JPH02213792A - Moving object detector - Google Patents

Abstract

PURPOSE:To prevent erroneous announcement by providing a transfer direction detecting circuit and a transfer interval deciding circuit and outputting a detection signal when the output value of an arithmetic circuit which subjects one value of direction signals to addition and the other value to subtraction exceeds the threshold. CONSTITUTION:A timer circuit 11 measures the generation intervals of the transfer signals Z and the output of the circuit 11 is inputted to a memory 12 and the transfer interval deciding circuit 13. The memory 12 temporarily stores the output value of the circuit 11 until the next output value is inputted. The circuit 13 compares the value inputted from the circuit 11 and the value stored in the memory 12 and outputs a signal C to be counted when the difference therebetween is within a prescribed range. The value in the memory 12 is not rewritten and the previous value is maintained when the signal C is not generated. The arithmetic circuit 10 adds or subtracts the signal C in corresponding to the direction signal D and a search signal is obtd. when the absolute value of the output value of the circuit 10 exceeds the prescribed value set in a threshold circuit 14.

Description

[Detailed description of the invention] [Industrial application field]

The present invention emits continuous energy waves such as ultrasonic waves and microwaves into a monitoring space, and detects the frequency shift of reflected waves caused by the movement of objects in the monitoring space. The present invention relates to a moving object detection device that detects the presence of a moving object.

[Conventional technology]

Generally, this type of moving object detection device emits continuous energy waves such as ultrasonic waves or microwaves of a predetermined frequency into the monitoring space, and the reflections that occur as the Doppler effect as the object moves within the monitoring space. The device is configured to detect frequency shifts in the waves. An example of a moving object detection device that realizes detection of a moving object based on this principle is shown in FIG. 3. In this configuration, a transmitting signal from an oscillation circuit 3 that emits at a constant frequency is converted into an ultrasonic wave by a transmitter 1 and radiated into a monitoring space, and the reflected waves from a moving object existing in the monitoring space are received by a receiver. 2 and converts it into a received signal Ein. The received signal Ein is mixed by a pair of mixers 5a and 5b with reference signals Eo and Eo' having the same frequency as the transmitting signal outputted from the transmitting circuit 3, respectively, to produce a pair of Doppler signals E, which are beat signals. E' is obtained. Here,
One reference signal Eo is obtained by passing the output of the oscillation circuit 3 through the phase shift circuit 4, and the other reference signal E0' is obtained as the output of the oscillation circuit 3. Therefore, both reference signals E o ,
E o ′ are set so that their phases are different from each other. As a result, a pair of Doppler signals E are obtained as beat signals at the outputs of the mixers 5a and 5b. The zero Doppler signals E and E', in which E' also has different phases, are input to the quadrant signal generation circuit 7 after being amplified by amplifier circuits 6a and 6b, respectively. Now, assuming that the phase difference between Doppler signals E and E' is 90 degrees, and considering a vector whose components are both Doppler signals E and E', this vector changes as the object moves, as shown in Figure 4. It will move on a vector plane. Here, the direction of rotation of the vector on the vector plane corresponds to whether the object approaches or moves away. Considering such a vector plane, the polarities of the Doppler signals E and E' can be combined to correspond to four quadrants (1) to (2) on the vector plane. That is, since the polarity of each Doppler signal E, E' is positive and negative, both Doppler signals E,
By combining E', four states can be expressed, and these four states correspond to each quadrant I to ■ on the vector plane. The quadrant signal generation circuit 7 outputs a quadrant signal Q corresponding to the quadrant in which the vector exists in the vector plane, and also outputs a quadrant signal Q corresponding to the quadrant in which the vector exists in the vector plane. When the boundary line of ~■ is crossed, a transition signal Z indicating that the change in the quadrant has shifted is outputted. The quadrant signal Q is input to the memory 8 and the transition direction detection circuit 9. The memory 8 temporarily stores the quadrant signal Q until the next quadrant signal Q is input. Also,
The transition direction detection circuit 9 compares the previous quadrant signal Q stored in the memory 8 with the current quadrant signal Q output from the quadrant signal generation circuit 7, and determines whether the vector is the boundary of the quadrant in the vector plane. When the robot moves beyond the line, it outputs a binary direction signal depending on whether the move is counterclockwise or clockwise. The transition signal Z and the direction signal are inputted to the arithmetic circuit 10, and the transition signal Z is added to one value of the direction signal, and the transition signal Z is added to the other value of the direction signal.
is subtracted. That is, the output value of the arithmetic circuit 10 corresponds to the difference between the transition in the clockwise quadrant and the transition in the counterclockwise quadrant. For example, if the above vector is a as shown in FIG.
” If we move in the vector plane with a trajectory of −e,
Since the boundary line of the quadrant is crossed counterclockwise at points other than 0, if counterclockwise rotation is determined to be addition in the arithmetic circuit 10, the transition signal 2 will be added at points other than 0, and subtracted at point 0. While performing such addition and subtraction, if the absolute value of the output value of the arithmetic circuit 10 exceeds a predetermined value set in the threshold circuit 14, the threshold circuit 14 outputs a detection signal, which is sent through the alarm drive circuit 15. The alarm is activated. Here, the arithmetic circuit 10 is reset at appropriate intervals to prevent the output value from being accumulated due to external noise or the like and from outputting the detection signal. As mentioned above, Doppler signal E. , E0' as components changes in the quadrant on the vector plane, it is possible to detect the presence of a marked object in the monitoring space.

