JP3556808B2 - Tractor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of a tractor having a lift rod cylinder.
[0002]
[Prior art]
In general, a tractor of this type includes a lift rod cylinder for forcibly changing the inclination posture of a work machine and automatically controls the lift rod cylinder so that the work machine maintains a set inclination. In such a case, it is required to set a so-called dead zone in which the cylinder operation is stopped until the deviation of the detected position from the target position exceeds the dead zone set value, and to ensure control stability.
[0003]
[Problems to be solved by the invention]
However, in setting the dead zone, if the dead zone setting value is too large, the control accuracy is reduced.If the dead zone setting value is too small, frequent operations cannot be prevented. Therefore, an ambiguous intermediate setting value must be set. In fact, it was not possible to obtain. Therefore, it has been proposed that in a cylinder operating state, good control accuracy is secured by using a small dead band setting value, while in a cylinder stopped state, frequent operation is prevented by using a large dead band setting value. In such a case, it is permissible to stop for a long time in a state where the deviation is located between the small dead zone set value and the large dead zone set value, so that a control error may be tolerated for a long time and the work accuracy may be reduced. was there.
[0004]
[Means for Solving the Problems]
The present invention has been created with the object of solving these problems in view of the above-described circumstances,The invention of claim 1 isA lift rod cylinder for forcibly changing the inclination posture of the work machine; and an automatic control unit for automatically controlling the lift rod cylinder. The automatic control unit further includes a deviation for calculating a deviation between a target position and a detected position. In a tractor provided with arithmetic means and operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the automatic control unit includes a deviation in the operation stop state exceeding the dead zone set value, and Provide a delay processing means for limiting the output of the cylinder operation command until a predetermined timer time elapses when the delay processing range is within the set value.In the meantime, the plurality of delay processing ranges are set in multiple stages, and the delay processing time is set longer for the delay processing range closer to the dead zone, and when the deviation of the operation stop state exceeds the dead zone setting value, the count of all the delay timers is counted. Characterized by startingTractorIt is. By doing thisWhen the operation is stopped, even if the deviation exceeds the dead zone set value, if the deviation does not exceed the delay processing range set value, the lift rod cylinder is maintained in a stopped state, so that frequent operation is prevented and good stability is secured. In addition, if this state continues for a predetermined time, the lift rod cylinder is operated toward the dead zone, so that the control accuracy is higher than that in which the state deviating from the dead zone is allowed for a long time. Can be improved.When the deviation is small, the delay is long and the stability is emphasized. On the other hand, when the deviation is large, the delay is short and the control accuracy is emphasized. Therefore, the control accuracy is improved while ensuring the stability. be able to. Furthermore, since the delay processing in each delay processing range is canceled based on the time when the deviation deviates from the dead band, absolute delay processing centering on the dead band can be performed. As a result, small fluctuations in the deviation (noise , Etc.), and stable control can be performed. If the deviation greatly fluctuates, the delay processing can be quickly canceled to secure good control accuracy.
The invention according to claim 2 includes a lift rod cylinder for forcibly changing the inclination posture of the work machine, and an automatic control unit for automatically controlling the lift rod cylinder, and further includes a target position and a detection position. In the tractor provided with a deviation calculating means for calculating a deviation of the operation control means and an operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the deviation of the operation stop state is provided to the automatic control unit. When the value exceeds the dead zone setting value and is within the delay processing range setting value, in providing the delay processing means for limiting the output of the cylinder operation command until a predetermined timer time elapses, the plurality of delay processing ranges are set in multiple stages. In addition, the delay processing time is set longer for the delay processing range closer to the dead zone, and when the deviation of the operation stop state enters each delay processing range, the corresponding delay timer is set. So as to start counting, when the delay timer time of the delay processing range close to the dead zone has elapsed than the delay processing range of current position, a tractor, characterized in that to release the delay processing range at least the current position. In this way, when the operation is stopped, the lift rod cylinder is maintained in the stopped state unless the deviation exceeds the dead zone set value but does not exceed the delay processing range set value. If this condition continues for a predetermined period of time, the lift rod cylinder is operated toward the dead zone, so that the state deviating from the dead zone can be tolerated for a long time. As a result, the control accuracy can be improved. When the deviation is small, the delay is long and the stability is emphasized. On the other hand, when the deviation is large, the delay is short and the control accuracy is emphasized. Therefore, the control accuracy is improved while ensuring the stability. be able to. Furthermore, since the delay processing of each delay processing range is canceled based on the time when the deviation enters each delay processing range, relative delay processing can be performed in each delay processing range, and as a result, deviation fluctuations Can be performed as much as possible, and control with an emphasis on stability can be performed. In addition, in canceling the delay processing of each delay processing range based on the time when the deviation enters each delay processing range, it is possible to prevent the delay time from becoming unnecessarily long and to improve control accuracy. .
