Kinematic analysis respectively to the unitary and the double cross universal joints are carried out.The influence factors of the torque fluctuation on the steering system output shaft are determined.Using the RecurDyn software

double cross universal joints parameterization model are established.Defining variables and coordinates as parameter-based design variables

the optimization design aimed at the minimum torque fluctuation to the driveshaft can be made with the constant-velocity condition for spatial double cross universal joints.An optimum hardpoint layout is obtained

a smooth torque on steering drive output shaft without any undulation is achieved.