线性控制系统的最重要问题是稳定性的问题。稳定性是指控制系统在外作用消失以后自动地恢复原有的平衡状态或自动地趋向于一个新的稳定平衡状态的性能。如果系统不能恢复稳定平衡状态,则认为系统是不稳定的。系统设计人员应在列出系统传递函数后即进行稳定性分析。线性系统的闭环传递函数可写成 The most important problem with linear control systems is stability. Stability refers to the control system automatically disappears after the disappearance of the original equilibrium state or automatically toward a new stable equilibrium performance. If the system can not restore stable equilibrium, the system is considered unstable. The system designer should perform a stability analysis after listing the system transfer functions. The closed loop transfer function of a linear system can be written as