JP4895260B2 - Attitude control device - Google Patents

Description

  The present invention relates to a posture control device that performs automatic height control, automatic tilling control, and automatic tilt control of a tiller that is connected to a vehicle main body so as to be movable up and down and tiltable to the left and right.

  As an attitude control device for controlling the attitude of a tiller that is movable up and down and tiltable to the left and right with respect to a vehicle body such as a tractor, for example, an elevator actuator for raising and lowering the tiller with respect to the vehicle body A tilting actuator for tilting the cultivator with respect to the vehicle main body, a vertical position operating means for setting the vertical height of the cultivator, and a cultivating depth for setting the cultivating depth of the cultivator Setting means; inclination setting means for setting an inclination state of the tiller with respect to the vehicle body; vertical position detecting means for detecting the vertical position of the tiller; and tillage position detecting means for detecting the position of the tiller. And a tilting state detecting means for detecting the tilting state of the tiller, and a control means for operating the lifting actuator and the tilting actuator. Automatic height control that causes the lower position to follow the set height position by the vertical position operating means, and automatic tillage control that causes the detected tillage position of the tiller to follow the set tillage position by the tillage depth setting means, There is known an attitude control device configured to be able to perform automatic tilt control that causes a detected tilt state of the tiller with respect to the vehicle body to follow a tilt state set by the tilt setting means (for example, see Patent Document 1 below). ).

In such a posture control device, when the vertical position operating means is lowered from the non-plowing work state, the tiller is controlled to be lowered by the automatic height control. Then, when the cultivator comes in contact with the ground or when the cultivator reaches a set tilling depth position set by the tilling depth setting means, the automatic height control is switched to the automatic tillage control.
On the other hand, the automatic tilt control is activated regardless of which control mode of the automatic height control or the automatic tilling depth control is activated.

By the way, it is desirable that the automatic tilt control operates with good responsiveness during the plowing work state, but when operated during the non-plowing work state, the cultivator tilts unexpectedly, and in some cases, the There are inconveniences such as the tiller coming into contact with the ground.
From this point of view, it has been proposed that the control accuracy of the automatic tilt control is relaxed when the vehicle body travels at a high speed exceeding a predetermined threshold vehicle speed.
Such regulation of the automatic tilt control is to pretend that the vehicle body is in a non-plowing work state when the speed of the vehicle body is higher than the threshold vehicle speed, and deteriorates the controllability of the automatic tilt control. This is useful in that the tiller can be effectively prevented from tilting in the left-right direction when the vehicle body is traveling at high speed.

However, the unintentional tilting control of the tiller in the left-right direction as described above may also occur when the vehicle body travels at a speed lower than the threshold vehicle speed.
That is, for example, after performing continuous tillage work while moving the vehicle body substantially straight from one side to the other side in the field, the vehicle at the direction change place (headland) at the other side end of the field. When changing the direction of the main body, or when moving the vehicle main body to perform the tilling work on the headland in the field after the end of the continuous tilling work, the operator raises the tiller. In order to save time and descent time, normally, the tiller is lifted slightly from the tillage ground by the vertical position operating means without raising the tiller to the highest position where the automatic tilt control is released. In this state, run the vehicle body.
When traveling in such a field, the vehicle body normally travels at a speed lower than the threshold vehicle speed.
Therefore, in the conventional method of controlling automatic tilt control, when the field cultivator travels in the field with the field cultivator positioned above the ground and below the highest position, the field cultivator Contrary to the intention, it can be tilted to the left or right.

In addition, the vehicle traveling in a state where the tiller is located above the ground and below the highest position is performed when the tilling work to another field is performed after the end of the tilling work in one field. Is also done.
When the cultivator tilts to the left or right unexpectedly by the automatic tilt control during the movement to another field, the balance of the vehicle body is lost, and in some cases, the cultivator comes into contact with the road. In addition, there is a risk of damaging the cultivator.
JP-A-8-205609

  The present invention has been made in view of such a conventional technique, and has an automatic height control, an automatic tilling depth control, and an automatic inclination control with respect to a cultivator coupled so as to be movable up and down with respect to the vehicle body and tiltable to the left and right. An attitude control device that performs the automatic tilt control when the vehicle main body travels in a non-plowing work state in which the tiller is positioned below the highest position and above the ground. It is an object of the present invention to provide a posture control device having a simple structure that can prevent a large tilt against the intention.

In order to solve the above-described problems, the present invention provides a posture control apparatus according to a first aspect described below.
(1) 1st attitude control device Automatic height which makes the detection vertical position of the cultivator connected to the vehicle main body so that it can be moved up and down and tilted to the left and right follow the set height position set for the cultivator. Control control, automatic tilling control for causing the tilling position of the tiller to follow the set tilling position, and automatic tilting control for causing the detected tilting state of the tiller to follow the set tilting state. When the vehicle speed of the vehicle body is higher than a predetermined threshold vehicle speed, the control accuracy of the automatic tilt control is eased and the set height position is the tiller. An attitude control device configured to lower the threshold vehicle speed as the set height position increases when the contact height is higher than the contact position .

Further, as a specific mode for relaxing the control accuracy of the automatic tilt control, the automatic tilt control is executed based on a relative tilt angle of the cultivator with respect to the vehicle body, which is input through a filter, When executing the automatic tilt control, the automatic tilt control is performed by at least one of the following means: reduction of the control gain of the automatic tilt control , expansion of the dead zone width of the automatic tilt control, or change of the filtering condition of the filter . The aspect comprised so that control accuracy may be eased can be illustrated.
The degree of relaxation of the control accuracy of the automatic tilt control is preferably configured to be changed according to the threshold vehicle speed. As such a specific aspect, when the vehicle speed of the vehicle main body is higher than the threshold vehicle speed, an aspect of increasing the degree of relaxation of the control accuracy of the automatic tilt control as the vehicle speed increases can be exemplified.

The present invention also provides an attitude control device according to a second aspect described below.
(2) Second attitude control device Automatic height that causes the detected vertical position of a cultivator coupled so as to be able to move up and down and tilt to the left and right with respect to the vehicle body to follow the set height position set for the cultivator. Control control, automatic tilling control for causing the tilling position of the tiller to follow the set tilling position, and automatic tilting control for causing the detected tilting state of the tiller to follow the set tilting state. An attitude control apparatus configured as described above, wherein the automatic tilt control is stopped when a vehicle speed of the vehicle body is higher than a predetermined threshold vehicle speed.

  The attitude control device according to the second aspect is preferably configured to change the threshold vehicle speed in accordance with the set height position. In this case, as a specific mode in which the threshold vehicle speed is changed according to the set height position, when the set height position is higher than the ground contact position, the threshold vehicle speed is decreased as the set height position increases. The aspect which is made can be illustrated.

  By the way, from the viewpoint that the automatic height control can be regarded as a non-plowing work state, the present invention provides posture control apparatuses of the following third and fourth modes.

(3) Third attitude control device Automatic height that causes the detected vertical position of a tiller coupled to be able to move up and down and tilt to the left and right with respect to the vehicle body to follow the set height position set for the tiller. Control control, automatic tilling control for causing the tilling position of the tiller to follow the set tilling position, and automatic tilting control for causing the detected tilting state of the tiller to follow the set tilting state. A posture control device configured as described above, wherein the control accuracy of the automatic tilt control is relaxed during the automatic height control.
In the attitude control device of the third aspect, as a specific aspect for relaxing the control accuracy of the automatic tilt control, the automatic tilt control is input to the vehicle main body relative to the vehicle body, which is input through a filter. It is executed based on an inclination angle, and at the time of execution of the automatic inclination control , at least one of the reduction of the control gain of the automatic inclination control, the expansion of the dead band width of the automatic inclination control or the change of the filtering condition of the filter The aspect comprised so that the control precision of the said automatic inclination control may be eased with a means can be illustrated.
The degree of relaxation of the control accuracy of the automatic tilt control is preferably configured to be changed according to the set height position. As such a specific mode, when the set height position is higher than the ground contact position, a mode of increasing the degree of relaxation of the control accuracy of the automatic tilt control as the set height position becomes higher can be exemplified.

(4) Fourth attitude control device Automatic height control for detecting the vertical position of the tiller connected so as to be able to move up and down with respect to the vehicle body and tiltable to the left and right, and detection of the tiller performing an automatic tilling depth control to follow the tilling depth position to the set set tilling depth position relative to the tiller, and the automatic tilt control to follow the detected tilt state to set the inclined state relative to the vehicle body of said tiller An attitude control apparatus configured as described above, wherein the automatic inclination control is stopped during the automatic height control.

According to the attitude control device according to the first aspect of the present invention, the threshold vehicle speed, which is a criterion for reducing the control accuracy of the automatic tilt control, is changed according to the height position set by the vertical position operating means. Since the structure of the cultivator is undesirably large due to the automatic tilt control when the vehicle body is traveling in a non-cultivated work state in which the cultivator is positioned below the highest position and above the ground. It is possible to effectively prevent tilting.
Accordingly, the running balance of the vehicle body can be maintained well, and inconveniences such as contact of the tiller with the ground or the like can be prevented.

In such a configuration, when the set height position is higher than the ground contact position, if the threshold vehicle speed is decreased as the set height position is increased, automatic tilt control is conventionally performed. Even during low-speed traveling, the amount of tilting of the cultivator by the automatic tilt control can be suppressed.
Therefore, when traveling on the field or on the road in a non-plowing work state in which the cultivator is positioned below the highest position and above the ground, the vehicle body can maintain a good traveling balance, The inconvenience that the cultivator comes into contact with the ground or the like can be prevented.

