The structure and principle of two different types of ema are systematically presented . the load characteristics and mechanical characteristics are analyzed with emphasis on the influence of the hinge torque on their dynamics and static characteristics 系统描述了两种不同类型的电动舵机的结构、工作原理，分析了其负载特性及机械特性，并着重讨论了铰链力矩对舵机动、静态特性的影响。
