Technical development trend of automobile anti-theft system 1. The alarm setting/releasing device basically uses the door lock operation to set the whole system to work; At the same time, the pre-tightening state is released by unlocking operation. The simplest method is to set a switch on the door lock device, which is suitable for detecting the locked or unlocked state. When the lock button in the car is operated, the whole system is also in danger of releasing the alarm state. Therefore, there is also a Taopan switch integrated with the door key lock. As long as the door key lock is not operated, the unlock signal will not be output. This method has been widely used. 2. Detector/Sensor This is a device for detecting abnormal conditions. Generally, a switch is installed to detect the switch of the door, trunk and engine compartment cover. The detection of window glass damage depends on the impact sensor of piezoelectric element, speaker or ultrasonic sensor using dumper effect, or the combined detection method of the above sensors. However, because they indirectly measure the change of physical quantity when the window glass is broken, it is often prone to misoperation. In addition, the acceleration sensor is generally used to detect the vibration or inclination of the vehicle, but it is also prone to misoperation due to interference and human error. The way to detect the abnormal situation when stealing a car is usually to detect the voltage change of the battery. But it can't detect improper intrusion into the car. Therefore, in the future, it is necessary to develop a sensor to correctly detect improper intrusion in the train. Third, stop the stolen vehicle starting device (roadblock) The so-called "roadblock" is a device that stops the vehicle from running by mechanical or electrical means. Usually, the engine is prevented from starting. Figure 1 is a conceptual diagram of the wire blocking device. The identity authentication device (ID for short) is a key switch or an electronic key (using an electrically controlled key). Identity verification device is a control device that compares and judges identities by key operation and outputs permission signals. The so-called licensing device is a device that starts the engine according to the licensing signal from the identity authentication device. These devices include engine ECU, fuel pump or valve, ignition relay, starter relay, etc. Diesel engine is a kind of fuel pump with electronic control device. Here are four kinds of "trippers": (1) key switch trippers. Figure 2 shows the after-sales service trippers. The identification device can use an existing door key or password key, which is a mechanical key. Because the licensed device adopts on-off control, it is easy to be damaged by mechanical properties or may be improperly connected, so the safety is poor. (2) Remote key line arrester Figure 3 shows the remote key line arrester, which is convenient and safe to use. When the remote key is used to lock the operation, the engine is prohibited from starting: when the lock is released, the engine can be started. This method, combined with the remote control key, can reduce the burden of the on-board system and ensure the safety. But the ID code is easily interfered by radio waves and infrared rays, which is very dangerous. Therefore, it is necessary to adopt a variable code mode, and the ID code can be changed every time. In the future, we should study the emergency methods when the remote control switch fails or the battery is dead. (3) Resistive adhesion type trip arrester Figure 4 is a resistive adhesion type trip arrester used in the United States. When operating the ignition system, the device can read the resistance value of the chip embedded in the keyboard through the contact and compare it with the preset fixed resistance value. Only when the resistance values match can the engine be started. The blocking device is cheap, and the user does not need special operation. However, the fixed resistance value is only 16, so the safety is poor. In addition, the contact reliability is poor by reading the resistance value through the contact. However, the anti-theft effect of using electric pedestrian brakes is still worthy of attention. (4) Repeater/transponder pedestrian arrester Repeater is a general term for communication satellites in a broad sense. In the aspect of vehicle anti-theft device, it is a small transponder that uses identification tags to manage people or things in a non-contact way. Its basic working principle is that when the interrogator provides electromagnetic power, the identity authentication or data preset in the transponder is automatically transmitted to the interrogator, and the common frequency is about 120KHz. Fig. 5 shows the actual repeater type blocking device since 1994. When the ignition system works, the power supply is provided by the antenna (coil) on one side of the key cylinder. The transceiver installed on the key base will automatically output the ID code according to the power supply. The ID code receives the signal through the antenna, and then converts it into digital through the R/F circuit of ECU, and reads it in the CPU. The read ID code is compared with the ID code stored in EEPROM memory, and when the ID codes are consistent, the permission code is output to the engine ECU, so the engine ECU and starter are started. This pedestrian arrester is completely controlled by electronic code, non-contact, and has nothing to do with the early warning setting/disarming state of the alarm device, and can always maintain its own function. It also does not need special operation of users, so it has the advantages of high security, high reliability and convenient use. If you add a detector/sensor, you can have alarm and anti-theft functions. The following describes the "trip arrester" developed by mitsubishi electric Company. The device has been matched with automobile factory since 1995 and put into batch application. The device consists of the following parts: ① the key of the repeater. A miniature repeater is installed in this key switch to write the identification code: ② Keyball loop antenna, which reads the identification code in a non-contact way through electromagnetic engagement when the engine is started; ③ The electronic control unit of "Pedestrian Brake" is the control part that sends the starting signal to the engine starter when the identification codes are consistent. In this device, it is completely controlled by electronic password and can be put into operation without special operation of the driver, which has the advantages of confidentiality, reliability and convenience. This device sells well in the North American market. The device has the following five characteristics: ① high security-excellent security because the repeater is equipped with billions of identification codes; (2) High reliability-due to the non-contact identification code communication mode using electromagnetic bonding technology, it has high reliability; (3) Convenient operation-the driver can use the device without special operation, and there will be no mistakes such as forgetting to operate, so it is convenient to use; (4) Small size and light weight-the electronic control unit of the device has the advantages of small size and light weight due to the application of high-density surface mount technology and special integrated circuit, and its cost performance is equivalent to that of an excellent computer; ⑤ The radio wave laws and regulations applicable to all countries include European laws and regulations-the "pedestrian arrester" law was implemented in Europe from June 1997, and it is also applicable to the insurance laws and radio wave laws and regulations of the insurance industry in all countries. Fig. 6 is the system block diagram of Mitsubishi relay line arrester, and table 1 is the specification of the electronic control unit (CPU) of the device. Finally, it is mentioned that the anti-theft device proposed by France to monitor cars through artificial satellites has also been put into practical use.