Research On The Path Following Control Of Tractor-semitrailer

With the rapid development of our national economics,rotation volume of road freight transport is growing rapidly.Tractor-semitrailer features to higher transportation capacity,lower cost and convenient for drop and pull transport.Due to such advantages of tractor-semitrailer,it was already widely used in logistics industry and has become the mainstay in road freight transport.But it has some shortcuts,such as a high center of mass,long body,big volume and the effect at the hinge point between two rigid bodies.The existence of this weakness make semitrailer difficult to following tractor path when tractor-semitrailer is in the conditions of high speed cornering,avoidancing of emergency and overtaking,which was easily leads to some dangerous accidents,such as jackknifing,swing and side-slipping,and also form a great security threat to the surrounding vehicles and people.Therefore,it has great significance to study the path following control of tractor-semitrailer,it is also crucial for improving both safety of roads and riding stability of vehicle.Aiming at semitrailer following tractor path,this paper studied the path following control of tractor-semitrailerpath by using the fuzzy control and differential braking method.First of all,a nonlinear tractor-semitrailer vehicle simulation model was established based on TruckSim,which was used to output some parameters of the tractor and semitrailer,such as vehicle speed,yaw rate,etc.Secondly,a simplified 4-DOF tractor-semitrailer reference model was established,and compared the simulation results with TruckSim.The results shou that the four DOF simplified reference model can be well simulated tractor-semitrailer basic motion characteristics.Thirdly,a tractor-semitrailer path following control strategy that combines fuzzy control and differential braking was put forward.Taking the path deviation between tractor and semitrailer and its variable ratio as input,and the additional yaw moment as output,the fuzzy controller was designed.A selection rule of the target brake wheel was formulated by contrast actual yaw response with expected yaw response,and adopted differential braking controller to produce the additional yaw moment.Finally,the control strategy proposed above has been analyzed and verified under single lane change,steering wheel angle sine input,double lane change and steering wheel angle step input condition through MATLAB/Simulink and TruckSim software.The results show that the control method can effectively improve the ability of the semitrailer following the tractor,moreover effectively avoid occurrence of dangerous accident such as jackknifing,swing and side-slipping,etc.