JPS61215167A - Steering control device of working vehicle - Google Patents

Abstract

PURPOSE:To improve the straight-running feature near a neutral position by providing a neutral-position correction means of the target steering angle on a steering control device electrically applied with the target steering angle. CONSTITUTION:When the steering angle psi is near the angle psi0 corresponding to a neutral position, the output signal Vi of a potentiometer R0 detecting the steering quantity of a handle is fed to an A/D converter 17 via a neutral-position correction circuit A as a neutral-position correction means so that the target steering angle psi is maintained at this neutral angle psi0 regardless of its value. When the input signal voltage Vi to the circuit A is between an upper limit value and a lower limit value with relation to the neutral-position voltage Vn, the neutral-position voltage is outputted as the output signal V0 of the target steering angle psi.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a system for detecting a target steering angle that is given by electrically detecting the amount of operation of a steering wheel and a detected steering angle of a steering wheel. The present invention relates to a steering control device for a working vehicle, which includes means for power steering the steering wheels.

[Conventional technology]

In the above-mentioned type of steering control device for a work vehicle, for example, the work vehicle is equipped with a means for teaching a travel route in advance or detecting a travel route so that the work vehicle travels automatically, or is driven automatically by remote control, or In order to make it possible to select the driving mode of a work vehicle according to various work situations, such as when a person gets on the work vehicle and manually steers it, target steering angle information is converted into an electrical signal. At the same time, in order to control the target steering angle so that the actual steering angle matches the target steering angle, it has been considered to employ a steering control means that can perform power steering operation on the steering wheels. In addition, in order to improve the steering performance of the work vehicle, both the front and rear wheels can be configured to be steerable, and the front and rear wheels can be steered in the same direction, the front and rear wheels can be steered in relatively opposite directions, or , we have adopted a steering control means that allows power steering operation, with the aim of making it possible to easily change the steering operation mode, such as steering only one of the front and rear wheels, without changing the hardware configuration. It is considered to do.

In order to perform this power steering operation, it is possible to simplify the configuration by performing the steering operation using only electrical signal processing, and the steering operation handle, which is not required during automatic driving or remote control, can be installed inside the vehicle body, for example. This has the advantage of being able to reliably prevent the handle from coming into contact with another object and moving unexpectedly, causing the work vehicle to travel in an unexpected direction. Furthermore, even if the handle moves for some reason when the handle is not needed, an arrangement that electrically detects the amount of operation has the advantage that the detected value can be easily invalidated. During steering, a configuration is adopted in which the amount of steering wheel operation is electrically detected to provide a target steering angle.

[Problem that the invention seeks to solve]

However, in this type of steering control device,
Since the steering wheel is power-steering operated so that the electrically given target steering angle matches the actual steering angle of the steering wheel, the steering wheel is in neutral corresponding to the straight-ahead state of the vehicle. If the position and the neutral position of the target steering angle do not match, there is an inconvenience that the vehicle body will not go straight even though information about the target steering angle is given to make the vehicle go straight. In addition, if the signal that provides information on the target steering angle changes even slightly, the actuator for steering operation operates to follow the change, so when the target steering angle is in the vicinity of the neutral position, especially during manual steering using the steering wheel, etc. If the steering wheel that gives the angle is operated even slightly, the vehicle body will meander,
On the contrary, there arises a disadvantage that the operability during manual steering becomes poor, and the power steering actuator operates frequently, which adversely affects the durability of the actuator.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a steering control device for power steering operation in which a target steering angle is electrically given, in the vicinity of the neutral position of the steering angle corresponding to straight-ahead driving. The goal is to maintain good straight running performance in
In particular, the object is to improve the operability during artificial maneuvering near the neutral position.

[Means for solving problems]

The steering control device for a work vehicle according to the present invention is characterized in that when the target steering angle is near the neutral position corresponding to a straight-ahead state, the steering control device for a work vehicle is characterized in that regardless of the given target steering angle, the neutral position is The present invention is provided with means for correcting the neutral position of the target steering angle so that the angle corresponds to the angle corresponding to .

[For production]

That is, near the neutral position corresponding to straight-ahead driving, the target steering angle is maintained at an angle corresponding to the neutral position so that even if the target steering angle changes somewhat, the steered wheels maintain the straight-ahead state. Thus, the neutral position of the target steering angle is corrected. To correct this neutral position, for example, the target steering angle, which is electrically detected from the amount of steering wheel operation, is set to a signal corresponding to the angle corresponding to the neutral position, regardless of the detected angle near the neutral position. Alternatively, variations in steering wheel operation may not be physically detected as variations in the target steering angle in the vicinity of the neutral position, and as a result, the operation of the means for providing the target steering angle may vary in the vicinity of the neutral position. The target steering angle is controlled to be an angle corresponding to the neutral position so that the steering wheel is maintained at the neutral position even when the steering wheel is in the neutral position.

