oscillatory instability

oscillatory instability exists if a small temporary disturbance or control input causes an oscillatory vehicle response of ever-increasing amplitude about the initial trim. Note: divergent instability may be illustrated by operation above the critical speed of an oversteer vehicle. Any input to the steering wheel will place the vehicle in a turn of ever-decreasing radius unless the driver makes compensating motions of the wheel to maintain general equilibrium. This condition represents divergent instability. A linear mathematical analog of a vehicle is divergently unstable when its characteristic equation has any positive real roots.