Design and development of hydro-pneumatic suspension system for mobile heavy duty transporters

Mechanical suspension systems using linear springs are passive systems designed to provide reasonable ride comfort for certain road roughness and load values. These systems cannot provide the desired driving comfort under changing loading and road unevenness conditions. In systems generally used in off-road activities such as military vehicles, construction equipment, heavy-duty trucks, tractors, mobile cranes it is preferred to use the Hydro-Pneumatic Suspension System (HPS), in order to effectively control the linear, roll and pitch oscillations of the vehicle. Since the spring constant and natural frequency of the HPS system increases with increasing load/deflection, HPS ensures the driving comfort of the vehicle, and on the other hand stabilizes the boom, tower ands similiar structures mounted on the vehicle by reducing lineer vibrations. In this thesis, an experimental method is presented for the design of HPS with optimum performance characteristics in terms of driving comfort for use in heavy-duty vehicles. In this context, an experimental system was designed and produced to design HPS, and the experimental plan to be used to determine the HPS parameters suitable for the desired performance characteristics was determined by the Taguchi Experimental Design Method. Road data for roads with different characteristics to be used in HPS design were obtained through a data acquisition system. Applying the experimental plan obtained by Taguchi method, the experimental data obtained were processed with nCode software and the system was optimized in terms of driving comfort. Obtained results are presented in the form of graphs. In order to verify the designed experimental system with numerical methods, CAD model of the developed system was created using a quarter vehicle model with two degrees of freedom. System identification of HPS was performed by using MATLAB software. Obtained data were parameterized and the transfer function that best describes the system was obtained by running Hooke-Jeeves and Bees Algorithms simultaneously. The performance of the designed HPS with the presented experimental method has been verified using the obtained transfer function.