| With the fast increase of diesel cars, it has obvious rising trend to NOx and diesel particulate matter emissions, which has serious damage to the ecological environment and human health. Free acceleration method and LugDown are main detection methods of the diesel exhaust emissions. Free acceleration method didn’t carry any load, which is more sensitive to operation of human. While LugDown can actually simulate the travel situation of car. In this paper, vehicle emissions detected system based on LugDown had been designed and implemented, and the paper further study the key technologies involved.The main work of this paper is as follows:1. By collecting, collating relevant references at home and abroad, it is summarized for theory and detected process of LugDown, and vehicle emissions test system structure based on LugDown is designed.2. By Simulation comparing classic PID control algorithm and fuzzy PID control algorithm,the result show Fuzzy PID control algorithm make the system stable in a shorter time. The paper proposes constant power control,constant speed control, and constant torque control based on fuzzy PID.3. Analyzed input and output signals of digital and analog. Signal conditioner that designed achieves the signal filtering,amplifying and high precision of A/D conversion. Signal conditioner can process the signal of power in the signal filtering,amplifying and high precision of A/D conversion,and the isolation of the digital signal.4. Vehicle emissions test system based on LugDown consists of parameter calibration model of the dynamometer and test model. Parameter calibration model of the dynamometer implement speed and torque,basic inertia, load response time, coasting time of constant load,coasting time of variable load,the parasitic power. Test model includes wheel edge power scanning and smoke data collecting.The result obtained by testing the system that is designed and implemented based on LugDown shows that the system has strong robustness and good control effect,and meet the relevant standards and the application of the actual scene. |