  Further, if the degree of relaxation of the control accuracy of the automatic tilt control is changed according to the vehicle speed of the vehicle body, the running balance of the vehicle body during high-speed running can be maintained better.

According to the attitude control device of the second aspect of the present invention, the automatic tilt control is stopped when the vehicle speed of the vehicle main body is higher than a predetermined threshold vehicle speed. When the speed is higher than the threshold vehicle speed, the automatic tilt control is stopped.
Therefore, the operation contrary to the meaning of the automatic tilt control can be reliably prevented.

In such a configuration, if the threshold vehicle speed is configured to change according to the set height position, the tiller is positioned in a non-plowing work state in which the tiller is positioned below the highest position and above the ground. When the vehicle body is traveling, the automatic tilt control can reliably prevent the tiller from tilting against the intention.
Accordingly, the running balance of the vehicle body can be maintained well, and inconveniences such as contact of the tiller with the ground or the like can be prevented.

Further, when the set height position is higher than the ground contact position, the threshold vehicle speed is reduced as the set height position is increased. In addition, the tiller can be prevented from tilting by the automatic tilt control.
Therefore, when traveling on the field or on the road in a non-plowing work state in which the cultivator is positioned below the highest position and above the ground, the vehicle body can maintain a good traveling balance, The inconvenience that the cultivator comes into contact with the ground or the like can be prevented.

According to the attitude control device of the third aspect of the present invention, the automatic height control is regarded as a non-plowing work state and is configured to relax the control accuracy of the automatic tilt control. When the vehicle body is running in a non-plowing work state where the machine is positioned below the highest position and above the ground, the automatic tilt control effectively enables the tiller to tilt unexpectedly greatly. Can be prevented.
Accordingly, the running balance of the vehicle body can be maintained well, and inconveniences such as contact of the tiller with the ground or the like can be prevented.

In such a configuration, if the degree of relaxation of the control accuracy of the automatic tilt control is changed in accordance with the set height position, low-speed traveling that has been conventionally performed by the automatic tilt control is performed. Even at times, the amount of tilting of the tiller by the automatic tilt control can be suppressed.
Therefore, when traveling on the field or on the road in a non-plowing work state in which the cultivator is positioned below the highest position and above the ground, the vehicle body can maintain a good traveling balance, The inconvenience that the cultivator comes into contact with the ground or the like can be prevented.

According to the posture control apparatus of the fourth aspect of the present invention, the automatic height control is regarded as a non-plowing work state and the automatic tilt control is stopped. When the vehicle body is traveling in a non-plowing work state positioned below the raised position and above the ground, the automatic tilt control can effectively prevent the tiller from tilting unexpectedly.
Accordingly, the running balance of the vehicle body can be maintained well, and inconveniences such as contact of the tiller with the ground or the like can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic side view of a farm tractor that is an example of a working vehicle to which the attitude control device according to the present embodiment is applied. FIG. 2 is a schematic plan view of the tractor shown in FIG. FIG. 3 is a schematic side view of the tiller lifting mechanism in the tractor shown in FIG. 4 is a schematic plan view of the tiller lifting mechanism shown in FIG. FIG. 5 is a schematic cross-sectional view of the rotary tiller along line VV in FIG. FIG. 6 is a schematic rear view of the rotary tiller. FIG. 7 is a hydraulic circuit diagram of the tractor.

As shown in FIGS. 1 to 4, a tractor 100 as a working vehicle includes a vehicle main body 50 and a rotary cultivator 400 connected to a rear portion of the vehicle main body 50.
The vehicle body 50 includes a traveling machine body 1, a pair of left and right front wheels 2 and a pair of left and right rear wheels 3 that support the traveling machine body 1, and an engine 4 mounted on the front portion of the traveling machine body 1. In addition, the rear wheel 3 and the front wheel 2 are operatively driven by the power from the engine 4 so as to travel forward and backward. Reference numeral 5 in the figure denotes a bonnet 5 that covers the engine 4.
Further, the tractor 100 has a cabin 6 provided on the upper surface of the traveling machine body 1. Inside the cabin 6 are installed a control seat 7 and a control handle (round handle) 8 configured to move the steering direction of the front wheel 2 to the left and right by steering. A step 9 where an operator gets on and off is provided on the outer side of the cabin 6, and a fuel tank 10 for supplying fuel to the engine 4 is provided on the inner side of the step 9 and below the bottom of the cabin 6. Is provided.

As shown in FIGS. 1 to 4, the traveling aircraft body 1 includes an engine frame 13 having a front bumper 11 and a front axle case 12, and left and right aircraft bodies that are detachably fixed to the rear portion of the engine frame 13 with bolts. Frame 15.
A transmission case 16 is connected to the rear part of the body frame 15 for appropriately shifting the rotation of the engine 4 and transmitting it to the rear wheel 3 and the front wheel 2 via the rear wheel shaft 3a and the front wheel shaft 2a, respectively. ing. The rear wheel 3 is attached via a rear axle case 17 mounted so as to protrude outward from the outer surface of the mission case 16.
A PTO shaft 18 for outputting the driving force of the rotary tiller 400 is provided on the rear end surface of the transmission case 16 so as to protrude rearward.

The rotary tiller 400 is connected to the rear portion of the mission case 16 via a three-point link mechanism 300 including a pair of left and right lower links 311 and 312 and a top link 320.
As shown in FIGS. 1 and 3, the left and right lower links 311, 312 are connected to the left and right side surfaces of the rear portion of the transmission case 16 so as to be rotatable via lower link pins 313, and the rear ends The side is connected to the front end portion of the lower link frame 440 in the rotary tiller 400 via a lower hitch pin 314.
The top link 320 has a front end connected to a top link hitch 210 at a rear portion of the working machine lifting mechanism 200 described below via a top link pin 211, and a rear end connected to a front end of the upper link frame 410 below an upper hitch pin 321. It is connected through.

As shown in FIGS. 3 and 4, a hydraulic working machine elevating mechanism 200 for elevating and lowering the rotary tiller 400 is detachably attached to the rear upper surface of the transmission case 16.
As shown in FIGS. 3, 4, and 7, the hydraulic working machine lifting mechanism 200 is operated by a single-acting lifting control hydraulic cylinder 220 that acts as a lifting actuator and a piston in the hydraulic cylinder 220. And a pair of left and right lift arms 221 and 222 that are pivoted to each other.

The left lift arm 221 in the traveling direction is connected to the corresponding left lower link 311 via a left lift rod 231.
The lift arm 222 on the right side in the traveling direction is connected to the corresponding lower link 312 on the right side via a right lift rod 232.
That is, the lift control hydraulic cylinder 220 causes the pair of left and right lift arms 221 and 222 to swing about the rotation axis along the vehicle left-right direction, so that the rotary tiller 400 has the top link 320 and the The pair of lower links 311 and 312 are moved up and down around the front end portions.

A double-acting tilt control hydraulic cylinder 240 that functions as a tilting actuator that tilts the rotary tiller 400 with respect to the vehicle body 50 is interposed in the right lift rod 232.
That is, as the piston rod 241 of the tilt control hydraulic cylinder 240 advances and retreats, the rotary tiller 440 causes the other of the pair of left and right lift rods 231 and 232 (here, the left lift rod 231) and the other lift. The connecting point with the lower link 311 corresponding to the rod 231 (that is, the position displaced to the one side from the center D in the horizontal direction of the rotary tiller 400) is used as a fulcrum Q (see FIG. 2) to tilt. ing.

  As shown in FIGS. 1, 2, 5, and 6, the rotary tiller 400 includes a horizontally long main beam 420 and a chain case having upper ends connected to left and right ends of the main beam 420. 431 and the bearing plate 432, a tilling claw shaft 433 rotatably supported at both left and right ends on the lower ends of the chain case 431 and the bearing plate 432, and a radial detachable attachment to the tilling claw shaft 433. A plurality of tilling claws 434, a tilling upper surface cover 435 disposed so as to cover the rotation trajectory of the tilling claws 434, and left and right disposed so as to cover the left and right sides of the rotation trajectory of the tilling claws 434. A tilling side cover 436, a tilling rear cover 437 arranged to cover the rear of the rotation trajectory of the tilling claw 434, and a front end side are attached to the main beam 420. A tilling depth adjusting frame 438 extending long rearwardly, the upper link frame 410 rotatably connected to the main beam 420, the lower link frame 440 integrally connected to the main beam 420, and the upper A tilling depth adjusting shaft 439 that can be extended and contracted is provided to connect the rear end side of the link frame 410 and the middle portion in the front-rear direction of the tilling depth adjusting frame 438.

Specifically, the top link 320 is configured to be expanded and contracted by the rotation of the turnbuckle 320a so that the length of the top link 320 can be changed and adjusted (see FIGS. 3 and 4). The upper link frame 410 is rotatably connected to the main beam 420 via a tilling depth adjustment fulcrum shaft 411 at an intermediate portion in the front-rear direction (see FIG. 1). The tilling depth adjusting frame 438 is integrally connected to the main beam 420 at the front end side.
By providing such a configuration, when the tilling depth adjusting shaft 439 is expanded and contracted by rotating the tilling depth adjusting handle 439a (see FIG. 1), it is supported by the pair of left and right lower links 311 and 312 and the top link 320. The rotary cultivator 400 is configured to change to a forward or backward inclined posture, and thereby, a cultivating depth position hD (cultivating depth) by the cultivating claws 434 can be manually changed. ing.

