controlled interlock mechanism such as the above conventional technology, the operation by the operator tends to be complicated. With such a control device, operation becomes more complex. Therefore, it is desired that the necessary functions be satisfied while the operation is as labor-saving as possible.

If the vehicle enters a large pothole and the engine stops while the vehicle is tilted, and the degree of inclination of the vehicle and the degree of inclination of the work equipment are significantly different, the engine is restarted and the work equipment is When the left/right tilt control of the machine is automatically started, the tilt of the work equipment is rapidly corrected according to the degree of the tilt, so the tilting of the work equipment causes a large shake of the vehicle. If the left/right tilt control is not predicted, it will feel very strange.

The present invention has been made to solve the above-mentioned problems.

(Means and operations for solving the problem) In order to solve the above problem, the present invention provides a current value calculator that calculates the current value of the left and right tilting stroke based on the value detected by the sensor, and a horizontal a target value setter that sets a stroke target value for left/right tilt control based on the value detected by the sensor; a subtracter that calculates the stroke target value from the current stroke value; storage means for storing the value of at least twice; and 2 values stored in the storage means.
It is equipped with a sign discriminating means for discriminating the positive or negative sign of the value for two times, and a left-right tilting control inhibiting means for prohibiting the left-right tilting control of the working machine, and the sign discriminating means for discriminating the positive or negative sign of the stored value for the two times determined by the sign discriminating means. The present invention is characterized in that, when the signs become different signs, the left/right tilting control inhibiting means is canceled and the left/right tilting control is started.

In the present invention having the above configuration, when the engine is stopped during left-right tilting control of the working machine and then started again, after the stroke target value of the left-right tilting control and the current stroke value substantially match, , the lateral tilting control inhibiting means is canceled and automatic lateral tilting control is started.

Therefore, if the vehicle gets stuck in the pothole and tilts significantly and the engine stops, after restarting the engine,
Either run the vehicle for a short time to correct the vehicle's inclination and make the stroke target value match the current value, or operate the knob for setting the stroke target value to change the stroke target value to match the current value. Automatic left/right tilt control is restarted only after this.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 7 is a side view of a traveling working vehicle to which the present invention is applied, and FIG. 8 is a perspective view showing the main parts of a working machine and a coupling mechanism section connected to the rear of the traveling working vehicle.

In the figure, a working machine 3 such as a tillage rotor is connected to a vehicle 1 via a connecting mechanism 2.

The work machine 3 is connected to the vehicle 1 via a three-point lifting link mechanism consisting of a top link 4 and a pair of left and right lower links 5 and 6. Further, a hydraulic cylinder 7 and lift arms 8 and 9 driven by the cylinder 7 are attached to the vehicle 1 side.

Lower links 5.6 and lift rods 10.1 respectively
Since it is connected to lift arms 8 and 9 via 1,
The work machine 3 is raised and lowered by the expansion and contraction operations of the hydraulic cylinder 7.

The vehicle 1 is provided with a horizontal sensor 12 that is made up of a rotary potentiometer, and the lift rod 1i is made up of a hydraulic cylinder 13 that expands and contracts the rod and a linear potentiometer that detects the amount of expansion and contraction of the lift rod 11. A stroke sensor 14 is provided.

The tilt of the vehicle 1 detected by the horizontal sensor 12 is adjusted so that even if the vehicle 1 rolls, the work equipment 3 is maintained horizontally with respect to the ground or at a predetermined angle from the horizontal. Depending on the extent, the hydraulic cylinder 13 can be driven and controlled while the amount of expansion and contraction is monitored by the stroke sensor 14.

When controlling the work equipment 3 to be held at a predetermined angle from the horizontal with respect to the ground, a predetermined value is set using a setting knob (not shown), and the detection value of the horizontal sensor 12 is set to the corresponding value. This can be achieved by correcting the tilting target value using a predetermined value.

The lift arms 8 and 9 are provided with a lift sensor 15 composed of a rotary potentiometer that detects the lift angle, and the work equipment 3 is raised to a non-working position and returned to a working position according to the sensor output. It is possible to control the lowering of the

On the other hand, on the working machine 3 side, a pillar 16 is provided which traces the ground and whose opening degree θ changes depending on the depth of tillage when the working machine 3 is in the working position. The opening degree θ of the pillar 16 is detected via a rod 17A by a pillar sensor (angle sensor) 18A composed of a rotary potentiometer.

