Research On Parameter Identification And Multi-target Braking Force Distribution For Heavy Duty Vehicle

As an important part of active safety system,braking system technology develops from the traditional brake system,Anti-lock Brake System(ABS),Electronic Pneumatic Brake System(EBS).EBS not only considerably enhances both vehicle and thus road safety,especially by reducing the stopping distance and improving braking stability,but also represents a major improvement in terms of economy and driving comfort by means of braking by wire,shorter response times and simultaneous response,reduction of the number of individual components and connecting elements,synchronization of axle brake lining wear,and the improvement in the compatibility between the tractor and trailer.This paper is financially supported by Jilin Province Science and Technology Development Plan Projects "Heavy Duty Vehicle Electronic Pneumatic Brake System Development and Matching"(No.: 20150204066GX)and "Integrated control and matching of commercial vehicle electronic pneumatic brake and auxiliary brake(20160101275JC).Based on the analysis of vehicle mass and road slope estimation,braking force distribution control for Heavy Duty Vehicle(HDV)in literature both domestic and abroad,aiming at enhancing HDV brake safety,comfort and economy,multi-forgetting-factors Recursive Least Square Method based vehicle mass and road slope estimation algorithm is proposed,and then the multi-target braking force distribution algorithm is proposed.Finally,the multi-target braking force distribution control algorithm is verified both by computer simulation and hardware in the loop test rig.The main work of this paper is summarized as followed:(1)Establishing the HDV power system and longitudinal dynamic model for recursive least squares method.The power system model,which takes moment of inertia into consideration,includes the engine,transmission and main reducer.The longitudinal dynamic model consists of air resistance,rolling resistance and slope resistance.In addition,a test road model is established in Truck Sim environment to verify the vehicle mass and road slope estimation algorithm.(2)Concerning the fact that HDV mass and the road slope vary in different rates,this paper proposed the multi-forgetting-factors Recursive Least Square Method to identify the vehicle mass and road slope.The multi-forgetting-factors Recursive Least Square Method decouples the updating step of the covariance of different parameters.Different forgetting factors updates different parameters by scaling the covariance making the parameter estimated independently.(3)Multi-target braking force distribution control algorithm.Under normal braking condition,heavy-duty-vehicle braking force is proportional to the vertical axle load,braking distance is shortened and at the same time the tractor and trailer obtained ideal coupling force at the hitch,enhancing the heavy duty vehicle safety and comfort.When the tractor front and rear axle brake friction lining wear is not balanced,tractor brake force is adjusted in the range permitted by the ECE regulation to balance lining wear,thus the tractor brake linings can be replaced simultaneously.Therefore,the multi-target braking force distribution algorithm improves the brake safety while taking into account the comfort and economy.(4)Building the HDV EBS hardware in the loop test rig.The test rig consists of the EBS key components,pneumatic braking system,the Lab VIEW real-time simulation system and the d SPACE system.The Truck Sim vehicle model runs in the Lab VIEW real-time simulation system via the dynamic link library file,and the Micro Auto Box acts as controller running the braking force distribution control algorithm.The braking force distribution control algorithm is the condition of validated in empty,laden braking.