JPH0432351B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses ultrasonic waves to measure the distance, speed, etc. from a quay of a ship that is about to berth, and notifies the ship so that it can slow down appropriately. This invention relates to a tracking gate setting device for an ultrasonic measurement system in a system that supports berthing.

[Prior Art] In this type of berthing support system, the berthing speed of a ship is generally determined using an ultrasonic range finder.
The distance is detected at a predetermined sampling period, and the distance is measured based on the change in this distance over time.

The ultrasonic range finder is configured to measure the time interval between the transmission of a pulsed transmission wave and the reception of a reflected wave from a detection target, and obtain target information from this time information. In this type of measuring instrument, noise due to obstacles, medium density changes, multiple reflections, etc. is frequently received before and after the original received wave.

As an example, a received waveform received by an ultrasonic range finder is shown in FIG. 7a. In the same figure,
The waveform indicates the transmission leakage signal, , indicates the noise signal, and indicates the reflected echo signal from the measurement object targeted by the ultrasonic range finder.
indicates the multiple reflection echo.

As shown in the figure, if a noise signal exists before the target reflected echo signal, the ultrasonic range finder misidentifies the noise signal as the target reflected echo signal and makes an erroneous measurement.

In order to prevent such erroneous measurements, the ultrasonic range finder captures the desired reflected echo signal at the initial point of measurement and then removes the noise signal, as shown in Figure 7b above. A mask gate may be applied using a mask signal.

This mask gate opens just before the expected reception of the desired reflected echo signal, and operates to enable subsequent signal components to be received. Figure 7c
shows the signal waveform obtained in this case.

Further, this mask signal may be set so that the mask gate is opened only when the target reflected echo signal is expected to arrive, and then closed again. This example is shown in dashed lines in Figure 7b. In this case, the signal portion shown in c in the same figure disappears.

The mask signal described above is controlled to move in synchronization with the movement of the target reflected echo signal (movement of the arrival time), so it is called a tracking gate, and it always detects the arrival of the target reflected echo signal. It is controlled to open just before.

In measuring instruments such as ultrasonic range finders, only the noise that exists before the target reflected echo signal causes erroneous measurements, so a mask gate is applied using a mask signal as shown in Figure 7b above. As a result, a signal waveform as shown in FIG.

The circuit shown in FIG. 8 is an example of such a conventional noise removal circuit for a measuring instrument having a gate function. This noise removal circuit includes an amplifier 1 that amplifies an input signal, a mask signal generation circuit 2 that generates a mask signal, and an analog switch 3 that opens and closes using the mask signal as a control signal.
This analog switch 3 is closed during the mask signal generation period when the mask signal shown in FIG. 7b is at a high level, and prevents output of the input signal.

[Problems to be solved by the invention] As mentioned above, the conventional gate setting function can be expected to have some effect on noise removal, but depending on the measurement state, it may have the following problems. Ta.

In other words, due to a sudden displacement of the measurement target, the reflected echo signal shown as a waveform in FIG. If this happens, the output signal waveform will be 0, as shown in FIG. Further, for some reason, the received wave does not arrive, so the output signal waveform may become 0.

In such a case, the current measurement data cannot be used as the basis for the tracking gate for the next measurement, so the predicted arrival time for the next measurement is calculated using the measurement data used the day before last, and based on this, This means that a tracking gate must be set. Therefore, the error increases accordingly, and there is a possibility that the reflected echo signal may not be captured even during the next measurement. The longer this situation continues, the more the error increases, creating a vicious cycle, which in turn poses a problem in berthing support for ships.

