Measurement And Control System Based On Computer For Type Dynamic Test-Bed

This paper based on deeply understanding of the tire dynamic test-bed principle and measure function. Designed and constructed the system solution of computer information measurement and control system of the tire dynamic test-bed. Online measurement and control for each kind of parameters and the anticipated technical specification are achieved. 1 Measure and control system of mechanics parameters In view of the mechanics parameters of tire dynamic test-bed, the paper selected the representative significance tri-divided force, the longitudinal loading force and the vertical loading force parameters measurement and control system as main research content, in consideration of the system stability, the reliability and the anti-interference ability, deeply researched every hardware composition of the measurement and control system, designed the corresponding hardware system. (1) Proposed the performance and the targets of tri-divided force, the longitudinal loading force, the vertical loading force. The technical solution was designed based on the performance and targets parameters. Some of the mechanics parameters are just for measurement. This kind of signals is measured by industrial personal computer with hight speed data acquiring card. The another parameters are both for measurement and control. This kind of signals is acquired by industrial personal computer and MCU using parallel data acquisition. The data acquiring veracity are guaranteed and the system's real-time are enhanced. (2) By studying several kinds of sensors signal transmissions, proposes one kind has the isolation enlarges the link the signal pattern, uses the high performance survey amplifier and the isolation amplifier composition signal system, enhanced the system stability and the anti-interference ability. (3) According to the measuring accuracy request, uses high performance A/D transformation chip ADl674 as the core of MCU data acquisition system. Developed the corresponding MCU data acquisition system by deeply analyzing its interface timing. This system costs low. Its structure is simple and works reliably. (4) Develops the serial communication interface circuit that controlled by industrial personal computer and MCU. The interface has single power supply and works reliably. (5) Program data acquisition and control programme using Visual C++ under 32 bit operating systems for the high speed data acquisition card. Program data acquisition software using the assembly language for MCU data acquisition system. 2 The angle parameters measurement and controls The tire dynamic test-bed has high measure precision in angular displacement, and it is also the test-bed's technical key in measure system of the lateral inclination angle and the lateral deviation angle. Uses the photoelectric encoder as angular displacement sensor, and designs a kind of auto measurement and control system composed by phase-identifying circuit, synchronic reversible counter, interface, and AT89C52MCU. (1) Encoder choice: At present the absolute photoelectric encoder only has highest pulse 1024p/R, but increase photoelectric encoder has the highest pulse 25000P/R. To meet the target of the measurement system. The tire dynamic test-bed angular displacement measurement system chooses Japanese SUMTAK LFA18000 increase photoelectric encoder. (2) The signal processes circuit design: Firstly, measuring the lateral inclination angle and the lateral deviation angle by the photoelectric encoder. Secondly, the signal turned into digital signal via phase-identifying circuit then sending to the synchronic reversible counter. AT89C52 controls parallel I/O interface, acquires the signals, processes the data and achieve the auto measurement of lateral deviation angle angular displacement. The system uses the DS12887 chip that has the electricity protection function which prevents the data loss. At the same time, the angular displacement data delivers by the control system after the D/A and the linear isolation amplifier. Achieved the tire dynamic test-bed angular displacement and angle speed control. (3) Software frame design: The tire dynamic test-bed angular displacement automatic measurement and control system software design mainly includes the monitor routine, the data fixed time gathers the severance service subroutine, the lateral inclination angle, the lateral deviation angle processing subroutine, the digital filter programme and control programme est., proposed the operation pattern and the formula. The monolithic integrated circuit figures out the tire laboratory bench according to the sampling value size idea lateral inclination angle, the side angle of deflection, transforms it the separation BCD code delivers the LED display circuit demonstration, realized lateral inclination angle, the side angle of deflection high accuracy automatic survey. Proved by the experiment. This system has high measuring accuracy, good reliability and strong anti-interference ability. 3 Measures and controls the displacement parameter The test-bed's reciprocating-motion displacement range is wide, the high measuring accuracy is its main characteristic, the paper designs a automatically measure system that take the magnetostriction transducer as the core, carries on data gathering through the MAX195A/D converter. We used MCS-51 series AT89C52 to handle the tire dynamic test-bedreciprocating-motion displacement. (1) The design of the Tire dynamic test-bed reciprocating-motion displacement automatic measure and control system It mainly includes the magnetostriction linear displacement sensor, the signal processing circuit, the A/D converter. The photoelectric insulator, the linear insulator amplifier and the reciprocation-motion control system and so on. The magnetostriction transducer examined the tire test-bed reciprocation-motion displacement, turns the analog voltage signal after the signal processing circuit, controls the MAX195A/D converter by the AT89C52 carries on the quantification and gathering, realizes automatic measurement which the tire dynamic test-bed's reciprocation-motion. Simultaneously sends the signal to control system through the linear insulator amplifier, realizes the control of the tire test-bed reciprocation-motion. When the reciprocation-motion displacement is -2.5m~+2.5m, the magnetostriction linear displacement sensor transforms it to -10V~+10V direct current signal output. The request of the signal gathering system is very high. And the A/D converter is requested to have the characteristic which have high accuracy and is easy to isolate. We choose the MAXIM Corporation 16 serial MAX195A/D converter toincluded in the signal of reciprocation-motion displacement data gathering system, guarantees the measuring accuracy of the system. We Used the 6N136 photoelectric insulator, satisfied the request of the system conversion rate, like this, namely guarantee the system's reliability, also realized the high accuracy measure the reciprocation-motion displacement. (2) The design of software The software design of the tire dynamic test-bed reciprocation-motion displacement automatic measure and control system mainly includes the system monitor program, the A/D transformation interrupt service subroutine, the program of calculate the reciprocation-motion displacement, the digital mean filter and the control program of displacement and so on. (3) The conclusion of test The tire dynamic test-bed reciprocation-motion control system has two ways which is the speed control and the displacement controls, under the remote control mode, controls by the industry control machine designates according to the speed control or the displacement. Under the local control mode, it only can carry on the displacement controls, may set the test-bed by software starts in the free position or stops. The range of displacement control is 0 ~ 5m, the static error is smaller than 2mm, stable time is smaller than 350ms. The range of speed control is 10 ~ 200mm/s, the static error is smaller than 2mm/s, stable time is smaller than 200ms. Completely meets requirements. 4 The design of software We used assembly language to program the measure and control of the mechanicscomponent, the angle component and the displacement component; the serial communication program between the MCU and the main control computer; the monitor program of the main control computer.