According to the output of the pillar sensor 18A, the hydraulic cylinder 7 is driven to maintain the tilling depth at a set value, thereby controlling the tilling depth.

The vehicle 1 is provided with an operator's seat 17, and an operation switch 18 for manually controlling the elevation and descent of the working machine 3 is provided near the seat.

The operation of the working machine 3 depending on the position of the operation switch 18 will be explained with reference to FIG.

The operation switch 18 is operated within a range between a lower position A and an upper position. When the operation switch 18 is in the N position, the work equipment 3 is in a neutral state where the lifting and lowering is stopped, and
In the position C and D the working implement 3 is lowered, and in the C and D positions the working implement 3 is raised.

No matter which position the operating switch 18 is moved to, it returns to the neutral position N when the operator releases his/her hand. However, in the A and D positions, the lifting and lowering of the work implement 3 does not stop even if the switch 18 returns to the N position.

That is, when the operation switch 18 is operated to the -HA position, the work equipment 3 does not stop until it descends to the lowest position, and when it is operated to the D position, the work equipment 3 does not stop until it rises to the highest position. Do not stop.

FIG. 1 shows a block diagram of an electrical control system in such a traveling work vehicle.

Here, the height of the working machine 3 with respect to the vehicle 1 is controlled.
means for stopping the control function of the elevation control drive unit; and controlling the horizontal tilting by tilting the work implement 3 to the left and right with respect to the vehicle 1;
means for stopping the control function of the left-right tilt control drive unit;
The release is conditioned on the degree of deviation of the current stroke value from the left/right tilting stroke target value or the position of the operation switch.

In FIG. 1, the current value of the left-right tilt stroke is calculated by the current value calculator 19 based on the detection result detected by the stroke sensor 14, and the left-right tilt target value of the left-right tilt control is calculated by the horizontal sensor 12. The target value is set in the target value setting device 20 based on the detected detection result.

The left-right tilt target value for the left-right tilt control is set, for example, as follows from the detected value of the horizontal sensor 12.

When the vehicle 1 is tilted by an angle α from the vertical, the work implement 3 connected to the vehicle 1 is also tilted by the angle α.

In this case, in order to tilt the work implement 3 left and right and hold it in a horizontal position, the work implement 3 may be tilted by an angle α in the opposite direction to the tilt direction of the vehicle 1.

Since the horizontal sensor 12 is mounted on the vehicle 1, the tilt angle of the vehicle 1 itself can be detected by the horizontal sensor 12. Therefore, a value obtained by inverting the sign of the detected value of the horizontal sensor 12 is set as the horizontal tilting target value when the working machine 3 is tilted left and right and held in a horizontal posture.

The horizontal tilt control is not limited to the above-mentioned horizontal posture control, but the work equipment 3
may be held at an arbitrary angle β from the horizontal. In this case, the angle β may be set using a setting knob, and the value obtained by adding the angle β to the value α detected by the horizontal sensor 12 may be set as the left/right tilting target value.

Note that the detection value of the stroke sensor 14, which is made up of a linear action type potentiometer, detects the amount of left and right inclination based on the setting knob made up of a rotary type potentiometer, and the amount of swing of a pendulum, which is linked to the rotary type potentiometer. The current value is converted by the current value calculator 19 so that it can be compared with the tilt target value, which is set based on the detected value of the horizontal sensor 12 configured as shown in FIG. .

In the subtracter 21, the target value is subtracted from the current value, and the result is stored in the A storage section 22.

When the latest subtraction result is input to the A storage section 22, the stored contents of the A storage section 22 are transferred to the B storage section 23. Then, the values in the storage units A and B are determined by the determining means 24 as to whether the positive or negative signs thereof are different.

Furthermore, the subtraction result of the subtractor 21 is the slope protection dead zone (RO
M value) is compared with the slope protection dead zone comparison means 40.

Note that the subtraction results may be stored alternately in the A storage section and the B storage section.

The left-right tilt control drive section 27 controls the left-right tilt of the working machine 3 by turning on and off the left-tilting valve 25 and the right-tilting valve 26 according to a timetable described later, and expanding and contracting the hydraulic cylinder 13. Left/right tilt control prohibition means 2
8, the ink is locked.

