In industrial production testing, it is frequently necessary to collect analog quantities such as temperature, flow rate, and pressure, control switching quantities such as relays and contactors, and perform precise displacement control of stepper motors and servo motors. Therefore, it is essential to develop a computer-based machine tool testing system that integrates various control quantities into a closed-loop control system. This paper uses a computer as the main controller, employing Windows-style interface software. This system boasts fast calculation and testing speeds, strong information processing capabilities, high system integration, a user-friendly interface, and convenient operation, automating the multi-parameter testing process and improving testing efficiency and accuracy. System Main Functions and Features The system is designed for integrated testing of parameters that significantly affect machine tool performance. It features the following functions and characteristics: (1) The system measures the load of the reducer and performs no-load, load, inertial load, clutch engagement/disengagement, and hysteresis tests. It can simultaneously test the X, Y1, and Y2 axes. (2) The system provides online measurement and height adjustment accuracy for the automatic height adjustment system. It can test up to 8 machine heads simultaneously and provides automatic setting and user-defined feed distance. The error value is calculated and displayed in real-time as the machine head feeds. (3) It has automatic test time setting, virtual load addition, and load adjustment functions. (4) The system has a high-temperature aging test function and automatically monitors and records the system status. (5) Measurement data is dynamically displayed. If data exceeds the standard, an alarm is immediately triggered or the experiment is stopped. (6) Test results are automatically analyzed and printed, and related file operations can be performed for in-depth analysis and statistical analysis of the test results. System Hardware Structure and Composition The system adopts a modular structure with a computer as the main controller. The computer possesses abundant hardware and software resources and powerful system functions, boasting high computing and control speeds and excellent control performance in on-site control. Other parts of the system are connected to the computer via interface cards, controlled by it, and simultaneously providing test data. The hardware structure diagram of the system, executed through the interface software on the computer, is shown in Figure 1. It mainly consists of the following parts: [IMG=System Structure Diagram]/uploadpic/THESIS/2007/12/2007121710251150803H.jpg[/IMG] Figure 1 System Structure Diagram Main Controller The system's main controller comprises an industrial control computer, a standard keyboard, a mouse, a CRT color monitor, and a printer. As the system's main controller, the computer controls the actions of other parts through the interface cards, collects test data, performs complex calculations and analyses on this data, completes various integrated system test functions, and displays the test results dynamically in real time during the testing process. If any deviations are detected, an alarm is triggered, and the fault time is automatically recorded so that the operator can take appropriate measures. The operator can perform human-machine interface operations via monitor, keyboard, and mouse, selecting corresponding test items, inputting necessary test parameters, monitoring the entire test process, performing corresponding file operations, and printing test results via printer. Interface Module The interface module mainly includes an isolation driver card and input/output interface cards. The input/output interface cards are responsible for the computer's control of the test device and data acquisition. They are divided into digital signal interfaces and analog signal interfaces. The analog input (AI) uses Advantech PCI-726, and the analog output (AO) uses Advantech PCI-1710. The isolation driver card uses Advantech PCI-734 for digital input (DI) and digital output (DO). The specific number of channels is determined as follows: Digital Input (DI): Torque sensor 3 channels, encoder 18 channels, fault alarm 3 channels; Analog Input (AI): Proximity sensor 8 channels; Digital Output (DO): Clutch 3 channels, pulse disable 3 channels, SV-ON 3 channels, pulse train 3 channels, symbol 3 channels, C-MODE 3 channels; Analog Output (AO): Servo command: 3 channels, load control: 3 channels; Total: DI: 24 channels, AI: 8 channels, DO: 18 channels, AO: 6 channels. This system uses PCI bus input/output interface cards. Due to the large number of test and control quantities, three interface cards are used, and their base addresses are set to 300H and 330H respectively through hardware wiring. The analog signal input and output channels are independent, with a resolution of 12 bits. Their signal ranges are as follows: Input range: -10V to +10V; Output range: -10V to +10V. The interface card's digital input and output signals are TTL level compatible, facilitating connection to other components. Their characteristics are as follows: Input low level VIL ≤ 0.8V; Input high level VIH ≥ 2.0V; Output low level VOL ≤ 0.5V; Output high level VOH ≥ 2.4V. To ensure system safety, an isolation driver card is used to isolate computer signals from external signals through opto-isolation and other means, amplifying the interface card's output signals to the required strength for servo drivers and clutches. The motion control module mainly includes a servo system and a loading system. The servo system consists of a servo motor driver, a servo motor, and an opto-encoder. Its main function is to control the tested reducer to operate according to a specific motion law during the test. This system employs three Panasonic (MINAS) servo systems to control the X, Y1, and Y2 axes respectively. The system offers three control modes: speed control, position control, and torque control, meeting various motion control requirements during testing. Before use, parameter settings are required as follows: NO.25=10000, NO.26=7200, NO.27=1, NO.29=3. The servo driver is controlled by a computer interface card. When the interface card's servo command output is +3V, the servo motor speed is 1500 rpm. The computer also controls the servo driver's sign bit, output disable, SV-ON bit, and C-MODE bit via the interface card. A sign bit of 1 corresponds to the CCW direction (forward rotation); a pulse output of 1 disables the servo motor; SV-ON is active low; C-MODE is active low for speed control and active high for position control. During testing, the computer modifies these control signals according to the program, adjusting the servo motor's operation in different modes and states depending on the test item. The loading system is primarily responsible for providing a virtual load to the shaft end. The loading controller receives analog signals from the computer and adjusts the current flowing through the loading device accordingly, thereby controlling the shaft end torque. Sensor Module The proximity sensor uses a WYD series DC displacement sensor with a range of 20mm and an output voltage of 0-5V. This sensor is integrated with the electronic circuitry, making it easy to install and use without the need for an external amplifier. It can be directly connected to a computer input/output interface card for analog-to-digital conversion and data processing, providing the computer with minute changes in relative displacement. The system uses eight proximity sensors for testing and precision adjustment. The torque sensor uses a JN338 torque sensor, which enables non-contact energy and signal transmission, independent of rotation, speed, and direction. The output signal is a pulse signal. The incremental photoelectric encoder serves as both a speed and displacement sensor. Its output is provided to the servo system for motion control and to the computer for data acquisition. The computer converts and counts the encoder output signal using software. The product of the total count and the pulse equivalent is the displacement, and the displacement over a short period is the instantaneous speed. Interface Software Development The main application of the system interface software was developed using the visual programming tool Visual Basic 6.0 under the Windows operating system. The software interface adopts a Windows style, and its block diagram is shown in Figure 2. [IMG=System Software Block Diagram]/uploadpic/THESIS/2007/12/2007121710251941229Y.jpg[/IMG] Figure 2 System Software Block Diagram Visual Basic 6.0 is a powerful high-level visual programming language, but it cannot directly access the computer's input/output interfaces. To solve this problem, a dynamic link library (DLL) was developed using C++. All hardware port access functions are implemented in the DLL. When a port needs to be accessed, the corresponding DLL function is called for dynamic linking. This not only achieves the intended functions but also optimizes the software structure and saves a significant amount of system resources. Conclusion The machine tool testing system designed in this paper operates smoothly, has a user-friendly interface, is easy to operate, and has high control precision. The positioning accuracy of the X-axis, Y1-axis, and Y2-axis all reach 0.024 mm, and the repeatability of the X-axis, Y1-axis, and Y2-axis all reach 0.015 mm.