JPH104739A - Cutting height control device in combine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When controlling the elevation of a combine harvesting pretreatment device using an elevation hydraulic cylinder 9, not only the ground height,
Smooth and accurate control is realized by controlling in consideration of the degree of change in the vertical position of the machine body between the mowing pre-processing device and the traveling body. SOLUTION: In the case where an operation instruction amount corresponding to a ground height detection value detected by an ultrasonic sensor 20 attached to a mowing pre-processing device is calculated, and a lifting and lowering hydraulic cylinder 9 is controlled to move up and down based on the calculated operation instruction amount, The vertical position of the aircraft relative to the aircraft is detected at an appropriate sampling timing by the vertical position sensor 22 provided between the apparatus and the harvesting pre-processing device. The rate of change is stored in advance, and a correction value for the operation instruction amount is calculated based on a deviation between the detected rate of change of the aircraft vertical position and the standard rate of change of the aircraft vertical position calculated at each of the predetermined timings. The correction amount is added to the operation instruction amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the height of a pre-cutting device in a combine by ground using an ultrasonic sensor, and controlling the elevation of the pre-cutting device so as to reach a preset cutting height. It is about.

[0002]

2. Description of the Related Art Conventionally, a non-contact type ultrasonic sensor has been used as a cutting height detecting device in a combine, as disclosed in Japanese Patent Application Laid-Open No. 58-142279. That is being done. In this type of ultrasonic sensor, a short pulse-like transmitted wave is emitted toward the ground, the reflected wave is received by a receiver, and the time from when the ultrasonic wave is transmitted to when the reflected wave is received by the receiver. The height of the ground is detected by measuring the time length, and a very short (msec.) Pulse-like ultrasonic wave is emitted at one time, so that the field scene (ground) is extremely limited. The point is to be detected, but the field scene is muddy, and since there are footprints of workers and grooves and cracks, it is easy for the detection value to be a strong noise signal of high and low, and the ground height is accurate without error. Can not be detected.

For this reason, for example, Japanese Patent Application Laid-Open No. 58-82316
In Japanese Unexamined Patent Publication (Kokai) No. 60-259105 and JP-A-60-259105, the ground height is recognized from the average value of the detection results measured a plurality of times, and the cutting pretreatment device is set to a hydraulic cylinder so that the cutting height is set from the average value. It is proposed to control the elevation. In addition, the present applicant previously disclosed in Japanese Patent Application Laid-Open Nos. 6-296413 and 6-303816 a detector for detecting a height to ground with an ultrasonic sensor, and applying a rule of fuzzy inference. It has been proposed to determine the operation output signal of the hydraulic cylinder.

[0004]

However, in spite of the above-mentioned processing by the control device, if the detection output from the ultrasonic sensor is an abnormal output signal such as a noise, the operation output of the hydraulic cylinder is accurately determined. The problem of being unable to find a signal could not be solved. Also, in hydraulic circuits such as hydraulic cylinders and their control valves, accurate control of cutting height is required because the viscosity of pressure oil fluctuates greatly due to environmental temperature and control characteristics change due to individual differences in operating characteristics of control valves. There was also a problem that it was not possible to stably.

[0005] In the present invention, even in the above situation,
It is an object of the present invention to solve the problem that the elevation control of the pre-cutting device can be smoothly and accurately performed so that the ground height of the pre-cutting device can be maintained in a predetermined state.

[0006]

Means for Solving the Problems To solve the above-mentioned problems, the invention according to claim 1 is arranged so that a cutting pre-processing device is moved up and down by a lifting hydraulic cylinder with respect to a traveling machine body. Calculate the operation instruction amount corresponding to the ground height detection value detected by the ultrasonic sensor attached to the device,
In the cutting height control device in the combine which is configured to control the lifting hydraulic cylinder based on this, the lifting position sensor provided between the traveling machine and the pre-cutting device determines the lifting position of the machine body. It is configured to detect at an appropriate sampling timing, and to control the operation instruction amount to be corrected by the anti-aircraft vertical position detection value.

[0007] The invention described in claim 2 is the first invention.
In the cutting height control device in the combine described in the above,
The cutting height control device includes a storage unit that stores in advance a standard rate of change of the aircraft vertical position per unit time corresponding to the operation instruction amount in the standard work environment, and a detection versus aircraft vertical position change calculated at each predetermined timing. Calculating means for calculating a correction value for the operation instruction amount based on a deviation between the rate and the standard rate of change of the vertical position of the vehicle.

