<div>Figure 1 Electromechanical car mirror wiper system</div><div>The 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 is</div><div>Where K1 is the motor torque constant and ia is the armature current.</div><div>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 or</div><div>Where eb is the back emf, <i>K</i> 2 is the back emf constant of the
motor, and is the angular displacement of the motor shaft.</div><div>The speed of an armature-managed dc servomotor is managed via the
armature voltage e(t). The differential equation for the armature
circuit is</div><div>Substituting Equation (2) in to Equation (3) yields:</div><div>Taking the Laplace transform the equation will be</div><div>The equation for torque equilibrium is</div><div>Taking the Laplace transform the equation will be</div><div>Where 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.</div><div>By eliminating from Equations (5) and (7), we obtain</div><div>We 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,</div><div>The wiper arm speed can be evaluated by using an integrator to the wiper
arm position as</div><div>Substituting Equation (10) in to Equations (9) and to Equations (8)
gives us the transfer function between the applied voltage and the wiper
speed as</div><div>The parameters of the system is shown in Table 1 below.</div><div>Table 2 Parameters of the system</div>