Application Of EZMP In Vehicle Pitch And Roll Evaluation And Active Suspension Control

During the driving process,the driving operation and road conditions will cause the body to produce vertical,pitch and roll movements,which have a certain impact on riding comfort and driving safety.Active suspension can control the body motion,and how to design the controller to take into account the movement of the body in three directions is the focus and difficulty of research.In response to this difficulty,this paper studies the active suspension multi-target switching control strategy to suppress the body motion.Around this control strategy,the following researches have been done:Firstly,the advantages of EZMP are analyzed,and EZMP theory is introduced into the vehicle pitch and roll stability evaluation system,and the vehicle pitch and roll evaluation indexes are derived.Considering the terrain angle,defining the vehicle support polygon,graphically analyzing the evaluation indexes,and proposing to use this index as the main control target and the main judgment condition of the switching control strategy for multi-objective switching control strategy,to provide the logic switching rule formulation of the control strategy and the input of control parameters conditions.The roll evaluation index is simplified and compared with the existing two evaluation indexes.It is consistent,which proves the correctness of the index and verifies the correctness of the pitch evaluation index.Secondly,taking a certain SUV as the research object,the relevant parameters of suspension and stabilizer are obtained through measurement,and then combined with other known relevant parameters,the vehicle dynamics model is established in ADAMS/Car.According to the needs of simulation conditions,the C-level pavement model and sine wave pavement model are established in ADAMS/Car.The establishment of vehicle model and road model laid a foundation for the subsequent joint simulation to verify the effectiveness of the multi-target switching control strategy.Then,to solve the problem that the multi-directional motion controller structure of the car body is more complicated and the practical application is more difficult,fuzzy PID controllers for vertical motion,roll motion and pitch motion control are designed respectively,and based on pitch and roll stability evaluation indicators and steering wheel angle as judgment conditions,using Stateflow to establish a system switching control model,the switching control system model is combined with the corresponding three fuzzy PID controller models to obtain the final multi-objective switching fuzzy PID controller model.For different driving states of the vehicle,a control strategy of switching control targets is adopted to solve the problem.Finally,a brief introduction to the working principle of electromagnetic linear actuator,taking a linear motor customized by a teaching and research team as an example,establishes its mathematical model,and verifies the accuracy of the mathematical model through the thrust characteristic test data.Based on ADAMS and MATLAB,a joint simulation model combining vehicle model,pitch and roll evaluation index model,multi-objective switching fuzzy PID controller model and actuator mathematical model was established,and straight driving conditions on C-grade road,double-shift line driving condition double-shift line on smooth road,and acceleration uphill and deceleration downhill conditions was designed for joint simulation,the simulation results show that: compared with the passive suspension,the active suspension significantly suppresses the changes of the body's vertical acceleration,roll angle,roll angular velocity,pitch angle,pitch angular velocity,roll evaluation index and pitch evaluation index,and pitch and roll evaluation indexes can also comprehensively and accurately evaluate vehicle pitch and roll characteristics.