JPH02228565A - System for judging measuring state of speed - Google Patents

Abstract

PURPOSE:To distinguish erroneous measurement from non-speed state of operation clearly by comparing an output of a reception intensity detection means with a reference voltage to output a signal of a state different depending on the erroneous measurement or a non-speed state by stoppage. CONSTITUTION:A photo detector 8 receives reflected light from a road surface where a vehicle runs and a counter 9 performs a counting operation based on an output of the photo detector 8. A reception intensity detection means 10 obtains a signal corresponding to an intensity of the light received based on the output of the photo detector 8. A comparison means 13 compares the output of the reception intensity detection means 10 with a specified reference voltage. A state judging means 11 inputs an output of the comparison means 13 and a signal attributed to an overflow of the counter 9 and outputs a signal of a state different depending on an erroneous measurement or a non-speed state by stoppage. A phase altering means 12 may be replaced with the reception intensity detection means 10 and inputs a signal based on the output of the photo detector 8 to alter a phase of the signal. Then, the signal is outputted to the comparison means 13.

Description

[Detailed Description of the Invention] [Summary] A device is used that can obtain speed information based on reflected light reflected from a running vehicle on the road surface and perform arithmetic processing to visually determine the speed. has been done.

In such a device, when the vehicle is stopped, that is, when the vehicle is in a no-speed state, the speed information remains unchanged and 0 is displayed as the speed display.

On the other hand, for example, when the vehicle approaches a tunnel or the like and the reflected light from the road surface on which the vehicle is traveling suddenly decreases, the vehicle may enter a state similar to a no-speed state even though it is not actually a no-speed state. In order to distinguish between such states, the present invention determines whether, when a signal corresponding to speed is not input from the measurement target, is this due to an erroneous measurement or is it a state of no speed? to be able to judge. To this end, a speed measurement state determination method is provided in which a state determination means that inputs a signal based on the difference between them is provided, and the output of the state determination means can be used to issue an alarm, correct a control system, and the like.

[Industrial application field]

The present invention relates to a speed measurement state determination method for a speed measurement device that measures the running speed of a train, automobile, motorcycle, or other vehicle.

(Prior Art) A traveling speed measuring device that receives reflected light from a running train, car, motorcycle, or other vehicle on the road surface on which it is traveling, and can measure the traveling speed of the vehicle based on the intensity of the reflected light. It has been known.

Such a traveling speed measuring device has a light receiving element that receives the reflected light, and after converting a change in the physical quantity detected by the light receiving element into a voltage change, or directly obtains a detected voltage corresponding to the speed from the light receiving element. Sometimes, it is directly amplified by an amplifier circuit, binarized based on the output of the amplifier circuit, and inputted to the frequency counter 1 as shown in FIG.

A sampling time control pulse Tr from a sampling time control signal generation circuit 2 is inputted to the frequency counter 1, and the counting operation is performed by the sampling time control pulse T6, for example, by counting the count pulses that have arrived within a certain period of time. , converts the count value into a speed value and outputs it. The output of the frequency counter 1 is input to a driver 4 that drives a display 3 composed of a 7-segment numeric display element, etc. The driver 4 drives the display 3, and the count result of the frequency counter 1 is By reading the display, it is possible to know the traveling speed of the vehicle. On the other hand, the traveling speed measuring device is provided with a comparator that compares the count result with the upper and lower limits (■, VL) of the measurement range in order to check whether the count result of the frequency counter is within a predetermined measurement range. It will be done.

Figure 6 shows the count result ■9 and the lower limit of the measurement range■,
A comparator 5 is shown which compares the lower limit value ■L to the comparator 5 from the comparison lower limit data generating means 6. Further, the output of the comparator 5 is input to a display zero reset circuit 7, and the output of the display zero reset circuit 7 is input to the driver 4. When the count result falls below the lower limit value (VL>VM), a control pulse is issued from the comparator 5 to the display zero reset circuit 7, and as a result, a reset signal is sent from the display zero reset circuit 7 to the driver 4. Output and reset the display to zero.

[Problem to be solved by the invention]

By the way, in the conventional traveling speed measuring device as described above, even if the vehicle has stopped and is in a state of no speed, or even if there is an erroneous measurement due to some kind of failure, the input of the frequency counter l is When the vehicle is in an unmanned state or a state close to it, the display on the display 3 is reset to zero.

However, if the application is to be applied, for example, to an automatic control system that controls an engine system, such as a carburetor brake, etc., according to the running speed of the automobile, that is, the count result of the frequency counter 1,
It is necessary to clearly distinguish between the no-velocity state and the erroneous measurement, so that correct control can be performed in accordance with the actual situation.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a speed measurement state determination method that can clearly distinguish between the no speed state and the erroneous measurement.