The present invention has been made to solve the above problem, and when a reflected echo signal cannot be captured within the tracking gate, the lost reflected echo signal is recaptured and used as a reference for later tracking gate setting. A tracking gate setting device for a berthing support system that can break the vicious cycle of increased tracking gate errors, always set the tracking gate accurately, and do not interfere with ship berthing support. The purpose is to provide

[Means for solving the problem] The first invention of the present application uses ultrasonic waves to measure the distance from the quay of a ship that is attempting to berth, and notifies the ship of the distance, thereby assisting the ship to appropriately slow down and berth. It is a tracking gate setting device for the ultrasonic measurement system in the system, and as shown in Figure 1, it is a tracking gate setting device for the ultrasonic measurement system. The predicted arrival distance is calculated, and the predicted arrival time of the received wave after the transmitted wave is transmitted at the next measurement time is calculated from the predicted arrival distance and the speed of sound, and a tracking gate with a preset time width is calculated based on the predicted arrival time. tracking gate signal forming means for forming a signal;
reception off detection means for detecting that the reflected wave could not be received within the tracking gate set above and outputting a reception off signal; and gate setting means for fully opening the gate for the received signal upon receiving the reception off signal.

Further, the second invention of the present application, as shown in FIG.
The first aspect of the present invention is characterized in that, as a further feature, gate width changing means is added, which detects the distance of the ship from the quay and changes the time width of the tracking gate.

[Function] In the above configuration, the tracking gate signal forming means first calculates the predicted travel distance based on the distance from the quay to the ship, the speed, and the ultrasonic transmission period calculated from the previous measurement values. demand. Here, for the distance and speed, the obtained data is used as is in the measurement data processing means of the support system. However, it may be calculated separately.
The predicted travel distance is calculated by calculating the expected travel distance of the ship from the speed and transmission period, assuming that the ship's speed remains constant until the next measurement, and using this result and the position of the ship at the time of the previous measurement. calculate.

The predicted arrival time is determined by calculating the time required for the ultrasonic pulse to travel back and forth based on the predicted arrival distance calculated above. The tracking gate signal is set in consideration of a preset time width based on the predicted arrival time. That is, since the gate may arrive in a shorter or longer time than the calculated predicted arrival time, the actual gate is set to be shorter than the predicted arrival time by a set time width.

Although this time width may be constant, more preferable results can be obtained if the width is varied depending on the distance of the ship from the quay. For example, make the width wider for long distances and narrower for short distances. The width can be simply changed in two stages: long distance and short distance, or it may be made to gradually become narrower as the distance increases.

The tracking gate signal is configured to have different high and low levels, for example, depending on when it is in the receivable time domain and when it is not receivable. For example, the former is set to low level, and the latter is set to high level.

The reception off detection means detects that the reflected wave cannot be received within the tracking gate set above and outputs a reception off signal. Detection of reception off is performed by checking the presence or absence of a reception signal at the front end of the support system.

The gate setting means receives the tracking gate signal and sets a gate for the received signal.
That is, when the tracking gate signal is in the receivable time domain, for example, the gate is opened while the tracking gate signal is at a low level. On the other hand, when the tracking gate signal is in the unreceivable time region, for example, the gate is closed while it is at a high level.

Further, the gate setting means receives the receiving off signal and fully opens the gate for the received signal when the tracking gate signal at the time of the next measurement is in the unreceivable time region. This makes it possible to capture a new reflected wave echo during the next measurement when wave reception is off. Thereafter, a tracking gate can be set based on this newly captured reflected wave echo. Therefore, the accuracy of the tracking gate is not deteriorated.

[Example] An example of the present invention will be described with reference to the drawings.

<Configuration of First Embodiment> FIG. 2 shows the configuration of an embodiment of the tracking gate setting device of the present invention.

The tracking gate setting device shown in the figure includes a microcomputer 30 that functions as a tracking gate signal forming means, a gate width changing means, and a reception off detection means, and a gate setting means 40.

The microcomputer 30 includes a microprocessor 31, a counter 32, a memory 33,
I/O port 34 and bus 35 connecting these
It is equipped with In addition to the gate setting means 40, the I/O port 34 is connected with a receiving circuit 50, a time measuring circuit 60, and a timing signal generating circuit 70, which constitute part of the front end.

The gate setting means 40, as shown in FIG.
A flip-flop circuit 41 that is set by a gate open signal that opens a tracking gate and reset by a gate close signal that closes the tracking gate; and a flip-flop circuit 42 that is set by a reception off detection signal and reset by a reception input signal.
, an OR gate 43 that takes the logical sum of the outputs of the flip-flop circuits 41 and 42, an AND gate 44 that takes the logical product of the output of the OR gate 43, and the inverted signal of the transmission mask signal, and the output of the AND gate 44. and an AND gate 45 that performs logical product with the received input signal. In this gate setting means 40, an AND gate 45 serves as a gate for a received input signal, and other circuit elements are gate control elements therefor. Note that the transmission mask signal input to the AND gate 44 is a mask signal for preventing malfunctions due to leakage input in the reverberation time region during and immediately after transmission of the transmission wave.

