Vehicle central control door lock controller is related to vehicle driving stability and safety. Centralized control of several door lock and start-up is carried out. Door locks are the main components of automobiles. Nowadays, they are gradually changing from mechanical to intelligent electronic. In this regard, combined with practical research, the author makes a brief analysis of the design and development of the door lock controller and remote controller for automobile central control. With the progress and development of science and technology, the improvement of people’s living standards, driving safety and convenience have higher requirements, remote control door lock has become an important electrical configuration. In the design process, it is necessary to enhance the remote control function under the condition of the original central control door lock, so as to realize the function of unlocking the car door without keys and unlocking the car door without keys. With the progress and development of science and technology, the automotive central control door lock has gradually changed from electrical energy to mechanical energy, and the use of motors to drive gears to switch the door. The main structure is door lock switch, door lock executive unit and door lock control equipment.
The wireless remote control of the central control door lock (Fig. 1) is that the door can be opened and locked remotely without unlocking the key. The principle of remote control is that tiny radio waves are emitted around the driver, the antenna of the car receives the radio signals, and the signal code is judged by the electronic controller ECU. Subsequently, the system actuator is used to open and close the system.
The design of remote control principle is more complex. It not only needs to pay attention to economic input but also to security and stability. The password is not repeated, and it is difficult to crack. The static current consumption of the whole machine is maintained at about 10 mA. The remote controller reacts quickly within 20m. Practice has proved that the current of the car lock door is about 10A in the course of operation, because there are four doors and lights in the car, which will produce a large current of about 10-30A in the course of operation. Therefore, the thickness of PCB is about 1.6 mm, and the thickness of copper foil is 35 microns. Only by meeting the standard requirements can the controller be ensured to have sufficient current drive, so that the door lock block can move while the whole controller is stable without heating deformation, line bursting, plate burning problems. The static power consumption current of the whole machine is maintained at 10 mA and 12 volts with the automobile power supply. The lock block action is provided with high current from the automobile power supply.
The whole machine requires lower current for relays, MCUs, receiving and decoding circuits.
It is about 10 mA-30 mA. The 78L05 three-terminal voltage regulator circuit is selected. 78L05 has simple circuit and few peripheral components. The input end can use 100uF electrolytic capacitor and filter capacitor 0.1uF. The maximum current of the circuit is 100-150 mA, the input voltage is about 17-7 volts, and the output voltage is 5 volts safe and stable. Despite the simplicity of the circuit, the stability of the circuit board requires that the output be secure. Therefore, in the process of component selection, do a good job of identification, avoid the selection of inferior products. In addition, circuit board layout is also the key. Because it needs to be in the same board with the receiving and decoding circuit, it will affect the decoding to a certain extent and require power supply to the receiving and decoding circuit, MCU and relay respectively. Therefore, the circuit should keep a certain distance from the receiving circuit, thereby reducing the impact on the receiving decoding, and be close to the relay so as to facilitate the circuit board Layout. The controller is the decoding core of the receiving remote controller, and the design process plays an important role. SYN480 decoder chip is chosen as receiving and decoding chip. It has high inheritance, simple peripheral circuit design and less component use. The receiving distance should be up to 20m, and it can receive fixed code and rolling code. The frequency is maintained at 2500 Hz. Reality makes the first edition of the whole machine, installed to the car test found that the receiving distance is about 10 meters, the effect is not ideal. The reason is that there is no great effect to change the circuit components. The automobile shell has a greater impact on the chip, and the remote control transmits less signals. Therefore, it is difficult to correctly decode the execution action. Re-select components and test, select SYN510, thermostatic element the chip and SYM480R for the same company. Its operation principle is the same, the circuit design is the same; however, the receiving sensitivity is raised to – 110 dbm, which can meet the requirements of the hull of the bow automobile. The circuit design of this link is simple.
It controls the power supply pin of the relay, opens and closes the on-off pin switch of the automobile power supply control relay and controls the action of the lock block. In the circuit board design process, the copper sheet connecting the pins of the lock block should be kept at a certain width and bear a larger current. Tin plating is added to the copper sheet of the pin to increase the current level. The design of remote controller is related to the receiving sensitivity and distance, especially the circuit board antenna design. The transmitting antenna of remote controller is closely related to the receiving distance. It can satisfy the requirement of 20m distance through multiple circuit boards and board throwing detection designs. Every circuit board has more problems than antenna design. The state, thickness, impedance and receiving distance of copper sheet have great influence.
Through continuous testing, it is concluded that the impedance is close to 50 ohms, the transmission power is concentrated, and the effect is ideal.
Software design is divided into: main MCU flow compilation and remote control password burning. The former design is its core, so it focuses on analysis. Select the M8 series MCU – STM8S103 of an enterprise, its port configuration and use of ADC, timer and other resources to initialize, according to the relevant manual, directly apply. Emphasis is laid on the analysis of receiving telemetry, degree and speed. Interruption and search are selected for processing, and annotation is carried out when interruption occurs. After labeling the command bits of the encoding head, the decoding label is positioned, and the receiving part of the rolling code and the fixed code is carried out in the main loop, decoding, comparing diagnosis and executing actions. The interrupt uses lift interrupt and receives the upper end to position the decoding mark. In the main program, the data are received until 66 bits of data are received, decoded and identified. Firstly, the door locks do not move. This problem is concentrated in the main power supply circuit of the central control door lock, which checks whether the motor can run normally and whether the fuse is fused or not. If the fuse occurs, it should be replaced in time; if the fuse does not occur, it may be due to the short circuit of power supply and door lock actuator circuit, it is required to use the multimeter to find the fault location and check the short circuit or disconnection of the wireless circuit and the hitching point. Second, the door cannot be opened properly. The main causes of this problem are short circuit of connection line, bad contact of connector, damage of door lock motor and damage of door lock operation mechanism. Third, the speed control fails. Because the speed sensor is damaged or ABS controller is damaged, the speed control circuit is out of order. In this regard, first check the plug-in connection with the iron point, power supply status; if it is still not solved, you can monitor the speed sensor. The fault detection is carried out by the method of banning new parts. If this problem is solved effectively, the main cause of failure is to ban damaged components. Comprehensive analysis shows that in recent years, the research and design of automotive central control door lock controller and remote controller have been paid attention to. Paying attention to the design of automotive central control door lock controller and remote controller plays an important role in the practical effect. In the future design of central control door lock controller and remote controller, attention should be paid to the core process, and feasible methods should be formulated to ensure that they play an effective role.