A New Method for Sensorless Estimation of the Speed and Position in
  Brushed DC Motors Using Support Vector Machines
Ernesto Vazquez-Sanchez Jaime Gomez-Gil Jose-Carlos Gamazo-Real Jose Fernando Diez-Higuera
Currently, for many applications, it is necessary to know the speed and
position of motors. This can be achieved using mechanical sensors coupled to
the motor shaft or using sensorless techniques. The sensorless techniques in
brushed dc motors can be classified into two types: 1) techniques based on the
dynamic brushed dc motor model and 2) techniques based on the ripple component
of the current. This paper presents a new method, based on the ripple
component, for speed and position estimation in brushed dc motors, using
support vector machines. The proposed method only measures the current and
detects the pulses in this signal. The motor speed is estimated by using the
inverse distance between the detected pulses, and the position is estimated by
counting all detected pulses. The ability to detect ghost pulses and to discard
false pulses is the main advantage of this method over other sensorless
methods. The performed tests on two fractional horsepower brushed dc motors
indicate that the method works correctly in a wide range of speeds and
situations, in which the speed is constant or varies dynamically.