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  literature survey SIMULINK SIMULATION MODELOF POWER-ASSISTED STEERING Jiří Tůma This paper deals with the SIMULINK simulation of the Power-Assisted Steering (PAS)of hea!-dut! tru #s$ The SIMULINK linmod and bode  fun tions are used for e%tra ting linear models in the form of the state-spa e matri es and to reate &ode phase and fre'uen ! plots$  This paper is intended to present a SIMULINK simulation model of the PAS. This model isused for extractin linear model in the form of the state!space matrices and to provide further fre uency domain analysis usin #ode phase and manitude fre uency plots. In this case$simulation is a tool for studyin influences of the PAS parameters on the PAS dynamic %ehaviour.&i '.Model of po(er!assisted steerin created %y usin SIMULINK %loc) at (hich theli%rary Concl!ion The SIMULINK linmod and bode functions are used for extractin the linear model of the po(er!assisted steerin in the form of the state!space matrices and to create #ode phase andfre uency plots. *ynamic stiffness of the po(er!assisted steerin as the ratio of the Laplacetransform of external force to the Laplace transform of actuator displacement is a su%+ect of ananalysis. The #ode plots of analytical and experimental dynamic stiffness are used for estimationof the system parameters values. The relationship %et(een static and dynamic stiffness isimportant for sta%ility of the po(er!assisted steerin. AERONAUTICAL STEERING SYSTEM DYNAMIC MODELING  Ricardo Rogge CaroneAeronautical steering system can be of various types. Small aircraft often use purely mechanical systems, directly connecting the pilot’s foot commands to the nose landing gear wheel – this is valid for regular tricycle landing gear conguration, which is the absolute maority of the cases of the industry. As the aircraft gets larger and heavier, the pilot is no longer able to provide enough power to !eep the system under safe operation. owered systems are the solution to provide ade#uate control for larger aircraft. $his category of steering systems also has variations% electrical or hydraulic powered, being the last one most found at present time. $he simplest system architecture with a control loop is shown at&igure ' – (ydraulic powered position control systemAll hydraulic powered systems must have a pressure supply, a directional valve and hydraulic actuators. $he directional valve is often combined with other components on a single manifold to comply with the system)s complementary yet of most importance functions% to provide shimmy damping on operation and automatic free castor engagement in failure mode.All the above mentioned characteristics must be analy*ed and carefully chosen to reach best solution for each givenapplication. $he problem investigated here is classied as a design review, when there)s an already functional design, rst by modeling it and validating its behavior and afterwards proposing the most e+ective design change to improve the system performance under etreme temperature condition.  (ydraulic ower SteeringSystem -esign in Road ehicles Analysis, $esting and /nhanced &unctionality  $he basic principle of a hydraulic power steering system is an ordinary hydromechanical servo parallel to a pure mechanical connection. A hydromechanical servo is a system that copies an operator applied movement, normally with the possibility to cope with higher forces or tor#ue. 0n a normal conguration of a follower servo, the force fed bac! to the driver is minimal.-riving a car is really a closed loop system, where the driver is the controllerand the steering unit is the actuator. $he steering system transfers the steeringwheel angle to the wheel angle, where the action changes the heading of thevehicle. As the main reference, the driver uses the visual information to placethe car on the road, he1she also uses the lateral acceleration and the tor#ue fedbac! via the steering wheel to ensure that the steering command is performedin the intended way. Components concerning the hydaulic 2 (ydraulic cylinder2 ump2 alve2 /pansion Chamber Attenuator, /CA2 Cooler  A. Small Aircraft Almost all airplanes with tricycle landinggear have some provisions for steering on the ground by controlling the nose wheel. Some of the smallest airplanes, however, have a castering nose wheel, and steering is done by independent use of the bra!es. 3ther small airplanes have the nose wheel connected to the rudder pedals, some directly, and others that are steerable up through a specied angle, after which the steering disconnects and the gear is free to caster up to the limit of its travel. B. Large Aircraft 4arge aircraft are steered on the ground by directing hydraulic pressure into the cylindersof a dual shimmy damper, as shown in &igure '56'. A control wheel operated by the pilot directs 7uid under pressure into one or the other of the steering cylinders. &luid from the opposite side of the piston in these cylinders is directed bac! to the system reservoir through a pressure relief valve that holds a constant pressure on the system to snub any shimmying. An accumulator in the line to the relief valve holds pressure on the system when the steering control valve is in its neutral position.  Basic Hydraulic System Schematic
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