JP3026668B2 - Electronic control unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device,
In particular, it relates to a structure for controlling a synchronization signal for preventing mutual interference when a plurality of devices are provided.

[0002]

2. Description of the Related Art There are various types of electronic control units. One example is an ultrasonic sensor, which emits ultrasonic waves to an object to be detected that is present at a relatively short distance. The detection of the presence, size, and thickness of the object is performed based on the change in the ultrasonic wave reflected from the object.

[0003] There are various uses of an ultrasonic sensor. For example, a sensor for preventing collision mounted on an automatic transport vehicle in a factory can be cited. For automatic guided vehicles,
A plurality of ultrasonic sensors are provided close to each other on the right and left sides of the vehicle so as to travel accurately in a certain traveling area and prevent collision during traveling. . At this time, ultrasonic waves emitted from one sensor may be received by another sensor and cause mutual interference.
When this mutual interference occurs, a malfunction occurs and a collision may occur.

In order to prevent such mutual interference, a method of alternately operating the sensors has been used.
In other words, while one sensor is performing the detection operation, the other sensor does not operate and waits, and the sensor that has been waiting immediately after the sensor that has operated has completed the detection operation starts the detection operation. Like that. FIG. 6 shows an ultrasonic sensor 5.
FIG. 2 shows a block diagram of a system in which 0 and 60 are operated alternately. From the output of a of the synchronization signal generator (sequencer) 55, a signal as shown by 100 in FIG. 4B is output. In response, the ultrasonic sensor 50 outputs the signal 10
The operation is performed only when 0 is at the HIGH level. On the other hand, a signal indicated by reference numeral 200 in FIG. 4B is output from the output b of the synchronization signal generator 55 and is provided to the ultrasonic sensor 60. Since the signal 200 is generated so that the phase of the signal 200 is opposite to that of the signal 100, the ultrasonic sensor 60 operates only during the idle period of the ultrasonic sensor 50. That is, both sensors operate alternately. Which of the two sensors 50 and 60 is operated first is set in the synchronization signal generator 55 in advance.

[0005]

However, the above ultrasonic sensor has the following problems. In order to operate the electronic control device alternately, it was necessary to be able to externally supply a synchronization signal. That is, a synchronizing signal generator must be prepared, resulting in a complicated system and a high price. When a conventional ultrasonic sensor is provided in close proximity, a synchronizing signal for controlling the detection operation of each sensor must be given in order to prevent mutual interference. is necessary. Furthermore,
Since the order in which the synchronization signals are issued must be set in advance, the setting is time-consuming. Furthermore, since a plurality of wirings are performed to connect an external device that emits a synchronization signal to a plurality of sensors, there is a problem that the wiring is troublesome and expensive.

Therefore, the present invention provides a device for generating a synchronizing signal in an electronic control device, and automatically determines the order and setting of the generation of the synchronizing signal in the electronic control device. It is an object of the present invention to provide an electronic control device in which wiring is easy.

[0007]

According to a first aspect of the present invention, there is provided an electronic control circuit, wherein a detection terminal is set to a first state after a lapse of a specific time for each device in response to a power supply input, and after the first state, each detection terminal is set to a first state. A signal output means for setting the detection terminal to the second state when the output time having substantially no difference between the devices has elapsed, and immediately after the detection terminal has changed to the second state, the state of the detection terminal of another device is changed. State detection means for detecting and outputting a master signal when the detection terminal of the other device is in the first state and outputting a slave signal when the detection terminal is in the second state, a master signal or slave output by the state detection means An operation executing means for receiving a signal, performing a master operation when a master signal is captured, and performing a slave operation when a slave signal is captured is provided.

In the electronic control device according to the second aspect, the detection terminal is connected to the detection terminal of another device by a single connection line, and the state detection means is connected to the detection terminal of the other device through the connection line. It is characterized by detecting whether the state is the first state or the second state.

[0009]

In the electronic control device according to the first aspect, the detection terminal is set to the first state after the elapse of a specific time which differs for each device. Next, after a certain output time is provided between the devices, the detection terminal is set to the second state. Then, immediately after the detection terminal enters the second state, the state of the detection terminal of another device is detected. At this time, if the state of the detection terminal of another device is the first state, the master operation is performed. On the other hand, the detection terminals of other devices also detect the state of the detection terminals immediately after the second state. At this time, if the detection terminal is in the second state, the slave signal operation is performed. Therefore, by detecting the state of the detection terminal of another device for each device, the master operation or,
The determination of the slave operation can be made between the devices without depending on the external device.