〔Effect of the invention〕

In other words, near the neutral position, even if the amount of steering wheel operation changes due to vibrations of the vehicle while driving, the target steering angle is automatically maintained at the angle corresponding to the neutral position. Depending on the angle variation, the steering wheel will not be steered, and the steering wheel will be maintained in a straight-ahead state.

Additionally, since the target steering angle is given as an electrical signal, the range in which the angle corresponding to the neutral position is maintained can be set regardless of the operation of the power steering actuator, and its adjustment is also easy. It can be carried out. Therefore, the artificial maneuverability near the neutral position can be made to match the actual steering feeling without impairing the controllability of the steering operation outside the neutral position.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

As shown in Figure 5, the fuselage frame (
1) Seat (2), handle (11), and transmission case (M) on the rear side, engine (E) on the front side
, and wheels (3) are provided at the bottom of the aircraft frame (1).
) and front and rear drive wheels (3F) and (3R) are provided, and a lawn mowing bag W (4) with a disc-shaped cutting blade inside is suspended in the middle part of these front and rear wheels (3F) and (3R) so as to be movable up and down. This constitutes a lawn mowing work vehicle as a four-wheel drive work vehicle.

As shown in FIG. 3, the output of the engine (E) is transmitted to the hydraulic continuously variable transmission (5) provided in the transmission case (M), and the output is transmitted to the transmission pedal (not shown) or the hydraulic continuously variable transmission (5). The front and rear wheels (3F) are operated to change speed by a motor (6) with a reduction gear as an actuator for automatic speed change.
, (3R) and the lawn mower (4) can be driven simultaneously. The shift operation position of the transmission device (5) is detected by a potentiometer (R3) that is linked to the rotation of the shift operation shaft (7), and is fed back to the control device (8).

Further, the front and rear wheels (3r') and (3R) are configured so that they can be steered not only as drive wheels but also as steering wheels, and can be operated manually using the handle (■) or by radio guidance. The power steering can be operated by either remote control using W, or automatic steering based on various preset control parameters, travel route detection information, etc., based on the given target steering angle (Ψ) and the front and rear wheels (3F). , (3R) potentiometers (R+), (R
Feedback control is performed so that the detected steering angle (φ) from z) matches the detected steering angle (φ).

The above-mentioned handle () I) is configured to move upwardly and downwardly with respect to the vehicle body (v), and when the handle is not needed, such as during remote control or automatic steering control, it can be lowered to the vehicle body (V) side. This is to prevent it from getting in the way while driving. and,
The amount of operation is detected by a potentiometer (Ro) that is linked to the rotational operation of the handle (H).

Moreover, since both of the front and rear wheels (3F) and (311) are configured to be able to be operated by steering,
Parallel steering type that moves the front and rear wheels (31'l) and (3R) in parallel without changing the orientation of the vehicle body (V) by steering the front and rear wheels (31'l) and (3R) in the same direction. Various types of steering are available, including a turning steering type that allows turning in a small turning radius by steering in the opposite direction, and a normal two-wheel steering type in which only the front wheels (3F) are operated like in a car. (
3F) and (3R) can be selected by simply changing the manner in which the target steering angle (Ψ) information for the power steering operation is given.

That is, reciprocating hydraulic cylinder (9F), (9
R) is provided so as to be freely movable in the left and right direction of the vehicle body (V), and is connected to the front and rear wheels (3F) and (3)1) respectively via steering tie rods (1o), and this hydraulic cylinder ( 9F), (9R) electromagnetic H/L/B (I IF), (l l I?)
It is configured to perform this by adding 0N10FF to l1iIJI+.

Then, the target steering angle (Ψ) given based on the detected value of the steering amount operated by the steering wheel ()l) or the detected value of the steering amount by remote control, and the front and rear wheels (3F), (3R). A potentiometer (R,) is provided for each as a steering angle detection means.

The electromagnetic valves (IIF) (IIR) (I
The power steering operation is performed by controlling the drive of the IR.

Further, as shown in FIG. 4, in the manual mode in which a person is on board and manually steers the vehicle, the parallel steering
Based on the steering type selection switch (SWI) that selects which steering type to perform steering operation, turning steering or two-wheel steering, and the guidance signal received by the receiver (12b), a transmitter (12a not shown) is activated. ) is provided with a remote control switch (SL) for instructing a remote control mode for remote control.