As shown in FIGS. 1, 5, and 6, a gear case 450 for inputting a driving force from the PTO shaft 18 is disposed at the left and right central portion of the main beam 420. The PTO shaft 18 and the PTO input shaft 451 on the front side of the gear case 450 are connected to each other via a telescopic transmission shaft 452 having universal joints at both ends.
The power from the PTO shaft 18 includes a bevel gear (not shown) built in the gear case 450, a rotating shaft (not shown) built in the main beam 420, a sprocket and a chain built in the chain case 431. (Not shown) or the like is transmitted to the tilling claw shaft 433. Thereby, the tilling claw 434 is rotated counterclockwise in FIGS. 1 and 5.

As shown in FIGS. 5 and 6, the tilling rear cover 437 is rotatably connected to the rear end side of the tilling upper surface cover 435 via a pivot shaft 437a along the left-right direction of the vehicle.
Further, a pair of left and right hanger frames 441 extending rearward and upward are provided upright on the rear upper surface of the tilling upper surface cover 435.
A pair of left and right hanger mechanisms 460 are provided between the rear end side of the top surface of the tilling rear cover 437 and the rear end side of the left and right hanger frame 441, and the tilling rear cover 437 is moved by the hanger mechanism 460. It can move up and down around the pivot shaft 437a.

Specifically, a pressure receiving shaft body 442 that is rotatable about an axis along the left-right direction of the vehicle is disposed at the rear end of each hanger frame 441. The pressure receiving shaft body 442 is provided with a through hole in a direction orthogonal to the axis.
Each hanger mechanism 460 includes an elongated round bar-shaped hanger rod 461 that is slidably inserted into the through hole of the pressure receiving shaft body 442.
The hanger rod 461 has a lower end portion rotatably connected to a bracket 462 provided on the upper surface of the rear portion of the tilling rear cover 437 via a support shaft 461a extending in the vehicle lateral direction (see FIG. 5). .
The hanger rod 461 has a lowering restriction pin 461b fixed above the pressure receiving shaft body 442, and the hanger rod 461 so as to be positioned between the lowering restriction pin 461b and the pressure receiving shaft body 442. A lowering restriction plate 463 externally inserted so as to be slidable in the axial direction, a rising restriction pin 461c fixed below the hanger rod 461 and above the support shaft 461a, and lowered by the rising restriction pin 461c. The hanger rod 461 is slidably inserted on the hanger rod 461 in an axially slidable manner, and the hanger is positioned between the lower seat plate 465 and the pressure receiving shaft body 442. A pressure-reducing compression spring 466 extrapolated to the rod 461 and a top plate 464 that engages with the upper end of the pressure-reducing compression spring 466 are provided.

The rotary tiller 400 provided with such a hanger mechanism 460 operates as follows.
That is, when the rotary tiller 400 is lifted away from the ground G by the lifting actuator, the rear end side of the tilling rear cover 437 rotates downward about the pivot shaft 437a.
At this time, the hanger rod 461 moves downward while being guided by the pressure receiving shaft body 442, but the lowering restriction pin 461b abuts on the lowering restriction plate 463 and the lowering restriction plate 463 is the pressure receiving shaft. By contacting the body 442, the downward movement of the hanger rod 461 is stopped. Therefore, the tilling rear cover 437 is maintained in a posture in which the rear end side is lowered to the lowest.

On the other hand, when the rotary cultivator 400 is lowered to the upper surface of the cultivated land and the cultivating claws 434 are landed or during the cultivating work, the rear end side of the cultivating rear cover 437 is at a contact pressure with the cultivated soil. It will pivot upward about the pivot shaft 437a.
At this time, the hanger rod 461 moves upward while being guided by the pressure receiving shaft body 442. By the upward movement of the hanger rod 461, the compression spring 466 for pressure reduction is compressed through the rising restriction pin 461 c and the lower seat plate 465.
That is, when the tilling rear cover 437 rotates upward about the pivot shaft 437a, the tilling rear cover 437 operates against the urging force of the compression spring 466 for pressure reduction. It is possible to effectively maintain the leveling action by the tilling rear cover while effectively preventing the scattering of soil to the rear of the tilling rear cover 437.

The tractor 100 further includes a lift control hydraulic cylinder 220 that functions as a lift actuator and a hydraulic circuit 500 that supplies and discharges hydraulic fluid to and from the lift control hydraulic cylinder 220 as a tilting actuator.
As shown in FIG. 7, the hydraulic circuit 500 includes a working machine hydraulic pump 501 rotatively driven by the engine 4, a shunt valve 505 fluidly connected to the discharge side of the hydraulic pump 501, There are provided an elevation control valve and an inclination control valve respectively disposed in the one side oil passage and the other side oil passage branched by the diversion valve 505.
In the present embodiment, the lift control valve has a lift control solenoid valve 502 and a lift control solenoid valve 503. The tilt control valve has a tilt control electromagnetic valve 504.
As shown in FIG. 7, the hydraulic circuit 500 includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like.

Next, the structure of the various operation means arrange | positioned in the said cabin 6 is demonstrated.
As shown in FIGS. 1 and 2, the steering handle 8 is provided on a steering column 19 located in front of the steering seat 7.
In the cabin 6, in addition to the control seat 7, the control handle 8 and the control column 19, a throttle lever 617 for adjusting the rotational speed (output) of the engine 4 and the traveling machine body 1 are braked. Left / right brake pedal 20 for operating, clutch pedal 21 for engaging / disengaging power transmission from the engine to the front wheel 2 and the rear wheel 3, and for shifting the traveling speed of the vehicle body 50 The transmission shift lever 24, the differential lock pedal 25 for locking the differential mechanism inserted in the power transmission path from the engine 4 to the rear wheel 3, and the output rotational speed from the PTO shaft 18 are shifted. A PTO speed change lever 23 is provided.

Further, a work implement elevating lever 22, an inclination setting device 623, and a tilling depth setting device 626 are arranged in the cabin 6.
FIG. 8 shows a schematic side view of the rotary tiller 400. FIG. 8A shows the lifted state of the rotary tiller 400 during automatic tillage control, and FIG. 8B shows the lifted state of the rotary tiller 400 during automatic height control.
The work implement lifting lever 22 acts as a vertical position operating means for manually changing the set height position (target height position) hS (see FIG. 8B) of the rotary tiller 400.
The vertical position operating means is configured to set a set lift angle (target lift angle) θS (see FIG. 8B) of the lift arms 221 and 222 as the set height position.
FIG. 9 shows a schematic rear view of the rotary tiller 400.
The inclination setter 623 acts as an inclination setting means for setting the inclination state tS of the rotary tiller 400. Specifically, as shown in FIG. 9, a relative set left / right tilt angle (target left / right tilt angle) φs in relation to the left / right direction of the rotary tiller 400 with respect to the vehicle body 50 is set in advance. For example, a variable resistor can be included.
The plowing depth setting device 626 functions as a plowing depth setting means for setting a set plowing depth position (target plowing depth position) hR (see FIG. 8A) of the plowing claw 434 in the rotary tiller 400.
Although the details will be described later, the tilling position of the rotary tiller 400 is controlled based on the rotation angle of the tilling rear cover 437 with respect to the tilling upper surface cover 435. Therefore, the plowing depth setting means sets a set turning angle (target turning angle) θR (see FIG. 8A) of the tilling rear cover 437 with respect to the tilling top cover 435 as the set plowing depth position. For example, a variable resistor may be included. The set rotation angle θR can be a rotation angle based on the vertical V, for example.

(First embodiment)
Next, a first embodiment of the attitude control device according to the present invention will be described.
FIG. 10 is a block diagram of the attitude control device according to the first embodiment.
The posture control device is configured to perform automatic height control, automatic tilling control, and automatic tilt control of the rotary tiller 400 that is connected to the vehicle body 50 so as to be movable up and down and tiltable to the left and right. Yes.

  Specifically, as shown in FIG. 10, the attitude control device includes the lift control hydraulic cylinder 220 that acts as the lift actuator, the tilt control hydraulic cylinder 240 that acts as the tilt actuator, The working machine elevating lever 22 acting as position operating means, the tilling depth setting device 626 acting as the tilling depth setting means, the inclination setting device 623 acting as the inclination setting means, and the rotary tiller 400, a vertical position detecting means for detecting the vertical position of the vehicle main body, a rear cover sensor 624 acting as a tilling position detecting means for detecting a tilling position of the rotary tiller 400, and an inclined state of the rotary tiller 400 A work machine position sensor 622 acting as an inclination state detecting means for detecting And 628, the automatic height control, and a posture controller 600 which acts as a control unit which controls the automatic plowing depth control and the automatic tilt control.

As described above, the rear cover sensor 624 functions as a tilling position detecting unit that detects the tilling position hD of the rotary tiller 400.
That is, the rotation position of the tilling rear cover 437 relative to the tilling upper surface cover 435 changes according to the tilling position hD (see FIG. 8A) of the rotary tiller 400. Accordingly, by detecting the rotation position of the tilling rear cover 437 relative to the tilling upper surface cover 435 by the rear cover sensor 624, the tilling position hD of the rotary tiller 400 can be detected.
Specifically, the rear cover sensor 624 detects a rotation angle θD of the tilling rear cover 437 relative to the tilling top cover 435 as a turning position of the tilling rear cover 437 relative to the tilling top cover 435 (see FIG. 8A). The detected rotation angle θD can be set to a rotation angle based on the vertical V, for example.
In the present embodiment, the rear cover sensor 624 is a potentiometer type disposed on the rear upper surface of the tilling upper surface cover 435 (see FIGS. 2, 5, 6 and 8).
The rear cover sensor 624 and the tillable rear cover 437 are connected via a sensor arm 437b, a sensor link 437c, and the like (see FIG. 2).