The output of the master signal and the output of the slave signal are determined based on the time difference of the unique time which differs for each device. Therefore, it is possible to determine the master operation and the slave operation by utilizing the individuality of each device.

In the electronic control device according to the second aspect, the detection terminal and the detection terminal of another device are connected by a single connection line. Therefore, it is not necessary to use a plurality of connection lines for signal output and signal capture, and wiring to other devices is facilitated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS There are various types of electronic control units, one of which is an ultrasonic sensor. The ultrasonic sensor detects an object by emitting ultrasonic waves to a detection object and detecting the reflected ultrasonic waves. That is, when the emitted ultrasonic wave is reflected by the detection object and received by the sensor, the presence of the detection object is confirmed. When the ultrasonic wave is not received, it is determined that the detection object does not exist.

There is a case where two such ultrasonic sensors are provided close to each other and each of them is independently detected. If the ultrasonic sensors are installed close to each other, there is a risk that the other sensors may receive ultrasonic waves emitted by one sensor during operation. In other words, an ultrasonic wave from the other sensor is received and a malfunction occurs, which causes inconvenience. Therefore, while one sensor is operating by issuing a synchronization signal, the other sensor stops, and detection is performed alternately.

In the control of such an ultrasonic sensor, it is necessary to determine before and after the operation of the sensor at the time of starting the operation immediately after the power is input. In other words, when starting the operation, it is determined which sensor is to be operated first,
After the operation is started, the operation is performed alternately by applying a synchronization signal. In deciding the operation of such a sensor, a sensor that operates before other sensors is called a master device, and a sensor that operates according to the master is called a slave device. The master device is a sensor that sends a synchronization signal for alternately operating the slave device, and the slave device receives the synchronization signal and operates. Hereinafter, the determination operation of the master device and the slave device, that is, the operation of recognizing which device is activated first will be described.

An embodiment in which the electronic control device according to the present invention is applied to an ultrasonic sensor will be described with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of the configuration of the ultrasonic sensor according to the present invention. The ultrasonic sensor 1 and the ultrasonic sensor 2 are devices having the same structure without a master-dedicated device or a slave-dedicated device, and these two sensors have two connection lines 7.
They are tied at 0,80. Each sensor is provided with a power supply circuit 20, 30, and supplies power to each part. The power switches (not shown) of the sensors 1 and 2 operate in conjunction with each other. Also, an ultrasonic sensor main body circuit 5 which performs detection and the like as an ultrasonic sensor
2,53 are also installed. Further, the CPUs 23 and 33 receive, via timers 25 and 35, crystal oscillation circuits 29 and 39, resistors 27 and 37 which are time constant components, capacitors 28 and
8 are connected. ROM21, 31, RAM22,
32 logic circuits 24, 34 are also provided in the sensor.

To operate the sensor, first, a power switch (not shown) is turned on to turn on the power supply circuit 20 (30), and a power supply voltage (supposedly 5 V) of 5 V is supplied to each section. The CPU 23 (33) resets the reset terminal C1 (C
The operation starts when the voltage input in 2) exceeds the threshold value. The reset terminal C1 (C2) has a resistor 27 (3
7), the capacitor 28 (38) is connected, and connected to the power supply circuit 20 (30) via a resistor. Therefore, after the power is turned on, the resistor 27 (37) and the capacitor 2
8 (38), the specific time ta (tb) determined by the time constant
Thereafter, the CPU 23 (33) starts operating. At this time, since the time constants of the resistor 27 and the capacitor 28 and the time constants of the resistor 37 and the capacitor 38 are not completely the same,
The specific time ta and the specific time tb will be slightly different. Since the power switch simultaneously supplies power to the power supply circuit 20 (30), it does not affect the time of the specific time ta and the specific time tb.

Each of the CPUs 23 and 33 has a specific time ta, t
After the elapse of b, the operation is performed according to the flowchart shown in FIG. 5, and it is determined whether the own side is a master or a slave. Here, the operation of the sensor will be described based on FIGS. 4A and 5. FIG. 4A shows detection terminals b1 and b2 of sensors 1 and 2.
3 shows the state of the signal. FIG. 5 is an operation flowchart of the sensor 1.

