Research On Electric Assisted Steering Control System Of Commercial Vehicle Based On Active Disturbance Rejection Control

At present the main form of commercial vehicle power steering system is hydraulic,but its power assist characteristic is single and there is serious oil leakage pollution.With the improvement of motor control performance,Electric Power Steering(EPS)has emerged.Compared with passenger cars,commercial vehicles have more complex body structures,greater steering resistance,and the driving conditions of which have more incalculable and adverse effects,resulting in the obstruction of the application of EPS in commercial vehicles in the industry.With the development of electronic control technology,the real vehicle application of commercial vehicle EPS has become possible.Many scholars have studied commercial vehicle EPS from the upper-level control strategy level,but it is difficult to eliminate the effects of random disturbance and load mutation.It is necessary to apply the anti-disturbance control technology to the development of commercial vehicle EPS.From the perspective of motor control,this paper has completed the basic modeling of the EPS mechanical system of commercial vehicles,the hardware design of power assist controller,and the research on the power assist control system based on PMSM active disturbance rejection.Mainly include the following:First,the power steering mechanical modeling: The force of each steering mechanism during the driving process is analyzed,and the equivalent steering shaft force model is established;based on the analysis of the resistance during the turning process,a simplified resistance model is constructed.A closed-loop control model is formed by cascading with the vehicle model,the assist characteristic function,and the motor disturbance rejection control.Second,the hardware driver for power steering is designed which mainly completes the collection of EPS system signals,motor control,and information interaction: the signal acquisition filter circuit is designed to collect the motor speed signal,UVW three-phase electrical signal and other signals;the inverter circuit driven by gate IC is designed to drive the motor;the low-speed CAN communication circuit is designed to realize real-time monitoring of system parameters.Third,research on assist control method based on active disturbance rejection: In this paper,the assist characteristic curve is designed,and it is determined according to the relationship between the maximum torque of the steering wheel and the vehicle speed,and the relationship between the kingpin resistance torque and the vehicle speed in the case of no assist,and the PMSM output torque target value is further determined.The PMSM closed-loop control based on ADRC is studied,ADRC is introduced into the speed loop for the problems of large dynamic characteristics of steering load and sudden change of negative influence factors during the steering process of commercial vehicles.The motor speed is observed by the extended state observer,the input signal is smoothed by the tracking differentiator,combined with the error feedback control law,the PMSM vector control of the speed loop based on ADRC is constructed to resist the internal and external disturbances of the system.Experiments such as random disturbance and load mutation are carried out to verify the effectiveness of the application of disturbance rejection control.In this paper,by analyzing the steering structure and working environment of commercial vehicles,a simplified modeling of the EPS system is conducted,an empirical method for solving the power assist curve is studied,and an electric power steering control arithmetic of commercial vehicles based on PMSM disturbance rejection control is proposed.The cascade closed-loop simulation experiment shows that the electric-assisted steering disturbance rejection control method studied in this paper has good power assist characteristics and anti-mutation disturbance performance.