JPH0155842B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a work vehicle such as a tractor, and more specifically, it is capable of automatically steering and going straight in a field, and also automatically runs around the edge of a field.
Furthermore, it is an object of the present invention to provide a working vehicle that can prevent the vehicle from running onto a ridge and falling over, thereby reducing the driver's labor burden and improving safety. The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a partially cutaway left side view of a tractor according to the present invention, and FIG. 2 is a schematic block diagram of an automatic steering/turning control device. During plowing work, this tractor automatically steers by following the boundary INT between cultivated and uncultivated land as a guide, and when it reaches the edge of the field, it automatically turns around on the headland and resumes plowing work while automatically steering. It is structured in such a way that Steering sensor 1 for detecting boundary INT is installed on the upper front part of the side of the bonnet.
There are one set each on the left and right sides of the aircraft. This steering sensor 1 incorporates an infrared light emitting element and a light receiving element, and projects infrared light emitted from the former onto a test object, and captures reflected infrared light from the test object with the latter, which is converted into an electrical signal. Three optical sensors for conversion and output are arranged side by side in the lateral direction of the aircraft body, and the detection castle faces a point a few 10 cm ahead of and slightly outside the landing point of the nose wheel 2. The electric signal is then input to an analog signal processing circuit 3 in order to represent the state of reflection on the object (field surface) by the level of the electric signal.
In Fig. 2, three optical sensors 1 of the steering sensor 1 are shown under conditions where automatic steering is ideally performed.
The relative positional relationship between a, 1b, 1c and the field surface is shown. The outermost optical sensor 1c (on the cultivated land side) only detects the cultivated land CDT, and the middle optical sensor 1b detects the cultivated land CDT and the uncultivated land UCT. and the innermost optical sensor 1a is in a state where it detects only the uncultivated land UCT. Although there are differences depending on the growth condition of grass, unevenness, wetness, etc. of uncultivated land, in general, uncultivated land has a higher reflectance than cultivated land, so the amount of light received by each of the optical sensors 1a, 1b, and 1c, in other words, , the level of the output electric signal of each is highest in 1a, next in 1b, and lowest in 1c. The output electrical signals A, B, and C of the optical sensors 1a, 1b, and 1c are converted into A-B, B-C by the signal processing circuit 3.
Then, P=(A-B)-(B-C) is obtained by performing each subtraction process, and then subtracting the difference between them. Now, as shown in Fig. 2, if the detection area of the intermediate optical sensor 1b covers half of the cultivated land CTD and half of the uncultivated land UCT, B = (A + C) / 2, so P = 0. , when the aircraft is moving near uncultivated land (or cultivated land), the uncultivated land (or cultivated land) occupies a larger portion of the detection area of the optical sensor 1b, so B>(A+C)/2. [B
<(A+C)/2]. Therefore, P<0 [or P
>0], and the absolute value of P is determined depending on the magnitude of deviation from the state shown in Figure 2. In short, P is the deviation between steering sensor 1 and the boundary line INT, which serves as a tracing guide for automatic steering. It serves as a signal that represents the amount of energy. A mileage meter (not shown) is provided on the wheel or a part that rotates in conjunction with the wheel, and the measured value is input to the data processing device 6. Reference numeral 4 denotes a steering angle sensor which can horizontally rotate the left and right front wheels 2 in conjunction with each other in order to detect the horizontal rotation angle of the left and right front wheels 2 with respect to the center line in the left-right direction of the aircraft body, that is, the steering angle. Specifically, a potentiometer is used to obtain an output signal corresponding to the steering angle. Then, the output signal D of the steering angle sensor 4 (however, if the steering angle to the plowed side is negative,
(assuming the steering angle toward the uncultivated side is positive) is the signal processing circuit 3
It is input to the differential amplifier in the signal processing circuit 3 together with the above-mentioned deviation amount detection signal P to obtain a signal corresponding to the difference between the two, E=PD. This difference signal E is obtained by subtracting the actual steering angle from the deviation amount between the steering sensor and the boundary line, so in short, it is the required steering amount (the steering amount that is required even more than the current state). It is a signal representing the For example, even though the aircraft is moving straight (D=0), P>
0 (or P<0), E>0 (or E<
0), which means that it is necessary to move the machine toward the uncultivated side (or the plowed side) by an amount corresponding to the absolute value. Also P>0 (or P<0)
However, due to the automatic steering control etc.

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Claims (1)

[Claims] 1 a steering device that performs steering operation in response to a control signal;
A control circuit that provides a control signal to the steering device, a sensor that identifies and detects the presence or absence of cultivated land, and means that detects the distance between the ridge and the aircraft body in relation to the traveled distance, and the distance detection means If the detected distance is greater than a certain value, the steering device is controlled based on the output of the sensor, and if the detected distance is less than a certain value, a control signal to cause the aircraft to turn is sent to the steering device. A work vehicle characterized by being configured to provide.