Research On Integrated Control Strategy Of ADM System Of 8WD Wheeled Off-Road Vehicle

The vehicle Automatic Drive-train Management(Abbr: ADM) system is a kind of new-type anti-slip driving control technology, namely the implementation of all wheel drive and lock or unlock of differential locks and driving engagement mechanism are controlled by ADM component automatically. By judging the vehicle running state and road surface state, ECU switches the number of driving wheels automatically, utilizing adhesion force between wheels and road surface to the maximum extent, which makes the vehicle having the best driving form all the time. So, the vehicle Automatic Drive-train Management (ADM) system has the following advantage:(1) ADM system can make vehicle in the best driving state, raise the mobility of the vehicle;(2) ADM system can improve average speed and passing capacity on various kinds of road surfaces, realizing running all the roads with no parking and increasing passenger's possibility of survival;(3) ADM system is an automatic system and needn't have driver judge and handle, which makes driver concentrate on change direction, apply the brake, throttle control and changing of road surfaces, lightens driver's tired intensity and tense degree greatly and improves vehicle security;(4) ADM system can improve average efficiency of power train, reduce oil consumption notably and lengthen the continuous distance traveled of the vehicle; (5) ADM can use also use other CAN bus information while the system work。The paper combines the project"Technology Research for Automatic Drive-train Management (ADM) System of 8WD Wheeled Off-Road Vehicle"on the basis of the earlier research of ADM system, according to the vehicle dynamic parameters in the driving process, and handling correlation knowledge of automobile theory and automobile dynamics, making much further analysis and correlation research for identification technology of ramp driving and steering driving state. The ramp fuzzy logic recognition module is designed and a general method of turning identification basing on velocity difference of different wheels is put forward. According to the need of road condition recognition on the vehicle dynamic parameters, establishing ground-tire model to establish foundation for road condition recognition basing on BP neural network. Road condition recognition method is designed by using BP neural network, and the joint mode of neurons on every layer are defined by training road condition recognition model basing on BP neural network, moreover, making demonstration on recognition effect for several typification road. The paper researches combination control strategy of ADM system by combining driving state recognition with road condition recognition. ADM controller model is established by using Matlab/Stateflow, moreover, combination control strategy emulation model is established and the model is analysed and researched, which will make control strategy of ADM system more perfect.Firstly, the paper introduces the developmental course, structural composition, as well as operating principle of ADM system, and some analysis with interrelated theory has been conducted. The working conditions of differential locks and driving gear meshing engagement devices are analyzed on the basis of control principles of ADM system. At the same time, according to the earlier research into the project and vehicle road test, the control strategy of ADM system is summarized. In the light of possible pecial driving conditions and several typification road conditions, the total requirement of control strategy of ADM system is brought forth.Secondly, the paper researches ramp driving and steering driving state recognition via analysing the characteristics of longitudinal dynamics on straight driving vehicles. In course of ramp driving state recognition of 8WD Wheeled Off-Road Vehicle, According to the relationship among throttle control, vehicle speed, acceleration and slope angle, the whole process begins with establishing the method of fuzzy identification, carrying through the recognition by throttle control, vehicle speed and acceleration. Base on fuzzy control theory, in term of the design method of fuzzy identifier, and according to the practical requirement of system to design the ADM fuzzy identifier. And an identification effect graph is produced to observe the identification effect. In course of steering driving state recognition, the kinematic model of vehicle steering state is built. With the help of MATLAB, a graph showing the relationship between the external steering wheel on the first axis and velocity difference of different wheels is drawn up. We can identify the steering angle of the wheel on vehicle speed, velocity difference and slip rate. Slip rate is brought forth while vehicle steer, the slip rate makes effect on road condition recognition.Thirdly, in course of road condition recognition, the concept of road condition factor is brought based on the study on some ingredients affect the adhesive performances between road surface and tire, and hereby classify the road condition. The factors like road condition, vehicle speed, wheel load and wheel slip ratio etc, which impact on characteristic adhesion coefficient. Based on the double exponential road-vehicle dynamics model, the road condition recognition model that make the vehicular dynamics parameters as input vectors based on the error-back-propagation BP neural network is proposed, the structure of BP neural network is designed, while the joint mode of neurons on every layer are defined by studying and testing with network. The road condition factor is chosen to be the output of the road discriminating system by vector operations to output of BP neural network. The validity and reliability of the road condition identifying system based on BP neural network are demonstrated by testing the neural network and analyzing the recognizing results on manifold road condition. The neural network based on road condition recognizing system is testified to have a wide applying range, strong memories, good faults tolerance and discriminating rate.Finally, the paper does some researches about the integrated control strategy of ADM system by combining driving state recognition with road condition recognition. Integrated control strategy of ADM system is established, and simply introduces the principle and function of Stateflow. Signal creater simulated model is established by using Matlab/Stateflow. And it establishes engine model, the drive line model, driving wheel dynamics model, vehicle dynamics model and identification machine model. It also establishes simulated model of integrated control strategy of ADM system and does some researches and analysis.The paper does some researches on integrated control strategy of Automatic Drive-train Management (ADM) system, which will make control strategy of ADM system more perfect and improve its performance. As a essential technology of ADM anti-slip control system, the research based on the integrated control strategy of identifying driving condition and road condition has great means and practical value to realize the ADM products. By the way of research on integrated control strategy of ADM system and wide use on off-road vehicle, it has great means of improving the passing ability and flexibility of off-road vehicle.