The invention of claim 3 isA lift rod cylinder for forcibly changing the inclination posture of the work machine; and an automatic control unit for automatically controlling the lift rod cylinder. The automatic control unit further includes a deviation for calculating a deviation between a target position and a detected position. Calculation means and when the deviation exceeds the dead band setting value A tractor provided with an operation command output means for outputting a cylinder operation command to the automatic control unit, when the deviation of the operation stop state exceeds the dead band set value and is within the delay processing range set value, a predetermined timer In providing the delay processing means for limiting the output of the cylinder operation command until the time elapses, the plurality of delay processing ranges are set in multiple stages, and the delay processing time is set longer for the delay processing range closer to the dead zone. The tractor is characterized by canceling a delay processing range closer to a dead zone than a located delay processing range. In this way, when the operation is stopped, the lift rod cylinder is maintained in the stopped state unless the deviation exceeds the dead zone set value but does not exceed the delay processing range set value. If this condition continues for a predetermined period of time, the lift rod cylinder is operated toward the dead zone, so that the state deviating from the dead zone can be tolerated for a long time. As a result, the control accuracy can be improved. When the deviation is small, the delay is long and the stability is emphasized. On the other hand, when the deviation is large, the delay is short and the control accuracy is emphasized. Therefore, the control accuracy is improved while ensuring the stability. be able to. Further, when the deviation is to return to the delay processing range on the dead zone side, the lift rod cylinder is operated immediately, so that the delay time is prevented from becoming unnecessarily long and control accuracy can be improved.
The invention according to claim 4 includes a lift rod cylinder for forcibly changing the tilt posture of the work machine, and an automatic control unit for automatically controlling the lift rod cylinder, and further includes a target position and a detection position. In the tractor provided with a deviation calculating means for calculating a deviation of the operation control means and an operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the deviation of the operation stop state is provided to the automatic control unit. When the value exceeds the dead zone setting value and is within the delay processing range setting value, in providing the delay processing means for limiting the output of the cylinder operation command until a predetermined timer time elapses, the plurality of delay processing ranges are set in multiple stages. In addition, the delay timer time is set longer in the delay processing range closer to the dead zone, and when the delay timer time elapses in each delay processing range, the operation speed differs. The cylinder operation command is output at the same time as the cylinder operation command in the delay processing range closer to the dead zone. A tractor that outputs an operation command. In this way, when the operation is stopped, the lift rod cylinder is maintained in the stopped state unless the deviation exceeds the dead zone set value but does not exceed the delay processing range set value. If this condition continues for a predetermined period of time, the lift rod cylinder is operated toward the dead zone, so that the state deviating from the dead zone can be tolerated for a long time. As a result, the control accuracy can be improved. When the deviation is small, the delay is long and the stability is emphasized. On the other hand, when the deviation is large, the delay is short and the control accuracy is emphasized. Therefore, the control accuracy is improved while ensuring the stability. be able to. Furthermore, in the delay processing range far from the dead zone, the lift rod cylinder is operated quickly to improve the control accuracy, while in the delay processing range near the dead zone, the lift rod cylinder is operated slowly to prevent the so-called hunting phenomenon. it can. In addition, since the lift rod cylinder is operated at a speed one step slower even during the delay processing, it is possible to improve control accuracy while ensuring stability.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, one embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling body of a tractor. A working machine 3 such as a rotary is connected to a rear portion of the traveling body 1 via a lifting link mechanism 2 so as to be able to move up and down. The working machine 3 moves up and down with the vertical swing of a lift arm 5 that suspends the lifting link mechanism 2 via the lift rod 4, while a lift provided on one of the left and right lift rods 4. The rod cylinder 6 inclines left and right as the rod cylinder 6 expands and contracts, but all of these basic configurations are the same as in the past.
