JPH0232189B2 - SOKOSHARYO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a traveling vehicle, and more particularly to a traveling vehicle configured such that both front wheels and rear wheels can be steered.

In recent years, this type of vehicle, especially self-driving vehicles such as lawn mowers and other self-driving work vehicles, has been equipped with steering controls for both the front and rear wheels to enable more precise control of the vehicle depending on the work type. Increasingly, so-called four-wheel steering systems are being adopted.

However, in the case of the above automatic driving vehicle,
A steering wheel similar to a car is provided so that it can be operated manually in cases where automatic driving, which performs all steering operations automatically, is not possible or in emergencies. When moving backwards while moving the vehicle in parallel, the movement of the vehicle and the direction of the steering wheel operation are opposite, so this may be connected to the feeling of a driver who is accustomed to operating the steering wheel in normal two-wheel steering (for example, in a normal car). First, the vehicle body sometimes moves in the opposite direction to the intended direction, resulting in poor operability.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is that when driving backwards by steering the front and rear wheels in the same direction, the steering wheel is operated in the same way as normal two-wheel steering. An object of the present invention is to provide a traveling vehicle equipped with a means that allows the user to perform operations intuitively.

In order to achieve the above object, the traveling vehicle according to the present invention includes a means for detecting the steering amount of each of the front wheels and the rear wheels, a means for instructing a target steering amount that is artificially changed and set, and a transmission device configured to drive the vehicle in reverse. a means for detecting that the state has been set, a target steering amount by the instruction means and a steering amount detected by the detection means, and the front and rear wheels are steered until the detected steering amount matches the target steering amount. When a mode is set in which the comparison control means and the front wheels and the rear wheels are operated in the same direction, the polarity of the target steering amount with respect to the neutral position is reversed based on the detection operation of the backward movement state detection means. The present invention is characterized in that it further comprises a polarity reversal means for applying the polarity to the comparison control means.

Because of the above characteristics, the following excellent effects have been achieved.

That is, when the vehicle is in a mode in which the front and rear wheels are operated in the same direction to move the vehicle body in parallel and the vehicle is moving backward, the polarity of the target steering amount is automatically reversed from that when traveling forward and compared with the detected steering amount. Therefore, even if the steering wheel is used as a means of instructing the target steering amount, for example, the steering wheel can be operated with the same feeling as normal two-wheel steering operation, making it extremely useful. The operability has improved.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a lawn mower 4 equipped with a disc-shaped cutting blade is movable up and down in the middle of a vehicle body 1, which is configured to be able to steer both front wheels 2, 2 and rear wheels 3, 3. In addition, there is a handle 5 for steering operation, a gear change lever 6 for operating the traveling speed, and a steering mode, that is, steering operation for only the front wheels 2, 2, and steering operation for the front wheels 2, 2 and rear wheels 3, 3. Mode selection for selecting three steering modes: an operation in which the vehicle body 1 is moved in parallel by steering in the same direction, and an operation in which the vehicle body 1 is turned by steering the front wheels 2, 2 and rear wheels 3, 3 in opposite directions. A switch Sw is provided to configure a lawn mowing work vehicle as a traveling vehicle that can be directly driven manually.

A control system for controlling the traveling speed and the steering operations of the front and rear wheels 2 and 3 based on information from the steering handle 5, the speed change lever 6, and the mode selection switch Sw will be described below.

As shown in FIG. 2, the control system includes a potentiometer R ₁ as a means for detecting the rotation angle of the steering handle 5 and instructing a target steering amount θ, and _a an inverting amplifier A ₁ which inverts the polarity of the output signal with respect to the output signal of the potentiometer R ₀ as a means of setting the neutral position, and the actual steering amount θ of the front wheels 2, 2 and rear wheels 3, 3, respectively; The polarity is inverted by the signals from potentiometers R ₂ and R ₃ as means for detecting _F and θ _R , and the target steering amount θ input via the steering mode selection switch Sw or by the inverting amplifier A ₁ . Deviation amplifiers A ₂ and A ₃ serve as comparison control means for amplifying the difference between the target steering amount and the signal selected by the switch circuits S and S ₁ having the configuration described later, and the outputs of these amplifiers A ₂ and A ₃ are used. Therefore, it is constituted by valve drive circuits 11 and 12 that respectively drive electromagnetic valves 9 and 10 that operate hydraulic cylinders 7 and 8 that actually steer the front wheels 2 and 2 and the rear wheels 3 and 3, respectively.

The switch circuits S and _S1 correspond to the output signal of a potentiometer _R4 provided in the continuously variable transmission device 13 whose shift position can be arbitrarily controlled by the speed change lever 6, and the neutral position of the transmission device 13. The mode is switched by a comparator A ₄ that compares the output signal of a potentiometer R ₅ with the output signal of a potentiometer R 5 that sets a neutral signal to set the mode. Output to selection switch Sw potentiometer R ₁
The output of the signal is automatically switched to an inverted signal. The potentiometer _R4 and the comparator _A4 constitute a backward state detection means.

Then, the mode selection switch Sw is set to the front wheel 2,
2 and the rear wheels 3 in the same direction, and when the transmission 13 is operated in the reverse direction, the operation direction of the steering wheel 5 and the vehicle body 1 are automatically changed. The polarity of the target steering amount θ is reversed so that the detected steering amounts θ _F and θ _R are intuitively connected to the direction of movement of the
The steering operation is performed so that the detected steering amounts θ _F and θ _R match the target steering amount θ. The inverting amplifier _A1 and the switch circuits S and _S1 constitute a polarity inverting means.

The valve driving circuits 11 and 12 are constructed of circuits having the same structure, each consisting of comparators A ₅ and A ₆ ' and switch circuits A ₆ and A ₆ '.
Further, in FIG. 2, E is an engine.

By the way, in this embodiment, the steering operation is performed directly using the steering wheel 5, but since each control parameter such as the target steering amount θ and the shift position of the transmission 13 can be given as an electric signal, it is possible to perform the steering operation by radio control or the like. The present invention can be similarly implemented using remote control or an automatic driving system that automatically runs based on each control parameter.

[Brief explanation of drawings]

The drawings show an embodiment of a traveling vehicle according to the present invention,
Figure 1 is an overall plan view of the lawn mowing vehicle, and
The figure is a block diagram of the control system. 2...front wheel, 3...rear wheel, 13...transmission,
A ₂ , A ₃ ... Comparison control means, θ ... Target steering amount, θ _F , θ _R ... Detected steering amount, R ₁ ...
Target steering amount indicating means, R ₂ , R ₃ ... Steering amount detecting means.

Claims (1)

[Claims] 1. A running vehicle configured such that both front wheels 2, 2 and rear wheels 3, 3 can be steered, and the steering amounts θ _F and θ _R of the front wheels 2, 2 and rear wheels 3, 3 are detected, respectively. means R ₂ and R ₃ ; means R ₁ for instructing the target steering amount θ which is artificially _changed ; The target steering amount θ is compared with the steering amounts θ _F , θ _R detected by the detection means R ₂ , R ₃ , and the front and rear wheels 2, 3 are rotated until the detected steering amounts θ _F , θ _R match the target steering amount θ. Comparison control means A ₂ , A ₃ for steering and driving the front wheels 2 ,
2 and the rear wheels 3 and 3 in the same direction, the polarity of the target steering amount θ with respect to the neutral position is reversed based on the detection operation of the backward movement state detection means, and the comparison is performed by reversing the polarity of the target steering amount θ with respect to the neutral position. A running vehicle comprising polarity reversal means for applying control means A ₂ and A ₃ .