Electric power steering system(EPS) is a new power steering technology for vehicle and important device
for improving vehicle’s dynamics and static performances. EPS can be divided into the following three forms:
the Column assist type EPS(C-EPS), the Pinion assist type EPS(P-EPS), and the Rack assist type EPS(R-EPS).
System stiffness of Different types of EPS which effects on steering performance, are known by simulation
result and measuring products. P types of EPS are more stiffer than C types of EPS and contribute to steering
performance at on centre range of vehicles. By analyzing of performance with types of EPS, this paper
proposed improving method for C-EPS stiffness.