Problem M to be Solved by the Invention In the above configuration, when the number of occurrences of transition of the quadrant in the vector plane of the □ vector whose components are the Doppler signals E and E' reaches a predetermined value, the moving object moves in the monitoring space. Since the arithmetic circuit 10 is determined to be present and the arithmetic circuit 10 is reset at appropriate intervals, false alarms can be prevented for relatively short-term noises. By the way, the interval at which the transition occurs is the Doppler signal E. It depends on the period of E', and the shorter the period of the Doppler signals E and E', the shorter the transition interval. Further, the period of the Doppler signals E and E' becomes shorter as the difference between the output frequency of the oscillation circuit 3 and the frequency of the received signal Ein becomes larger. Therefore, if there is a noise source with a relatively large frequency difference with respect to the output frequency of the oscillation circuit 3, and the noise continues to occur for a long time, the output value of the arithmetic circuit 10 will change in a short time. increases or decreases, and the output value of the arithmetic circuit 10 exceeds a predetermined value set in the threshold circuit 14 during the reset period of the arithmetic circuit 10, resulting in a problem that false alarms occur. The present invention aims to solve the above-mentioned problems, and even if there is a noise source with a relatively large frequency difference with respect to the output frequency of the oscillation circuit and the noise continues for a long time, it will not cause false alarms. The object of the present invention is to provide a moving object detecting device that does not cause such problems.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a transition direction detection circuit that generates a binary direction signal corresponding to the direction in which a quadrant has changed based on a quadrant signal, and a transition direction detection circuit that generates a binary direction signal corresponding to a direction in which a quadrant has changed based on a quadrant signal. A transition interval determination circuit is provided that generates a counted signal of a constant value when the current transition signal generation interval is within a predetermined time range, and adds the counted signal to one value of the direction signal. For the other value of the direction signal, when the output value of the arithmetic circuit for subtracting the signal to be counted exceeds a predetermined threshold value, the threshold circuit outputs a detection signal.

[Effect]

According to the above configuration, addition and subtraction are performed in the arithmetic circuit only when the generation interval of the current transition signal is within a predetermined time range with respect to the generation interval of the past transition signal. If noise with a large frequency difference continues and the generation interval of transition signals is short, no countable signal corresponding to this transition signal is generated, and no addition or subtraction is performed in the arithmetic circuit. In other words, since the noise sources described above do not affect the output value of the arithmetic circuit, it is possible to prevent false alarms from occurring.

