Closed loop control system and method using back EMF estimator
AssigneeHoneywell Inc.
InventorsDale D. Davidson, Hamid R. Sadeghpour
Life of this patent
Estimating the term…
Abstract
A feedback control system which uses estimated back electromotive force(EMF) from a controlled actuator to provide feedback into the control system and improve control of the actuator. Back EMF is estimated from current through the actuator and voltage across the actuator. The estimated back EMF signal is fed back into the control system where it serves as a rate term. In the preferred embodiment the back EMF signal is used in combination with an actuator position signal which is also feedback into the control system. A complementary filter conditions both the rate and position signals for improved performance. The invention is particularly suited for controlling linear actuators which do not provide conventional rate feedback signals.
Claims25
A feedback control system for controlling an actuator in response to a command signal, said control system comprising:
- a) a first input for receiving said command signal;
- b) a second input for receiving a current signal indicative of the current through said actuator;
- c) a third input for receiving a voltage signal indicative of the voltage across said actuator;
- d) a fourth input for receiving a position signal indicative of the position of said actuator;
- e) a back EMF combiner having,
- 1) a first input in communication with said current signal,
- 2) a second input in communication with said voltage signal, and,
- 3) an output communicating a rate signal indicative of the rate of movement of said actuator;
- f) a position command combiner having,
- 1) a first input in communication with said command signal,
- 2) a second input in communication with said position signal, and,
- 3) an output communicating a position displacement signal indicative of the difference between the signals received by said first input and said second input;
- g) a displacement combiner having,
- 1) a first input in communication with said displacement signal,
- 2) a second input in communication with said rate signal, and,
- 3) an output communicating a rate error signal indicative of the difference between the signals received by said first input and said second input;
- and,
- h) a filter, interposed between said back EMF combiner and said second input of said displacement combiner, said filter conditioning said rate signal so as to minimize the effect of motor impedance variations.
A closed loop digital control system controlling an actuator having an electrical motor, said control system receiving a position command representative of a desired actuator position and generating an actuator command in response thereof, said control system comprising:
- a) current feedback means for generating a digital current signal representative of the electric current through said actuator;
- b) voltage feedback means for generating a digital voltage signal representative of the voltage across said actuator;
- c) back EMF combining means, in communication with said current signal and said voltage signal, for generating a rate signal representative of the rate of movement of said actuator;
- d) displacement combining means, in communication with said position command and said rate signal, for generating a rate error signal;
- and,
- e) filter means, interposed between said back EMF combining means and said displacement combining means, for conditioning said rate signal such that motor impedance variation of said electric motor is minimized.
A closed loop control method for controlling an actuator using estimated back electromotive force comprising the steps of:
- a) providing a current signal indicative of electrical current through said actuator;
- b) providing a voltage signal indicative of voltage across said actuator;
- c) combining said current signal and said voltage signal to form a rate signal indicative of the rate of movement of said actuator;
- d) conditioning said rate signal to diminish the effect of motor impedance variation;
- and,
- e) feeding said rate signal back into said control system.
Dependencies are inferred from the claim text.