In the sensor 1, the CPU 23 starts operating immediately after the elapse of the specific time ta, and controls each unit according to the program stored in the ROM 21. Also, C
The PU 23 gives a predetermined output time t2 to the detection terminal b1 (FIG. 4A).

The output time t2 is obtained by counting the clock signal transmitted from the crystal oscillator 29 by the timer 25.

In order to give the output time t2 accurately, first, the timer 25 is set to 0 (FIG. 5, step S
1). Next, the CPU 23 determines whether or not the number of clock signals counted by the timer 25 is equal to a predetermined time t2 (FIG. 5, step S3). if,
When the CPU 23 determines that the number of clock signals counted by the timer 25 and t2 are not the same, the timer 25 counts the number of clock signals again. Here, when it is determined that the number of clock signals and t2 are the same, the CPU 23 sets the detection terminal b1 to the HIGH state (FIG. 5, step S
5). Immediately after the detection terminal b1 is set to the HIGH state, the time point J is set, and the state of the input terminal a1 at this time point is read (FIG. 4A, FIG. 5, step S7).

Then, the CPU 23 determines whether the read state of the input terminal a1 is LOW or HIGH (FIG. 5, step S9). In the present embodiment, at time J, the detection terminal b1 of the sensor 1 is HIGH, but the detection terminal b2 of the sensor 2 is LOW. Accordingly, the HIGH signal transmitted by itself and the LOW signal of the sensor 2 are input to the AND circuit 41 in the logic circuit 24 of the sensor 1. AN
Since HIGH and LOW are input to the D circuit 41, LOW which is the first state is output to the input terminal a1.

When LOW is output to the input terminal a1, the sensor 1 is set as a master device (FIG. 5, step S11). Then, the sensor operation is performed as the master device (FIG. 5, step S13). If the input terminal a1 is H
If it is IGH, it is set as a slave device and performs a sensor operation as a slave device (FIG. 5, step S1).
2. Step S14).

The operation of the sensor 2 is performed according to the same flow as in FIG. 5, but differs as follows. As shown in FIG. 4A, the specific time tb of the sensor 2 is different from the specific time ta of the sensor 1 by td. Accordingly, the output time t2 is given to the detection terminal b2 of the sensor 2 with a delay of td. That is, the detection terminal b2 of the sensor 2 becomes HIGH after being shifted by td from the sensor 1 (FIG. 4).
A).

The state of the input terminal a2 is read as the time point G immediately after the detection terminal b2 becomes HIGH (FIG. 4A, FIG. 5, step S7). Next, it is determined whether the read state of the input terminal a2 is LOW or HIGH.
The determination is made in U23 (FIG. 5, step S9). The AND circuit 51 in the logic circuit 34 of the sensor 2 has its own transmitted H
IGH and HIGH of the sensor 1 are input. That is, A
Since HIGH and HIGH are input to the ND circuit 51, HIGH in the second state is output to the input terminal a2.

When HIGH is output, the sensor 2 is set as a slave device (FIG. 5, step S12).
Then, the sensor operation is performed as a slave device (FIG. 5, step S14).

The operation after the sensor 1 is set as the master device and the sensor 2 is set as the slave device will be described with reference to FIG. 4B. The synchronization signal 91 is continuously transmitted from the detection terminal b1 of the sensor 1 of the master device to the sensor 2 as the slave via the connection line 80. This synchronization signal 91 is constantly monitored at the input terminal a2 of the sensor 2.

The sensor 1 outputs a LOW synchronization signal 91 and starts operating as a sensor (FIG. 4B).
Α). Then, the sensor 1 stops operating after elapse of t seconds (β in FIG. 4B). At the same time as the operation of the sensor 1 is stopped, the synchronization signal 91 is set to the HIGH state.

On the other hand, the sensor 2 starts operating after receiving the HIGH state of the synchronization signal 91 (γ in FIG. 4B). Then, the detection operation is performed, and after elapse of t seconds, the operation is stopped (ε in FIG. 4B). When sensor 2 stops operating, sensor 1
Starts working again. As described above, the sensor 1 and the sensor 2 operate alternately.