In the present embodiment, a lift angle sensor 627 is provided as the vertical position detecting means.
The lift angle sensor 627 is configured to detect the height of the rotary tiller 400 relative to the body (the relative height of the rotary tiller 400 with respect to the vehicle body 50) hL (see FIG. 8B). ing.
Specifically, the lift angle sensor 627 is configured to detect the lift angle θL (see FIG. 8B) of the lift arms 221 and 222. For example, a potentiometer type sensor can be used. .
The lift angle sensor 627 is disposed at a connection point between the work implement lifting mechanism 200 and the left lift arm 221 (see FIGS. 3 and 4).

  The vehicle speed sensor 628 is for detecting the rotational speeds of the front and rear four wheels 2 and 3 (the vehicle speed v of the vehicle body 50).

The work machine position sensor 622 is configured to detect a relative inclination angle φ (see FIG. 9) in the left-right direction of the rotary tiller 400 with respect to the vehicle body 50. For example, a potentiometer type sensor is used. Can be used.
The work machine position sensor 622 is not shown in detail, but may be disposed at, for example, the center of the main beam 420 located above the tilling top cover 435.
The work implement position sensor 622 is electrically connected to the attitude control controller 600 via a filter unit 625 for extracting a signal output in a limited band from the output of the work implement position sensor 622. ing.
By providing such a filter unit 625, it is possible to suppress the influence of a change in detection sensitivity of the work implement position sensor 622. This will be described in detail later.

The posture control controller 600 is configured to input signals from the various setting means and sensors and to output control signals to the lifting actuator and the tilting actuator.
That is, as shown in FIG. 10, the attitude controller 600 has an input system with the tilt setting device 623, the tilling depth setting device 626, the machine body rolling sensor 621, the work machine position sensor 622, and the lift angle sensor 627. The rear cover sensor 624, the work implement lifting lever 22, the lift angle sensor 627, and the like are electrically connected, and the output system is the ascending control solenoid valve 502, the descending control solenoid valve 503, and the tilt controlling solenoid valve. 504 is electrically connected.

Specifically, as shown in FIG. 10, the attitude control controller 600 includes a central processing unit 601 (hereinafter referred to as a CPU) including a control calculation unit that executes calculation processing based on signals input from the various sensors. A ROM 602 that stores a control program P1 and the like, stores predetermined data related to various relational expressions or control maps described later, and a RAM 603 that temporarily holds data generated during the calculation of the CPU 601 is provided. .
Such an attitude controller 600 is connected to the battery 612 via the power application key switch 611. The key switch 611 is connected to a starter 613 for starting the engine 4.

In the present embodiment, as shown in FIG. 10, an electronic governor controller 614 that controls the rotation of the engine 4 is connected to the attitude controller 600.
The electronic governor controller 614 is connected to a governor 615 that adjusts the fuel of the engine 4 and an engine rotation sensor 616 that detects the rotational speed of the engine 4.

  When the throttle lever 617 is manually operated by an operator, the electronic governor controller 614 sets the rotation of the throttle lever 617 based on the detection information of the throttle potentiometer 618 that detects the rotation position of the throttle lever 617. The throttle solenoid 619 performs control to automatically adjust the position of a fuel adjustment rack (not shown) so that the number matches the number of revolutions of the engine 4. As a result, the rotation of the engine 4 can be maintained at a predetermined number of rotations according to the position of the throttle lever 617, regardless of load fluctuations.

Further, the attitude control device according to the present embodiment is provided with a body rolling sensor 621.
The airframe rolling sensor 621 is for detecting an inclination angle of the vehicle main body 50 with respect to the left-right direction. For example, a pendulum type sensor can be used.
In the present embodiment, the airframe rolling sensor 621 is disposed on the upper surface of the working machine lifting mechanism 200 and at a position behind the control seat 7 (see FIGS. 1 to 4).

  The posture control controller 600 configured in this way includes automatic height control for causing the detected vertical position hL of the rotary tiller 400 to follow the set height position hS by the vertical position operating means, and detection of the rotary tiller 400. Automatic tilling control for causing the tilling position hD to follow the set tilling position hR by the tilling depth setting device 626 and the detected inclination state t (see FIG. 9) of the rotary tiller 400 with respect to the vehicle body 50 are the inclination setting device. It is configured to be able to execute automatic tilt control to follow the set tilt state tS by 623.

The automatic height control is executed during the posture control of the rotary tiller 400 by the posture control device, and when the automatic tillage depth control is not in operation.
That is, when the work implement elevating lever 22 is lowered from the state where the rotary tiller 400 is located at the highest position, or when the work implement elevating lever 22 is raised from the plowing operation state of the rotary tiller 400. When this happens, the automatic height control is executed.
At the time of execution of the automatic height control, the posture controller 600 determines that the detected height position hL based on the detected lift angle θL of the lift angle sensor 627 is set by the work implement lifting lever 22. Then, an automatic height control amount of the lift control hydraulic cylinder 220 is calculated so that the lift control hydraulic cylinder 220 is driven using the calculated automatic height control amount.

The automatic tilling control is executed at the time of tilling work of the rotary tiller 400.
For example, when the rotary tiller 400 that is lowered by the automatic height control is grounded by lowering the work implement lifting lever 22 from a state where the rotary tiller 400 is located at the highest position, or When the set working depth position hR set by the working depth setting device 626 is reached, the automatic height control is shifted to the automatic working depth control.
At the time of execution of the automatic tilling depth control, the posture control controller 600 sets the set tilling depth position hR in which the detected tilling position hD based on the detected rotation angle θD of the rear cover sensor 624 is set by the tilling depth setting device 626. Then, the automatic tilling control amount of the lifting control hydraulic cylinder 220 is calculated so that the lifting control hydraulic cylinder 220 is driven using the calculated automatic tilling control amount.

The automatic tilt control is always operated during the posture control of the rotary tiller 400 by the posture control device.
That is, the automatic tilt control is executed regardless of whether the automatic height control or the automatic tilling depth control is executed.
At the time of execution of the automatic tilt control, the posture controller 600 causes the detected tilt position t based on the detected tilt angle φ of the work implement position sensor 622 to be the set tilt state tS set by the tilt setter 623. Then, an automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated, and the tilt control hydraulic cylinder 240 is driven using the calculated automatic tilt control amount.

Further, the attitude controller 600 is configured to relax the control accuracy of the automatic tilt control when the vehicle speed v of the vehicle body 50 is higher than a predetermined threshold vehicle speed vS.
That is, when the vehicle speed v of the vehicle body 50 is higher than a predetermined threshold vehicle speed vS, it is assumed that the vehicle is in a non-plowing state, and the control accuracy of the automatic tilt control is relaxed. As a result, the controllability of the automatic tilt control is deteriorated, and it is possible to prevent the inconvenience that the rotary tiller 400 tilts in the left-right direction when the vehicle body 50 is traveling at a high speed. .
The control accuracy of the automatic tilt control is reduced by reducing the automatic tilt control gain Ga by “reducing the control gain” or by increasing the dead zone width δ when performing the automatic tilt control. Alternatively, it is executed by performing at least one of “filtering condition change” for changing the filtering condition of the filter unit 625.

Further, the attitude controller 600 changes the threshold vehicle speed vS, which is a criterion for whether or not to reduce the control accuracy of the automatic tilt control, according to the set height position hS in the automatic height control. It is configured.
That is, in the present embodiment, the threshold vehicle speed vS is changed in accordance with the set height position hS of the work implement lifting lever 22, whereby the rotary tiller 400 is moved to the highest position. When the vehicle main body 50 is traveling in a non-plowing work state that is positioned below and above the ground G, it is effective that the rotary tiller 400 tilts unexpectedly by the automatic tilt control. Can be prevented.
Accordingly, it is possible to maintain a good traveling balance of the vehicle body 50 and to prevent inconvenience such as the rotary tiller 400 coming into contact with the ground G or the like.

In the present embodiment, when the set height position hS is higher than the ground contact position hE, the threshold vehicle speed vS is decreased as the set height position hS increases.
According to such a configuration, it is possible to suppress the amount of tilting of the rotary tiller 400 by the automatic tilt control even during low-speed traveling where conventional automatic tilt control has been performed.
Accordingly, when the rotary tiller 400 is positioned below the highest position and above the ground G, the vehicle main body 50 is well balanced when traveling in the field or on the road in a non-plowing work state. While being able to maintain, the trouble that the said rotary tiller 400 contacts the ground etc. can be prevented.

FIG. 11 is a control map showing the relationship between the threshold vehicle speed vS and the set height position hS.
Specifically, the ROM 602 stores in advance a first relational expression or control map indicating the relationship between the threshold vehicle speed vS and the set height position hS of the work implement lifting lever 22.
As the first relational expression in this case, for example, if the reference threshold vehicle speed (reference threshold vehicle speed) is vS ′, when the set height position hS is equal to or lower than the ground contact position hE, When vS = vS ′ and the set height position hS is higher than the ground contact position hE, a relational expression such that vS = A1 × hS + B1 (where hS> hE) can be given. Here, A1 is a proportionality constant, and B1 is a constant.
FIG. 11 is a graph when the first relational expression is a control map. In FIG. 11, the set height position hS of the work implement lifting lever 22 is taken on the horizontal axis, and the threshold vehicle speed vS is taken on the vertical axis.

With such a configuration, the attitude controller 600 sets the threshold vehicle speed vS to the reference threshold vehicle speed vS ′ when the set height position hS of the work implement lifting lever 22 is the same position as the ground contact position hE or lower than the ground contact position hE. When the set height position hS is higher than the ground contact position hE, the threshold vehicle speed S is lowered as the set height position hS changes from “low” to “high”.
Note that data in which the set height position hS of the work implement elevating lever 22 and the corresponding threshold vehicle speed vS are associated with each other may be stored in advance in the ROM 602 as a table map.

Preferably, the degree of relaxation of the control accuracy of the automatic tilt control may be changed according to the vehicle speed v of the vehicle main body 50.
That is, when the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, the degree of relaxation of the control accuracy of the automatic tilt control can be increased as the vehicle speed v increases.

FIG. 12 shows a control map showing the relationship between the automatic tilt control gain Ga and the vehicle speed v of the vehicle body 50.
For example, when the control accuracy of the automatic tilt control is reduced by the “reduction of control gain”, the ROM 602 shows the relationship between the automatic tilt control gain Ga and the vehicle speed v of the vehicle body 50. A second relational expression or a control map is stored in advance.
As the second relational expression in this case, for example, when the reference automatic inclination control gain (reference automatic inclination control gain) is Ga ′, the vehicle speed v of the vehicle body 50 is equal to the threshold vehicle speed vS or the vehicle speed. When the vehicle speed is lower than vS, Ga = Ga ′, and when the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, Ga = A2 × v + B2 (where v> vS). Relational expressions can be mentioned. Here, A2 is a proportionality constant, and B2 is a constant.
FIG. 12 shows a case where this second relational expression is a control map. In FIG. 12, the vehicle speed 50 of the vehicle body 50 is taken on the horizontal axis, and the automatic tilt control gain Ga is taken on the vertical axis.

By providing such a configuration, the attitude control controller 600 sets the automatic inclination control gain Ga to the reference automatic inclination when the vehicle speed v of the vehicle body 50 is the same speed as the threshold vehicle speed vS or lower than the threshold vehicle speed vS. When the control gain Ga ′ is set and the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, the vehicle body 50 is automatically tilted as the vehicle speed v changes from “low speed” to “high speed”. The control gain Ga is reduced.
Note that data in which the vehicle speed v of the vehicle main body 50 and the corresponding automatic inclination control gain Ga are associated may be stored in advance in the ROM 602 as a table map.

FIG. 13 is a control map showing the relationship between the dead zone width δ and the vehicle speed v of the vehicle body 50.
In place of or in addition to the “reduction of control gain”, when the control accuracy of the automatic tilt control is relaxed by “increasing the dead zone width”, the ROM 602 stores the automatic tilt control. A third relational expression or a control map indicating the relationship between the dead zone width δ used at the time and the vehicle speed v of the vehicle body 50 is stored in advance.
As the third relational expression in this case, for example, if the width of the reference dead zone (reference dead zone width) is δ ′, the vehicle speed v of the vehicle main body 50 is the same speed as the threshold vehicle speed vS or lower than the vehicle speed vS. In this case, when δ = δ ′ and when the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, a relational expression such that δ = A3 × v + B3 (where v> vS) is established. Can be mentioned. Here, A3 is a proportionality constant, and B3 is a constant.
FIG. 13 shows a case where this third relational expression is used as a control map. In FIG. 13, the vehicle speed 50 of the vehicle body 50 is taken on the horizontal axis, and the dead zone width δ is taken on the vertical axis.

By providing such a configuration, the attitude control controller 600 sets the dead zone width δ to the reference dead zone width δ when the vehicle speed v of the vehicle body 50 is the same speed as the threshold vehicle speed vS or lower than the threshold vehicle speed vS. When the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, the dead zone width δ is increased as the vehicle speed v of the vehicle body 50 changes from “low speed” to “high speed”. Make it wide.
Note that data in which the vehicle speed v of the vehicle main body 50 and the dead zone width δ corresponding thereto are associated may be stored in advance in the ROM 602 as a table map.
Here, the dead zone means that the tilt control hydraulic cylinder 240 is not driven if the detected tilt position t of the rotary tiller 400 is within a predetermined vertical range centered on the tilt position ts set by the tilt setter 623. If the detected tilt position t is outside the range of the vertical width, the tilt control hydraulic cylinder 240 is moved up and down to indicate an operation gap that brings the tilted state of the rotary tiller 400 closer to the set tilt state tS.

FIG. 14 is a control map showing the relationship between the cut-off frequency fc and the vehicle speed v of the vehicle body 50.
In place of or in addition to the “reduction of the control gain” and / or the “expansion of the dead zone width”, in addition, when the control accuracy of the automatic tilt control is relaxed by the “change of the filtering condition”, The ROM 602 stores in advance a fourth relational expression or control map indicating the relationship between the cutoff frequency fc of the filter unit 625 and the vehicle speed v of the vehicle body 50.
As the fourth relational expression in this case, for example, if the reference cutoff frequency (reference cutoff frequency) is fc ′, the vehicle speed v of the vehicle body 50 is the same speed as the threshold vehicle speed vS or lower than the vehicle speed vS. In this case, when fc = fc ′ and the vehicle speed v of the vehicle main body 50 is higher than the threshold vehicle speed vS, a relational expression such that fc = A4 × v + B4 (where v> vS) is given. be able to. Here, A4 is a proportionality constant, and B4 is a constant.
FIG. 14 shows a case where this fourth relational expression is used as a control map. In FIG. 14, the vehicle speed 50 of the vehicle body 50 is taken on the horizontal axis, and the cutoff frequency fc is taken on the vertical axis.
By providing such a configuration, the attitude control controller 600 sets the cutoff frequency fc to the reference cutoff frequency fc ′ when the vehicle speed v of the vehicle body 50 is the same speed as the threshold vehicle speed vS or lower than the threshold vehicle speed vS. When the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, the cutoff frequency fc is lowered as the vehicle speed v of the vehicle body 50 is changed from “low speed” to “high speed”. .
Note that data in which the vehicle speed vS of the vehicle main body 50 and the corresponding cutoff frequency fc are associated with each other may be stored in advance in the ROM 602 as a table map.
That is, the cut-off frequency fc of the filter unit 625 is variable according to control information corresponding to the vehicle speed v of the vehicle body 50. That is, the cutoff frequency fc is calculated based on the control information of the vehicle speed 50 of the vehicle body 50, and the control information of the calculation result is transmitted to the film unit 625, thereby forming the filter unit 125 having the cutoff frequency fc. The

As the filter unit 625, a low-pass filter (low-pass filter, LPF), a high-pass filter (high-pass filter, HPF), a band filter (band-pass filter, BPF), or a band elimination filter (band elimination filter, BEF). Can be adopted. In the present embodiment, a low-pass filter is employed as the filter unit 625. As is well known, the low-pass filter is configured such that a signal in a frequency range higher than the cutoff frequency fc is substantially 0 (zero), and a signal in a frequency range equal to or lower than the cutoff frequency fc is passed as it is. The cut-off frequency fc is a boundary value between the frequency pass band and the attenuation band.
In the present embodiment, the cutoff frequency fc employed by the filter unit 625 is variable. For example, in the case of an LC filter (a filter composed of a coil and a capacitor), this variable configuration can be realized by using a variable capacitor. In the case of an RC filter (a filter composed of a resistor and a capacitor), it can be realized by a combination of a variable resistor and a variable capacitor.

Next, an example of the attitude control operation of the rotary tiller 400 by the attitude controller 600 will be described in detail below.
In this attitude control device, the attitude control is performed when the work implement elevating lever 22 is operated so that the rotary tiller 400 is positioned below the highest position, or when an automatic control switch (not shown) is turned ON. Start operation.

FIG. 15 is a flowchart showing a control flow by the attitude control device according to the first embodiment.
First, it is determined whether or not the detected height position hL of the rotary tiller 400 is higher than the set height position hS (step S1).
Specifically, when it is determined that the detected height position hL based on the detected lift angle θL read by the lift angle sensor 627 is higher than the set height position hS based on the set lift angle θS of the work implement lifting lever 22 On the other hand, the process proceeds to step S2, whereas if it is determined that the detected height position hL is equal to or less than the set height position hS, the process proceeds to step S6.

If it is determined in step S1 that the detected height position hL of the rotary tiller 400 is higher than the set height position hS, it is determined whether or not the automatic tilling control is being performed (step S2).
Specifically, when it is determined that the automatic plowing depth control is not being performed, the process proceeds to step S3. On the other hand, when it is determined that the automatic plowing depth control is being performed, the process proceeds to step S4.

When it is determined in step S2 that the automatic tilling depth control is not being performed, it is determined whether or not the tilling position hD of the rotary tiller 400 is deeper than the setting tilling position hR of the tilling depth setting device 626 (step S3). ).
Specifically, it is determined that the detected tilling position hD based on the detected vertical turning angle θD read by the rear cover sensor 624 is deeper than the set working depth position hR based on the set turning angle θR of the working depth setting device 626. If it is determined that the plowing depth position hD is equal to or shallower than the set plowing depth position hR, the process proceeds to step S6.

If it is determined in step S2 that the automatic tilling depth control is being performed, and if it is determined in step S3 that the detected tilling position hD is deeper than the set tilling position hR, the tilling depth of the rotary tiller 400 is Automatic plowing depth control is performed for causing the position hD to follow the set plowing depth position hR of the plowing depth setting device 626 (step S4).
Specifically, the detected tilling position hD based on the detected vertical turning angle θD read by the rear cover sensor 624 is equal to the set tilling position hR based on the set turning angle θR of the tilling depth setting device 626. Then, the raising control electromagnetic valve 502 or the lowering control electromagnetic valve 503 is operated to perform the lowering or raising operation of the rotary tiller 400 by the raising / lowering control hydraulic cylinder 220, and the process proceeds to step S5.

