Dynamic Performance of a Three-Wheeled Vehicle Steering System, Part 1: Steering System Incorporating Directional Control Valve

Abstract

During taxing, the aircraft can be treated as a three wheeled vehicle. This work deals with the dynamic behavior of this three-wheeled vehicle during the steering mode. Conventionally the hydraulic power steering systems incorporate either hydraulic or electrohydraulic servo-systems. Nevertheless, Part 1 of this paper deals with the dynamic behavior of a steering system incorporating three directional control valves of poppet type in one housing. A nonlinear mathematical model of the directional control valve assembly was developed and used to simulate the valves dynamic behavior. The validity of the simulation program was evaluated in the steady state by comparing simulation results with results of experimental work conducted on the studied valves. The construction of the mechanical parts is explained and the kinematics of the steering system was analyzed and presented. The transient response of the steering system incorporating the directional control valve assembly was calculated, presented and discussed.

Dynamic Performance of a Three-Wheeled Vehicle Steering System, Part 2: Steer by Wire and Vehicle Dynamics during Steering

“…The step response of the system also has been calculated, presented and analyzed. The flow characteristics of the directional control valves were evaluated experimentally in Part 1, [1]. The simulation results showed good agreement with the experimental results which validates the simulation program in the steady state operating mode.…”

“…1. It consists of a hydraulic generator, a symmetrical hydraulic cylinder, (12), and an EHSV, (9) in lieu of the DCV assembly used in Part 1, [1]. The supply pressure (P P ) is kept practically constant due to the effect of the pump controller, considering the high pump flow rate and the very low flow demands of the steering system.…”

“…The motion of the steering actuator piston under the action of pressure, viscous friction, rolling resistance forces and inertia of moving and rotating parts was previously described in Part 1, [1].…”