Next, another embodiment is shown in FIG. In this embodiment, the ultrasonic sensors 1 and 2 are connected to one connecting line 9.
The difference is that the connection is made via a 0. Logic circuit 24,
FIG. 3 shows details of 34. Also in this embodiment, after the end of the specific times ta and tb, the CPU 23,
1 is the same as that of FIG. 1 in that the terminals b1 and b2 are reset to LOW level after being reset, and to HIGH level after a lapse of t2.

The CPU 23 of the sensor 1 changes the terminal b1 from the LOW level to the HIGH level after a lapse of t2 after the reset.
Change to level (at time J in FIG. 4A). However, at this time, the terminal b2 of the CPU 33 of the sensor 2
W level. Both ends of the connection line 90 are pulled up. Therefore, both the detection terminals d1 and d2 are LOW.
Level. The CPU 23 of the sensor 1 captures the state of the terminal d1 from the terminal a1. Here, since it is at the LOW level, the operation is performed as the master device (see step S9 in FIG. 5).

On the other hand, the CPU 33 of the sensor 2 also changes the terminal b2 from the LOW level to H
Change to IGH level (point G in FIG. 4A). At this time, the terminal b1 of the CPU 23 of the sensor 1 has already been set to HI.
GH level. Therefore, both the detection terminals d1 and d2 become HIGH level. The CPU 33 of the sensor 2 takes in the state of the terminal d2 from the terminal a2. Here, HI
Since it is at the GH level, it operates as a slave device (see step S9 in FIG. 5).

As described above, the same operation as the circuit of FIG. 1 can be performed in the embodiment of FIG. That is, in this embodiment, an AND gate function is provided by pulling up both ends of the connection line 90. Therefore, in this embodiment, only one connection line needs to be used, and connection is easy. In this embodiment, the first state is set to LOW level, and the second state is set to H level.
Although the first state is set to the HIGH level, the second state may be set to the LOW level.

[0033]

In the electronic control device according to the first aspect, the state of the detection terminal of another device is identified, so that the master operation or the slave operation can be determined between the devices without relying on an external device. Can do it. Therefore, there is no need to provide an external device, and the master operation and the slave operation can be automatically determined only by supplying the power input.

The master operation and the slave operation are determined by utilizing the individuality of each device. Therefore, the master operation or the slave operation can be reliably determined without preparing a device dedicated to the master operation or the slave operation.

In the electronic control device according to the second aspect, since a signal is output to and taken in from another device, it is not necessary to use a plurality of connection lines, and wiring to the other device is facilitated. Therefore, it is possible to reduce the labor and cost for wiring.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultrasonic sensor which is an embodiment of an electronic control device according to the present invention.

FIG. 2 is a block diagram when a single connection line is used between the ultrasonic sensors shown in FIG. 1;

FIG. 3 is a block diagram of a logic circuit between the ultrasonic sensors shown in FIG. 2;

FIG. 4 is a timing chart showing the operation of the sensor for determining the order of operation of the ultrasonic sensor shown in FIG. 1 and after the order is determined.

FIG. 5 is a flowchart for explaining the operation of the electronic control device shown in FIG. 1;

FIG. 6 is a side view illustrating a state of detection by a conventional ultrasonic sensor.

[Description of Signs] 20, 30 ... Power supply circuit 23, 33 ... CPU 24, 34 ... Logic circuit 27, 37 ... Resistance 28, 38 ...・ Capacitor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01S ⁷ /00-7/64 G01S 15/00-17/88

Claims (2)

(57) [Claims] 1. A detection terminal is set to a first state after a lapse of a specific time which differs for each device in response to a power supply input. Signal output means for setting the detection terminal to the second state, immediately after the detection terminal has entered the second state, detects the state of the detection terminal of another device, the detection terminal of the other device is the first A state detection means that outputs a master signal in the case of the state, and outputs a slave signal in the case of the second state. The master signal or the slave signal output by the state detection means is fetched, and the master operation is performed when the master signal is fetched. And an operation executing means for performing a slave operation when a slave signal is taken in, and an electronic control device characterized by comprising: 2. The electronic control device according to claim 1, wherein the detection terminal is connected to the detection terminal of another device by a single connection line, and the state detection means is connected to the detection terminal of another device through the connection line. Wherein the electronic control unit detects whether the state is the first state or the second state.