As shown in FIG. 6, the transmitter (12a) includes a steering lever (13) that can be operated forward, backward, left, and right, and a gear shift lever (14) that can be operated forward, backward, and stopped.
), and is configured to switch between the parallel steering type and the turning steering type by operating the steering control lever (13) in the front and rear directions, and to give the target steering angle (instep) by operating the left and right sides of the steering lever (13). It is.

Then, as shown in FIG. 4, a first channel (C
H2), second channel for steering operation (CHz),
Each signal of the third channel (CHZ) for speed change operation is F/V.
After being converted into voltage signals by the converter (15), the signals are input to the multiplexer (16) together with the detection signals from the potentiometers (Ro) to (R3), and then converted into digital signals by the A/D converter (17) 4. became
Each of the switches (SW, ).

I10 boat (18) (with signal from (S匈2)
The control device (hereinafter abbreviated as PTO (18))
8) is input to the CPU (19) of the transmission device (5), and controls the speed change operation position operation motor (6) of the transmission device (5) based on the detected speed change position by the potentiometer (R3) and the third channel (CHz) for speed change operation. A control signal is sent to the motor drive circuit (22) to drive the motor drive circuit (22) so that the gear shift position coincides with the target shift position, and an electromagnetic valve (IIF) to power-steering the front and rear wheels (3F) and (3R).

(IIR), the potentiometer (R1), (+1
2) calculates a control signal to the valve drive circuit (20F) and (2OR) that drive the valve drive circuit (20F) and (2OR) so that the detected steering angle (φ) matches the target steering angle (Ψ), and sends the result to the output PIO (21 ).

By the way, in the above-mentioned turning steering type, the front and rear wheels (
Since the steering directions of (3F) and (3R) are opposite to each other, the steering type selection switch (S
No. 1 for selecting the steering type when turning steering type is selected by I4+> or during remote control.
A potentiometer (R) detects the amount of operation of the handle (11) based on the signal level of the channel (CI+).
o) Or a second steering wheel for remote control.
By reversing the polarity of the target steering angle (Ψ) given by the channel (C11□), the rear wheel (3R)
The electromagnetic valve drive circuit (2011) on the side is manually operated. In the case of a two-wheel steering type, in order to fix this rear wheel (3R) in a neutral state, that is, in a neutral position and not to operate the steering, the electromagnetic valve drive circuit (2OR) on the rear wheel (3R) side is installed. Input the angle (Ψ0) signal corresponding to the neutral position (N) to the front wheel (3F) side electromagnetic valve drive circuit (20
Only F) is activated.

-4. When manually steering the steering wheel (11), play is provided in the operation of the steering wheel (11) in the vicinity of the neutral position (N) of the steering angle corresponding to the straight-ahead state, and if there is a slight change in the operating position, the steering wheel is operated In order to prevent this from occurring and improve maneuverability, if the target steering angle (P) is near the angle ('Pa) corresponding to the neutral position (N), the target steering angle In order to maintain the angle ('P) at this neutral angle ('Po), the output signal (Vi) of the potentiometer (Ro) that detects the steering amount of the steering wheel (■) is adjusted to the neutral position as a neutral position correction means. The A/D via the correction circuit (A)
It is configured to be input to a converter (17).

That is, as shown in FIG. 1, the neutral position correction circuit (A) is a buffer circuit (^.) that receives the output signal (Vi) of the potentiometer (Ro), and the output of this buffer circuit (80) is The neutral angle ('
Pa), that is, the upper limit value (Vu) and lower limit value (Vd) that are preset for the neutral position voltage (Vn) corresponding to the neutral angle (Ψ0).
A comparator (AI) that checks whether there is a difference between
), (At), potentiometer (Rn) that sets the neutral position voltage (Vn), adds or subtracts a predetermined voltage (Va) to the output of the buffer circuit (^.) with respect to this neutral position voltage (Vn). and the comparator (AI).

The output voltage (Vo ) to (K4) for switching between the two modes. In addition, (0,) to (03) in FIG. 1 are the respective outputs (Pu), (
This is an inverter that inverts the logic of Pd).

As shown in FIG. 2, the input signal voltage (Vi) to the neutral position correction circuit (A) is between the upper limit value (Vu) and lower limit value (Vd) with respect to the neutral position voltage (Vn). If the neutral position voltage (Vn) is between the two, turn off the analog switches (Kl) to (K3) and turn on the other analog switches (K2) and (K4. Ψ) is output as an output signal (Vo). On the other hand, when the input signal (Vi) is equal to or higher than the upper limit value (Vu), the adder (A2) outputs a voltage obtained by subtracting a predetermined value (Va) from the input signal (Vi), and the lower limit 4fi (
Vd) or less, correct the respective human input signals (Vi) so that the other adder (8) outputs a voltage obtained by adding a predetermined value (Va) to the input signal (Vi) using b. Control is performed so that the feeling of operating the steering wheel (H) matches the actual steering operation.

