Design And Research On The Three Degrees-of-Freedom Synthetic Test-Bed Of Coach-Bus

The three degrees-of-freedom (3-DOF) synthetic test-bed of coach-bus is important test equipment that engages in the handling stability studies of vehicles, the ride comfort researches of high-speed vehicles, the security researches and other studies of buses. The test-bed is a typical integration equipment of mechanical, electricity and liquid which involving machinery, hydraulic and control technology, and including three degrees of freedom movements of rolling, pitching and heaving. The significance of design and build the 3-DOF synthetic test-bed is lies in using this equipment in the laboratory environment to simulation and reconstruction the posture angle changes under the incentive when bus running on the actual state of roads, on this base to study the impact of structural characteristics to the stability of buses. Through the high-profile rolling and dropping tests of vehicles, used to engage in the studies of deformation of the high-profile vehicles, and the occupant protection and other relative tests and scientific researches of coach-buses.Firstly, this paper discussed the significance of research and development of the 3-DOF synthetic test-bed to the handing stability study, the ride comfort research and the security research of bus. According to the design index and development function, this paper has designed several kinds of test bench building programs; based on the analysis of the platform mechanical properties and kinetic characteristic to determine the final layout of the bench. Meanwhile carry on the essential mechanism verification and kinematic position analysis to the synthetic test-bed. On this base, we carried on the engineering design to the mechanical platform body of the bench, conducted on the moving platform structure mechanical analysis and the calculation of static strength, and also designed the test platform hinge form and base's structural style simultaneously.And then, we have designed the hydraulic system of the test-bed, unified the bench's function requests and the machinery design, this paper has carried on the computation and selection to the hydraulic system's components and auxiliaries, and has given ways to check the performance of the hydraulic system.Finally, the paper completed the task of control system study of the synthetic test-bed, and has designed the electro-hydraulic servo system's control unit and feedback unit. On account of control precision of the control system, this paper has designed the digital PID control algorithm, and has given the simulation result which had indicated satisfying control precision, and meets the control precision's requirement of the control system to the 3-DOF synthetic test-bed of the coach-bus.