Polygonal curves of assistant torque characteristic design for electric power steering system

To solve how to design assistant torque characteristic for Electric Power Steering (EPS), polygonal curves of assistant torque were developed based according to assistant torque characteristic rules. The new method focused on designing slope coefficient and turning point coordinates which determined polygonal curves shape absolutely. The less turning point coordinates were the better assistant torque performance the vehicle had. With the vehicle speed accelerating, the more the turning point coordinates were, the better the road feel drivers had. The results indicated that the polygonal curves of assistant torque characteristic could relieve the contradictions between the steering agility and the road feel.