The computer management system for automobile comprehensive performance testing stations is based on the "Technical Specification for Computer Control System of Automobile Testing Station" (JT/T478-2002) (hereinafter referred to as the Specification) and the mandatory national standard "Comprehensive Performance Requirements and Testing Methods for Operating Vehicles" (GB18565-2001), and complies with the requirements of the "Technical Specification Document for Automobile Comprehensive Performance Testing Station in Guangdong Province". The testing station should establish a computer management system to realize the real-time control of the automobile testing process, data acquisition, processing of testing information, storage, transmission, printing, and reporting functions using computer technology. 1 Specification for Computer Management System of Automobile Comprehensive Performance Testing Station The Specification clearly defines the basic division unit of the testing system, including testing channels, testing units, and business nodes. It breaks through the concept of testing lines in the past and adopts testing channels, so that testing units can be arbitrarily combined into testing lines, realizing the testing scheduling function required by the Specification [1]. The process monitoring, business management, data processing, and information transmission implemented by the computer management system comply with the requirements of relevant national and industry standards and specifications, ensuring reliable transmission, authentic data, standardized forms, and unified standards. The standard clearly defines basic business information, including vehicle structure information, vehicle characteristic information, and inspection information. Based on this, this system adds a vehicle information database and an electronic file database for operating vehicles. The vehicle information database meets the testing requirements of the "Comprehensive Performance Requirements and Testing Methods for Operating Vehicles" (GB18565-2001) and establishes an electronic file data model for operating vehicles. Queries include public and internal queries, and statistics are provided at the substation, city, and province levels, meeting the needs of the higher-level competent authority for vehicle technical management. The standard clearly requires in inspection control: firstly, it must meet the inspection, external inspection, and calibration requirements for vehicles with 18 axle configurations; secondly, it emphasizes the signal acquisition requirements for analog sampling, specifying a recording point interval of no more than 10 ms and a synchronization signal interval of no more than 0.5 ms. 2. Computer Management System Environment The inspection station's inspection units and business nodes use the Windows 2000 Server and Microsoft Windows 2000 Professional system platforms. The system database uses the standard version of Microsoft SQL Server 2000. A network communication platform is established using the TCP protocol, implementing a QS topology network architecture. The detection system is developed using Visual C++ 6.0, and the database statistics are developed using Delphi. 3 Functional structure of computer management system The functions of the computer management system are divided into three categories: detection station detection management system, industry management system and data interface system. The detection station establishes a computer management system and uses computer technology to realize the functions of vehicle detection process control, detection data acquisition, detection information processing, detection information transmission and detection information reporting, as shown in Figure 1 [2]. The network layout is shown in Figure 2. 3.1 Detection station detection management system The detection station detection management system includes a central management subsystem, a business processing subsystem, a detection scheduling subsystem, a detection control subsystem, a station affairs management subsystem, and a maintenance management subsystem [2]. 3.1.1 Central management subsystem The central management subsystem manages system parameters, user permissions, and logs to realize data management. It monitors the network operation status. 3.1.2 Business processing subsystem The business processing subsystem includes: (1) Login: including the input of basic vehicle information, vehicle model parameters and characteristic information, detection category, etc. (2) Final inspection: Vehicle inspection status query, inspection data and curve, image query, inspection report printing and other related business processing. The system automatically judges the inspection data and can automatically generate re-inspection items based on the inspection results, and provides technical judgment result input, internal query, etc. (3) Online photography: Each vehicle inspection line in the inspection center is equipped with a camera lens, which automatically takes pictures of the vehicles that are inspected online, transmits and archives them, as vehicle inspection image information, and as the source of vehicle photos for establishing vehicle electronic files. After each inspection, the latest vehicle photos are stored in the electronic file. 3.1.3 Inspection scheduling subsystem (1) The inspection station workflow is basically a flow operation mode. Through inspection process management, vehicles are inspected in accordance with the prescribed order and method. (2) Inspection disorder scheduling. Ordered inspection reporting becomes disordered inspection, further deepening the inspection function, automatically sorting and inspecting vehicles for initial inspection and re-inspection, improving the operability