Adaptive and reconfigurable system for DC motor control

• US 7,835,630 B2
• Filed: 04/03/2008
• Issued: 11/16/2010
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Kazanzides, Peter, Ekekwe, Ndubuisi John, Etienne-Cummings, Ralph
• Primary Examiner(s): Leykin; Rita
• Application Number:
  US12/061,896
• Publication Number:
  US 20080247735A1
• Time in Patent Office: 957 Days
• Field of Search: 318/800, 318/805, 318/803, 318807-811, 318/34, 702/127, 702/108, 702/85, 735/142.6, 324/415, 324/160, 324/163, 324/165, 324/76.47, 324/76.55, 324/76.79, 324/514.16
• US Class Current: 388/815
• CPC Class Codes: H02P 6/17 and for generating speed information

Abstract

An integrated circuit for controlling a DC motor is disclosed. The integrated circuit includes at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the motor, the DPS being in signal communication with the motor for receiving a pair of signals having a quadrature relationship; and at least one programmable gain amplifier (PGA) electrically coupled to the motor, the PGA being configured to receive a feedback signal indicative of current flowing through the motor and to apply a second signal to the motor for adjusting the speed of the motor; and at least two analog-to-digital converters (A/D), one A/D being used to quantize the output of the PGA for an off-chip processor; and another A/D to provide motor reference position from an analog sensor, such as a potentiometer; and at least two digital-to-analog converters (D/A), one D/A used to set the motor voltage; and another D/A used to set the motor current limit. The integrated circuit can be incorporated into a larger motor control loop which further includes a summing amplifier for providing the feedback signal to the motor that is indicative of current flowing through the motor; a buffer amplifier electrically for sensing the output current of the motor, and a processor for providing control signals to the system monolithic module and for receiving the measurements of speed, position, and direction of the motor.

Claims

1. An integrated circuit for controlling at least one motor comprising:

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the at least one DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship;

at least one programmable gain amplifier (PGA) electrically coupled to the at least one motor, the PGA being configured to receive a feedback signal indicative of current flowing through the at least one motor and to apply a second signal to the at least one motor for adjusting the speed of the at least one motor;

wherein the at least one DPS is configured to measure the speed of the at least one motor based on one of frequency counting and period counting;

wherein frequency counting is implemented by counting a number of pulses from the pair of signals having a quadrature relationship that occur within a fixed time window;

wherein the circuitry for measuring the speed of the at least one motor based on frequency counting comprises;

a toggle flip flop for receiving a fixed time pulse;

a counter electrically coupled to the toggle flip flop, the toggle flip flop enabling the counter for a fixed period of time, the counter receiving the one of the pair of signals, the counter being configured to count a number of pulses from the one of the pair of signals for the time the counter is enabled so as to provide an indication of the frequency of the at least one motor; and

a latch and PISO electrically coupled to the counter for storing and parallel in-serial out register serializing the indication of the frequency of the at least one motor.

2. The integrated circuit of claim 1, wherein the at least one DPS further comprises:

a QDECODER circuit block for decoding the pair of signals having a quadrature relationship to an UP or DOWN signal for providing an indication of the direction of rotation of the at least one motor and for providing a count signal indicative of a quadrature pulse count;

an UP/DOWN synchronous counter electrically coupled to the QDECODER circuit block for counting the quadrature pulse count; and

a parallel in-serial out register (PISO) electrically coupled to the UP/DOWN synchronous counter for serializing the quadrature pulse count so as to provide an indication of motor position.

3. An integrated circuit for controlling at least one motor, comprising:

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the at least one DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship;

at least one programmable gain amplifier (PGA) electrically coupled to the at least one motor, the PGA being configured to receive a feedback signal indicative of current flowing through the at least one motor and to apply a second signal to the at least one motor for adjusting the speed of the at least one motor;

wherein the at least one DPS is configured to measure the speed of the at least one motor based on one of frequency counting and period counting;

wherein period counting is implemented by counting a number of pulses from a timer that occur between consecutive pulses from the pair of signals having a quadrature relationship;

wherein the circuitry for measuring the speed of the at least one motor based on period counting comprises;

a toggle flip flop for receiving one of the pair of signals;

a counter electrically coupled to the toggle flip flop, the counter receiving an external clock, the counter being configured to count the number of pulses from the external clock that occur between successive pulses of the one of the pair of signals so as to provide an indication of the time period of the at least one motor; and

a latch and PISO electrically coupled to the counter for storing and serializing the indication of the time period of the at least one motor.

4. The integrated circuit of claim 3 wherein the at least one DPS further comprises:

a QDECODER circuit block for decoding the pair of signals having a quadrature relationship to an UP or DOWN signal for providing an indication of the direction of rotation of the at least one motor and for providing a count signal indicative of a quadrature pulse count;

an UP/DOWN synchronous counter electrically coupled to the QDECODER circuit block for counting the quadrature pulse count; and

a parallel in-serial out register (PISO) electrically coupled to the UP/DOWN synchronous counter for serializing the quadrature pulse count so as to provide an indication of motor position.