Then, the interlock caused by the left/right tilting control inhibiting means 28 is canceled according to the determination result of the code determining means 24. The interlock of the left/right tilting control inhibiting means 28 is also released by operating the position of the operation switch 18, as will be described later.

The elevation control drive section 31 controls the height position of the working machine 3 by turning on and off the ascending valve 29 and the descending valve 30 according to a timetable described later, and expands and contracts the hydraulic cylinder 7. The ink is locked by the inhibiting means 32.

The interlock by the elevation control inhibiting means 32 is released by moving the operation switch 18 to the N position.

Note that the upper limit comparing means 36 compares the current horizontal tilt value with the stroke upper limit value of the hydraulic cylinder 13 set in the stroke upper limit setting device 33, while the lower limit comparing means 37 compares the current horizontal tilt value with the current horizontal tilt value. The stroke lower limit value set in the stroke lower limit setter 34 is compared.

If the comparison result of the comparison means 38.37 indicates that the current stroke value exceeds the upper limit stroke value, the gate 38 is opened and the current stroke value is replaced with the upper limit stroke value; If the current stroke value is below the lower stroke limit, the gate 38 is opened and the current stroke value is replaced by the lower stroke limit.

To summarize the above, in this embodiment, the interlock of the lateral tilting control drive section 27 of the work equipment 3 is calculated by the current value calculator 19 with respect to the lateral tilting stroke target value set by the target value setting device 20. It is canceled by the result of determining the sign of the deviation of the current stroke value, the result of comparing the deviation with the slope protection dead zone, or by operating the position of the operation switch.

The interlock of the elevation control drive unit 31 is released by setting the operation switch to the N position.

Therefore, in the present invention, when the engine is started, unexpected left/right tilt control or elevation control is not started.

Said left tilt valve 25. Valve for right tilt 26° Valve for elevation 29. The lowering valve 30 is turned on every preset cycle for an on-time period calculated using a calculation table to be described later, and drives the hydraulic cylinder 7.13.

FIG. 5 shows a time chart of the on-time. As shown in the figure, the valves 25, 26, 29.30 are
Intermittent operation is performed by repeatedly turning on and off.

Therefore, the larger the ratio of on-time ON in each period f, the closer to continuous operation, so the hydraulic cylinder 7.13
As the average driving speed of the hydraulic cylinder 7 becomes faster and the ratio of ON time becomes smaller, the intermittent operation becomes more noticeable, and the hydraulic cylinder 7
．． 13, the average exhaustion speed becomes slower.

FIG. 4 shows a diagram of the relationship between the on-time and the deviation.

In the figure, the horizontal axis represents the deviation of the current stroke value from the stroke upper limit value or the stroke lower limit value, and the vertical axis represents the on-time.

The relationship between on-time and deviation can be defined as curve S1 or S2. When the deviation becomes larger than the dead zone P, the valve 25.degree.

In the relationship of curve S1, the on-time increases until the deviation reaches ~I, and in the range where the deviation is less than or equal to M, the valve is intermittently turned on according to the on-time, and when the deviation is greater than or equal to M, the lift valve is turned on. are continuous.

In the relationship of curve S2, two stages of on-time can be set depending on the magnitude of the deviation.

It is arbitrary to select either the curve S1 or the curve S2.

The table shown in FIG. 4 is prepared for lifting and lowering. You can also use the same timetable for both.

As described above, when the current stroke value deviates significantly from the stroke target value, the driving speed of the hydraulic cylinder is fast, and when the deviation of the current stroke value from the stroke target value decreases, the driving speed slows down. This reduces the impact and overrun that occur when the hydraulic cylinder drive is stopped after the working machine 3 is raised and lowered and tilted left and right.

Next, the control flow of this embodiment will be explained in detail with reference to the flowcharts of FIGS. 2 and 3.

In the figure, the initial flag indicates the lifting valve 29 that drives the hydraulic cylinder 7 for lifting and lowering the working machine 3.
This is a flag for determining whether to calculate the on time of the descending valve 30 or to set "0" to the on time without calculating the on time.

In addition, the horizontal prohibition flag can be set by calculating the ON time of the left tilting valve 25 and the right tilting valve 26 that drive the hydraulic cylinder 13 for horizontally tilting the work equipment 3, or by calculating the ON time without calculating the ON time. This flag is used to determine whether to set "0" to "0".