of vehicle inspection. (3) Parallel inspection unit scheduling. Multiple inspection units can inspect the same inspection items, so the vehicle to be inspected can be inspected in any inspection unit. After the inspection is completed, other parallel inspection units automatically end the inspection. (4) Online emergency dispatch has the ability to dispatch vehicles to be inspected and accept any item and any number of inspections within the inspection unit. The inspection order and inspection items of the workstations can be changed online. (5) Workstation dispatch can be configured arbitrarily without being restricted by lines. As an extension of arbitrary dispatch, users can configure the workstation dispatch order arbitrarily according to the inspection needs of the inspection vehicles without being restricted by lines, thereby enhancing the user's flexibility. (6) Multiple vehicles can be inspected simultaneously within the inspection unit. The inspection unit is further subdivided into several inspection procedures. Vehicles to be inspected are dispatched to the inspection procedures within the inspection unit to be inspected, thereby realizing the simultaneous inspection of multiple vehicles within the inspection unit. 3.1.4 The inspection control subsystem has the ability to output the signal of the vehicle driver of the inspection unit, complete data acquisition and processing, value transformation and judgment, and perform project inspection and data storage according to the logged items. Inspection data and single evaluation results are stored in the database in real time. The inspection data that has been saved cannot be changed. The curve data should save the actual collected data, and the curve image is generated from the data. (1) Network mode: After logging in, the system automatically selects the inspection items according to the login type (e.g., vehicle license plate number, vehicle model, chassis number, engine number, etc.). After logging in, the vehicle can be dispatched online through the dispatch subsystem and inspected by the process control program according to the set method and sequence. During this period, any workstation and any project can also be dispatched. During the inspection process, the workstation machine transmits data to the server database in real time. (2) Standalone mode: For individual project inspections, standalone mode can be used. After the vehicle arrives at the designated workstation equipment, the inspection program is started on the workstation machine to quickly carry out the inspection. Since there is no need to enter vehicle information, when evaluating the inspection results, the relevant vehicle information should be considered (e.g., for headlight luminous intensity testing, the appropriate standard should be selected according to the actual lamp system of the vehicle for manual evaluation). It has the function of calibrating the measured values ​​of each controlled device. The system can send real-time data from the calibration process to the system display screen, showing the zero-point output, AD value, and calibration value of each analog input channel of the controlled equipment; when the communication protocol is supported, the system calibration interface displays the readings of the digital communication transmission quantities in real time. 3.1.5 Station Management Subsystem. Automatically backs up information on a regular schedule; saves all entered vehicle information; vehicle inspection data is stored for at least two years. Vehicle management statistics and queries, inspection station vehicle information statistics and queries; statistical queries of the number of qualified vehicles and the pass rate. 3.1.6 Maintenance Management Subsystem. This system can maintain various codes, including: vehicle parameter maintenance, repair unit code maintenance, operating unit code maintenance, evaluation standard maintenance, external inspection item maintenance, etc. To ensure data fairness and reliability, all maintenance work is performed by personnel with relevant permissions. 3.2 Industry Management System. The industry management system includes the inspection station opening and closing management subsystem, the inspection information management subsystem, the daily administrative management subsystem, and the industry statistics and analysis subsystem. 3.2.1 Inspection Station Opening and Closure Management Subsystem. This subsystem manages relevant information about the inspection station opening and closing management system. 3.2.2 The Testing Information Management Subsystem uses the internet to manage the basic situation of testing stations, including the automatic collection of information such as infrastructure, personnel, testing instruments and equipment, operating status, and testing volume. It can monitor the real-time power-on status of computers at each or all business nodes; monitor the real-time connection, communication, power-on, and vehicle inspection status of computers at each workstation; and monitor the real-time inspection location of each vehicle under inspection. It also manages the query, statistics, and file management of testing information. 3.2.3 The Daily Administrative Management Subsystem handles the registration and information maintenance of affairs by industry management departments. 3.2.4 The Industry Statistics and Analysis Subsystem performs statistical analysis of vehicle testing data from testing stations. 3.3 The Data Interface Management System includes the Instrument and Equipment Interface Management Subsystem and the Higher-Level Authority Management Subsystem. 