Steering Energy-saving Control Of Four-wheel Independent-drive Articulated Vehicle

With the intensification of environmental protection and energy issues,engineering vehicles have gradually entered the era of new energy.As a typical representative,electric articulated-steering vehicle with independent-wheel-drive(IWDASV)have received widespread attention from the academic and industrial circles.Compared with the centralized drive articulated-steering vehicle,the torque of each wheel of the electric articulated-steering vehicle with independent-wheel-drive is independently controllable,which has unique dynamic control advantages and sufficient energy saving potential.Articulated-steering vehicles usually use a hydraulic steering system which can quickly and flexibly complete vehicle steering,but also has the disadvantages of high energy consumption and low efficiency.In response to this problem,this paper proposes a Differential Drive Collaborative Steering(DDCS)technology which is a vehicle steering energy-saving technology based on the advantages of independently controlling the torque of each wheel of the electric articulated-steering vehicle with independent-wheel-drive.The DDCS system applies differential torque to the front and rear axles of the articulated steering vehicle,which make the front and rear bodies of the vehicle form an additional yaw moment about their respective centroids to assist the hydraulic steering system in steering.The DDCS system achieves steering energy-saving without changing the driving power and the driving state of the vehicle,which points out a new direction for energy saving optimization of articulated steering vehicles.Firstly,on the basis of summarizing the research status of articulated-steering vehicles and direct yaw moment control,this paper proposes the DDCS system for electric articulatedsteering vehicle with independent-wheel-drive.Then,according to the needs of the DDCS system,this paper makes a theoretical analysis of the kinematics,dynamics and hydraulic steering system of the articulated-steering vehicle.Furthermore,this paper presents the control ideas and prerequisites of the DDCS system and theoretically analyzes the feasibility.Then,an articulated-steering vehicle simulation platform is set up based on the AMESim software,and a physical prototype of the articulated steering vehicle is built.Simulation tests and physical prototype tests are performed respectively.The results verifies the feasibility and energy saving effect of the DDCS system,and the steering energy consumption of the hydraulic steering system is obviously decreased.In addition,this paper develops the control strategy of the DDCS system and makes a theoretical analysis of the influence of the distribution coefficient of the differential torque between the shafts on the energy consumption of the powertrain system.The optimization results of the distribution coefficient of the differential torque between the shafts are obtained through simulation tests.Moreover,the influence of DDCS system on vehicle motion is discussed.Based on this,the optimal function of differential torque is formulated,and the optimal differential torque MAP is obtained.Then,the DDCS system is designed,and the slip rate control strategy is introduced.Finally,in order to better verify the control strategy of the DDCS system,a joint simulation model based on MATLAB/Simulink and AMESim is established and comparative simulation tests are performed under the typical conditions of low-ehicle-speed fast-steering and highvehicle-speed low-steering of wheel loaders.The simulation results show that the DDCS system can save vehicle steering energy without changing the driving state of the vehicle.At the same time,the simulation results also show that the DDCS system does not require additional training for the driver when the vehicle is equipped with this system and does not affect the driving experience of the driver,which is a significant advantage of this system.