The linear mathematical model (transfer function) for the Futaba S-140 Servo is approximately

The nonlinear mathematical model contains the rate limit on the motor. The servo is only capable of moving at rates less that 252 degrees per second.

One caution if you use the nonlinear model. You must express your commanded surface deflection in degrees or you will get the wrong surface motion out. The nonlinearity expects the units of degrees per second on the surface rate.

For the Tower Hobbies information on this servo, click here.

• servo.m A Matlab (not Simulink) script to analyze the servo poles and plot a bode plot of the linear servo model
• S148Linear.mdl A Simulink model of the linear servo.
• servoNL.mdl A Simulink model of the nonlinear servo including the rate limit.
• sim1.mdl A Simulink model for generating time responsed of both linear and nonlinear servo models.
• AAE451Lib.mdl A Simulink library containing both linear and nonlinear servo models.