3.3.1 The Instrument and Equipment Interface Management Subsystem enables real-time recording of testing data, sending of testing commands, querying of testing status, and transmission of testing data. 3.3.2 The Higher-Level Authority Management Subsystem offers both upload and download methods. "Distribution" refers to the management department distributing data to the testing station, such as vehicle model data. "Upload" refers to the testing station uploading data to the superior authority. 4. Main Features of the Computer Management System 4.1 Signal Transmission and Processing of the Computer Testing and Control System The signal transmission of this control system is mainly divided into four types: measurement signals; switch input signals; switch output signals; and process indication signals. Through these four types of signals, the workstation computer can accurately measure and control the vehicle position and equipment position, and collect real-time data from the sensors at each workstation. 4.1.1 Measurement Signals Measurement signals mainly come from the sensors in each workstation test bench. During a measurement project, the sensor of the object being measured converts the non-electrical signal (such as force, velocity, displacement, etc.) of the measured physical quantity into a weak electrical signal (voltage or current). After pre-amplification, this signal is converted into a "standard" signal (e.g., -5 to +5 V) and sent to the corresponding industrial control computer. After hardware pre-processing, an A/D conversion is performed. Finally, the application program performs relevant data processing calculations and result judgments, ultimately restoring the digital quantity to the same physical quantity as the measured quantity. The workstation transmits this measured value to the detection business management subsystem via the network. 4.1.2 Switch Input Signals The switch signals in the measurement and control system mainly include three categories: vehicle arrival signal, equipment arrival signal, and sampling signal. The vehicle arrival signal is the main basis for computer control in automated detection. It is generally detected using limit switches, mainly used to determine the movement of headlights, etc. Opto-isolators are used to isolate the computer's ground from the ground of the high-voltage control devices. This filters out interference signals generated by the high-voltage control devices, greatly improving the anti-interference capability of the input/output channels. The signal after opto-isolation is sent to the input/output card and converted into a computer digital signal. 4.1.3 Switch Output Signal Measurement and Control Subsystem The switch output signals in the measurement and control subsystem mainly control the movement of the detection equipment, such as the speedometer's lifting and lowering, the brake motor's starting and stopping, and the automatic movement of the headlights. The computer's digital signal is converted into a voltage signal after passing through the input/output card. This signal is then sent to the relay isolation driver board for isolation and amplification. The use of the relay driver board prevents the computer from forming a direct coupling circuit with the high-voltage control circuit. Because the operating voltage for controlling the movement of the detection equipment is high (up to 380 V) and the power is large, intermediate relays are needed for further amplification before driving the relevant high-voltage control circuits. 4.1.4 Process Indication Signal Measurement and Control System The process indication signals mainly provide indicative signals to the vehicle operator and workstation operator, telling them what operation should be performed. At present, the process indicator device used in the comprehensive vehicle performance testing station is mainly an LED matrix display screen, 16 dot matrix, divided into 2 rows, each row can display 8 Chinese characters. The computer measurement and control management system uses a large screen color TV as the process indicator, which has a good effect. 4.2 System security [3] System security includes database security and query statistics system security. The database management system DBMS supports two industrial standards, SQL and ODBC, as well as TB-level data capacity. The database uses SQL server database, which itself has C2 level security. The query statistics system uses username and password to authenticate users. Only users who meet the conditions can use the system, and the system can manage the permissions of each user. 4.3 Data security protection measures (1) Real-time data acquisition and display measures; (2) Real-time monitoring measures of the main control: After the vehicle has completed all the tests, the control system immediately stores the complete test data and judgment results of the vehicle into the database; (3) Access control; (4) No abnormal data input ports are provided. 5. Fault Tolerance When the testing system encounters human interference, or when a controlled device fails and recovers, or when a partial hardware failure occurs in the control system of a vehicle inspection unit and recovers, this system is capable of automatically resuming testing in the vehicle queue before the power outage upon power restoration. This ensures the continuity of testing, data integrity, and data validity for all vehicles in the queue. 6. Conclusion The computer-controlled measurement and control and network management system plays an increasingly important role in the upgrading and transformation of comprehensive vehicle performance testing stations. The local area network formed by this system is connected to the information center of the superior authority, enabling the superior authority to understand and supervise the vehicle inspection status of the testing station and the testing status of operating vehicles.