Figure 1 Electromechanical car mirror wiper systemThe motor shown is a servomotor, a dc motor designed in particular for use in a control system. The operation of this device is as follows: A fixed voltage is carried out to the field winding. A voltage is implemented as an input to the servo motor and the angular position c of the wiper arm is the output of the device. The input voltage is implemented to the armature circuit of the dc motor. A constant voltage is carried out to the field winding. If an errors exists, the motor develops a torque to rotate the output load in the sort of way as to reduce the error to zero. For constant field current, the torque evolved by using the motor isWhere K1 is the motor torque constant and ia is the armature current.When the armature is rotating, a voltage proportional to the fabricated from the flux and angular velocity is brought on within the armature. For a constant flux, the brought about voltage eb is without delay proportional to the angular velocity orWhere eb is the back emf, K 2 is the back emf constant of the motor, and is the angular displacement of the motor shaft.The speed of an armature-managed dc servomotor is managed via the armature voltage e(t). The differential equation for the armature circuit isSubstituting Equation (2) in to Equation (3) yields:Taking the Laplace transform the equation will beThe equation for torque equilibrium isTaking the Laplace transform the equation will beWhere J0 is the inertia of the combination of the motor, load, and gear train referred to the motor shaft and b0 is the viscous-friction coefficient of the aggregate of the motor, load, and gear train mentioned the motor shaft.By eliminating from Equations (5) and (7), we obtainWe assume that the gear ratio of the gear train is such that the output shaft rotates n times for each revolution of the motor shaft. Thus,The wiper arm speed can be evaluated by using an integrator to the wiper arm position asSubstituting Equation (10) in to Equations (9) and to Equations (8) gives us the transfer function between the applied voltage and the wiper speed asThe parameters of the system is shown in Table 1 below.Table 2 Parameters of the system