5. An integrated circuit for controlling at least one motor comprising:

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the at least one DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship;

at least one programmable gain amplifier (PGA) electrically coupled to the at least one motor the PGA being configured to receive a feedback signal indicative of current flowing through the at least one motor and to apply a second signal to the at least one motor for adjusting the speed of the at least one motor;

at least one digital-to-analog converter (D/A) configured to set the motor voltage;

at least one second digital-to-analog converter (D/A) configured to set a maximum limit on motor current;

at least one analog-to-digital converter (A/D) electrically coupled to the at least one PGA for receiving a measurement of the feedback signal of the at least one PGA as an indication of motor current; and

at least one second A/D for measuring the initial position of the at least one motor.

6. The integrated circuit of claim 5, further comprising at least one serial-to-parallel interface (SPI) circuit for providing clock and control signals to the at least one DPS and for synchronizing the signals for indicating the speed, position, and direction of the at least one motor.

7. The integrated circuit of claim 5, wherein the at least one DPS further comprises:

a QDECODER circuit block for decoding the pair of signals having a quadrature relationship to an UP or DOWN signal for providing an indication of the direction of rotation of the at least one motor and for providing a count signal indicative of a quadrature pulse count;

an UP/DOWN synchronous counter electrically coupled to the QDECODER circuit block for counting the quadrature pulse count; and

a parallel in-serial out register (PISO) electrically coupled to the UP/DOWN synchronous counter for serializing the quadrature pulse count so as to provide an indication of motor position.

8. A motor control circuit for controlling at least one motor, comprising:

an integrated circuit, comprising;

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship;

at least one programmable gain amplifier (PGA) electrically coupled to the at least one motor, the PGA being configured to receive a feedback signal indicative of current flowing through the at least one motor and to apply a second signal to the at least one motor for adjusting the speed of the at least one motor;

at least one summing amplifier electrically coupled to the at least one PGA for providing the feedback signal to the at least one motor that is indicative of current flowing through the at least one motor;

at least one buffer amplifier electrically coupled to the at least one motor and to the at least one PGA for sensing the output current of the at least one motor;

a processor for providing control signals to the at least one DPS, for providing a control voltage to the at least one summin amplifier and for receiving the measurements of speed position, and location of the at least one motor;

wherein the at least one DPS is configured to measure the speed of the at least one motor based on one of frequency counting and period counting;

wherein frequency counting is implemented by counting a number of pulses from the pair of signals having a quadrature relationships that occur within a fixed time window;

wherein the at least one DPS further comprises circuitry for measuring the speed of the at least one motor based on frequency counting, comprising;

a toggle flip flop for receiving a fixed time pulse from the processor;

a counter electrically coupled to the toggle flip flop, the toggle flip flop enabling the counter for a fixed period of time, the counter receiving the one of the pair of signals, the counter being configured to count a number of pulses from the one of the pair of signals for the time the counter is enabled so as to provide an indication of the frequency of the at least one motor; and

a latch and PISO electrically coupled to the counter for storing and serializing the indication of the frequency of the at least one motor.

9. The motor control circuit of claim 8, further comprising at least one incremental encoder optically coupled to the at least one motor for providing the pair of signals having a quadrature relationship.

10. The motor control circuit of claim 8, further comprising at least one potentiometer for setting the initial position of the at least one motor, the potentiometer being coupled to at least one A/D.

11. The motor control circuit of claim 8, wherein the at least one DPS further comprises:

a QDECODER circuit block for decoding the pair of signals having a quadrature relationship to an UP or DOWN signal for providing an indication of the direction of rotation of the at least one motor and for providing a count signal indicative of a quadrature pulse count;

an UP/DOWN synchronous counter electrically coupled to the QDECODER circuit block for counting the quadrature pulse count; and

a parallel in-serial out register (PISO) electrically coupled to the UP/DOWN synchronous counter and the processor for serializing the quadrature pulse count so as to provide an indication of motor position.

12. The motor control circuit of claim 8, wherein an integrated circuit for controlling at least one motor, comprising:

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the at least one DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship.

13. A motor control circuit for controlling at least one motor, comprising:

an integrated circuit, comprising;

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship;

at least one programmable gain amplifier (PGA) electrically coupled to the at least one motor, the PGA being configured to receive a feedback signal indicative of current flowing through the at least one motor and to apply a second signal to the at least one motor for adjusting the speed of the at least one motor;

at least one summing amplifier electrically coupled to the at least one PGA for providing the feedback signal to the at least one motor that is indicative of current flowing through the at least one motor;

at least one buffer amplifier electrically coupled to the at least one motor and to the at least one PGA for sensing the output current of the at least one motor;

a processor for providing control signals to the at least one DPS, for providing a control voltage to the at least one summin amplifier and for receiving the measurements of speed position, and location of the at least one motor; and

wherein period counting is implemented by counting a number of pulses from a timer that occur between consecutive pulses from the pair of signals having a quadrature relationship.

