## DC-motor
Figure 1 shows a DC motor
(Faulhaber) including: ·
a speed sensor in the form of a tachometer, which gives a voltage
proportional to the rotational speed, ·
a servo amplifier, ·
a power supply. The control signal is in
the range of ±10V, and the tachometer voltage is in the range of
approximately ±10V, corresponding to a speed of ± 2krpm. A load inertia has
been added to the motor. The time constant of the motor including load and
tachometer is approximately 0.3s. The gain from control signal [V] to
tachometer measurement [V] is approximately 0.85.
Figure 1 ## Mathematical model
Various mathematical
models may represent the motor more or less accurately, e.g. - A differential equation
model representing “time-constant dynamics”: T*dS/dt + S = K*(C + L)
(1) where S [krpm] is the
speed. C [V] is the control signal. L [V] is an equivalent voltage
representing the load torque. L is in the range of ± 10 V. Approximate values
of the model parameters are: K = 0.17 krpm/V, T = 0.3 s. For the tachometer, the
following relation between the speed measurement S S where K ## Experimental data
logfile1.txt
is a text file containing time, control signal, and speed measurements as
tachometer voltage from an experiment where the control signal was adjusted
manually. Updated 18. March 2018. Finn Aakre Haugen (finn@techteach.no). |