As shown in FIG. 4, the reception circuit 50 includes a flip-flop circuit 51 that is set by a transmission command pulse signal and reset by a reception input signal pulse or reception off signal, and a logic circuit between the output of the flip-flop circuit 51 and a clock pulse. It is configured to include an AND gate 52 that takes the product, and an OR gate 53 that takes the logical sum of the reception input signal pulse and the reception off signal.

As shown in FIG. 4, the time measuring circuit 60 includes a counter 61 that starts counting with a transmission command pulse and counts clock pulses outputted via the AND gate 52.

The timing signal generation circuit 70 outputs timing signals such as a transmission command pulse signal, a transmission mask signal, and a clock pulse. The transmission command pulse is output according to a preset transmission cycle. This transmission cycle is not limited to one type, but can be set in multiple types, and the optimum transmission cycle can be selected according to the position of the ship. In the case of this embodiment, the microprocessor 31 selects the transmission cycle based on whether the position of the ship calculated from the measured value is within a preset distance range. For example, the transmission cycle is set to 1.0 seconds when the ship is farther than 30m from the quay, and when the ship is closer than 30m from the quay.
It is set to 0.5 seconds.

Although not shown on the front end,
In addition, it has a transmitter that outputs burst pulses as a transmission wave, an amplifier that amplifies the received signal, a detector that extracts the pulse envelope from the burst pulse, a noise removal circuit that removes noise, etc.
The transducer is connected.

<Operation of the first embodiment> The operation of the present embodiment configured as described above will be explained with reference to the above-mentioned figures and FIGS. 5 and 6.

The microprocessor 31 first sets a tracking gate signal (step 1). This setting is performed, for example, by the procedure shown in FIG.

That is, the microprocessor 31 uses the memory 33
The previous measured value (time required for ultrasonic round trip) stored in is read out, and the distance to the target ship is calculated from the measured value and the underwater sound speed (step 11).
In the memory 33, the microprocessor 31 stores the measurement values sent from the time measurement circuit 60 in a preset area. At that time, the previous measured value is updated with the new measured value.

Note that in this embodiment, the previous value is used as the measured value, but a moving average value for a plurality of measurements may be calculated and this moving average value may be used as the measured value for the above calculation.

Next, the microprocessor 31 stores the calculated distance value in a specific area of the memory 33. Thereafter, the speed of the ship is calculated from the distance and the transmission period of the ultrasonic waves (step 12). Note that the ultrasonic transmission cycle is stored in advance as a constant in memory or in a program, but in this example,
The memory 33 stores data for two types of transmission cycles. Therefore, here, it is calculated based on the data of the transmission cycle used for the measurement. The selection of this transmission cycle will be described later.

Next, the microprocessor 31 calculates the predicted moving distance of the ship from the above-mentioned calculated speed and the transmission cycle at the next measurement, and combines this predicted moving distance with the calculated distance stored in the above-mentioned memory 33. Calculate the predicted reach distance (distance between the ship and the quay) from (Steps 13 to 16).

In this case, the microprocessor 31 first
It is determined whether the distance from the ship's quay according to the previous measurement is within the preset short range (step 13), and based on the result, one of the two types of transmission cycles preset in the memory 33 is selected. (steps 14a, 14b), and calculate the predicted travel distance of the ship (steps 15a, 15b). A predicted travel distance is calculated based on this predicted travel distance (step 16).

Also, at this time, if the ship enters a short distance area and a different transmission cycle than the previous one is selected,
A command is given to the timing signal generation circuit to change the transmission cycle (step 17).

Furthermore, based on the calculation result of the predicted travel distance and the speed of sound, the round trip time required for the ultrasonic pulse at the time of next transmission is calculated to determine the predicted arrival time of the received wave (step 17).