Further, in the cutting height control apparatus for a combine according to the present invention, at least the value at the end of work among the correction values obtained by the calculating means is stored in a non-volatile memory. At the time of resumption, the latest correction value is applied.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described. FIG. 1 shows a side view of a combine, and a traveling body 1 of the combine has a pair of right and left traveling devices each having a traveling crawler 2. 3 is mounted so as to be adjustable in relative vehicle height via a hydraulic cylinder (not shown), and the traveling machine body 1 includes an operator's cab 4, a threshing device 5, a grain tank 6, and Is provided with a discharge auger cylinder 7 for transporting grains.

A cutting pre-processing device 8 is mounted at the front of the traveling machine body 1 via a lifting hydraulic cylinder 9 so as to be able to move up and down. The cutting pre-processing device 8 has a lower end inclined forward and an upper end rearward. The culm-raising device 10, a weeding body 11 in front of the lower end thereof, a cutting blade 12 on the lower rear side of the culm-raising device 10, a culm conveying device 13, and the like, as shown in FIGS. 3 and 4. A plurality of bearing brackets are provided, in which the base end of a front downwardly inclined elevating and lowering cylinder frame 14 having a front end mounted on the mowing pretreatment device 8 is fixed to a horizontal cylinder 15, and the horizontal cylinder 15 is provided at a front portion of the traveling body 1. 16 (one of which is not shown) is rotatably supported, and power from an engine (not shown) on the traveling body 1 is transmitted to transmission shafts 17 and 19 which are disposed on the inner diameters of the horizontal cylinder 15 and the vertical cylinder frame 14, respectively. , Bevel gear pair 18
Power is transmitted to each section of the pre-cutting device 8 via the like.
Then, the lifting pre-processing device 8 is mounted on the lifting hydraulic cylinder 9 mounted between the middle part of the lifting cylinder frame 14 and the traveling body 1.
Is driven up and down.

An ultrasonic sensor 20 for detecting the ground height between the pre-cutting device 8 and the field scene 21 is arranged on a bracket (not shown) provided on the back side of the culm raising device 13. As shown in FIG. 5, a transmitter (horn) of the transmitter 20a and the receiver 20 in the ultrasonic sensor 20 are provided.
The receiving section b is arranged so as to face the field scene 21. The elevating position sensor 22 is for detecting the relative height between the traveling body 1 and the pre-cutting device 8, and is fixed to the bearing bracket 16 as shown in FIGS. 3 and 4 in this embodiment. The sensing rotary arm 23 of the rotary potentiometer type lift position sensor 22 is brought into contact with a sensor shaft 24 fixed to the outer surface of the horizontal cylinder 15, and the rotation angle θ of the horizontal cylinder 15 is detected. Frame 14
, And thus the vertical position of the pre-cutting device 8 with respect to the traveling machine body 1 (the vertical position of the machine body).

FIG. 5 is a functional block diagram of a cutting height control device 40 according to the present invention. The control device 40 is an electronic control device such as a microcomputer, and executes various arithmetic processes and controls (not shown). Central processing unit (CP
U), a read-only memory (ROM) for storing a control program, a random-access memory (RAM) for temporarily storing various detection values, data, and the like, and stored data even when the control device is turned off. Memory, a clock as a timer function, an interface, a bus, and the like.

An ultrasonic wave is transmitted to the transmitter 20a of the ultrasonic sensor 20 at an appropriate time interval T1 via a transmission drive circuit 41 in accordance with a command from the control device 40, and a reflected wave reflected from an object or the like is reflected. Is received by the receiver 20b, and the detection signal is input to the control device 40 via the reception amplifier circuit 42. The detection signal of the elevation position sensor 22 is also A /
The control device 40 is provided via the D converter at each time interval T1.
To enter.

Also, a cutting height setting device 25, a manual switch 43 for performing a cutting and threshing operation in a manual mode, an automatic switch 44 for setting the same operation to an automatic control mode, Each signal of the joystick 45 for manually finely raising and lowering the processing device 8 is also input to the control device 40. The operation lever of the joystick 45 can be tilted back and forth and is urged to automatically return to the neutral position. When the operation lever is tilted forward, it continues to descend at the minimum speed, and when tilted rearward, the minimum speed is maintained. To continue rising.

The control device 40 outputs a predetermined elevating command signal to the first driving circuit 46 and the second driving circuit 47 in accordance with a predetermined calculation result to be described later.
6 operates the electromagnetic solenoids 49a and 49b of the hydraulic switching valve 49 in the hydraulic circuit 48 in response to the output from the hydraulic circuit 48, and in accordance with the output from the second drive circuit 47, an electromagnetic proportional pressure reducing valve 50 which is an example of a high-speed response electromagnetic valve. Electromagnetic solenoid 5
By operating Oa, the single-acting hydraulic cylinder 9 for raising and lowering the pre-cutting device 8 is operated.

In the hydraulic circuit 48 shown in FIG. 5, a pair of left and right rolling control hydraulic cylinders for controlling the relative left and right vehicle height of the single-acting lifting hydraulic cylinder 9 and the right and left traveling devices 3 and the traveling body 1 are provided. Pressure oil is also supplied to a hydraulic control valve 51 and the like (not shown). In this case, as shown in FIG.
A relief valve 54 is inserted in the oil supply path 53 to the fuel cell 9. 4
In the middle of the hydraulic pipe from the output port of the hydraulic switching valve 49 of the port 3 position switching electromagnetic type to the single-acting hydraulic cylinder 9, a check valve 5 is provided.
5 and the slow return check valve 56 are connected. The other output port of the hydraulic switching valve 49 is configured to supply oil to the other hydraulic control valves 51 at the same time.

A return throttle pipe 57 connected between the check valve 55 and the slow return check valve 56 of the hydraulic pipe has a variable throttle valve 58 for lowering the piston rod of the single-acting hydraulic cylinder 9 and an emergency lowering valve 59. And are connected in parallel. The variable throttle valve 58 is a two-port two-position switching type valve.
The pilot port has one of the aforementioned high-speed response solenoid valves.
The output port of the electromagnetic proportional pressure reducing valve 50 is connected as an example.

The operation control of the hydraulic cylinder 9 for lifting and lowering the pre-cutting device is executed as follows. That is, when the electromagnetic hydraulic switching valve 49 is switched to extend the hydraulic cylinder 9, when the electromagnetic solenoid 49a is operated by pulse width modulation control (PWM), the hydraulic pressure is appropriately adjusted by the electromagnetic proportional pressure reducing valve 50. Pilot pressure is variable throttle valve 5
8, the degree of throttle of the variable throttle valve 58 is arbitrarily changed, and is drained from the return oil pipe 57 to the oil tank 60. In that case, the operating speed of the hydraulic cylinder 9 is adjusted according to the degree of throttle of the variable throttle valve 58.

When the hydraulic cylinder 9 is to be reduced, the hydraulic switching valve 49 is set to neutral, the electromagnetic proportional pressure reducing valve 50 is operated by the pulse width modulation control (PWM) method in the same manner as described above, and the pilot pressure of the pilot pressure is reduced. The throttle opening of the variable throttle valve 58 is adjusted by the adjustment, whereby the operating speed of the hydraulic cylinder 9 is adjusted. Next, the control for determining the operation command amount of the cutting height in the control device 40 will be described with reference to the main flowchart of FIG. 7. At every predetermined time interval T1 (in this embodiment, every 100 ms) from 20a,
The transmitted wave P2 (P2 <P1) in the duty section T2 is output. In the receiver 20b, the transmitted wave P2 from the transmitter 20a is reflected on the ground, and receives the received wave P3 after an appropriate time T3 from the start of emission of the transmitted wave P2.

The detection value K of the detection signal P3 is read at each corner and stored in a memory in the control device 40 (S1). On the other hand, the target cutting height value G set by the cutting height setting device 25 is read (S2). Next, a deviation amount D (= K−) of the detection value K of the cutting height with respect to the cutting height set value G.
G) (S3), and the first order difference ΔD (= D _{n + 1} −D _n ) of the difference D is calculated (step S4).
These values are stored again (step S5), and the deviation amount and the first-order difference amount are converted into variables using a fuzzy inference rule table (see FIG. 7) stored in a ROM (not shown) of the control device 40 in advance. As an input, a calculation is performed so as to output an operation instruction amount X (step S6), and control is performed such that the cutting pre-processing device 8 is raised and lowered according to the magnitude of the operation instruction amount (step S7).

The elevation control of the pre-cutting device 8 will be described in detail below. The first-order difference ΔD of the deviation D is the rate of change of the deviation D for each sampling time (100 msec. In the embodiment). become. The deviation D and the first-order difference Δ
A fuzzy inference rule table (see FIG. 7) is prepared in which D is a variable input and the operation instruction amount X is an output, and the operation instruction amount X is obtained by referring to this fuzzy inference rule table.

In this case, the two variable inputs (deviation D and first-order difference ΔD) of the fuzzy inference rule table are
In order to allocate to each of the 15 stages (elements), the following preparation operation is performed. That is, first, the deviation amount D
Of the table set U [0, 1, 2, $ 14]
Assign to elements. At this time, in order to determine the magnitude relationship based on the central element “U7” of the 15 elements, first, the sign of the deviation D is determined. When the deviation amount D is positive, the value of the deviation amount D is compressed to 1/10 to obtain a value D ', and the operation of the element U ← U7 + D' is executed.

When the deviation D is negative, the value of the deviation D is set to 10
Compressed by a factor of 1 to find the value -D '
The operation of 7-D 'is executed, whereby the deviation D is assigned to each element of the standardized table set U. Therefore, element U
7 indicates that there is little difference between the height position of the pre-cutting device 8 and the set cutting height. On the side closer to the element U0, the pre-cutting device 8 approaches the ground more greatly than the set cutting height. ing. Further, approaching the element U14 indicates that the pre-cutting device 8 is far away from the ground for the set cutting height.

Next, the first-order difference ΔD is also assigned to the fifteen elements of the standardized table set V [0, 1, 2,. At this time, in order to determine the magnitude relationship based on the central element “V7” of the 15 elements, first, the sign of the first order difference ΔD is determined. When the first-order difference ΔD is positive, the value of the first-order difference ΔD is compressed to one tenth to obtain a value ΔD ′, and the operation of the element V ← V7 + ΔD ′ is executed.

When the first order difference ΔD is negative, the first order difference Δ
The value of D is compressed to one-tenth to obtain a value −ΔD ′, and the operation of the element V ← V7−ΔD ′ is further executed. Thereby, the first-order difference amount ΔD is assigned to each element of the standardized table set V. Among the elements of the table set V, near the V7, it indicates that the vertical movement (change rate) of the pre-cutting device 8 is small, and as it approaches V0, the degree of the approach of the pre-cutting device 8 to the ground is reduced. It means that it is fast,
As it approaches 14, it means that the degree of separation of the pre-cutting device from the ground is high.

In this way, the elements of the two sets of tables are determined, and in the fuzzy inference rule table of FIG. 7, the operation instruction amount X (membership value), which is the intersection of the elements.
Ask for. The operation instruction amount X is an integer value from -10 to 10 and has 17 steps. A value of 0 indicates no elevation, a positive value indicates a command to raise the pre-cutting device 8, and a negative value indicates a command of the pre-cutting device 8.
Is a descending command.

Next, the oil temperature of the hydraulic circuit 48 and the hydraulic switching valve 4
In order to execute the correction of the cutting height control error based on the characteristics of FIG. In the embodiment, when only 100 msec.) Is executed,
Detection value of vertical position sensor 22 (body vertical position)
A map (see FIG. 8) with the change rate Y is created and stored in the memory (non-volatile memory) of the control device 40.

Subsequently, as shown in the subroutine flowchart of FIG. 9, following the start, the operation instruction amount X during the actual work is read (S10), and the detection of the elevation position sensor 22 during the actual work is performed. The change rate y is calculated from the value (S11), and the standard change rate Y for X is read out from the map of FIG. 7 (S12). Then, the deviation Δy between the standard change rate Y and the actual change rate y (=
Y−y) is calculated (S13).

Next, the control correction amount Δx (= Δy × correction constant + correction offset value) is calculated (S14), and (after correction) the operation instruction amount X ← X + Δx (S15).
A predetermined elevating command signal is output to drive circuits 46 and 47, and a hydraulic switching valve 49 is provided in accordance with the output from the drive circuits 46 and 47.
By operating the electromagnetic solenoid and the electromagnetic solenoid of the pressure-reducing control valve 50, the hydraulic cylinder 9 for raising and lowering the pre-cutting device 8 is operated (S16).

