The Study On ABS Fatigue Test Machine And Its Control System

With the increase of drive speed and the car density of the road, the request of the safe drive becomes more and more important. So there is great demand to development automobile safety's driving system. At present, the auto safety travel system already became an important aspect of the field which the car industry changes from the automobile to electric. Applied the brake to guard against holds the system (Anti-lock Braking System-ABS) was an auto safety travel system important constituent. The brake is most important part of auto safety travel system。The fatigue limit research has the extremely vital significance not only on the aviation, astronautics, the shipbuilding, the atomic energy, the state-of-art industry sector, but also on reliability and a service life of the automobile product. Especially in the recent several decades, with increase in the automobile number, wearily destroy the accident are emerge one after another incessantly. Therefore, it is important to develop ABS's research of fatigue limit in the automobile manufacture industry.Whether made in domestic or import, the price of a completed function, the versatile good testing machines quite expensive. Based on the above reasons, in line with embarks from the reality, face to our country automotive industry it is necessary to develop effective, special-purpose ABS fatigue testing machine is an important topic. The ABS brake fatigue test platform is one kind of test equipment in kind, it reappears the ABS brake each kind of load which receives in the braking process iunder the laboratory condition, which adapt examines the traditional endurance test to the forecast experiment. This forecast experiment provide the data for the new brake development, the application.In this paper, the key point design is the control system. The hydraulic pressure servo-control is a quite emerging science and technology, it not only is a hydraulic pressure technology new branch, but also is an important constituent of control domain. Every partially using the hydraulic servo system in the hydraulic transmission or the operation the system all abbreviationally named hydraulic servo. The servo system calls the servo system or the tracking system too. In recent years, with the development of mechanical work precision, the speed of response and the automaticity enhancement, there is the more and more high request to the hydraulic control technology. In this situation, it is difficult to only use the hydraulic control technology oneself to satisfy this request. The integration of machine, the electricity, the fluid is precisely produces under this kind of background.The ABS fatigue test platform control system is comprised of the amplifier, the electro hydraulic servo valve, the hydraulic cylinder and the pressure transmitter and so on. In this topic, use electricity-fluid proportional control direction valve□□electro hydraulic servo valve. Electro hydraulic-servo valve works in step less control way. When the control system input voltage moves high, the error signal increases; when the electro hydraulic servo valve input current increases, the valve opens the mouth to increase, servo delivery rate increase. When the control system input voltage lowers, the error signal reduces, the electro hydraulic servo valve input current reduces, the valve opens the mouth to reduce, the servo delivery rate reduces. In conclusion, the valve aperture size and the electric current is the proportion relationship. In this system, the output (pressure) can automatically, fast and accurately follows the input value (corresponding physical quantity expected value or given value) changes, at the same time, the output string large scale is enlarged.The work principle of ABS weary test platform control system: When pressure voltage signal ur and the pressure transmitter feedback voltage signal uf is different, the amplifier does not lose to the servo valve the electric current i to cause hydraulic cylinder output hydraulic pressure PL, until ur=uf, affects in the load the pressure is the given value.The dynamic, the static characteristic of electro hydraulic servo valve have the very tremendous influence on the properties pressure control system performance. Firstly the paper it can be obtained the servo valve the transfer function from the analysis dynamic, the static characteristic. After that the entire valve of controlled the hydraulic cylinder system was carrying on mathematics modeling, the simulation analysis .(1) The electro hydraulic servo valve transfer function :(2) The modeling of the valve controls the hydraulic cylinder system 1. slide-valves linearized current capacity equations: QL=KqXv-KcPL2. Hydraulic cylinder oil stream equation of continuity:3. Hydraulic cylinder and load strength balance equation:The transfer function of controlling the hydraulic cylinder system resulted from above three formulas:Depending on the classics control theory frequency range analytic method, the split-ring transfer function bode diagram and the unit step leap responses of ABS brake fatigue test platform control system were made by MATLAB simulation software. It can be gained system is stable from split-ring transfer function bode diagram of control system. It can received that not only value very in a big way from the unit step leap response chart, the time excessively is also long. After the PID adjustment, the step leap input time domain response curve demonstrated has satisfied the performance requirement, simultaneously may see the peak-to-peak value from in the control system split-ring transfer function bode diagram value and the phase value for all has the enhancement. The split-ring passes through the frequency distinct enhancement thus enhanced the system rapidity and the controllability. Afterwards we carries on the hardware and software design to the ABS brake fatigue test platform control system electric control. The control system electrically controlled installment (ECU) is adapt the monolithic integrated circuit. The signal is produced by the software .This method enhanced the system reliability; The servo valve actuation uses the monolithic integrated circuit to actuate so that the design of software and hardware be simple. In the experimental part, it has confirmed the servo valve static state, the dynamic character. This shows that pressure system have attained the design requirements.Following conclusion through the research analysis:1. Uses the microcomputer control and the pressure negative feedback control ABS brake weary test platform, has the high control precision, the stability and the good dynamic response.2. Uses integrated, the structure design hydraulic pressure loading system reasonably, the arrangement, the noise small, the work is reliable.3. Uses the PID control method to improve the system the speed of response and the tracking accuracy, has satisfied the system anticipated request.4. Carries on the computer using MATLAB/AMESim software to imitate the value simulation, simple, is accurate, for promulgates various parameters the change rule to build the foundation.5. In electrohydraulic servo valve control hydraulic cylinder pressure system, because the servo valve pressure increases very high, this makes the system the output load pressure to be very easy to achieve saturated, may control the sector changes narrowly. In order to enhance the system control, may through use the servo valve aperture pattern or put on additional together with the hole causes the system control the enhancement.6. Through the debugging, the pressure output curve which obtains achieved the design the request, proved this article designs the control system is successful, in the practical application, has the very good feasibility.