The microprocessor 31 forms a tracking gate by setting gate open timing and gate close timing with a constant width around the predicted arrival time of the received wave (step 18). This width is set as an allowable width before and after the predicted arrival of the received wave. In this embodiment, the front and back are set to be symmetrical, but it does not necessarily have to be symmetrical.

In this embodiment, this allowable width is made to differ depending on whether the position of the ship is inside or outside the above-mentioned short distance range. That is, in a long-distance area, where the speed of the ship is high, the error tends to be large, and the allowable range is correspondingly set large. On the other hand, in a short distance area,
Because the speed of the ship is low and the influence of erroneous measurements is large, the allowable range is set narrowly.

Considering this permissible width, the larger the permissible width is, the shorter the gate will open after transmission.

The set numerical value of the tracking gate set above is stored in a preset area of the memory 33. In this embodiment, the set value of this gate is set as a target value by a numerical value corresponding to the counted value of the counter 32, which will be described later. The microprocessor 31 then resets the counter 32 and prepares for a new count. The above processing is performed after the previous measurement is completed.

Thereafter, when the transmission command pulse is input from the timing signal generation circuit 70, the microprocessor 31 sends a clock enable signal to the counter 32, and the clock oscillator (not shown) inside the microprocessor 31 starts counting clocks. (Step 2).

Next, it is checked whether the count value has reached the target value (the time from transmitting the ultrasonic pulse to the tracking gate opening timing) (step 3), and if it has not reached the target value, this step is repeated. When the target value is reached, a gate open signal is output (step 4).

After this, the microprocessor 31 resets the counter 32 and sends a clock enable signal to start counting clocks from a clock oscillator (not shown) inside the microprocessor 31 (step 5).

Next, the microprocessor 31 checks the output level of the flip-flop circuit 51 of the receiving circuit to detect the presence or absence of a received signal. If there is a received signal, proceed to step 9. On the other hand, if there is no received signal, the process moves to step 7. Step 7
Now, it is checked whether the count value has reached the target value (the time from the tracking gate opening timing to the tracking gate closing timing). The process returns to step 6 until the target value is reached. Thereafter, steps 6 and 7 are repeated until a received signal is input or the count value reaches the target value.

In this state, when the count value reaches the target value without receiving a received signal, the microprocessor 31
determines that the wave cannot be received and outputs a reception off signal (step 8), followed by a gate close signal (step 9).

On the other hand, if the received signal is input before the count value reaches the target value, a gate close signal is output (step 9).

According to this embodiment, the tracking gate signal is formed as described above. Setting of the tracking gate using this gate signal is performed by the circuit shown in FIG.

In the figure, first, the flip-flop circuit 4
When both 1 and 42 are in the reset state, the output of OR gate 43 is at a low level. Therefore, the output of the AND gate 44 becomes low level, the AND gate 45 remains closed, and the input of the received input signal is blocked.

Next, as described above, the microprocessor 31
When a gate open signal is output from the I/O port 34, the flip-flop circuit 41 is set. At this time, if the transmission mask signal is at a low level, the output of the AND gate 44 becomes a high level, and the gate of the AND gate 45 enables input of the reception input signal. In this state, when a received signal is input, the output of the AND gate 45 becomes high level.

On the other hand, when the gate close signal is output from the microprocessor 31, the flip-flop circuit 4
1 is reset, its output becomes low level, and the gate of AND gate 45 is closed.

When the tracking gate is set as described above, the flip-flop circuit 5 of the receiving circuit 50
1 is set by the transmission command pulse and becomes high level, opening the AND gate 52 and allowing input of the clock pulse. As a result, the counter 61 of the time measurement circuit 60 measures the time required from transmitting the ultrasonic pulse to receiving the reflected wave.

Here, when a reception off signal is output during a certain transmission period, the flip-flop circuit 42 is set by this signal. At this time, the flip-flop 51 shown in FIG. 4 is reset and time measurement is stopped. Note that at this time, the results measured by the time measurement circuit are meaningless and are therefore not adopted as measurement values.