At this time, when the integer value of the corrected operation instruction amount X is +10, the up / down electromagnetic solenoid of the hydraulic pressure switching valve 49 is continuously ON, and when it is -10, the descending electromagnetic solenoid is continuously ON. If the quantity X is 9, 8, 6, 5, 4,
In the case of 3, 2, 1 (positive), when the duty ratio of ON / OFF of the electromagnetic solenoid of the pressure reducing control valve 50 is changed according to the magnitude of the value, the amount of oil returned to the hydraulic tank is “9”. Adjust so that the number is small, and if it is "1", it is large. Lowering (the operation instruction amount X is 9, 8, 6, 5, 5, 4, 3, 2, 1
In the case of (negative), the opposite adjustment is performed.

Note that the control correction amount Δx calculated in S14 is rewritten as a new value each time the calculation is performed, and the final value is stored in a non-volatile memory when the harvesting and threshing operation is completed. Is the initial control correction amount Δ
By using the variable x, when the work is resumed when the oil temperature is low, for example, after the work is stopped for a short time, it is possible to continue accurate cutting height elevation control.

The hydraulic switching valve 49 and the pressure reducing control valve 5
In the drive circuits 46 and 47 (see FIG. 10) for performing the PWM control (pulse width modulation control) for controlling the output signal by changing the ON / OFF duty ratio of the electromagnetic solenoid of 0 (see FIG. 10), the PWM cycle is set to a high speed of about 2 kHz. And a small ripple amplitude generated by a dither generator 64 (oscillator) on the way from the D / A converter 62 for converting the output signal from the control device 40 to an analog signal to the current amplifying circuit 63. By adding (superimposing) an AC component to the DC output current, a pilot spool in the hydraulic circuit 48,
Eliminates static friction on the main spool, improves hysteresis characteristics, and eliminates poor control due to minute dust. In this case, as shown in FIG. 11, if the ON duty ratio is large (Duty + Δα) every 10 msec. Of the on-duty time, the dither is small (Duty−
Δα) alternately appear. Also, ON / OFF of the electromagnetic solenoid of the hydraulic pressure switching valve 49 and the pressure reducing control valve 50.
When the operating time per cycle is fixed at, for example, 150 msec., When the ON duty section thereof is fixed at 100 msec. And the like, and the OFF duty section is controlled so as to be longer or shorter according to the vehicle speed, for example, a field scene Even if there are cracks and small irregularities in the
The amount of lifting and lowering of the pre-cutting device and the speed thereof can be suppressed.

The current output from the current amplification circuit 63 to the hydraulic switching valve 49 and the electromagnetic solenoid of the pressure reduction control valve 50 is fed back to the A / D converter 62 via the feedback correction circuit 65, thereby raising and lowering the hydraulic cylinder. 9 can follow the output signal in real time. Further, when operating with the operation lever of the joystick 45, the operation lever rises or descends only during the ON period due to the tilt of the operation lever. In addition, when the output is set so as to be a continuous output with a duty ratio of 100% of the PWM, a small amount of height of the pre-cutting device 8 can be operated according to the operator's intention. When a plurality of switches are simultaneously (or substantially simultaneously) input, the highest priority is given to raising and lowering the pre-cutting device 8 in the manual mode when the manual switch 43 is turned on. Is set to operate the joystick 45 and finally to the automatic control mode.

Further, a grain culm sensor (not shown) which is turned on when the harvested culm is detected is provided in the pre-cutting device 8, and when the input signal from the grain culm sensor is off, the cutting and threshing operation is performed. It is determined that the operation has not been performed, and a section in which the input signal is ON and the traveling body has moved only a predetermined distance by the vehicle speed sensor is determined to be the work start time. In this non-cutting threshing work execution and work start time,
By performing the ascending / descending control using a value twice as large as the operation instruction amount X obtained as a result of the calculation as the actual operation instruction amount, a quick ascending / descending operation can be obtained.

[0035]

As described above, according to the first aspect of the present invention,
According to the invention described in the above, the mowing pre-processing device is configured to be moved up and down by a lifting hydraulic cylinder with respect to the traveling machine body,
A harvester in a combine which is configured to calculate an operation instruction amount corresponding to a ground height detection value detected by an ultrasonic sensor mounted on a mowing pre-processing device, and to control the lifting hydraulic cylinder up and down based on the calculated operation instruction amount. In the height control device,
Control is performed so that the lifting position sensor provided between the traveling aircraft and the pre-harvesting device detects the lifting position of the aircraft at an appropriate sampling timing, and corrects the operation instruction amount with the detected value of the aircraft lifting position. It is configured so that

The detected value of the vertical position of the aircraft between the traveling vehicle and the mowing pre-processing device can be detected more stably than the detected value of the ground height and has less variation. When the correction is made, the stable and accurate control can be executed as compared with the case where the elevation of the pre-cutting device is controlled only by the ground height detection value. In particular, when noise is included in the reception signal of the ultrasonic sensor, it is possible to reliably prevent the disturbance from occurring in the elevating operation of the pre-cutting device.