Next, the automatic tilt control is performed with reference control accuracy (step S5).
Specifically, the filter unit 625 reads the reference automatic inclination control gain Ga ′, the reference dead band width δ ′, and the reference cutoff frequency fc ′ from the ROM 602, and sets the read reference cutoff frequency fc ′ as the read reference cutoff frequency fc ′. Form. Next, the detected tilt position t is determined by the reference automatic tilt control gain Ga ′ and the detected tilt position t based on the detected tilt angle φ by the work implement position sensor 622 through the formed filter unit 625. The automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated so that the set tilt position tS set by the tilt setter 623 is reached. If the difference between the detected tilt position t of the rotary tiller 400 and the set tilt position ts set by the tilt setter 623 is within the reference dead band width δ ′, the tilt control hydraulic cylinder 240 is not driven, If the difference amount deviates from the reference dead zone width δ ′, the tilt control hydraulic cylinder 240 is driven using the calculated automatic tilt control amount, and the process proceeds to step S11.

On the other hand, if it is determined in step S1 that the detected height position hL of the rotary tiller 400 is equal to or less than the set height position hS, the height position hL of the rotary tiller 400 is Automatic height control is performed to follow the set height position hS (step S6).
Specifically, the detected height position hL based on the detected lift angle θL read by the lift angle sensor 627 is equal to the set height position hS based on the set lift angle θS of the work implement lifting lever 22. The raising control electromagnetic valve 502 or the lowering control electromagnetic valve 503 is operated to perform the lowering or raising operation of the rotary tiller 400 by the elevation control hydraulic cylinder 220, and the process proceeds to step S7.

Next, the threshold vehicle speed vS is changed according to the set height position hS in the automatic height control (step S7).
Specifically, the first relational expression or control map is read from the ROM 602, and the set height position hS by the work implement lifting lever 22 is handled using the read first relational expression or control map. The threshold vehicle speed vS is calculated. In this case, the threshold vehicle speed vS becomes the reference threshold vehicle speed vS ′ when the set height position hS of the work implement lifting lever 22 is the same position as the ground contact position hE or lower than the ground contact position hE, and the set height When the position hS is higher than the ground contact position hE, the set height position hS becomes a value that is decreased as the setting height position hS changes from “low” to “high” (see FIG. 11).

Next, it is determined whether or not the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS (step S8).
Specifically, when it is determined that the detected vehicle speed v of the vehicle body 50 detected by the vehicle speed sensor 628 is higher than the threshold vehicle speed vS calculated in step S7, the process proceeds to step S9. If it is determined that the detected vehicle speed v is the same speed as the threshold vehicle speed vS or lower than the threshold vehicle speed vS, the process proceeds to step S10.

  When it is determined in step S8 that the vehicle speed v of the vehicle main body 50 is higher than the threshold vehicle speed vS, the “control gain reduction”, the “dead zone width increase”, or the “filtering condition change” Among these, the automatic inclination control is performed by relaxing the control accuracy of the automatic inclination control by at least one of the means (step S9).

  Specifically, when the control accuracy of the automatic tilt control is reduced by “reducing the control gain”, the vehicle speed v of the vehicle main body 50 and the second relational expression or control map stored in advance in the ROM 602 are used. Based on the above, the automatic inclination control gain Ga is obtained. In this case, the automatic inclination control gain Ga becomes a value that decreases as the vehicle speed v of the vehicle body 50 changes from “low speed” to “high speed” (see FIG. 12). Next, an automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated based on the obtained automatic tilt control gain Ga and the detected tilt position t based on the tilt angle φ detected by the work machine position sensor 622. The tilt control hydraulic cylinder 240 is driven using the automatic tilt control amount thus calculated, and the process proceeds to step S11.

  Further, when the control accuracy of the automatic tilt control is reduced by the “expansion of the dead zone width”, based on the vehicle speed v of the vehicle body 50 and the third relational expression or control map stored in advance in the ROM 602, A width δ of the dead zone is obtained. In this case, the width δ of the dead zone becomes a value that becomes wider as the vehicle speed v of the vehicle body 50 changes from “low speed” to “high speed” (see FIG. 13). Next, the automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated so that the detected tilt position t by the work implement position sensor 622 becomes the set tilt position tS set by the tilt setter 623. If the difference between the detected tilt position t of the rotary tiller 400 and the set tilt position ts set by the tilt setter 623 is within the obtained dead zone width δ, the tilt control hydraulic cylinder 240 is not driven. If the difference amount deviates from the obtained dead zone width δ, the tilt control hydraulic cylinder 240 is driven using the calculated automatic tilt control amount, and the process proceeds to step S11.

  Further, when the control accuracy of the automatic tilt control by the “expansion of filtering conditions” is relaxed, based on the vehicle speed v of the working vehicle 50 and the fourth relational expression or control map stored in advance in the ROM 602, The cutoff frequency fc of the filter unit 625 is calculated. The cut-off frequency fc in this case becomes a value that is lowered as the vehicle speed v of the vehicle body 50 is changed from “low speed” to “high speed” (see FIG. 14). Next, the filter unit 625 having the calculated cut-off frequency fc is formed, and the detected tilt position t is detected by the work machine position sensor 622 via the filter unit 625, and the detected tilt position t is the tilt angle. The automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated so that the set tilt position tS set by the setter 623 is reached. The tilt control hydraulic cylinder 240 is driven using the automatic tilt control amount thus calculated, and the process proceeds to step S11.

On the other hand, when it is determined in step S8 that the vehicle speed v of the vehicle body 50 is the same speed as the threshold vehicle speed vS or lower than the threshold vehicle speed vS, the automatic tilt control is performed with reference control accuracy (step S10). .
Specifically, the filter unit 625 reads the reference automatic inclination control gain Ga ′, the reference dead band width δ ′, and the reference cutoff frequency fc ′ from the ROM 602, and sets the read reference cutoff frequency fc ′ as the read reference cutoff frequency fc ′. Form. Next, the detected tilt position t is determined by the reference automatic tilt control gain Ga ′ and the detected tilt position t based on the detected tilt angle φ by the work implement position sensor 622 through the formed filter unit 625. The automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated so that the set tilt position tS set by the tilt setter 623 is reached. If the difference between the detected tilt position t of the rotary tiller 400 and the set tilt position ts set by the tilt setter 623 is within the reference dead band width δ ′, the tilt control hydraulic cylinder 240 is not driven, If the difference amount deviates from the reference dead zone width δ ′, the tilt control hydraulic cylinder 240 is driven using the calculated automatic tilt control amount, and the process proceeds to step S11.

  In step S11, it is determined whether or not the posture control operation is being performed. When it is determined that the posture control operation is being performed, the operations from step S1 to step S10 are sequentially repeated, whereas when it is determined that the posture control operation has been completed, End attitude control.

(Second Embodiment)
Hereinafter, a second embodiment of the attitude control device according to the present invention will be described.
The posture control device according to the second embodiment is substantially the same as the posture control device shown in FIG. 10 except that the posture control controller 600 is different. Therefore, the block diagram of the attitude control device according to the second embodiment is substituted for the block diagram shown in FIG. 10, and the detailed description thereof is omitted.

  An attitude control controller 600a of the attitude control apparatus according to the second embodiment includes a ROM 602a instead of the ROM 602 in the attitude control controller 600 of the attitude control apparatus according to the first embodiment. Note that reference numerals of the attitude control controller 600a and the ROM 602a are given in parentheses after the attitude control controller 600 and the ROM 602 shown in FIG. The same applies to a third embodiment to be described later.

The posture control device is the posture control device according to the first embodiment, instead of a configuration that relaxes the control accuracy of the automatic tilt control when the vehicle speed v of the vehicle body 50 is higher than a predetermined threshold vehicle speed vS. When the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, the automatic tilt control is stopped.
That is, when the vehicle speed v of the vehicle body 50 is higher than a predetermined threshold vehicle speed vS, the automatic tilt control is stopped by assuming that the vehicle body 50 is in a non-plowing state. Thereby, the operation | movement contrary to the meaning of the said automatic inclination control can be prevented reliably.

Further, the attitude controller 600a is configured to change the threshold vehicle speed vS according to the set height position hS in the automatic height control.
That is, in the present embodiment, the threshold vehicle speed vS is changed in accordance with the set height position hS of the work implement lifting lever 22, whereby the rotary tiller 400 is moved to the highest position. When the vehicle body 50 is traveling in a non-plowing work state positioned below and above the ground G, the automatic tiller reliably prevents the rotary tiller 400 from tilting unexpectedly. it can.
Accordingly, it is possible to maintain a good traveling balance of the vehicle body 50 and to prevent inconvenience such as the rotary tiller 400 coming into contact with the ground G or the like.

Further, when the set height position hS in the automatic height control is higher than the ground contact position hE, the attitude controller 600a decreases the threshold vehicle speed vS as the set height hS increases. It is configured. Accordingly, even when the vehicle is traveling at a low speed where automatic tilt control has been performed in the past, the rotary tiller 400 can be prevented from tilting due to the automatic tilt control.
Therefore, the traveling balance of the vehicle main body 50 is well maintained when traveling on the field or on the road in a non-cultivated working state in which the rotary tiller 400 is positioned below the highest position and above the ground G. In addition, the inconvenience that the rotary tiller 400 contacts the ground or the like can be prevented.

The ROM 602a stores the control program P2 and the like, and the first relational expression or control map used in the first embodiment, the reference threshold vehicle speed vS ′, the reference automatic inclination control gain Ga ′, the reference dead band width δ ′, and the reference It stores predetermined data relating to the cutoff frequency fc ′.
Next, an example of the attitude control operation of the rotary tiller 400 by the attitude control device according to the second embodiment will be described below with reference to FIG.

FIG. 16 is a flowchart showing a control flow by the attitude control device according to the second embodiment.
The processing flow of the control program P2 shown in FIG. 16 is provided with step S9a instead of step S9 in the processing flow of the control program P1 shown in FIG. The processing flow in FIG. 16 is substantially the same as the processing flow in FIG. 15 except for step S9a. Therefore, step S9a will be mainly described here.

  When it is determined in step S8 that the vehicle speed v of the vehicle body 50 is higher than the threshold vehicle speed vS, the automatic tilt control is stopped and the process proceeds to step S11 (step S9a).

  On the other hand, when it is determined in step S8 that the vehicle speed v of the vehicle body 50 is the same speed as the threshold vehicle speed vS or lower than the threshold vehicle speed vS, the automatic inclination control is performed with reference control accuracy, and the step S11 (Step S10).

(Third embodiment)
Hereinafter, a third embodiment of the attitude control device according to the present invention will be described.
The attitude control controller 600b of the attitude control apparatus according to the third embodiment includes a ROM 602b instead of the ROM 602 in the attitude control controller 600 of the attitude control apparatus according to the first embodiment.

The posture control device is the posture control device according to the first embodiment, instead of a configuration that relaxes the control accuracy of the automatic tilt control when the vehicle speed v of the vehicle body 50 is higher than a predetermined threshold vehicle speed vS. In the automatic height control, the control accuracy of the automatic inclination control is relaxed.
In other words, the posture controller 600b presumes that it is in a non-plowing state during the automatic height control, and relaxes the control accuracy of the automatic tilt control. Thus, when the vehicle main body 50 is traveling in a non-plowing work state in which the rotary tiller 400 is positioned below the highest position and above the ground G, the rotary tiller 400 is controlled by the automatic tilt control. Can be effectively prevented from tilting unexpectedly.
Accordingly, it is possible to maintain a good running balance of the vehicle body 50 and to prevent inconvenience such as the rotary tiller 400 coming into contact with the ground or the like.

Preferably, the degree of relaxation of the control accuracy of the automatic tilt control can be changed according to the set height position hS in the automatic height control. As a result, the amount of tilting of the rotary tiller 400 due to the automatic tilt control can be suppressed even during low-speed traveling where automatic tilt control is conventionally performed.
Accordingly, when the rotary tiller 400 is positioned below the highest position and above the ground G, the vehicle main body 50 is well balanced when traveling in the field or on the road in a non-plowing work state. While being able to maintain, the trouble that the said rotary tiller 400 contacts the ground etc. can be prevented.
In the present embodiment, when the set height position hS in the automatic height control is higher than the ground contact position hE, the attitude controller 600b controls the automatic tilt control as the set height position hS increases. The degree of relaxation of the control accuracy is increased.

  The ROM 602b stores a control program P3 and the like, and stores various data related to various relational expressions or control maps described later.

FIG. 17 is a control map showing the relationship between the automatic tilt control gain Ga and the set height position hS of the work implement lifting lever 22.
For example, when the control accuracy of the automatic tilt control is reduced by the “reduction of the control gain”, the ROM 602b stores the automatic tilt control gain Ga and the set height position hS of the work implement lifting lever 22. Is stored in advance as a fifth relational expression or control map.
As the fifth relational expression in this case, for example, when the reference automatic tilt control gain (reference automatic tilt control gain) is Ga ′, the set height position hS of the work implement lifting lever 22 is the ground contact position hE. When the position is lower than the ground position hE, Ga = Ga ′, and when the set height position hS is higher than the ground position hE, Ga = A5 × hS + B5 (where hS> hE). Can be mentioned. Here, A5 is a proportionality constant, and B5 is a constant.
FIG. 17 shows a case where this fifth relational expression is used as a control map. In FIG. 17, the set height position hS of the work implement lifting lever 22 is taken on the horizontal axis, and the automatic tilt control gain Ga is taken on the vertical axis.

By providing such a configuration, the posture control controller 600b sets the automatic inclination control gain Ga when the set height position hS of the work implement lifting lever 22 is the same position as the ground position hE or lower than the ground position hE. When the reference automatic inclination control gain Ga ′ is set and the set height position hS is higher than the ground contact position hE, the set height position hS is automatically changed from “low” to “high”. The inclination control gain Ga is reduced.
Data associated with the set height position hS of the work implement lifting lever 22 and the automatic tilt control gain Ga corresponding thereto may be stored in advance in the ROM 602b as a table map.

FIG. 18 is a control map showing a relationship indicating the relationship between the dead zone width δ and the set height position hS of the work implement lifting lever 22.
In place of or in addition to the “reduction of control gain”, when the control accuracy of the automatic tilt control is relaxed by “increasing the dead zone width”, the ROM 602b includes the automatic tilt control. A sixth relational expression or control map indicating the relationship between the dead zone width δ used at this time and the set height position hS of the work implement lifting lever 22 is stored in advance.
As the sixth relational expression in this case, for example, if the reference deadband width (reference deadband width) is δ ′, the set height position hS of the work implement lifting lever 22 is the same position as the ground contact position hE or When lower than the ground contact position hE, δ = δ ′, and when the set height position hS is higher than the ground contact position hE, a relational expression such that δ = A6 × hS + B6 (where hS> hE). Can be mentioned. Here, A6 is a proportionality constant, and B6 is a constant.
The case where this sixth relational expression is used as a control map is shown in FIG. In FIG. 18, the set height position hS of the work implement lifting lever 22 is taken on the horizontal axis, and the dead zone width δ is taken on the vertical axis.
By providing such a configuration, the posture controller 600b allows the dead zone width δ to be set when the set height position hS of the work implement lifting lever 22 is the same position as the ground position hE or lower than the ground position hE. When the reference dead zone width δ ′ is set and the set height position hS is higher than the ground contact position hE, the dead zone width δ increases as the set height position hS changes from “low” to “high”. To widen.
Note that data in which the set height position hS of the work implement lifting lever 22 and the width δ of the dead zone corresponding thereto are associated may be stored in advance in the ROM 602b as a table map.

FIG. 19 shows a control map showing the relationship between the cutoff frequency fc and the set height position hS of the work implement lifting lever 22.
In place of or in addition to the “reduction of the control gain” and / or the “expansion of the dead zone width”, in addition, when the control accuracy of the automatic tilt control is relaxed by the “change of the filtering condition”, In the ROM 602b, a seventh relational expression or a control map indicating the relationship between the cutoff frequency fc of the filter unit 625 and the set height position hS of the work implement lifting lever 22 is stored in advance.
As the seventh relational expression in this case, for example, when the reference cutoff frequency (reference cutoff frequency) is fc ′, the set height position hS of the work implement lifting lever 22 is the same as the grounding position hE or grounding When lower than the position hE, fc = fc ′, and when the set height position hS is higher than the ground contact position hE, a relational expression such that fc = A7 × v + B7 (hS> hE) is established. Can be mentioned. Here, A7 is a proportionality constant, and B7 is a constant.
FIG. 19 shows a case where this seventh relational expression is used as a control map. In FIG. 19, the set height position hS of the work implement lifting lever 22 is taken on the horizontal axis, and the cut-off frequency fc is taken on the vertical axis.
By providing such a configuration, the attitude controller 600b allows the cutoff frequency fc to be a reference cutoff when the set height position hS of the work implement lifting lever 22 is the same position as the ground position hE or lower than the ground position hE. When the frequency fc ′ is set and the set height position hS is higher than the ground contact position hE, the cut-off frequency fc is lowered as the set height position hS changes from “low” to “high”. .
Note that data in which the set height position hS of the work implement lifting lever 22 and the cutoff frequency fc corresponding thereto are associated may be stored in advance in the ROM 602b as a table map.

  Next, an example of the posture control operation of the rotary tiller 400 by the posture control device according to the third embodiment will be described in detail below with reference to FIG.

  FIG. 20 is a flowchart showing a control flow by the attitude control device according to the third embodiment.

  The processing flow of the control program P3 shown in FIG. 20 is provided with step S9b instead of the steps S7 to S10 in the processing flow of the control program P1 shown in FIG. The processing flow in FIG. 20 is substantially the same as the processing flow except for step S7 to step S10 in FIG. 15 except for step S9b. Therefore, step S9b will be mainly described here.

  After the step S6 for performing automatic height control for causing the height position hL of the rotary tiller 400 to follow the set height position hS of the work implement lifting lever 22, the "reduction of control gain", the " The automatic inclination control is performed by relaxing the control accuracy of the automatic inclination control by at least any one of “expanding dead band width” or “changing the filtering condition” (step S9b).

  Specifically, when the control accuracy of the automatic tilt control is reduced by the “reduction of control gain”, the set height position hS of the work implement lifting lever 22 and the fifth pre-stored in the ROM 602b. The automatic inclination control gain Ga is obtained based on the relational expression or the control map. In this case, the automatic inclination control gain Ga becomes a value that decreases as the set height position hS of the work implement lifting lever 22 changes from “low” to “high” (see FIG. 17). Next, an automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated based on the obtained automatic tilt control gain Ga and the detected tilt position t based on the tilt angle φ detected by the work machine position sensor 622. The tilt control hydraulic cylinder 240 is driven using the automatic tilt control amount thus calculated, and the process proceeds to step S11.

