Driver ride comfort is the important goal in truck ride analysis; as well as the semi-trailer vertical and pitch motions are important. Therefore the purpose of this study is to improve truck semi-trailer ride comfort using different control strategies based on fuzzy logic control theory. The simulation analysis is based on half truck semi-trailer
model with fourteen degrees of freedom. The effect of time lag is considered where as
the influence of truck speed on ride comfort performance has been investigated. The
obtained theoretical results shows that, using fuzzy logic control with active suspension
system for different control strategies gives a significant improvement in truck
semi-trailer ride comfort and did not have a negative effect on the semi-trailer vertical and pitch motions.