The two flags are set when the control power source is activated.

First, it is determined whether the engine is stopped (step S
In l), if the engine is stopped, the judgment in step S1 is affirmative, the initial flag and the horizontal prohibition flag are set (step S2), the ATT control process (step 519) is executed, and the program is started at the beginning of the program. return.

In this case, the ATT control process (step 519) is performed as shown in FIG.

In FIG. 3, the initial flag was set in step S2, so whether the initial flag is "0" or "
1" (step 3191) becomes "1", and "O" is set as the elevating/lowering on time per cycle of the working machine 3 (step 5192).

Since the horizontal prohibition flag was also set in step S2, it is determined whether the horizontal prohibition flag is "1" or "0" (step S51).
94)) becomes "1", and "02" is set as the left/right tilt ON time of the working machine 3 (step 5195).

Therefore, in step S1 of FIG. 2, if the engine is stopped, the ascending valve 29 and the descending valve 30. Valve for left tilt 25. The ON time of the right tilting valve 26 is "0" in both cases, and the working machine 3 is not controlled to move up and down nor to control its left and right tilting.

When the engine is started, the determination in step S1 is negative, and the process proceeds to step S3, where the state of the initial flag is determined.

Since the initial flag remains in the state set in step S'2 when the engine is stopped, it is determined to be "1", and it is determined whether or not the operation switch 18 is in the neutral position N (see Fig. 6). Step S4).

When the operation switch 18 is in the N position, the initial flag is cleared (step S5).

Initial flag force (when cleared, the determination in step 5191 in the ATT control process becomes "0",
The elevating and lowering on time of the work equipment 3 is calculated (step 31
93).

The on-time calculation is performed based on the calculation table shown in FIG. 4 above.

Once the initial flag is cleared, it will not be set unless the engine is stopped.
The calculation of the lift-on time is performed repeatedly.

Thereafter, when the operation switch 18 is moved to a position other than the neutral position N, the on/off operations of the ascending valve 29 and descending valve 30 are performed according to the position of the switch 18 and the result of the above-mentioned elevation ON time calculation. The working machine 3 is raised and lowered.

In the determination in step S8, the state of the horizontal prohibition flag is #1.
#, so next it is determined whether the current value of the left/right tilting stroke exceeds the stroke upper limit STMAX (
Step S9). If the current stroke value exceeds the upper stroke limit, the current stroke value is replaced with the upper stroke limit (step 510), and step 5
Proceed to step 13.

If the current stroke value does not exceed the stroke upper limit,
The determination in step S9 is negative, and it is determined whether the current stroke value is below the stroke lower limit STMIN (step 511).

If the current stroke value is below the lower stroke limit, the current stroke value is replaced with the lower stroke limit (step 512), and the process proceeds to step S13.

Here, if the stroke target value can only be set within the range of the stroke upper limit value and the stroke lower limit value, and the work equipment 3 is stopped in an overrun state,
If the current stroke value is outside the range of the stroke upper limit value and the stroke lower limit value and exceeds the upper limit value or the lower limit value by more than the slope protection dead zone, the stroke target value and the current stroke value should be made to substantially match. There are some things that I can't do.

Therefore, by replacing the stroke upper limit value or stroke lower limit value with the current stroke value as described above,
This eliminates the problem that the stroke target value cannot substantially match the current stroke value.

If the current stroke value is within the range between the stroke upper limit and the stroke lower limit, step SIO and step S12 are skipped and the process proceeds to step S13.

In step S13, the stroke target value is subtracted from the current stroke value and stored in the A storage section.

The value stored in the A storage section is the absolute value and R
A slope protection dead zone set as OM data is compared (step 514). If the value in the A storage section is within the tilt protection dead zone, the determination in step S14 is affirmative, and the horizontal prohibition flag is cleared (step 818).

As a result, in the ATT control process (Step 519), the ON time of the left/right tilting valve is calculated (Step S196), and the left/right tilting control is started.

On the other hand, if the value in the A storage section is outside the range of the slope protection dead zone, the determination in step S14 is negative, and the process proceeds to step S15, where it is determined whether or not step S15 is to be processed for the first time. .