[0006]
Numeral 7 denotes an electromagnetic switching valve for a lift rod for extending and retracting the lift rod cylinder 6. An extension solenoid 8 and a reduction solenoid 9 for switching the electromagnetic switching valve 7 for the lift rod can be intermittently driven based on an inching pulse. Therefore, the operation speed of the lift rod cylinder 6 can be controlled based on the duty setting (ON time / cycle) of the inching pulse.
[0007]
Reference numeral 10 denotes a control unit constituted by using a microcomputer. On the input side of the control unit 10, a lift rod sensor 11 for detecting the cylinder length of the lift rod cylinder 6 and a right and left inclination angle of the traveling body 1 are detected. Tilt sensor 12, automatic tilt switch 13 for turning on / off the automatic tilt control, tilt setting volume 14 for setting the target tilt of the automatic tilt control, tilt sensitivity for setting the sensitivity of the automatic tilt control in accordance with the type of work equipment and the like. A setting switch 15, a tilt manual switch 16 for manually operating the lift rod cylinder 6, and the like are connected via an input interface circuit. On the output side, an extension and reduction solenoid 8 of the lift rod electromagnetic switching valve 7, 9 are connected via an output interface circuit.
[0008]
In the main routine of the control unit 10, after performing "initial setting" for setting a telescopic delay timer described later, resetting a telescopic delay timer elapsed flag, resetting a telescopic delay range passage flag, and the like, the tilt sensitivity setting is performed. "Sensitivity set" for switching the setting time of the expansion / contraction delay timer, the width of the expansion / contraction delay range, the inclination comparison output control mode, etc., the inclination automatic target value, the inclination manual target value, the parallel return target value or the current value according to the switching position of the switch 15. "Tilt control" for setting the target position stop value to the lift rod target value, "Tilt setting volume check" for checking the operation of the tilt setting volume 14, and lift rod according to the deviation between the lift rod sensor value and the lift rod target value. A subroutine such as “tilt comparison output control” that outputs an expansion / contraction command is repeatedly executed. , The following, among these subroutines will be described on the basis of "tilt control", "tilt setting volume check" and "slope comparison output control" (the Mode 1-4) to flow. Note that the control concept at the time of the extension operation and the control operation at the time of the contraction operation are substantially the same, so that the description (flow chart) at the time of the extension operation is omitted.
[0009]
In the "tilt control", first, whether the parallel return (the function of automatically returning the work equipment inclination to parallel when the work equipment is lifted) or not, or the automatic inclination (the function of automatically controlling the work equipment inclination with the target of the set inclination) ) Is determined. Then, when it is determined that the vehicle is in the automatic tilt state (parallel return determination has priority), the automatic tilt target value calculated based on the detection value of the tilt sensor 12 is set to the lift rod target value, while in the parallel return state. If it is determined that there is, the preset parallel return target value (or the current position stop target value) is set to the lift rod target value. The tilt manual target value calculated based on the signal is set as the lift rod target value. When the parallel return target value or the tilt manual target value is set, the expansion / contraction delay timer elapsed flag is set. That is, at the time of operating the tilt manual switch 16 or returning to the parallel state, since the expansion / delay delay process described later is canceled and the lift rod cylinder 6 is operated immediately, it is possible to ensure good responsiveness in the tilt manual operation. And a quick parallel return can be performed.
