Research On Estimation Algorithms Of Tire Slip Angle And Road Tire Friction Coefficient Vehicle With Steering-by-Wire

By wire technology is the development trend of future automotive technology,By wire technology has the characteristics of increased a lot of sensors, And increase these sensors provides new conditions for estimating tire slip angle and tire-road friction coefficient.In this paper, according to characteristics of steering by wire system, study on the estimation algorithm of tire-road friction coefficient and tire slip angle. First established a model of steering by wire system, and embedded it in software of Carsim, instead of the original steering system, finished the establishment of vehicle steering by wire system. Based on kalman filtering algorithm, making the steering motor current for control input and front wheel steer angle for measurement output, estimated the aligning torque of vehicle steering by wire. Secondly based on vehicle linear model and nonlinear tire model, based on extended kalman filtering theory, making the aligning torque and lateral acceleration for the measurement outputs, estimated vehicles tire-road friction coefficient and tire slip angle respectively. Finally considering vehicle response and tire-road friction condition affecting each other, using a duel extended kalman filtering algorithm estimated the tire-road friction coefficient and tire slip angle simultaneously. Main works for this paper as followed:1,vehicle steering by wire system model establishedFirst established a model of steering by wire system, including of steering assembly model, steering actuators assembly model and wheel kit assembly model . contains steering motor model and the fault-tolerant motor model. By selecting typical test conditions validate the precision of steering by wire system model. Then embedded model in software of Carsim, instead of the original steering system, finished the establishment of vehicle steering by wire system, lay the foundation for validation algorithm accuracy.2,the aligning torque of vehicle steering by wire estimatedEstablished total torque model of vehicle steering by wire system, it contains aligning torque model and steering motor torque model; in this paper also established steering system's mechanical torque model, simultaneousness the two model of torque, will get the relationship between aligning torque and steering motor current of steering system, Based on kalman filtering algorithm, making the steering motor current for control input and front wheel steer angle for measurement output, estimated the aligning torque of vehicle steering by wire. And choose typical test conditions based on Matlab/Simulink and Carsim simulation to verify the accuracy of the estimation results.3,Using extended kalman filtering theory estimated vehicles tire-road friction coefficient and tire slip angle respectivelyIn order to facilitate research, this paper studies the algorithm based on vehicle linear model and tire nonlinear brush model. Making the previous estimated tire slip angle and lateral acceleration for vehicle measurement output, using extended kalman filtering theory estimated vehicles tire-road friction coefficient and tire slip angle respectively, and choose typical test conditions based on Matlab/Simulink and Carsim simulation to verify the accuracy of the estimation results.4,Using duel extended kalman filtering algorithm estimated the tire-road friction coefficient and tire slip angleThis paper use two extended kalman filter parallel combinated, composition duel extended kalman filter and estimate the two variables simultaneously. Realize real-time updates between state and parameter estimation. In order to verify the accuracy of double extended kalman filter estimation, make the docking pavement for example, verified the union algorithm, Through the simulation can see duel extended kalman filter can be more accurate estimate the tire-road friction coefficient and tire slip angle.