Vehicle evaluation of the performance of magneto rheological dampers for heavy truck suspensions

This study is intended to complement many existing analytical studies in th e area of semi active suspensions by providing a field evaluation of semiac tive magneto rheological (MR) primary suspensions for heavy trucks. A set o f four controllable MR dampers are fabricated and used experimentally to te st the effectiveness of a semiactive skyhook suspension on a heavy truck. I n order to evaluate the performance of the semiactive suspensions, the perf ormance of the truck equipped with the MR dampers is primarily compared wit h the performance of the truck equipped with the stock passive dampers. The performance of the semiactive system and the original passive system are c ompared for two different driving conditions. First, the truck is driven ov er a speed bump at approximately 8-11 kmh (5-7 mph) in order to establish a comparison between the performance of the MR and stock dampers to transien t inputs at the wheels. Second, the truck is driven along a stretch of rela tively straight and level highway at a constant speed of 100 kmh (62 mph) i n order to compare the performance of the two types of dampers in steady st ate driving conditions. Acceleration data for both driving conditions are a nalyzed in both time and frequency domains. The data for the speed bumps in dicate that the magneto rheological dampers used (with the skyhook control policy) in this study have a small effect on the vehicle body and wheel dyn amics, as compared to the passive stock dampers. The highway driving data s hows that magneto rheological dampers and the skyhook control policy are ef fective in reducing the root mean square (RMS) of the measured acceleration at most measurement points, as compared to the stock dampers.