  When the control accuracy of the automatic tilt control is reduced by the “expansion of the dead zone width”, the set height position hS of the work implement lifting lever 22 and the sixth relational expression or control stored in advance in the ROM 602b Based on the map, the dead zone width δ is obtained. The width δ of the dead zone in this case becomes a value that is increased as the set height position hS of the work implement lifting lever 22 is changed from “low” to “high” (see FIG. 18). Next, the automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated so that the detected tilt position t by the work implement position sensor 622 becomes the set tilt position tS set by the tilt setter 623. If the difference between the detected tilt position t of the rotary tiller 400 and the set tilt position ts set by the tilt setter 623 is within the obtained dead zone width δ, the tilt control hydraulic cylinder 240 is not driven. If the difference amount deviates from the obtained dead zone width δ, the tilt control hydraulic cylinder 240 is driven using the calculated automatic tilt control amount, and the process proceeds to step S11.

  Further, when the control accuracy of the automatic tilt control is reduced by the “filtering condition expansion”, the set height position hS of the work implement lifting lever 22 and the seventh relational expression or control stored in advance in the ROM 602b Based on the map, the cutoff frequency fc of the filter unit 625 is calculated. The cut-off frequency fc in this case becomes a value that is lowered as the set height position hS of the work implement lifting lever 22 is changed from “low” to “high” (see FIG. 19). Next, the filter unit 625 having the calculated cut-off frequency fc is formed, and the detected tilt position t is detected by the work machine position sensor 622 via the filter unit 625, and the detected tilt position t is the tilt angle. The automatic tilt control amount of the tilt control hydraulic cylinder 240 is calculated so that the set tilt position tS set by the setter 623 is reached. The tilt control hydraulic cylinder 240 is driven using the automatic tilt control amount thus calculated, and the process proceeds to step S11.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the attitude control device according to the present invention will be described.
The posture control controller 600c of the posture control device according to the fourth embodiment includes a ROM 602c instead of the ROM 602b in the posture control controller 600b of the posture control device according to the third embodiment.

In the attitude control apparatus according to the third embodiment, the attitude control apparatus is configured to reduce the control accuracy of the automatic tilt control during the automatic height control. The automatic tilt control is configured to stop. Accordingly, when the vehicle main body is traveling in the non-plowing work state in which the rotary tiller 400 is positioned below the highest position and above the ground G, the rotary tiller 400 is controlled by the automatic tilt control. It is possible to effectively prevent a large tilt against the intention.
Accordingly, it is possible to maintain a good traveling balance of the vehicle body 50 and to prevent inconvenience such as the rotary tiller 400 coming into contact with the ground G or the like.

  The ROM 602c stores the control program P4 and the like, and predetermined data regarding the reference threshold vehicle speed vS ′, the reference automatic inclination control gain Ga ′, the reference dead band width δ ′, and the reference cutoff frequency fc ′ used in the third embodiment. Etc. are memorized.

  Next, an example of the attitude control operation of the rotary tiller 400 by the attitude control device according to the fourth embodiment will be described below with reference to FIG.

FIG. 21 is a flowchart showing a control flow by the attitude control device according to the fourth embodiment.
The processing flow of the control program P4 shown in FIG. 21 is provided with step S9c instead of step S9b in the processing flow of the control program P3 shown in FIG. The processing flow in FIG. 21 is substantially the same as the processing flow in FIG. 20 except for step S9c. Accordingly, only step S9c will be described here.

  Following the step S6 for performing automatic height control for causing the height position hL of the rotary tiller 400 to follow the set height position hS of the work implement lifting lever 22, the automatic tilt control is stopped, and the step S11 is performed. (Step S9c).

FIG. 1 is a schematic side view of a farm tractor as an example of a work vehicle to which the attitude control device according to the present embodiment is applied. FIG. 2 is a schematic plan view of the tractor shown in FIG. FIG. 3 is a schematic side view of a tiller lifting mechanism in the tractor shown in FIG. FIG. 4 is a schematic plan view of the tiller lifting mechanism shown in FIG. 5 is a schematic cross-sectional view of the rotary tiller along the line VV in FIG. FIG. 6 is a schematic rear view of the rotary tiller. FIG. 7 is a hydraulic circuit diagram of the tractor. FIG. 8 is a block diagram of the attitude control device according to the first embodiment. FIG. 9 is a schematic rear view of the rotary tiller. FIG. 10 is a schematic side view of a rotary tiller. FIG. 11 is a control map showing the relationship between the threshold vehicle speed vS and the set height position hS. FIG. 12 is a control map showing the relationship between the automatic tilt control gain Ga and the vehicle speed v of the vehicle body. FIG. 13 is a control map showing the relationship between the width of the dead zone δ and the vehicle speed v of the vehicle body. FIG. 14 is a control map showing the relationship between the cutoff frequency fc and the vehicle speed v of the vehicle body. FIG. 15 is a flowchart illustrating a control flow by the attitude control device according to the first embodiment. FIG. 16 is a flowchart illustrating a control flow by the attitude control device according to the second embodiment. FIG. 17 is a control map showing the relationship between the automatic tilt control gain Ga and the set height position hS. FIG. 18 is a control map showing a relationship indicating the relationship between the width of the dead zone δ and the set height position hS. FIG. 19 is a control map showing the relationship between the cutoff frequency fc and the set height position hS. FIG. 20 is a flowchart illustrating a control flow by the attitude control device according to the third embodiment. FIG. 21 is a flowchart illustrating a control flow by the attitude control device according to the fourth embodiment.

DESCRIPTION OF SYMBOLS 50 ... Vehicle main body 220 ... Elevating actuator 240 ... Tilt actuator 400 ... Tiller 600 ... Control means 622 ... Inclination state detection means 623 ... Inclination setting means 624 ... Tillage position detection means 626 ... Plowing depth setting means hD ... Detection Plowing depth position hL ... Detected vertical position hS ... Set height position t ... Detected tilt state tS ... Set tilt state v ... Vehicle speed vS ... Threshold vehicle speed

Claims (9)

Automatic height control that allows the vertical position of the tiller connected to the vehicle body to be movable up and down and tiltable right and left to follow the set height position set for the tiller, and detection of the tiller An attitude control device configured to perform automatic tilling control for causing the tilling position to follow the set tilling position, and automatic inclination control for causing the detected inclination state of the tiller to follow the set inclination state. There,
When the vehicle speed of the vehicle body is higher than a predetermined threshold vehicle speed, the control accuracy of the automatic tilt control is relaxed, and when the set height position is higher than the ground contact position of the tiller, the set height An attitude control device configured to reduce the threshold vehicle speed as the position increases. The automatic tilt control is executed based on a relative tilt angle of the cultivator with respect to the vehicle body, which is input through a filter,
When executing the automatic tilt control, the automatic tilt control is performed by at least one of the following means: reduction of the control gain of the automatic tilt control, expansion of the dead zone width of the automatic tilt control, or change of the filtering condition of the filter. The attitude control apparatus according to claim 1, wherein the attitude control apparatus is configured to relax control accuracy.   The attitude control device according to claim 1 or 2, wherein a degree of relaxation of the control accuracy of the automatic tilt control is changed according to a vehicle speed of the work vehicle. Automatic height control that allows the vertical position of the tiller connected to the vehicle body to be movable up and down and tiltable right and left to follow the set height position set for the tiller, and detection of the tiller An attitude control device configured to perform automatic tilling control for causing the tilling position to follow the set tilling position, and automatic inclination control for causing the detected inclination state of the tiller to follow the set inclination state. There,
An attitude control device configured to stop the automatic tilt control when a vehicle speed of the vehicle body is higher than a predetermined threshold vehicle speed.   5. The posture according to claim 4, wherein when the pre-set height position is higher than the ground contact position of the tiller, the threshold vehicle speed is made lower as the set height position becomes higher. Control device. Automatic height control that allows the vertical position of the tiller connected to the vehicle body to be movable up and down and tiltable right and left to follow the set height position set for the tiller, and detection of the tiller An attitude control device configured to perform automatic tilling control for causing the tilling position to follow the set tilling position, and automatic inclination control for causing the detected inclination state of the tiller to follow the set inclination state. There,
At the time of the automatic height control, the posture control device is configured to relax the control accuracy of the automatic tilt control. The automatic tilt control is executed based on a relative tilt angle of the cultivator with respect to the vehicle body, which is input through a filter,
When executing the automatic tilt control, the automatic tilt control is performed by at least one of the following means: reduction of the control gain of the automatic tilt control, expansion of the dead zone width of the automatic tilt control, or change of the filtering condition of the filter. The attitude control apparatus according to claim 6 , wherein the attitude control apparatus is configured to relax control accuracy.   The attitude control device according to claim 6 or 7, wherein a degree of relaxation of the control accuracy of the automatic tilt control is configured to be changed according to the set height position. Automatic height control that allows the vertical position of the tiller connected to the vehicle body to be movable up and down and tiltable right and left to follow the set height position set for the tiller, and detection of the tiller An attitude control device configured to perform automatic tilling control for causing the tilling position to follow the set tilling position, and automatic inclination control for causing the detected inclination state of the tiller to follow the set inclination state. There,
An attitude control device configured to stop the automatic tilt control during the automatic height control.

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