The Driver Visual Speed Controlling Design Method For The Long Steep Downgrade Considering The Temperature Rise Of Drum Brake

Constrained by the complex landforms and ecological environment, There are often continuous long steep downgrades when the driver driving on the mountain road. And annual number of accidents and casualties remain high, which are caused by the brake failure resulted the fast speed that out of control. Traffic safety situation of the long steep downgrade is grim. People grasp the 80% outside world information through the vision, and the visual information is driver's important speed sensation source. The reasonable visual induction can let the driver have the vehicle speed over-estimated feeling and under-estimated the effectiveness of distance between vehicles, distance between vehicles, then may guide and force the driver to decelerate. Embark on visual perception of the driver, combined with speed and braking temperature characteristics to analyze the driver visual speed controlling design method for the long steep downgrade, it helps to realize the driver can control speed consciously, and the driver visual speed controlling method is a effective measurement that adapt to the China situation with the high accident rate, the heavy accident intensity, more overloading of vehicles, the excessively quickly vehicle speed and the limited controllable economic resource.This paper briefly defined the edge rate, from the perspective of time and spatial frequency, analyzed the edge rate's influence for the driver subjective perception of speed under driving condition, summarized the innovative applications of edge rate in transportation domain, and then selected the individual edge line unit spacing as the edge rate controlled variable. Subsequently, summarized the domestic and foreign description of the long steep downgrade, with the basis of downhill section accident statistics data of our country in recent years, analyzed the cause of the downhill accident from various aspects such as human's reason, vehicles, speed and road conditions. Then synthesis compared to domestic and foreign research of accident data, and the difference of road conditions, vehicles performance, selected brake rising temperature security value and reasonable speed control threshold value for the long steep downgrade. According to related analysis and conclusions, proposed the driver visual speed controlling design conception for the long steep downgrade, from the specific national conditions, determine the vehicle type for the speed control design, combined with conservation of energy, automobile dynamics, object kinematics and so on, the basic drive equations was given, then deduced the mathematical formula about downhill deceleration power and braking energy conversion, and decrypted its simplified application from the sight of energy changes. Next, on the basis of the existing basic theory, summarized and analyzed existing research on the comfort retardation rate, based on the measured data in the literature and combined with downhill characteristics, determined value scope of the comfort retardation rate for the steep downgrade, then made a adjustment to the design model for speed control by using constant edge rate, obtained the sensitive value scope of the edge rate on the basis of real road test data. Considering the relationship of downhill deceleration power and braking energy conversion, determined the logical relation about using the new design model that combined with speed and braking temperature characteristics. Finally, the design example was given, then on the basis the example, analyzed the relationships about vehicle's weight, speed and brake temperature.