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Aiming at steering stability and wheel angle tracking of steer-by-wire (SBW) three wheeled forklift, steering dynamic model and SBW system mathematical model of three wheeled forklift are established. A control strategy for the ideal transmission ratio is introduced based on this model, which ensures forklift steering gain invariant. A sliding mode controller can then be designed based on the bound information of uncertain system parameters, uncertain self-aligning torque, and external disturbances. The results of simulation show the control strategies above can effectively reduce the sideslip angle when the forklift is steering and improve the sensitivity and stability of the steering forklift; at the same time can effectively restrain the parameter perturbation of internal system and external disturbance, which improves the tracking performance of the wheel angle.

A circuit of 10bit,200MHz sampling frequency current steering DAC with hierarchical symmetrical switching sequences was presented,which compensate the gradient error.The DAC employs segmented architecture.An integral linearity error caused by error distributes of current sources was reduced by a new switching sequence called "hierarchi-cal symmetrical switching".The DAC was built in a video-rate adaptive equalizer IC,which was fabricated in a 0.35μm,3.3V CMOS process.The area of DAC is 1.26mm×0.78mm.When operating at 14.318 MHz（4Fsc） sampling freguency,the effective numbers of bits is 9.3.Both the integral and the differential linearity errors are less than ± 0.5LSB.