Research On Key Technologies Of Electric Power-assisted Variable-ratio Steering System For Sweeper

The electric power steering system is a new type of steering system developed in recent years.It has a series of advantages such as fuel saving,weight reduction,active safety improvement,and environmental protection.As a kind of special vehicle,the sweeping vehicle is used differently from general passenger vehicles or commercial vehicles.It has a large load,a slow speed,and frequent steering.When the electric power steering system is applied to it,the system volume will be too large.Large,heavy and other issues.In response to this problem,the paper proposes to combine the electric power steering system with the variable transmission ratio steering system to achieve the purpose of reducing the system volume and reducing the heavy steering.The main research contents of the paper are as follows:First,according to the variable transmission ratio design requirements and design goals,design the variable transmission ratio curve,select the relevant parameters of the mechanical structure,simulate the steering sensitivity and motor torque according to the mathematical model of the steering mechanism,and use MATLAB software to perform the motor selection according to the simulation conclusions And analyze the influence of variable transmission ratio function on sensitivity and motor selection.Secondly,in-depth study of the theoretical knowledge of gear meshing principles,learning variable gear ratio calculation and modeling methods.Calculate the contact line equation according to the gear equation and the meshing conditions,perform data processing,calculate the rack and tooth surface contact points,apply MATLAB to the surface fitting,obtain the rack and tooth surface,and perform secondary modeling in Solid Works 3D software to check the interference,Tooth profile correction is performed on the unmeshed area to obtain the tooth surface model.Finally,study and study the driving control theory of permanent magnet brushless DC motor,determine the driving scheme and carry out simulation analysis.Then build the motor test platform,which provides a good platform environment for the research and development of motor control.The result analysis shows that the use of electric power assisted variable ratio steering system can effectively reduce the size of the motor and improve the heavy steering problem of the vehicle.The design and method can also provide technical support for the application of EPS in other special vehicles.