JPH0214006B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a transmitter that emits ultrasonic waves towards the ground and a receiver that receives the reflected waves in order to detect the height above the ground of a working device in order to control the height above the ground. An ultrasonic sensor comprising: is provided on the working device;
The present invention relates to an agricultural working machine provided with a signal generating means that is set when the transmitter emits ultrasonic waves and is reset when the receiver receives reflected waves to generate an output signal corresponding to the time interval between transmitting and receiving the ultrasonic waves.

In conventional agricultural machinery of this type, it is necessary to detect the height from the ground so that the working device does not fall into high places on the ground, so ultrasonic sensors are used to transmit and receive ultrasonic waves. A means of measuring the height above ground based on the time interval of .

However, the absorption rate of ultrasonic waves varies depending on the target object, and the absorption rate is extremely high in areas such as straw and soft soil. Therefore, the amplitude of the received wave becomes smaller, making measurement unstable, and in some cases, the maximum distance that the work equipment can measure with its sensor (corresponding to the ultrasonic transmission period) without receiving the reflected wave. This has the disadvantage that the working device is automatically lowered unnecessarily by erroneously determining that the working device is at a height of

The present invention has been made in view of the above circumstances, and its object is to provide an agricultural machine equipped with an ultrasonic sensor that does not cause the above-mentioned malfunctions.

In order to achieve the above object, the agricultural machine according to the present invention is provided with means for forcibly resetting the signal generating means when a set reception time shorter than the ultrasonic transmission period has elapsed since the ultrasonic wave transmission. It has the following characteristics.

Due to the above characteristic structure, the following excellent effects have been achieved.

In other words, even if the ultrasonic sensor is unable to receive reflected waves from the ground, the signal generation means is automatically reset after a predetermined period of time has elapsed, so that abnormally high erroneous heights above the ground can be detected. As a result, measurement data is no longer output, and control malfunctions caused by this can be reliably prevented.

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

FIG. 1 is a side view of a reaping device 1 as a working device installed at the front of a combine harvester as an agricultural working machine. A weeding tool 5 is provided in front of the pulling device 2. And this weeding tool 5
The lower end tip portion of is fixed to a support frame 7 connected to the body frame 6. As shown in FIG. 2, a plate-shaped member 8 is provided with its front end fixed to the back of the weeding tool 5 and its lower end fixed to the upper part of the support frame 7, and the upper left and right sides of this member 8 have heights above the ground. A transmitter 10 and a receiver 11 of the ultrasonic sensor 9 are respectively attached to detect the ultrasonic wave.

The transmitter 10 of the ultrasonic sensor 9 emits ultrasonic waves towards the ground, and the receiver 11 receives the reflected waves, and measures the time from when the ultrasonic waves are emitted to when they are received. Accordingly, the height of the reaping device 1 above the ground is detected. Then, the reaping device 1 is automatically raised and lowered based on the detection result of the height above the ground, thereby automatically controlling the reaping height.

The measuring device 12 for controlling the operation of the ultrasonic sensor 9 and for generating an output signal corresponding to the time interval between transmission and reception of ultrasonic waves will be described below.

As shown in FIG. 3, the measuring device 12 includes an oscillator 13, a counter 14 that sequentially divides the output signal of the oscillator 13 at a predetermined ratio to generate a necessary control signal, and a predetermined frequency division of the counter 14. Output Q ₂ ,
A first flip-flop 15 generates a gate pulse T ₁ of an ultrasonic signal Q ₁ by Q ₃ , an AND signal of this flip-flop output T ₁ and the ultrasonic signal Q ₁ , that is, a predetermined period t ₁ and a predetermined A first gate 16 that outputs an ultrasonic signal at time t ₁ and a first amplifier 17 that receives an output signal T ₂ of this gate 16, amplifies it to a predetermined level, and drives the transmitter 10 of the ultrasonic sensor 9. , and a second amplifier 18 that amplifies and detects the reflected wave from the ground received by the receiver 11 of the ultrasonic sensor 9 to a predetermined level, and the output signal of this amplifier is waveform-shaped and converted into a digital signal. a comparator 19 that generates a signal, a second gate 20 that generates an OR signal of the output signal T ₃ of the comparator 19 and the predetermined frequency division ratio output signal Q ₄ of the counter 14;
is reset by the output signal _T4 of 0 and the first
The main part is a second flip-flop 21 as a signal generating means which is set by the output signal _T1 of the flip-flop 15 and generates a pulse signal _T5 corresponding to the ultrasonic transmission/reception time interval.

As shown in the timing chart of FIG. 4, when the receiver 11 emits a reflected wave, an "H" level pulse signal is output corresponding to the ultrasonic transmission/reception time interval _t2 . T ₅ is the second
However, if this receiver 11 is unable to receive the reflected wave for some reason, the second flip-flop 21 is forcibly reset by the reset means. In other words, the second flip-flop 21 is forcibly reset by the predetermined frequency division ratio output signal _Q4 of the counter 14 after a predetermined time _t3 has elapsed since the ultrasonic wave was transmitted.

In other words, the ultrasound transmission period starts from the time of ultrasound transmission.
When the set reception time t ₃ , which is shorter than t ₁ , has elapsed, the second
The flip-flop 21 is forcibly reset.

Therefore, the second flip-flop 21 is
Even if the receiver 11 is unable to receive a reflected wave, it is automatically reset, so that there will be no error in measuring the subsequent transmission and reception times of ultrasonic waves.

Since it is possible to determine whether or not the height above ground measurement data is normal based on the output signal Q ₄ of the counter 14 and the output signal T ₅ of the second flip-flop 21, it is possible to determine whether the height above ground measurement data is incorrect. Measured data is not used, and erroneous control can therefore be reliably prevented.

As shown in FIG. 1, the measuring device 12 is designed to prevent malfunctions in the control system caused by the lead wires from the ultrasonic sensor 9 to the measuring device 12 discarding external noise as much as possible. In addition, it is installed relatively close to the ultrasonic sensor 9 (in this embodiment, behind the lifting device 2) and separately from the machine-side control device 22.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the agricultural machine according to the present invention,
FIG. 1 is a front side view of the combine, FIG. 2 is a perspective view of the main parts, FIG. 3 is a block diagram of the measuring device, and FIG. 4 is a timing chart showing its operation. 1... Working device, 9... Ultrasonic sensor, 10
... transmitter, 11 ... receiver, 21 ... signal generating means.

Claims (1)

[Claims] 1 A transmitter 10 that emits ultrasonic waves towards the ground and a receiver 11 that receives the reflected waves in order to detect the height above the ground of the working device 1 in order to control the height above the ground.
An ultrasonic sensor 9 consisting of The agricultural machine is equipped with a signal generating means 21 that generates a corresponding output signal, and the signal generating means 21 is forcibly activated when a set reception time shorter than the ultrasonic transmission cycle has elapsed since the ultrasonic wave was transmitted. An agricultural machine that is equipped with a means to reset it.