[Means to solve the problem]

FIGS. 1(a) and 1(b) are block diagrams showing the principle of the present invention. In the speed measurement state determination method of the present invention, the light receiving element 8 receives reflected light from the road surface on which the vehicle travels.

The counter 9 performs a counting operation based on the output of the light receiving element 8. The received light intensity detection means lO obtains a signal corresponding to the received light intensity based on the output of the light receiving element 8. The comparison means 13 compares the output of the received light intensity detection means 10 with a predetermined reference voltage. The state determining means 11 is the comparing means 13
The output of the counter 9 and the signal caused by the overflow of the counter 9 are inputted, and signals of different states are outputted depending on whether it is an erroneous measurement or a no-speed state due to a stop.

Furthermore, when the received light intensity detecting means 10 is replaced by a phase changing means 12, the phase changing means 12 inputs a signal based on the output of the light receiving element 8, changes the phase of the signal, and outputs the signal. The comparing means 13 is the phase changing means 12.
The output of the light receiving element 8 is compared with a signal based on the output of the light receiving element 8. The state determining means 11 inputs the output of the comparing means 13 and the signal caused by the overflow of the counter 9, and outputs a signal of a different state depending on whether the vehicle is in an erroneous measurement or in a state of no speed due to a stop.

[For production]

The signal corresponding to the change in speed is generated by the light emitted from the light source being reflected by unevenness such as the unevenness of the measurement target such as the road surface under the vehicle, and the reflected light is captured by the light receiving element 8 and is reflected by the light receiving element 8. The output is binarized by a Schmitt circuit, for example, and then sent to the counter 9.
is input. On the other hand, a reference clock is input to the counter 9, and the counter 9 counts the reference clock during the period from the rising edge of the binary input pulse to the rising edge of the next pulse. Therefore,
When the automobile stops, the output state of the light receiving element does not change, so the state of the binarized input signal also does not change, and the period of ``I'' continues for a long time. Therefore, the counter 9 overflows.

On the other hand, a signal corresponding to the intensity of light received by the light receiving element 8 is detected by the received light intensity detecting means 10, and the signal and the predetermined reference voltage are compared by the comparing means 13, and the comparing means 13 outputs an output signal. The state determining means 11 obtains the AND of the signal based on the overflow of the counter 9. Therefore, in an erroneous measurement state, the intensity of the light received by the light receiving element 8 is weak, so that the output voltage of the received light intensity detecting means 10 is lower than the predetermined reference voltage.

Therefore, the output signal of the comparison means 13 and the counter 9
Since both the signal and the signal based on the overflow of are at the "H" level, the output of the state determining means 11 is also at the "H'" level. In addition, in the case of no speed, even if the signal based on the overflow reaches the °H" level, the intensity of the light received by the light receiving element 8 is strong, so the output of the comparing means 13 is at the "L II level, The state determining means 11
The output of is also at the "'L" level. In this way, since the output state of the state determining means 11 is different between the non-velocity state and the time of erroneous measurement, these can be distinguished.

As described above, even if the phase changing means 12 is used instead of the received light intensity detecting means 1O, it is possible to distinguish between a no-velocity state and an erroneous measurement.

That is, in the case of erroneous measurement, the intensity of the signal based on the output of the light receiving element 8 is weak, but since it contains an AC component, the comparing means 1
3, two signals having a phase difference are input. Therefore, the comparison means 13 outputs a pulse according to the phase difference. Therefore, the output of the state determining means 11 changes to the "H" level or to the "L11" level.

On the other hand, in the case of no speed, the signal based on the output of the light receiving element 8 does not include an AC component, and the comparison means 1
Since a voltage is applied to one input terminal of the state determination means 11 and the other input terminal is held at zero volts, the output of the comparison means 13 remains at the "L11" level. For example, if the output is taken out via a retrigger pull monostable multi-bicycle brake, it is possible to obtain a signal at the "L11 level" in the case of no speed, and a signal at the "H" level in the case of erroneous measurement. The states can be distinguished by:

〔Example〕

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

FIG. 2 is a block diagram showing an example of a traveling speed measuring device to which the speed measuring state determination method of the present invention is applied. In the same figure, the light receiving elements 14 and 15 are arranged with photodiodes, CdS
, a light receiving part is formed of an amorphous solar cell or other photoelectric conversion material, and an electrode 1 is formed on the light receiving part by vacuum evaporation or the like.
The two pairs of leads were pulled out through 6.16 and the whole was housed in a container having a light-receiving window. Note that this light receiving element 14.
For example, 15 is provided with two sets of a large number of phototransistors, for example, 20, connected in parallel on a printed circuit board,
Similar to the above, the entire device may be housed in a container having a light-receiving window.