[0010]
In the “tilt setting volume check”, the difference between the current tilt setting volume data and the tilt setting storage data in which the tilt setting volume data is stored at predetermined time intervals is calculated, and the calculation result is borrow (negative). Is determined, and if the determination is YES, the calculation result is converted to a 2's complement number. Then, the calculation result is compared with the operation confirmation data, and as a result, when it is determined that the calculation result is larger than the operation confirmation data, an expansion / contraction delay timer elapse flag is set. That is, when the inclination setting volume 14 is operated, the lift rod cylinder 6 is actuated immediately after the expansion / contraction delay processing described later is canceled, so that good responsiveness, operability, and setting accuracy are ensured when setting the inclination. You can do it.
[0011]
In the “inclination comparison output control (mode 1)”, first, the cylinder operation direction is determined based on the deviation between the lift rod sensor value and the lift rod target value, and it is determined whether the deviation is out of the dead zone. If the deviation is within the dead zone, the telescopic stop timer is output after resetting (or clearing) the telescopic delay timer, the telescopic delay timer elapsed flag, and the telescopic delay range passage flag. If the deviation is out of the dead zone, the expansion delay timer, the expansion delay timer elapsed flag, and the expansion delay range passage flag are reset, and then the reduction side processing is executed, while the operation direction is on the expansion side and the deviation is smaller. If it is outside the dead zone, the decompression side timer is executed after the compression delay timer, the compression delay timer elapsed flag, and the compression delay range passage flag are reset.
[0012]
In the reduction processing, first, it is determined whether the deviation is within the delay range (1 to 3) or outside the delay range. In other words, a delay range is set in a deviation range adjacent to the dead zone, and in this delay range, the expansion / contraction operation process (cylinder reduction command output) is restricted until a predetermined delay timer expires, while the expansion / contraction is performed immediately outside the delay range. Since the operation process is executed, even if the deviation at the time of the operation stoppage is out of the dead zone, if the deviation is within the delay range, the lift rod cylinder 6 can be kept stopped to prevent frequent operation. When a predetermined time has elapsed, the lift rod cylinder 6 is operated toward the dead zone, so that the inconvenience of accepting a state deviating from the dead zone for a long time can be eliminated.
[0013]
The delay range is divided into a plurality of delay ranges 1 to 3 in which range upper limit deviations H1 to H3 (H1 <H2 <H3) differ stepwise, and the delay timer time is set longer as the delay range is closer to the dead zone. ing. That is, if the deviation is relatively small even if it deviates from the dead zone, the expansion / contraction operation processing is delayed for a long time to prevent frequent operations, while if the deviation is large, the delay processing is canceled at a relatively early stage. Control accuracy is ensured.
[0014]
By the way, in the "inclination comparison output control (mode 1)", when the deviation is within the dead zone, the delay timers of the respective delay ranges 1 to 3 are cleared (set), and when the deviation is out of the dead zone, the delay timer is cleared. Not to run. That is, when the deviation deviates from the dead zone, the counting of all delay timers is started, so that the delay processing of each of the delay ranges 1 to 3 is canceled based on the deviation deviating from the dead zone. Therefore, since the absolute delay processing centered on the dead zone is performed, frequent operation can be prevented by allowing a small fluctuation of the deviation, while the delay processing is quickly canceled when the deviation largely fluctuates. As a result, good control accuracy can be ensured, and as a result, in mode 1, it is possible to execute automatic tilt control suitable for work that emphasizes control accuracy.