Further, the invention described in claim 2 is the same as that in claim 1
In the cutting height control device in the combine described in the above,
The cutting height control device includes a storage unit that stores in advance a standard rate of change of the aircraft vertical position per unit time corresponding to the operation instruction amount in the standard work environment, and a detection versus aircraft vertical position change calculated at each predetermined timing. Calculating means for calculating a correction value for the operation instruction amount based on a deviation between the rate and the standard rate of change of the vertical position of the vehicle.

As described above, the storage means for previously storing the standard rate of change of the body relative to the body per unit time corresponding to the operation instruction amount in the standard work environment, If the correction for the operation instruction amount is executed based on the deviation between the standard and the rate of change of the vertical position of the airframe, the viscosity of the pressure oil greatly varies depending on the environmental temperature in a hydraulic circuit such as a hydraulic cylinder and its control valve. Or the operating characteristics of the control valve change,
The correction can be made to a state close to the actual working environment, and accurate cutting height control can be stably executed.

Further, in the cutting height control apparatus for a combine according to the present invention, at least the value at the end of the work among the correction values obtained by the calculating means is stored in a non-volatile memory. At the time of resuming, if the latest correction value is configured to be applied, for example, even if the work is resumed after a short interruption of the work, the correction value was in reality because the environmental condition such as oil temperature is close to the actual substance of the work As a result, it is possible to stably execute accurate cutting height control.

[Brief description of the drawings]

FIG. 1 is a side view of a combine.

FIG. 2 is a plan view of the combine.

FIG. 3 is a side view showing a mounting position of a position sensor.

FIG. 4 is a plan view showing a mounting position of a position sensor.

FIG. 5 is a functional block diagram of a hydraulic circuit and control means.

FIG. 6 is a main flowchart of control.

FIG. 7 is an explanatory diagram of a fuzzy inference rule table.

FIG. 8 is a map showing a relationship between an operation instruction amount and a standard change rate.

FIG. 9 is a subroutine flowchart.

FIG. 10 is a functional block diagram of a second drive circuit 47.

FIG. 11 is a time chart showing a state of a PMW signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traveling body 3 Traveling device 8 Cutting pretreatment device 9 Elevating hydraulic cylinder 20 Ultrasonic sensor 22 Elevating position sensor 25 Cutting height setting device 40 Control device 48 Drive circuit 49 Hydraulic switching valve 50 Electromagnetic proportional pressure reducing valve

Claims (3)

[Claims] An operation corresponding to a ground height detection value detected by an ultrasonic sensor mounted on the mowing pre-processing device, wherein the mowing pre-processing device is moved up and down with respect to the traveling machine body by an elevating hydraulic cylinder. In the cutting height control device in the combine which is configured to calculate the indicated amount and control the lifting and lowering of the lifting and lowering hydraulic cylinder based on the lift amount, a lifting position sensor provided between the traveling machine and the cutting pre-processing device is provided. A cutting height control apparatus for a combine, wherein the control unit detects a lifting position of the aircraft body at a sampling timing and corrects the operation instruction amount with the detected value of the aircraft lifting position. 2. The cutting height control device according to claim 1, wherein the cutting height control device includes a storage unit for storing in advance a standard rate of change of the vertical position of the aircraft per unit time corresponding to an operation instruction amount in a standard work environment, and a detection operation calculated at each predetermined timing. 2. The computer according to claim 1, further comprising a calculating unit configured to calculate a correction value for the operation instruction amount based on a deviation between the anti-aircraft vertical position change rate and the standard anti-aircraft vertical position change rate. 3. Cutting height control device for combine harvesters. 3. The method according to claim 1, wherein at least a value at the end of the work among the correction values obtained by said calculating means is stored in a nonvolatile memory, and at least when the work is resumed, the latest correction value is applied. The cutting height control device for a combine according to claim 2.