JPH01212382A - Doppler sensor - Google Patents

Abstract

PURPOSE:To enhance the accuracy of a detection value even in a high speed region, by changing over the filter constant of a Doppler sensor for detecting ground speed on the basis of a microwave in a non-contact manner on the basis of the number of rotations of an engine and a gear change position. CONSTITUTION:A Doppler sensor 2 is connected to the CPU 1 provided to a tractor and an LPF 3 is inserted in said Doppler sensor 2 and, further, the number 4 of rotations of an engine and a gear change position 5 are connected to input the detection values of both of them to the CPU 1. The T-type LPF 3 is earthed by connecting a terminal 8 between coils L1, L2 and connecting a condenser C and a resistor R3 to the terminal 8. When an earth speed is within a low speed region, the vibration component of a machine body is inputted to the LPF 3 as a high-pass frequency component and almost cut. When the LPF 3 is inserted in the Doppler sensor 2 in order to cut the vibration component of the machine body, the component of a high-pass frequency band is also cut. Hereupon, the number 4 of rotations and the position 5 are preliminarily inputted to the CPU 1 and, when both of them are changed, a constant change-over order for changing over the constant of the LPF 3 is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Doppler sensor, and particularly to a Doppler sensor for detecting the ground speed of a tractor or the like.

[Prior Art] When measuring the ground speed of a tractor or the like, a Doppler sensor may be used. That is, when the ground speed of a tractor or the like is detected by a Doppler sensor, the ground speed of the tractor or the like is measured by detecting the microwave reception value of the Doppler sensor.

[Problems to be Solved by the Invention] When measuring ground speed with the Doppler sensor, vibrations of the aircraft mix into the Doppler sensor signal in low speed ranges, making it impossible to detect accurate values. Therefore, LPF
If a (low-pass filter) is inserted to cut the vibration component, the accuracy in the low ground speed range will be improved, but the accuracy in the high speed range will be reduced. Therefore, a technical problem arises that must be solved in order to obtain high accuracy of the detected value of the Doppler sensor even in the high-speed range, and it is an object of the present invention to solve this problem.

[Means for Solving the Problems] The present invention was proposed to achieve the above object, and the filter constant of the LPF of a Doppler sensor that non-contactly detects ground speed using microwaves is It is an object of the present invention to provide a Doppler sensor characterized in that it is configured to change gears depending on the position of the gear change.

"Operation" Since the LPF is inserted into the Doppler sensor of this invention, it is natural that vibration components of the aircraft body occurring in the low ground speed range are cut by the LPF.

In addition, at high ground speeds, the filter constant of the LPF is changed depending on the engine rotation speed and the gear change position, so for example, at ground speeds above -, the filter constant is changed. Thus, the cutoff frequency of the LPF can be set high. In such a case, for example, the ground speed of a tractor or the like can be expected to provide highly accurate detection values from the Doppler sensor in both low and high speed ranges.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings. A CPU (1) is provided in a tractor, etc. not shown,
A Doppler sensor (2) is connected to this CPU (+). And this Doppler sensor (2) has L P
F (3) has been inserted. Furthermore, the CPU(+)
The engine rotation speed (4) and gear change position (5) are connected and each detected value is input to the CPU (+). Therefore, the means for detecting the engine speed (4) and the means for detecting the gear change position (5) should not be particularly limited.

Therefore, the L inserted into the Doppler sensor (2)
P F (3) is generally not T-shaped as shown in Figure 2,
The π type is used. Then, the resonant frequency (f) in this L P
The output frequency band can be changed via F (3).

Figure 2 shows a T-type L P F (3), where C is a coil, C is a capacitor, and R
is resistance. In this T-type L PF (3),
A resonant circuit is formed by the inductance of the coil L, the capacitance of the capacitor C, or the resistance R, and the low frequency input from the input terminal (6) is output from the output terminal (7). Also, the terminal (
8) is connected to the capacitor C and the resistor R3 and grounded, so the coil L1, the resistor R1, the capacitor C, the resistor R3, etc. arranged in series form a high frequency band resonant circuit. The high frequency band is dropped through capacitor C and resistor R3. Then, only the low frequency band is passed through and output. Therefore, when the ground speed is in a low speed range, the vibration component of the aircraft becomes a high frequency component and is input to L P F (3), so that most of this vibration component can be cut out.

Also, as mentioned above, in an attempt to cut the aircraft vibration component, L
When the P F (3) is inserted into the Doppler sensor (2), even when the ground speed is high, the necessary high frequency band components are cut and the Doppler sensor (2)
accuracy is reduced. Therefore, input the engine speed (4) and gear change position (5) to the CPU (1),
When the engine speed (4) and the position of the gear change (5) change, a constant switching command for L P F (3) is outputted from CPtJ so as to switch the constant L P F (3). Therefore, since the constant of LPF (3) is generally determined by the above-mentioned value or C, the value of L or C is set to a value corresponding to a low speed of the ground speed and a value corresponding to a high speed, respectively, and these values are set alternately. This is done so that it can be switched. Alternatively, the L P F (3) may be operated only in the low speed range, and the operation of the L P F (3) may be cut off in the high speed range. Therefore, the engine rotational speed (4) and gear change position (5) to be changed will be explained with reference to FIG. The figure shows an example of the switching example.
Gear change position (5) G, L, L speed and M1 to M3
When the vehicle is at a high speed, the constant L P F (3) is switched to operate in a low speed range. Also, the gear change position (5) is M4 speed and the engine speed (4) is 20.
The same applies when the speed is 00 rpm or less. Furthermore, the same applies when the gear change position (5) is H1 speed and the engine speed (4) is 150 rpm.

Also, when the gear change position (5) is M4 speed and the engine speed (4) is 2000 rpm- or more, and when the gear change position (5) is H1 speed and the engine speed (4) is 1500 rpa+ When it is above, L P
The constant of F (3) is switched to operate in the high speed range. That is, as mentioned above, L P F (
In order to make LPF (3) work properly in the low and high speed ranges of ground speed, the filter constant is changed to alternately switch to the low speed equivalent value and the high speed equivalent value, so that LPF (3)
The most effective way to do this was to improve the accuracy of the Doppler sensor's detection values.

It should be noted that the present invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that the present invention extends to such modifications.

[Effects of the Invention] As described in detail in the above-mentioned embodiment, when the ground speed of a tractor or the like is measured by a Doppler sensor, the Doppler sensor has an LPF inserted, so that the ground speed is low. In this region, the LPF operates to cut the vibration component of the aircraft, improving the accuracy of the Doppler sensor in the low ground speed region.

In addition, in the high ground speed range, the filter constant of the LPF is changed to an appropriate value preset by the CPU command, the cutoff frequency is increased, and the necessary micro By improving the accuracy of wave output, the ground speed of tractors, etc. can be measured with high precision using a Doppler sensor.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a control circuit diagram, Fig. 2 is an LPF circuit, and Fig. 3 is an explanatory diagram showing an example of constant switching. Symbol explanation (+)...CPU (2)...Dotsupura sensor (3)...LPF (4)...Engine speed (5)... ...Gear change position patent application Person: Iseki Agricultural Machinery Co., Ltd. r-”--i Agent: Patent attorney Takayoshi Hayashi ゛X-
:-Nini′

Claims (1)

[Claims] A Doppler sensor that detects ground speed using microwaves in a non-contact manner, and is configured so that the filter constant of an LPF of the Doppler sensor is changed depending on the engine rotational speed and the gear change position.