An identification system in which a trigger signal, emitted on an object side and received by a portable code generator, is provided. Thus, when a user’s back is rested on the upper backrest and the lower backrest, the upper backrest and the lower backrest are pivotable relative to the support bracket to rest on the user’s upper and lower backs respectively to support the user’s whole back snugly and completely to prevent the user’s lower back from depending in the air so as to provide a comfortable sensation to the user. Two handles can be loosened to quickly rotate both a base support rod and a cradle support rod to desired positions, either for the driver’s use or the passenger’s use. The signal controller is connected between the first memory block and the second memory block and is configured to enable the third blocking signal when the second blocking signal is enabled, and to enable the first blocking signal when the fourth blocking signal is enabled. The operating system may be changed.