[0015]
In each of the delay ranges 1 to 3, the elapse of the corresponding delay timer is determined, the delay timer elapse flag is set, and thereafter the delay release state is maintained by referring to the content of the delay timer elapse flag. In each of the delay ranges 1 to 3 and outside the delay range, a delay range passage flag for confirming the passed delay ranges 1 to 3 is set. Then, in the delay range 1, the case where the reduced delay timer 1 has elapsed, the case where the passing flag of the reduced delay range 3 is set, the case where the passing flag of the reduced delay range 2 is set, and the reduced delay timer 2 or 3 Are set, and when the passage flag of the reduced delay range 1 is set and the elapsed flag of the reduced delay timer 2 is set, the reduced delay timer 1 elapsed flag is set. In the delay range 2, when the compressed delay timer 2 has elapsed, when the elapsed flag of the compressed delay timer 1 is set, when the passage flag of the compressed delay range 3 is set, When the passage flag is set and the elapse flag of the reduced delay timer 2 is set, the elapse flag of the reduced delay timer 2 is set. Has elapsed, the elapsed flag of the reduced delay timer 2 has been set, the elapsed flag of the reduced delay timer 1 has been set, and the passage flag of the reduced delay range 3 has been set. Is set to the elapse flag of the contraction delay timer 2. In other words, when the deviation reaches out of the delay range, or when any of the delay ranges is released based on the elapse of the delay timer, all the delay ranges 1 to 3 are released. After the rod cylinder 6 is once operated, the cylinder operation can be continued until the deviation enters the dead zone regardless of the fluctuation of the deviation.
[0016]
In each of the delay ranges 1 to 3, when the delay timer elapses, the expansion / contraction operation process set for each delay range is executed. Speed) is set, and a lower drive duty (low-speed operation signal) is output in a delay range closer to the dead zone. That is, in the delay range far from the dead zone, the lift rod cylinder 6 is operated quickly to improve the control accuracy, while in the delay range near the dead zone, the lift rod cylinder 6 is operated slowly to prevent the so-called hunting phenomenon. Has become.
[0017]
Next, differences between the “inclination comparison output control (mode 1)” and the “inclination comparison output control (mode 2)” will be described. In the "inclination comparison output control (mode 1)", as described above, all the delay timers 1 to 3 start counting when the deviation deviates from the dead zone. When the deviation enters each of the delay ranges 1 to 3, the corresponding delay timers 1 to 3 start counting. In other words, the relative delay processing is performed in each of the delay ranges 1 to 3 to cancel the delay processing in each of the delay ranges 1 to 3 based on when the deviation enters each of the delay ranges 1 to 3. As a result, in the mode 2, it is possible to execute the automatic tilt control suitable for the work in which stability is emphasized.
[0018]
Next, differences between the “inclination comparison output control (mode 2)” and the “inclination comparison output control (mode 3)” will be described. In the “inclination comparison output control (mode 2)”, the same delay release condition as that in the “inclination comparison output control (mode 1)” is adopted. A delay cancellation condition is added to cancel the current delay range when the delay timer of the delay range closer to the dead zone than the range has elapsed. That is, in releasing each delay range based on the time when the deviation enters each delay range, it is possible to prevent the delay time from becoming unnecessarily long. It is possible to execute automatic tilt control suitable for a task that emphasizes control accuracy.
[0019]
Next, differences between the “inclination comparison output control (mode 2)” and the “inclination comparison output control (mode 4)” will be described. In the “inclination comparison output control (mode 2)”, similarly to the “inclination comparison output control (mode 1)”, the lift rod cylinder 6 is kept stopped until the delay timer elapses. In the mode 4), the expansion / contraction operation of the adjacent delay range close to the dead zone is executed until the delay timer elapses. That is, since the lift rod cylinder 6 is operated at a one-step slower speed even during the delay processing, in the mode 4, it is possible to execute the automatic tilt control suitable for the work in which the control accuracy is more important than in the mode 2. ing. In each of the modes 1 to 4 of the “inclination comparison output control”, an automatic tilt control having a different sensitivity (balance between control accuracy and stability) is executed. By adjusting the number of delay ranges, delay range width, delay timer time, delay range output duty, and the like, extremely fine sensitivity adjustment can be performed according to the working machine, work conditions, and the like.