If it is the first processing, the horizontal prohibition flag has not been cleared yet, so the ATT processing (step 519) is performed.
The left and right ON time in is "0", and left and right tilting control is not performed.

In the second and subsequent executions of the program, the determination at step S15 becomes negative, and the value previously stored in the A storage section is transferred to the B storage section (step 516), and the current value in the A storage section is transferred to the B storage section (step 516). It is determined whether the positive and negative signs of the values in the B storage section are the same (step 517). The A and B storage units can be configured with shift registers, for example.

When the value in the A storage section 22 and the value in the B storage section 23 have the same sign, that is, the latest data stored in the A storage section 22 and the data stored in the B storage section 23 one cycle before. If the magnitude relationship between the current stroke value and the target stroke value does not change in , the horizontal prohibition flag is not cleared and the ATT control process (step 519) is performed.

At this time, the horizontal prohibition flag is not cleared, so
The left and right on time calculations in step 8196 are not performed;
Therefore, left-right tilt control is not performed.

In the latest data stored in the A storage section 22 and the data stored in the B storage section 23 one cycle ago,
If the magnitude relationship between the current stroke value and the target stroke value is reversed and the data in the A storage section 22 and the data in the B storage section 23 have different signs, that is, after reading the data one cycle ago, the latest If it is determined that there was a moment when the stroke target value and the current stroke value matched while the data was being read, the horizontal prohibition flag is cleared in step 818.

As a result, the ATT control process (step 5
In step 19), the left/right tilting control is started.

Furthermore, the left-right tilt control is also started by moving the position of the operation switch 18. That is, when the initial flag is cleared, the determination in step S3 becomes "0", so it is determined again whether or not the operation switch 18 is in the neutral position N (step S6).

If the operation switch 18 is moved from the N position,
The horizontal prohibition flag is cleared (step S7), and the state determination of the horizontal prohibition flag (step S194) in the ATT control process in FIG.
The left/right tilt on time of is calculated (step 8196).
.

The working machine 3 is controlled to tilt laterally so that the current value detected by the stroke sensor approaches the target value set based on the detection result of the horizontal sensor 12.

Then, the left-right tilt speed during the left-right tilt control is controlled so that it is fast when the deviation from the target value is large, and slow when the deviation is small, according to the calculation result of the left-right tilt on time in step 5196.

According to the present embodiment, as is clear from the above description, the lifting and lowering control of the work equipment is performed by pressing the operation switch after starting the engine.
It will not start until after it has been moved to a neutral position. Maru,
The left/right tilt control of the working machine is not started until after the operation switch is moved from the neutral position to the lifting operation position.

However, regarding the left-right tilt control, if the deviation of the current stroke value from the stroke target value is within the tilt protection dead zone, the left-right tilt control is automatically started when the engine is started.

On the other hand, if the current value of the horizontal tilting stroke deviates from the stroke target value by more than the tilt protection dead zone, the engine will be started and the horizontal tilting stroke of the work equipment will suddenly start. Rather, the left-right tilt control is started after the stroke target value is changed so that the current value of the left-right tilt stroke falls within the range of the tilt protection dead zone.

That is, in this embodiment, the ink lock for starting the lift control is released by switching the operating switch to the neutral position, and the ink lock for starting the left/right tilting control is released by switching the operating switch to a position other than neutral. It is designed to be canceled by switching or changing the stroke target value.

Furthermore, the release of the interlock of the left/right tilting control due to a change in the stroke target value is divided into cases where it is performed automatically and cases where it is performed manually depending on the degree of inclination of the work equipment, and where possible unnecessary manual operations are avoided. This makes it possible to eliminate

Then, in order to change the stroke target value so that the current horizontal tilting stroke value falls within the range of the tilt protection dead zone, the vehicle is driven, the tilt of the vehicle is corrected, and the horizontal sensor 12 is adjusted. Means is taken to change the stroke target value using the output signal or by operating a stroke target value setting knob.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects can be achieved.

(1) When starting the engine, unless the operator consciously moves the operation switch, the work equipment will not start unexpectedly tilting left or right.

(2) If the degree of inclination of the work equipment is small before starting the engine, the interlock of left and right tilting control can be automatically released, eliminating unnecessary manual operations and improving operability.

