Design Of Automatic Test Platform For Headlight Adjustor

As an important electric actuator in the auto headlamp control system, adjustor is the guarantee that headlight meets lighting needs while driving and ensures the safety of driving at night. The GB4785-2007and the United Nations Economic Commission for Europe ECE-R48terms clearly defined that headlight with more than2000Lm luminous flux light must install automatic leveling adjusting device.In accordance with the comprehensive performance test demands of the headlight adjustor; traditional test methods have been unable to meet requirements of the test efficiency, cost and other aspects. At present, the types of headlight adjustor automated testing equipment are very few and the existing equipments are usually based on virtual instrument technology. This method can reduce the cost of the test and quickly establishing experimental platform of control system. But taking into account the conditions of production, environment and other factors in the industrial field, highly integrated and stability automated testing equipment is required.To solve the needs of enterprises, this paper analysed the system functional requirements and designed the overall solution with a combination of upper and lower computer. This method can not only realize all detected functional requirements, but also has a good human-computer interaction, real-time curve, download the process, as well as the requirements of the data record.In order to simulate the actual load, electric servo loading was used in the testing platform. This paper established the mathematical model of the loading system and analysed the main reason for impact loading accuracy and measures to suppress the strong position interference. The loading system adopted structure invariance and PID feedback control to accurately track the load spectrum.On the hardware design, this paper developed a dedicated hardware circuit for the full functional test. It mainly includes excitation voltage generating unit, the voltage and current detection unit, displacement detection unit, communication unit, the motor drive unit, the alarm output, and the microcontroller system peripheral circuit and so on. All real-time testing data is uploaded to the PC for data processing by the communication unit.On the software design, this paper completed the program controlled PWM excitation voltage subroutine, load resistance detection and servo loading system, communication program design based on Modbus protocol and other ancillary function programs. On the basis of all functional test procedures, the automatic control program of headlight adjustor was completed.