A Study On Active Control Of Vehicle Speed

Serious traffic accidents happened frequently in mountain road in China, andmost of the reasons attribute to the drivers.Thinking to the deeper, road and trafficenvironment are not only the main excitation sources of the operating behavior of cardrivers, but also the platform on which the traffic accident happened. Many accidentshappened because of driver’s error operation of vehicles, which caused by misjudgmentto the real-time road conditions and driving environment. And the common form oferror operation is overspeed.Therefore, need to research the problem of vehicle safedriving in mountain road urgently from a people-vehicle-road (environment) systemperspective.The article relying on the existing research about active control system of vehiclespeed,study on vehicle speed and its control strategy on road sections of horizontal andvertical.The system’s basic principle is to use sensor technology to get road informationand vehicle speed, according to the road alignment information to control the brakepedal to emulate brake, in order to achieve effective active control of vehicle safe speed.For the problem of determining the safety speed value, from the system perspectiveof the people-vehicle-road, first of all, in this paper the principle of vehicle drivestability are used to analysis the vehicle’s mechanical, the condition of the rollover andsideslip is researched when the vehicle is on the place where the curves and longitudinalslope is combined. Then criticality safety speed can be obtained from the model.Themain road factors which are determine the vehicle safety speed. And then learn fromdrivers’ safety awareness of road alignment and speed decision-making mechanism, asafety awareness of road alignment fuzzy evaluated model are set up by using fuzzystatistic tests, fuzzy control and fuzzy logic deduction. Through getting input/outputsample data which is needed to establish fuzzy control rules for safety speed, a logicaldeduction calculation model of vehicle safety speed based on safety consideration,under the given road conditions is set up.The simulation calculated results compared tothe practical velocity, the average relative error is about6%and can be used as a systemsafety speed threshold in different road alignment.On the base of setting up safe driving speed logic and reasoning model，this thesistakes the safety of the real-time calculating speed as the goal of the system speed, in order to research the system achieving the upper control strategy of speed controlproblem. That is to say, it is according to the speed and road information detected by thesensor to decide the expectations of the vehicle acceleration. This thesis is according tothe vehicle deceleration characteristics in all conditions and highway route designstandard, and it takes the fuzzy control method to complete the design of the fuzzycontroller.This thesis establishes a simulation model of the system of speed control toanalyze the simulation of the slowdown process.The simulation results show that thecontrol strategy is effective and feasible, and it can satisfy the requirement of safety andpersonnel comfort.