(3) If the degree of inclination of the work equipment is large before starting the engine, you can run the vehicle to correct its position and automatically release the left/right tilt control interlock. Since it can also be operated and manually released, the operator can select an easier method to perform the work depending on the situation during work.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a control device showing an embodiment of the present invention, Fig. 2 is an operation flowchart of the control device shown in Fig. 1, Fig. 3 is a flowchart of on-time calculation, and Fig. 4 is a flowchart of on-time calculation. Relationship diagram, Figure 5 is an on-time time chart, Figure 6 is a schematic diagram of the operation switch of the working machine, Figure 7 is a side view of the traveling working vehicle, and Figure 8 is the working machine connected to the rear of the traveling working vehicle. FIG. 3 is a perspective view of the connecting portion. DESCRIPTION OF SYMBOLS 1... Traveling vehicle, 2... Connection mechanism part, 3... Ground work machine, 7.13... Hydraulic cylinder, 14... Stroke sensor, 15... Horizontal sensor, 18... Operation switch, 19...Current value calculator, 20...Target value setter, 21...Subtractor, 22...A storage unit, 23
. . . B storage unit, 24 . . . code determination means, 28 . . .
Agent for means prohibiting lateral tilting control Patent attorney Michihito Hiraki 18th 2nd m (Part 1) Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Procedural amendment (voluntary) 1988 November 27th

Claims (4)

[Claims] (1) In a ground-based work equipment position control device that controls a ground-based work equipment connected to a traveling vehicle so that it can move up and down and tilt left and right to a set ground attitude by tilting it left and right through the expansion and contraction of a hydraulic cylinder. , a target value setting device that sets a stroke target value of the hydraulic cylinder for controlling the set ground attitude based on a detected value of a horizontal sensor provided on the traveling vehicle; and a sensor that detects the amount of expansion and contraction of the hydraulic cylinder. a current value calculator that calculates a current horizontal tilting stroke value of the ground work equipment based on a detected value of the sensor; a subtracter that calculates a deviation of the current stroke value from the target stroke value; a sign determining means for determining whether the signs of the latest deviation obtained in and the immediately preceding deviation are different from each other; a right tilting valve that drives the hydraulic cylinder to extend and retract; and a left/right tilting device that controls the ON operation of the left tilting valve. a control drive unit; and a left-right tilt control inhibiting unit for prohibiting the left-right tilt control drive unit from turning on the valve; A ground work machine position control device characterized in that it is configured to release a control inhibiting means and start left and right tilting control for a set ground attitude. (2) When the current stroke value exceeds a preset stroke upper limit value, replace the stroke upper limit value with the stroke current value, and when the stroke current value falls below a preset stroke lower limit value. The ground work machine position control device according to claim 1, wherein the lower stroke limit value is replaced with the current stroke value. (3) In a ground work machine position control device that controls a ground work machine connected to a traveling vehicle so as to be able to move up and down and tilt left and right to a set ground attitude by tilting it left and right by the expansion and contraction operation of a hydraulic cylinder, a target value setting device that sets a stroke target value of the hydraulic cylinder for controlling the set ground attitude based on a detected value of a horizontal sensor provided on the traveling vehicle; and a sensor that detects the amount of expansion and contraction of the hydraulic cylinder. , a current value calculator that calculates a current horizontal tilting stroke value of the ground work equipment based on the detected value of the sensor; a subtractor that calculates a deviation of the current stroke value from the stroke target value; an inclination protection dead zone comparison means for comparing with the protection dead zone; a left-right tilt control drive section that controls the on-operation of the right-tilt valve and the left-tilt valve that drive the hydraulic cylinder to extend and retract; and the left-right tilt control drive section; lateral tilt control prohibition means for prohibiting on-operation of the valve, and when it is determined that the deviation is within the range of the tilt protection dead zone as a result of comparison by the tilt protection dead zone comparison means, What is claimed is: 1. A ground work machine position control device, characterized in that the device is configured to release the horizontal tilting control prohibition means and start the horizontal tilting control for the set ground attitude. (4) When the current stroke value exceeds a preset stroke upper limit value, replace the stroke upper limit value with the stroke current value, and when the stroke current value falls below a preset stroke lower limit value. The ground work machine position control device according to claim 3, wherein the lower stroke limit value is replaced with the current stroke value.