Although not shown, one lead of the light receiving element 14.15 is connected to the ground potential, that is, the common line of the power supply (hereinafter referred to as grounded).
The other lead is input to a current/voltage conversion amplifier 17.1, which is comprised of an operational amplifier or the like that converts current changes flowing through these light receiving elements 14.15 into voltage changes. These current/voltage conversion amplifiers 17.18
may be omitted, for example, when the light-receiving elements 14 and 15 are photodiodes or amorphous solar cells that generate a voltage by themselves when they receive light.

The outputs of the current/voltage conversion amplifiers 17 and 18 are input to an addition calculation circuit 19 configured as a received light intensity detection means using an operational amplifier or the like, and a differential calculation circuit 20 similarly configured using an operational amplifier or the like. There is. The output of the differential arithmetic circuit 20 is input to a Schmitt circuit 21, the output of the Schmitt circuit 21 is input to a counter control circuit 22 configured with a one-shot multi-by-break, etc., and the output of the counter control circuit 22 is input to a counter 23 is entered. A reference clock is input to the counter 23 from a reference clock generation circuit 24 composed of, for example, a crystal oscillation circuit or a frequency dividing circuit. Further, an overflow detection circuit 25 configured with, for example, a flip-flop element is provided to input the most significant bit of the counter 23.
The output of 5 is input to an AND gate 26.

On the other hand, the output of the addition calculation circuit 19 is sent to the comparator 27.
is input to one input terminal of the comparator 27.
The other input terminal of the reference voltage setting circuit 28 inputs the reference voltage. The output of the comparator 27 is input to the AND gate 26.

When the road surface on which the vehicle is running is illuminated by light from a light source such as a halogen lamp or sunlight, the light reflected from the road surface enters the light receiving element 14,15. The light receiving element 14, 15 flows in response to the strength of this reflected light.
The current change is converted into a voltage change by the current/voltage conversion amplifiers 17 and 18, and the voltage is obtained from their output terminals. The output voltages of both the current/voltage conversion amplifiers 17 and 18 are input to the differential arithmetic circuit 20,
A voltage corresponding to the difference is obtained at its output terminal. Since the common mode component of the input voltage is sufficiently suppressed in this voltage, the S/N ratio is greatly improved, and it can be used as a signal corresponding to speed (hereinafter simply referred to as speed signal). This speed signal is shown as an AC signal waveform with a symbol e in FIG. 3(a).

This speed signal is then binarized by the Schmidt circuit 21 and input to the counter control circuit 22. In FIG. 3(a) above, the 0 level is used as a reference for increasing and decreasing (+
), (-) and the voltage level range shown by a dashed line is the hysteresis width of the Schmitt circuit 21. The counter control circuit 22 generates a one-shot pulse in synchronization with the rising edge of the output pulse (FIG. 3(b)) of the Schmitt circuit 21, and outputs the one-shot pulse to the counter 2.
3. The counter 23 starts counting in response to a pulse issued from the counter control circuit 22, and continues counting until the next pulse is issued from the counter control circuit 22.

That is, the counter 23 is 'I'+ shown in FIG. 3(b).
, T2, and T3. Therefore, if the period is long like T2 shown in FIG. 3(b), the counter 2
3 causes an overflow. The overflow is detected by the overflow detection circuit 25, which responds to the falling edge of the most significant bit of the counter 23, and as a result, its output state changes to the "°H" level as shown in FIG. 3(C). This is supplied to one input terminal of the AND gate 26. Note that the overflow detection circuit 25
The "H" level output state continues until a signal that does not overflow the counter 23 is input to the counter 23 in subsequent speed signal cycles (
(See T3 in FIG. 3(C)).