【Example】

FIG. 1 shows a block diagram of this embodiment. Since the basic configuration for detecting a moving object is as explained in the "Prior Art" section, the same parts as the configuration explained in FIG. The same reference numerals are used to omit the explanation. Therefore, the following description will focus on the features of this embodiment. That is, in this embodiment, the transition signal Z generated from the quadrant signal generation circuit 7 is not directly input to the arithmetic circuit 10, but is processed by the timer circuit 11, memory 12, and transition interval determination circuit 13 before being input to the arithmetic circuit 10. The to-be-counted signal C is input to the . The timer circuit 11 is a circuit that measures the generation interval τd of the transition signal Z, and the output value of the timer circuit 11 is input to the memory 12 and the transition interval determination circuit 13. The memory 12 temporarily stores the output value of the timer circuit 11 until the next output value is input. The transition interval determination circuit 13 compares the value inputted from the timer circuit 11 and the value stored in the memory 12, and outputs the count signal C if the difference is within a predetermined range. Therefore, the transition interval determination circuit 13 determines the current generation interval τd1 of the transition signal and the generation interval τ of the previous transition signal.
d and -3, and it is determined whether or not to generate the count signal C based on the magnitude of τd and -τda-1. Furthermore, when the count signal C is not generated, the memory 1
The value within 2 is not rewritten and the previous value is retained. The counted signal C is, for example, a pulse signal, and the transition signal 2
When the transition interval determination circuit 13 satisfies the above-mentioned conditions when this occurs, one pulse is output. The arithmetic circuit 10 adds or subtracts this count signal C in correspondence with the direction signal, and when the absolute value of the output value of the arithmetic circuit 10 exceeds a predetermined value set in the threshold circuit 14, a detection signal is obtained. It is. By the way, the speed of a moving object existing in a monitoring space rarely changes suddenly, but generally changes continuously. Therefore, it can be assumed that the generation interval τd of the transition signal Z also does not change suddenly. Therefore,
If the transition interval determination circuit 13 sets the determination conditions, for example, 0.51: da-+<τd, <2τ7-3, it will be determined that the transition signal Z is generated by a reflected wave from a moving object. It is possible. Furthermore, if this condition is not satisfied, the transfer signal Z is determined to be noise and is ignored. In the above condition settings, even if the upper limit of the generation interval τd of the transition signal Z is infinite, there is no problem because it is regulated by the reset period of the arithmetic circuit 10, but the lower limit must be regulated to an appropriate value. To set the lower limit value, it is sufficient to consider the upper limit value υ of the speed of the moving object to be detected.In other words, if the wavelength of the energy wave to be transmitted is λ, the Doppler signal E
, E' can be approximated by λ/2υ. Since one cycle is divided into four quadrants, transition signal 2 ideally occurs four times in one cycle. Therefore, the lower limit value of the generation interval of the transition signal 2 may be set to λ/2υ÷4=^/8υ. With the above configuration, for example, when a quadrant signal Q with a short duration is generated, such as the fourth quadrant signal Q (denoted as IV) in FIG. However, since the interval between the occurrences of the transition signal 2 is short, the above condition cannot be satisfied, and this transition signal Z is ignored, and the count value which is the output of the arithmetic circuit 10 does not increase or decrease. In other words, when the interval between occurrences of the transition signal 2 is short, counting is not performed in the arithmetic circuit 10, and it is possible to prevent false alarms from occurring.

【Effect of the invention】

As described above, the present invention includes a transition direction detection circuit that generates a binary direction signal corresponding to the direction in which the quadrant has changed based on the quadrant signal, and also detects the current transition with respect to the generation interval of the transition signal in the past. A transition interval determination circuit is provided that generates a counted signal of a constant value when the signal generation interval is within a predetermined time range, and adds the counted signal to one value of the direction signal and calculates the value of the other direction signal. For the value of , the threshold circuit outputs a detection signal when the output value of the arithmetic circuit that subtracts the counted signal exceeds a predetermined threshold value, and the detection signal is output from the threshold circuit. Since addition and subtraction are performed in the arithmetic circuit only when the current transition signal generation interval is within a predetermined time range, noise with a large frequency difference with respect to the transmission frequency continues and the transition signal generation interval is If it is short, no count signal corresponding to this transition signal is generated, and no addition or subtraction is performed in the arithmetic circuit. In other words, the above-described noise source has the advantage of preventing the occurrence of false alarms because it does not affect the output value of the arithmetic circuit.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the same operation as above, Fig. 3 is a block diagram showing a conventional example, and Fig. 4 is an explanation of the operation of the moving object detection device according to the present invention. It is a diagram. 1... Transmitter, 2... Receiver, 3... Oscillation circuit,
4... Phase shifter, 5a, 5b...-Mixer, 6a, 6
b...Amplification circuit, 7...Quadrant signal generation circuit, 8...
・Memory, 9... Transition direction detection circuit, 10... Arithmetic circuit, 11... Timer circuit, 12... Memory, 13
... Transition interval determination circuit, 14... Threshold circuit, 15.
...Alarm drive circuit, C...signal to be counted, D...direction signal, E, E'...Doppler signal, E o, E
o'...Reference signal, Ein...Received signal, Q.
... Quadrant signal, Z... Transfer signal. Agent Patent Attorney Ishi 1) Voluntary author of the 7th Procedural Amendment) June 10, 1999

Claims (1)

[Claims] (1) An oscillation circuit that oscillates at a predetermined frequency, a transmitter that converts the transmission signal from the oscillation circuit into a continuous energy wave and transmits it to the monitoring space, and reflected waves from objects moving within the monitoring space. A receiver receives the signal and outputs a received signal, and a pair of reference signals that have the same frequency as the transmitted signal but have different phases are mixed with the received signal and converted into a pair of Doppler signals that have different phases. A quadrant signal generator that generates a quadrant signal corresponding to a quadrant on a vector plane of a vector whose components are a pair of mixers and a pair of Doppler signals output from both mixers, and also generates a transition signal when the quadrant changes. a transition direction detection circuit that generates a binary direction signal corresponding to the direction in which the quadrant has changed based on the quadrant signal; A transition interval determination circuit generates a counted signal of a constant value when the time range is within a time range of an arithmetic circuit that subtracts the count signal;
A moving object detection device comprising: a threshold circuit that outputs a detection signal when an output value of the arithmetic circuit exceeds a predetermined threshold value.