Research On Hierarchical Control Of The Bus Longitudinal Driving Assistance System Based On Functional Mode

With the arrival of the intelligent and network craze,the longitudinal driving assistance system,one of the key technologies of intelligent and connected vehicle,has attracted more and more attention.At first,the longitudinal driving assistance system gets the road and vehicle information ahead by all kinds of sensors of the perceptual layer,and then the environmental information is input into the decision layer for intelligent decision.Finally,the decision result is input to the executive layer to control the execution.When the bus is in danger of collision,it is very easy to make the bus side to slip and turn over because of turning to avoid the obstacle,which can cause more serious consequences,and the longitudinal control should be given priority.Therefore,further research on the bus longitudinal driving assistance system is of great significance for improving the level of road operation,reducing casualties and promoting the development of intelligent transportation.In this paper,hierarchical control research is based on three function modes:the adaptive cruise control system,the forward collision warning system and automatic emergency braking system,the ACC and AEB upper controller output desired acceleration,the lower controller performs robust control,and ultimately realizes the adaptive cruise and emergency braking function of the bus.As a transitional FCW upper controller,it is used for early warning before emergency braking.In this paper,the vehicle dynamics model and inverse longitudinal dynamics model are established based on the bus,and the upper and lower controllers are built on this basis.The upper controller divides the longitudinal driving assistance system into three subsystem function modes?ACC,FCW,AEB?.The ACC upper controller performs fuzzy control of desired acceleration based on the mode switching?speed control and distance control mode?of adding transitional area to realize the adaptive cruise function;the FCW upper controller based on the safety distance model of risk classification?to realize the early warning function,through hierarchical safety distance model is first divided into different risk levels,matching with the driver style in different risk levels corresponding to the expectations of TTC^-1;the AEB upper controller is based on the safety distance model of the braking process kinematics analysis to realize the emergency brake function.Then the ACC and AEB upper controller are verified by simulation test.Considering the influence of uncertainty on the system,we use the structure singular value?theory to consider the influence of parameter perturbation,unmodeled error and sensor noise interference on the system,and design the lower controller.In order to verify the effectiveness of the designed controller,the closed-loop system of the?controller is simulated and analyzed in frequency domain,and it is compared with the H_?controller.In order to verify the upper and lower control algorithms proposed in this paper,the ACC and AEB systems are divided into three typical working conditions to conduct simulation and analysis.The simulation results show that the designed upper and lower level controller can achieve the functions of constant speed cruise,car following and emergency braking,and the control effect can achieve the desired goal,so that the system has good robust stability and robust performance.Finally,to conduct the activation test by AEB system of the bus tests for early warning and emergency braking,the test results accord with the relevant regulations and standards.