| Summary: | 博士 === 國立交通大學 === 電機與控制工程系所 === 96 === The dissertation mainly addresses the research of front-wheeled steering (FWS) vehicles and discussion of H∞ robust control algorithm. The lane angle involving wheel-handling and sideslip angles is found in 2-degree-of-freedom (2DOF) dynamics steering vehicle model. Furthermore, the reality results of lateral position, velocity and acceleration are computed respectively in the lateral direction of body at the front wheels, the center of gravity (CG) and the rear wheels.
Then, two-type controllers of the auxiliary front-wheel steering angle and chauffeur are developed in the vehicle system. The former is a synthesized controller and it can restrain the angle component of front wheels when the vehicle travels along the curved and straight lane. Therefore, the turning situation in under-steer and over-steer area cannot be appearance. The synthesized controller can be obtained from the sideslip angle that it has the rear-wheel component and the front-axle concepts; however, it is unable to calculate immediately from 2DOF vehicle model. In order to eliminate the rear-wheel component, the front-axle angle controller considering the yaw rate concept is proposed. Indeed, the presented front-axle angle controller can remove the rear-wheel component via the theoretical analysis. Then, the created angle controller is set into a standard simulation tool, CarSim, and validated by the animation. Next, an estimated sideslip angle can be obtained from the geometry of body which can be regarded as a sub-model for which it is calculated by using the steady-state deflection angle concept. As well, this model can be analyzed in the third-type steering control structure.
The auxiliary driver behavior controller is a forward-looking steering controller (FLSC) whose objective can substitute for a driver behavior and FLSC can be derived from the theoretic inference. Moreover, the FLSC with three methodologies: 1) uses the cosine law to achieve the FLSC design, unfortunately, the inferred consequence is a regular value but it is not an altered value. Moreover, a unusual pre-filter is needed to form the system performance; 2) utilizes the concept of the lateral acceleration at the front-wheel position and then adds a proportional-integral compensator to perform the FLSC. Similarly, 3) the third compound FLSC, which contains of a proportional-integral and a proportional-derivative compensators, can be derived.
The signal of lateral displacement can be exerted in the unity feedback control steering system and consequently the designed controller can be obtained by using H∞ algorithm. Furthermore, the first-type is that the foregoing FLSC and, besides the lateral displacement signal, the signal of the wheel-handling or the yaw rate is involved in the advanced feedback steering system and then the offered controller is manipulated by H∞ algorithm. Obviously, the second-type is that the command of the wheel-handling consists of the front-wheeled slip and sideslip angles in the advanced feedback steering system. The third-type contains of the commands of the wheel-handling, the handling gain and the sideslip angle located at the CG. This system structure can be analyzed by using the H∞ robust algorithm. The forth-type presents an integral control structure is comprised of a modified driver command and the FLSC which the application is described by the formulated of the front-wheel lateral acceleration. Ultimately, all four-type control structures have a common input trajectory: Target path. The input track information can be represented by CarSim for which it can work together with MATLAB. The reasonable performance demonstrates follow a desired target path both accurately and stably under the variations of mass, forward velocity and road-tire contact.
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