On the other hand, if the amount of light incident on the light-receiving element 14.15 decreases due to some kind of failure, etc., as shown in FIG. Output also decreases. When the output voltage of the addition calculation circuit 19 becomes lower than the reference voltage of the reference voltage setting circuit 28, the output state of the comparator 27 changes from the "L" level to the "Hl+ level" as shown in FIG. 3(e). This output is supplied to the other input terminal of the AND gate 26. Therefore, since both input terminals of the AND gate 26 are at the "H11 level," the output state is as shown in FIG.
As shown in f), it changes from "Lo" level to "H" level. In this way, in the case of erroneous measurement due to some kind of failure, the output state of the AND gate 26 changes from the "'L level" to the "H1 level," and this can be used, for example, to activate an alarm circuit (not shown). This causes a light emitting element such as an LED to light up, a piezoelectric buzzer or a speaker to sound to notify that the measurement is incorrect, or sends the output signal of the AND gate 26 to a control circuit (not shown). It is possible to ensure that correct control is performed. On the other hand, when the vehicle is stopped and in a state of no speed, when the counter 23 overflows, the overflow detection circuit 25 outputs the "H"level;
The output of the addition calculation circuit 19, which is the total received light amount signal, does not indicate any abnormality since the light receiving elements 14 and 15 receive sufficient incident light, and the output state of the comparator 27 is "
Therefore, the AND gate 26
The output also maintains the L''' level.

FIG. 4 is a schematic circuit diagram showing another embodiment.

In the figure, the output (A) of the differential arithmetic circuit 20 is supplied to the Schmitt circuit 21 and the capacitor 2
9 and a resistor 30, and is also supplied to an inverting input terminal of an operational amplifier 31. Furthermore, the output of the differentiating circuit, that is, the capacitor 29
The output produced at the junction (B) of the resistor 30 is supplied to the non-inverting input terminal of the operational amplifier 31.

The output of the operational amplifier 31 is the A
The signal is supplied to the ND gate 26.

In this configuration, in the case of erroneous measurement, the strength of the signal based on the output of the light-receiving element 8 is weak, but it contains an alternating current component. Two signals with a phase difference (Φ) are input to. Therefore, the operational amplifier 31 outputs a pulse according to the phase difference as shown in the lower part of FIG. 5(a). Therefore, the AND gate 1
1's output changes to "H" level and "L" level. On the other hand, in the case of no speed, the signal based on the output of the light receiving element 8 does not include an AC component,
Since a voltage is applied to the inverting input terminal of the operational amplifier 31 and the non-inverting input terminal is held at zero volts, the output of the operational amplifier 31 remains at "L" level. If the output is taken out, for example, via a retrigger pull monostable multi-vibration brake, the
If the L" level signal is incorrectly measured, an "Hn level signal can be obtained, and the above-mentioned states can be distinguished from each other.

(Effects of the Invention) As described in detail above, according to the present invention, when a speed measuring device is in a state where no speed signal is input from the measurement target, it is possible to determine whether this is due to an erroneous measurement or not. Since we have made it possible to determine whether or not the vehicle is in a no-speed state as an electrical signal, it is possible to determine based on that state. By using the electrical signal as a control signal, it is possible to carry out correct control in accordance with the actual situation, or to prevent errors by issuing an alarm. It is possible to notify that the speed measurement is being performed, and a speed measuring device with extremely high reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1(a), ■) is a block diagram showing the principle of the present invention,
Fig. 2 is a block diagram showing an example of a traveling speed measuring device to which the speed measurement state determination method of the present invention is applied, and Figs. 3(a) to 3(f) show signal outputs of each part in contrast. FIG. 4 is a schematic circuit diagram showing another embodiment, FIG. FIG. 6 is an explanatory diagram showing the states of input and output signals of the operational amplifier 31 at the time of speed. FIG. 6 is a block configuration diagram showing an example of a conventional traveling speed measuring device. 8... Light receiving element, 9... Counter, lO... Received light intensity detecting means, 11... Status determining means, 12... Phase changing means,

Claims (2)

[Claims] (1) In a traveling speed measuring device that includes a light receiving element that receives reflected light from a road surface on which a vehicle runs, and measures the traveling speed of the vehicle based on a change in the output of the light receiving element, the output of the light receiving element a counter whose counting operation is controlled based on the above, a received light intensity detection means for detecting the received light intensity based on the output of the light receiving element, a comparison means for comparing the output of the received light intensity detection means with a predetermined reference voltage, and the comparison. A speed measurement state determination method comprising a state determination means for determining whether the speed is erroneously measured or not due to a stop, based on the output of the means and a signal caused by an overflow of the counter. (2) In a traveling speed measuring device that includes a light receiving element that receives reflected light from a road surface on which a vehicle runs, and measures the traveling speed of the vehicle based on a change in the output of the light receiving element, the output of the light receiving element A counter whose counting operation is controlled based on the above, a phase changing means for inputting a signal based on the output of the light receiving element, a comparing means for comparing the output of the phase changing means and a signal based on the output of the light receiving element, and the comparison. A speed measurement state determination method comprising a state determination means for determining whether the speed is erroneously measured or not due to a stop, based on the output of the means and a signal caused by an overflow of the counter.