Comparison of lead network, tachometer, and damper stabilization for electric servos

Three types of compensation widely used to achieve stable operation in instrument servomechanisms are: the lead network, tachometer feedback, and the viscous-coupled-inertia damper. The paper compares these types of compensation in such matters as servo bandwidth, velocity constant, torque constant, transient response, tolerance to gear-train backlash, noise, and required amplifier gain. The purpose of this comparison is to provide a basis for selection of the most appropriate type of compensation for a particular application. The paper also serves to illustrate a method of analyzing servo performance in terms of the asymptotic gain-crossover frequency. Although this method may be theoretically trivial, it actually is a powerful tool for analyzing the performance of feedback control systems.