Coefficient diagram method-based control of semi-active vehicle suspensions with performance evaluation over circular and trapezoidal speed humps at multiple speeds

The occurrence of abrupt vertical excitations, such as speed bumps, complicates the suspension system’s task of balancing stability with ride comfort. This paper uses the Coefficient Diagram Method (CDM) to design a semi-active suspension controller in a two-degree-of-freedom quarter-car to improve its performance in real-world disturbances. System investigated with controllers in different orders in displacement and acceleration cases. The model was initiated in Simulink, and circular/trapezoidal speed humps were applied to the vehicle at speeds of 5, 15, and 30 km/h. The root-mean-square values of body acceleration, body displacement, suspension working space, and tire dynamic load were used to evaluate performance, and it was benchmarked with a passive suspension. The outcome has indicated that acceleration feedback demonstrated the most significant decrease in body vertical acceleration of up to 69.3 percent and reduced dynamic tire load considerably. Displacement feedback, on the other hand, offered the greatest reduction in suspension working space (as much as 61.1 percent) and resulted in significant decreases in body motion, especially on trapezoidal humps. Although the speed increment during traveling through humps caused a decrease in overall gains, two strategies were repeatedly superior to the passive suspension. This evidence shows that CDM-based semi-active control would be an efficient and effective solution to adaptive suspension design with a possible application to vehicles that traverse urban settings where traffic-calming is commonplace.