Research On Longitudinal Control Of Cooperative Autonomous Land Vehicles

Control of cooperative autonomous land vehicles is one developing direction of the intelligent transport system.Based on the safety driving of cooperative vehicles,platoon could shorten inter-distances between vehicles and reduce the fluctuation of vehicles' speed.It plays an important role on improving traffic safety and efficiency,reducing consumption of energy and transportation.Therefor,we study the longitudinal control of vehicles in a platoon and string stability in this essay,the main works and achievements are as follows:1?By adding wireless communication and choosing a constant time headway spacing policy between two vehicles,a speed planning algorithm is proposed based on states feedback of front vehicle,rear vehicle acquire speed of its front and adjust its speed according to the distance error,this algorithm is easy to implement and it guarantees safety of vehicle following.2?Another speed planning algorithm based on model predictive control is proposed,dynamic characteristics in the longitudinal direction of inter vehicles are modeled firstly and then we transform the control purpose into performance indicators and system constraints in frame of model predictive theoretical framework,finally the design of algorithm is translated into an online quadratic programming problem,a control sequence is calculated using rolling optimization theory,not only safety of the platoon can be satisfied by this algorithm,it can improve the ride comfort and fuel economy to some extent.3?Not only the spacing policy,but also information topological structure,communication time delay and noise could have big influence on the stability of the platoon and they could lead to driving unsmoothly,we validate these interference factors on simulations and by coupling Matlab with CarSim,we verify and compare the proposed algorithms in many aspects and results show that the state feedback algorithm is easy to be implemented in many situations and has high computational efficiency,however model predictive control could take multi-control objects into account,a more logical vehicle following speed can be obtained with this algorithm.