[0020]
In the apparatus configured as described above, the lift rod cylinder 6 that inclines the work machine 3 is automatically controlled to expand and contract based on the deviation between the lift rod target value and the lift rod detection value. Even if the deviation is out of the dead zone, if it is within the delay range, cylinder operation is limited until a predetermined timer time has elapsed, so that frequent operation can be prevented and good stability can be secured. In addition, when the timer time has elapsed, the lift rod cylinder 6 is operated toward the dead zone, so that the control accuracy can be improved as compared with the case where the state deviating from the dead zone is allowed for a long time. it can.
[0021]
Further, since the plurality of delay ranges 1 to 3 are set in multiple stages, and the delay timer time is set longer for the delay range closer to the dead zone, when the deviation is small, the delay is long and the frequent cylinder operation can be prevented. On the other hand, when the deviation is large, it is possible to secure a good control accuracy with a short delay.
[0022]
Further, in mode 1, when the deviation of the operation stop state deviates from the dead zone, the counting of all the delay timers 1 to 3 is started, so that an absolute delay processing centering on the dead zone can be performed. However, when it is not possible to perform stable control while allowing a small fluctuation of the deviation, and when the deviation largely fluctuates, the delay processing can be quickly canceled to secure a good control accuracy.
[0023]
In modes 2 to 4, when the deviation of the operation stop state enters each of the delay ranges 1 to 3, the corresponding delay timers 1 to 3 start counting. Processing can be performed, and as a result, control can be performed with an emphasis on stability while allowing deviation fluctuation as much as possible.
[0024]
In the mode 3, since the current delay range is canceled when the delay timers 1 and 2 of the delay ranges 1 and 2 which are closer to the dead zone than the current delay ranges 2 and 3, the deviation is reduced to each of the delay ranges 1 to 3. While the delay processing of each of the delay ranges 1 to 3 is canceled on the basis of the time of entering, the control accuracy can be improved by preventing the delay time from becoming unnecessarily long.
[0025]
In the modes 1 to 4, when the delay timers 1 to 3 have elapsed, the drive duty is output as low as the delay ranges 1 to 3 closer to the dead zone. Therefore, in the delay range 3 far from the dead zone, the lift rod cylinder 6 is moved. In the delay range 1 close to the dead zone, the lift rod cylinder 6 is operated slowly to prevent the so-called hunting phenomenon, while the control is performed quickly to improve the control accuracy.
[0026]
In the mode 4, the drive duty of the adjacent delay ranges 1 and 2 close to the dead zone is output until the delay timers 1 to 3 of the current delay ranges 1 to 3 elapse. The rod cylinder 6 can be operated, and as a result, control stability can be improved while ensuring stability.
[0027]
Further, since each delay range width and each delay time can be switched according to the type of the work machine 3, even if the degree of deviation of the deviation differs for each work machine 3, an appropriate delay range width and delay If the time is set, control having both good stability and control accuracy can be performed regardless of the type of the work machine 3.
[0028]
Further, when the tilt setting volume 14 is operated, all the delay ranges 1 to 3 are released, so that the responsiveness, operability and setting accuracy at the time of the tilt setting operation can be improved.
[0029]
Note that the present invention is not limited to the above-described embodiment, and for example, a delay range (a passed delay range) closer to the dead zone than the current delay range may be canceled. In this case, when the deviation tries to return to the delay range on the dead zone side, the lift rod cylinder can be operated immediately, so that the delay time is prevented from becoming unnecessarily long and control accuracy is improved. be able to.
[Brief description of the drawings]
FIG. 1 is a side view of a tractor.
FIG. 2 is a block diagram showing input and output of a control unit.
FIG. 3 is a flowchart showing a main routine.
FIG. 4 is a flowchart showing “tilt control”.
FIG. 5 is a flowchart showing “tilt setting volume check”.
