Nonlinear H∞ control of active suspensions

A nonlinear H_∞ control law based on a quadratic and quartic cost function is developed, and applied to a quarter-car, two-degree-of-freedom vehicle model. For small disturbances, the performance is similar to the system controlled by the linear H_∞ controller, but for large disturbances, the suspension travel and wheel hop are reduced at the expense of larger body acceleration. When the vehicle strikes isolated large bumps, the nonlinear suspension provides a safer ride at the expense of higher car body acceleration and decreased ride quality