In this embodiment, the upper limit value (Vu) is used as the predetermined voltage (±Va) to be added to or subtracted from the input signal (Vi).
, the lower limit value (Vd) is used as is, but it may be set separately.

Further, the input signal (Vi) is equal to the neutral position voltage (V
n) in the vicinity, instead of completely switching this input signal (Vi) to the neutral voltage (Vn),
By reducing the degree of amplification in the vicinity of the neutral voltage (Vn) of the neutral position correction circuit (A), fluctuations in the output (Vo) with respect to the input signal (Vi) are reduced, and the output (Vo) is reduced substantially in the vicinity of the neutral position (N). In this case, the target steering angle (Ψ) may be kept unchanged.

Examples according to c] Another example will be described below.

In the vicinity of the neutral position (N), the neutral position correction means corrects the target steering angle (P) to an angle ('I/.) corresponding to the neutral position (N). By changing the configuration to electrically convert the corresponding signal (Vi) into a voltage signal (Vn) corresponding to the neutral position (N), a potentiometer ( It is also possible to use means that prevents Ro) from physically detecting the rotational change.

That is, as shown in FIGS. 7(A) and (TI), the rotation operation of the handle (11) is controlled by the potentiometer (Ro
), the shifter (22) is spline-fitted to both the handle shaft (21a) and the shaft (21b) of the potentiometer (RQ) so as to be slidable in the axial direction thereof.
) and this shifter (22) are the two wheels (21a).

A spring (
23), and both the shafts (21a), (
Both shafts (21a),
(21b) urges the spring (24
) is fitted into the chic (22). Then, the shifter (22) is pressed by the spring (23),
With its lower surface sliding on the guide portion (25a) of the holder (25) that pivotally supports the shafts (21a) and (21b), it engages with the shafts (21a) and (21b) and Both shafts (21a) and (21b) are designed to rotate together. A projection (25b) is provided on the upper surface of the guide portion (25a) of the holder (25) at a position corresponding to the neutral position It (N), and a projection (25b) is provided at a position opposite to the projection (25b). (22
) is provided with a protrusion (22a) on the lower surface of the shifter (22) side protrusion (22a) near the neutral position (N).
22a) rides on the protrusion (25b) on the side of the holder (25), and the shifter (22) slides in the direction of the handle (H) against the biasing force of the spring (23), and the potentiometer (Ro) axis (21b
) is released from the shifter (22). Therefore,
Near the neutral position (N), the potentiometer (Ro) does not physically rotate even if the handle (H) is operated, and its output voltage (VO) does not vary.

[Brief explanation of drawings]

The drawings show an embodiment of the steering control device for a working vehicle according to the present invention, FIG. 1 is a circuit diagram showing the configuration of the neutral position correction means, FIG. 2 is an input/output characteristic diagram showing its operation, and FIG. 4 is a block diagram showing the overall configuration of the control system, FIG. 4 is a block diagram showing the configuration of the control device, FIG. 5 is an overall side view of the lawn mower, and FIG. 6 is a perspective view showing the schematic configuration of the transmitter.
FIG. 7(A) is a cross-sectional view of the main part of the handle shaft showing another embodiment of the neutral position correction means, and FIG. 7(0) is the Y-
It is a Y arrow view. (H)...Handle, (3)...Steering wheel, (A)...Target steering angle, (φ
)...Detected steering angle, (N)...
...Neutral position, ('PO) ...Neutral angle.

Claims (1)

[Claims] [1] The target steering angle (Ψ) given by electrically detecting the amount of operation of the steering wheel (H) and the detected steering angle (
A steering control device for a work vehicle, comprising means for power steering the steering wheel (3) so that the target steering angle (Ψ) coincides with a neutral state corresponding to a straight-ahead state. If it is near the position (N), regardless of the given target steering angle (Ψ),
Angle (Ψ_0) corresponding to the neutral position (N)
A steering control device for a working vehicle is provided with neutral position correction means for a target steering angle (Ψ) so that [2] The neutral position correction means converts a given target steering angle (Ψ) into a neutral angle (Ψ_
0) A steering control device for a working vehicle according to claim 1, wherein the steering control device converts the steering control device into a signal corresponding to 0). [3] The neutral position correction means moves the steering handle (H) to a neutral position (N).
The steering control device for a work vehicle according to claim 1, wherein the detected target steering angle (Ψ) does not physically change even if the steering angle is operated in the vicinity.