<div class="section abstract"><div class="htmlview paragraph">Vehicle intelligence with more precision and reliable steering mechanism for
safety, comfort, and energy-saving is the recent key technology in the
automobile industry. Due to its merits, the permanent magnet synchronous motor
(PMSM) has been utilized in automation industries to serve as the servo system
and is introduced in the vehicle field as the engine for the steering system. To
avoid the complexity of computing and the current coupling effect of vector
control which is easily affected by motor parameters changes, and to ensure that
the steer-by-wire motor precisely tracks position, this paper adopts the sliding
mode direct torque control method and proportional feedforward integrated with
the fuzzy-proportional integral (PI) controller to address this issue. The
proposed method is simulated and used to analyze the PMSM uncertainties changes
due to the road condition and ensure the steer-by-wire motor tracking precision.
The vehicle model is established in CarSim and combined with the simulated model
under double-lane shift and step angle signal scenarios to verify the precision
and steadiness of the steer-by-wire system. The steering resistance moment is
considered as the load for the steering actuator due to the road condition, and
the load observer is studied to mitigate the loading effect on the actuating
motor. The results demonstrate that the following curve angle under the proposed
method coincides highly with the reference signal with no fluctuation, and the
tracking position accuracy is improved by 78.3% compared to the traditional
proportional integral derivative (PID) controller. Moreover, through the
realistic design of the steer-by-wire system control strategy, the vehicle
handling stability is realized, which is beneficial to relieve driving fatigue
and improving steering efficiency.</div></div>