14. The motor control circuit of claim 13, wherein the at least one DPS further comprises circuitry for measuring the speed of the at least one motor based on period counting, comprising:

a toggle flip flop for receiving one of the pair of signals;

a counter electrically coupled to the toggle flip flop, the counter receiving an external clock, the counter being configured to count the number of pulses from the external clock that occur between successive pulses of the one of the pair of signals so as to provide an indication of the time period of the at least one motor; and

a latch and PISO electrically coupled to the counter and the processor for storing and serializing the indication of the time period of the at least one motor.

15. The motor control circuit of claim 13, further comprising at least one digital-to-analog (D/A) converter electrically coupled to the processor for providing the control voltage to the at least one summing amplifier.

16. The motor control circuit of claim 15, wherein the at least one summing amplifier further comprises a feedback resistor R₂ electrically connected between an output and an inverting input of the at least one summing amplifier and a second resistor R₁ electrically connected to the inverting input and electrically connected to an output of the at least one D/A, wherein the at least one buffer amplifier further comprises a resistor R_s that senses motor current and is electrically connected between an input to the at least one buffer amplifier and a ground node, and where the gain G₂ of the PGA is adjusted to maintain motor speed in response to changes in motor resistance R_m based on

17. The motor control circuit of claim 16, wherein the at least one summing amplifier further comprises an input for limiting the current to the at least one motor, and wherein the signal on the input for limiting current is varied while the control voltage to the at least one summing amplifier is held constant so as to control the torque of the at least one motor.

18. The motor control circuit of claim 17, wherein the signal on the input for limiting current is held constant while the control voltage to the at least one summing amplifier is varied based on an initial position measurement of the at least one motor and a current position measurement from the integrated circuit so as to control the position of the at least one motor.

19. The motor control circuit of claim 17, wherein the signal on the input for limiting current is held constant while the control voltage to the at least one summing amplifier is varied based on a current speed measurement from the integrated circuit so as to control the speed of the at least one motor.

20. The motor control circuit of claim 13, further comprising at least one incremental encoder optically coupled to the at least one motor for providing the pair of signals having a quadrature relationship.

21. The motor control circuit of claim 13, further comprising at least one potentiometer for setting the initial position of the at least one motor, the potentiometer being coupled to at least one A/D.

22. The motor control circuit of claim 13, wherein the at least one DPS further comprises:

a QDECODER circuit block for decoding the pair of signals having a quadrature relationship to an UP or DOWN signal for providing an indication of the direction of rotation of the at least one motor and for providing a count signal indicative of a quadrature pulse count;

an UP/DOWN synchronous counter electrically coupled to the QDECODER circuit block for counting the quadrature pulse count; and

a parallel in-serial out register (PISO) electrically coupled to the UP/DOWN synchronous counter and the processor for serializing the quadrature pulse count so as to provide an indication of motor position.

27. The motor control circuit of claim 13, wherein an integrated circuit for controlling at least one motor, comprising:

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the at least one DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship.

23. A motor control circuit for controlling at least one motor, comprising:

an integrated circuit, comprising;

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship;

at least one programmable gain amplifier (PGA) electrically coupled to the at least one motor, the PGA being configured to receive a feedback signal indicative of current flowing through the at least one motor and to apply a second signal to the at least one motor for adjusting the speed of the at least one motor;

at least one summing amplifier electrically coupled to the at least one PGA for providing the feedback signal to the at least one motor that is indicative of current flowing through the at least one motor;

at least one buffer amplifier electrically coupled to the at least one motor and to the at least one PGA for sensing the output current of the at least one motor;

a processor for providing control signals to the at least one DPS, for providing a control voltage to the at least one summin amplifier and for receiving the measurements of speed, position, and location of the at least one motor; and

wherein the processor updates input voltage to the at least one motor based on the update rule k(m+l)=k(m)−

μ

[ω

(m+l)−

ω

(m)] where k and ω

are the back emf constant and velocity of the at least one motor, where m is the time index for the update rule, and μ

is a user specified update rate.

24. The motor control circuit of claim 23, further comprising at least one incremental encoder optically coupled to the at least one motor for providing the pair of signals having a quadrature relationship.

25. The motor control circuit of claim 23, further comprising at least one potentiometer for setting the initial position of the at least one motor, the potentiometer being coupled to at least one A/D.

26. The motor control circuit of claim 23, wherein the at least one DPS further comprises:

a QDECODER circuit block for decoding the pair of signals having a quadrature relationship to an UP or DOWN signal for providing an indication of the direction of rotation of the at least one motor and for providing a count signal indicative of a quadrature pulse count;

an UP/DOWN synchronous counter electrically coupled to the QDECODER circuit block for counting the quadrature pulse count; and

a parallel in-serial out register (PISO) electrically coupled to the UP/DOWN synchronous counter and the processor for serializing the quadrature pulse count so as to provide an indication of motor position.

28. The motor control circuit of claim 23, wherein an integrated circuit for controlling at least one motor, comprising:

at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the at least one motor, the at least one DPS being in signal communication with the at least one motor for receiving a pair of signals having a quadrature relationship.