In this paper, we also gived some discussions about how to design thelight road to obtain large viewing angle and how to choose taking parameters to obtainhigh diffraction efficiency.

They include the deviation of right dihedral angle (for cube corner retroreflectors only) and working attitude (entrance angle, observation angle, rotation angle).

A new speed estimation method based on the inspection of instantaneous power angle was proposed to solve the problems associated with the conventional direct torque control(DTC) of permanent magnet synchronous motor(PMSM),such as high current,flux and torque ripple,variable switching frequency,and to eliminate speed sensor since it deteriorated system reliability and increased the cost of system.