FIG. 6 is a flowchart illustrating “inclination comparison output control (mode 1)”;
FIG. 7 is a timing chart showing an operation of “inclination comparison output control (mode 1)”.
FIG. 8 is a flowchart illustrating “inclination comparison output control (mode 2)”.
FIG. 9 is a timing chart showing the operation of “inclination comparison output control (mode 2)”.
FIG. 10 is a flowchart showing “inclination comparison output control (mode 3)”.
FIG. 11 is a timing chart showing the operation of “inclination comparison output control (mode 3)”.
FIG. 12 is a flowchart illustrating “inclination comparison output control (mode 4)”.
[Explanation of symbols]
1 traveling aircraft
3 Working machine
6 Lift rod cylinder
7 Electromagnetic switching valve for lift rod
10 control unit
11 Lift rod sensor
12 Tilt sensor

Claims (4)

A lift rod cylinder for forcibly changing the inclination posture of the work machine; and an automatic control unit for automatically controlling the lift rod cylinder. The automatic control unit further includes a deviation for calculating a deviation between a target position and a detected position. In a tractor provided with arithmetic means and operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the automatic control unit includes a deviation in the operation stop state exceeding the dead zone set value, and When providing the delay processing means for limiting the output of the cylinder operation command until the predetermined timer time has elapsed when the delay processing range is within the set value , the plurality of delay processing ranges are set in multiple stages and the delay close to the dead zone is set. When the deviation of the operation stop state exceeds the dead band set value, the delay timer time is set longer for the processing range. Tractor and butterflies. A lift rod cylinder for forcibly changing the inclination posture of the work machine; and an automatic control unit for automatically controlling the lift rod cylinder. The automatic control unit further includes a deviation for calculating a deviation between a target position and a detected position. In a tractor provided with arithmetic means and operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the automatic control unit includes a deviation in the operation stop state exceeding the dead zone set value, and When providing the delay processing means for limiting the output of the cylinder operation command until the predetermined timer time has elapsed when the delay processing range is within the set value, the plurality of delay processing ranges are set in multiple stages and the delay close to the dead zone is set. The delay timer time is set longer for the processing range, and when the deviation of the operation stop state enters each delay processing range, the corresponding delay timer starts counting. And so, when the delay timer time of the delay processing range close to the dead zone has elapsed than the delay processing range of current position, tractor and cancels the delay processing range at least the current position. A lift rod cylinder for forcibly changing the inclination posture of the work machine; and an automatic control unit for automatically controlling the lift rod cylinder. The automatic control unit further includes a deviation for calculating a deviation between a target position and a detected position. In a tractor provided with arithmetic means and operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the automatic control unit includes a deviation in the operation stop state exceeding the dead zone set value, and When providing the delay processing means for limiting the output of the cylinder operation command until the predetermined timer time has elapsed when the delay processing range is within the set value, the plurality of delay processing ranges are set in multiple stages and the delay close to the dead zone is set. more processing range by increasing the delay timer time, and cancels the delay processing range close to the dead band than the delay processing range of the current location tiger Data. A lift rod cylinder for forcibly changing the inclination posture of the work machine; and an automatic control unit for automatically controlling the lift rod cylinder. The automatic control unit further includes a deviation for calculating a deviation between a target position and a detected position. In a tractor provided with arithmetic means and operation command output means for outputting a cylinder operation command when the deviation exceeds a dead zone set value, the automatic control unit includes a deviation in the operation stop state exceeding the dead zone set value, and When providing the delay processing means for limiting the output of the cylinder operation command until the predetermined timer time has elapsed when the delay processing range is within the set value, the plurality of delay processing ranges are set in multiple stages and the delay close to the dead zone is set. When the delay timer time elapses in each delay processing range, the cylinder operation fingers with different operation speeds are set. And outputs the cylinder operation command of the adjacent delay processing range close to the dead zone until the delay timer time of the delay processing range currently located elapses. A tractor characterized by:

Images