Effect of Control Techniques on the Performance of Semiactive Dampers

A computer simulation is used to examine the effects that various control methods have on the performance of semiactive dampers in controlling the dynamics of a single suspension (quarter car) model. The level of dynamic control of this model has a direct bearing on the ride comfort and vehicle handling, when the single suspension is interpreted as a partial model of a vehicle. The dynamic results obtained when using two alternative semiactive control methods are compared to the results obtained when using the more conventional control methods of passive damping, Skyhook control, and Hybrid control. The conventional control methods results confirm that the semiactive damper possesses a number of benefits when compared to passive damping. In addition, the alternative control methods, which are Displacement Skyhook and Displacement Hybrid, do not show benefits that are superior to passive damping or the conventional semiactive control methods.

In support of the conclusions of this report, sufficient detail of the mathematical and numerical model is provided in the event that one should wish to recreate the results presented here. Next, the simulation results of each of the five control methods are presented individually. Several of the responses used in the results chapters are the transmissibility plots for the sprung and unsprung body displacement, the frequency spectrum of acceleration, and the frequency spectrum of the rattle space. In addition, the system response to a step input is calculated and, lastly, time traces are calculated, one at a time, for system excitations at the sprung and unsprung mass natural frequencies. The key dynamic measures studied are settling times, displacements, accelerations, and jerks. The responses just listed are then used in a comparison study between each of the presented control methods.