If you proceed to the next transmission cycle in this state,
Since the flip-flop circuit 42 is in the set state, one input of the AND gate 44 receives a high level signal. However, while the transmission mask signal is being input, it is inverted and input at a low level, so the output of the AND gate 44 is at a low level. From the time the transmission mask signal changes to low level, the output of the AND gate 44 becomes high level, and the reception signal can be input.
Therefore, if any signal is input from now on, it will be received by the receiving circuit.

In this way, when the reflected wave is received, the measurement result by the time measurement circuit 60 is used to set the tracking gate for the next transmission cycle.

<Modification of the embodiment> In the above embodiment, an example was shown in which the allowable width when setting the tracking gate is varied depending on the distance from the quay of the ship, but even if it is constant regardless of the distance good. In addition, the distance is not limited to two levels, and the allowable width may be finely changed.

[Effects of the Invention] As explained above, the present invention is capable of re-capturing the lost reflected echo signal when it is not possible to capture the reflected echo signal within the tracking gate, and using it as a reference for later setting of the tracking gate. It is possible to break the vicious cycle of increased tracking gate errors, to always set the tracking gate accurately, and to set the tracking gate of the berthing support system without interfering with ship berthing support. effective.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the tracking gate setting device of the berthing support system of the present invention;
The figure is a block diagram showing the structure of one embodiment of the tracking gate setting device of the present invention, FIG. 3 is a circuit diagram showing an example of the structure of the gate setting means used in the above embodiment, and FIG. A circuit diagram showing an example of the configuration of a receiving circuit and a time measuring circuit to be used, FIG. 5 is a flowchart showing the operation of the above embodiment, FIG. 6 is a flowchart showing details of the flowchart, and FIG. 7 is a conventional measurement FIG. 8 is a waveform diagram showing the operation of the dexterity noise removal circuit, and FIG. 8 is a block diagram showing the conventional noise removal circuit for measuring instruments. 30... Microcomputer, 31... Microprocessor, 32, 61... Counter, 33
... Memory, 34 ... I/O port, 40 ... Gate setting means, 50 ... Receiving circuit, 60 ... Time measurement circuit, 70 ... Timing signal generation circuit, 4
1, 42, 51...Flip-flop circuit, 4
3,53...Orgate, 44,45,52...
And gate.

Claims (1)

[Claims] 1. Tracking of an ultrasonic measurement system in a system that uses ultrasonic waves to measure the distance of a ship attempting to berth from a quay, notifies the ship, and supports the ship to appropriately decelerate and berth. This is a gate setting device that calculates the predicted arrival distance based on the distance from the quay to the ship calculated from the previous measurement values, the speed, and the ultrasonic transmission cycle, and then calculates the next measurement based on the predicted arrival distance and sound speed. a tracking gate signal forming means for calculating a predicted arrival time of a received wave after transmission of a transmitted wave at a given time, and forming a tracking gate signal having a preset time width based on the predicted arrival time; Receiving off detection means for detecting that the reflected wave could not be received within the gate and outputting a receiving off signal; receiving the tracking gate signal and setting a gate for the received signal; A tracking gate setting device for a berthing support system, comprising gate setting means for fully opening a gate for the received signal in response to the reception off signal. 2. A tracking gate setting device for an ultrasonic measurement system in a system that measures the distance from a quay of a vessel attempting to berth using ultrasonic waves, notifies the vessel, and assists the vessel in appropriately decelerating and berthing. , Calculate the predicted travel distance based on the distance from the quay to the ship, the speed, and the ultrasonic transmission cycle calculated from the previous measurement values, and use the predicted travel distance and sound speed to determine the distance after transmitting waves at the time of the next measurement. a tracking gate signal forming means for calculating a predicted arrival time of a received wave and forming a tracking gate signal having a preset time width based on the predicted arrival time; detecting a distance from a quay of a ship; Gate width changing means for changing the time width of the tracking gate; and a wave receiving unit for detecting that the reflected wave cannot be received within the set tracking gate and outputting a reception off signal. and gate setting means for receiving the tracking gate signal and setting a gate for the received signal, and for receiving the receiving off signal and fully opening the gate for the received signal. A tracking gate setting device for a berthing support system featuring: