System and method for failure detection of a robot actuator

1. A method comprising:

actuating a robot actuator using a computing device;

determining a first result of the actuation using a first sensor of the robot actuator;

determining a second result of the actuation using a second sensor of the robot actuator;

determining a first estimate of an internal state of the robot actuator using the first result of the actuation;

determining a second estimate of the internal state of the robot actuator using the second result of the actuation and a normalization function, wherein the normalization function normalizes the second result of the actuation for comparison with the first estimate of the internal state of the robot actuator;

determining whether a difference between the first estimate of the internal state of the robot actuator and the second estimate of the internal state of the robot actuator satisfies an error threshold; and

in response to determining that the difference does not satisfy the error threshold, providing an output indicative of a potential fault of the robot actuator.

2. The method of claim 1 :

wherein determining the first result of the actuation using the first sensor of the robot actuator comprises measuring actuator activity of a first component of the robot actuator, and

wherein determining the second result of the actuation using the second sensor of the robot actuator comprises measuring actuator activity of a second component of the robot actuator.

3. The method of claim 2 :

wherein the actuator activity of the first component of the robot actuator comprises a belt tension of a timing belt, and

wherein the actuator activity of the second component of the robot actuator comprises a motor position of a motor.

4. The method of claim 2 :

wherein the actuator activity of the first component of the robot actuator comprises a joint position of an actuated joint, and

wherein the actuator activity of the second component of the robot actuator comprises a motor position of a motor.

5. The method of claim 2 :

wherein the actuator activity of the first component of the robot actuator comprises a first actuator activity selected from the group consisting of: a belt tension of a timing belt, a motor position of a motor, a joint position of an actuated joint, a torque producing current of a motor driver, a temperature of the motor, a winding voltage of the motor driver, a motor velocity of the motor, and a joint velocity of the actuated joint, and

wherein the actuator activity of the second component of the robot actuator comprises a second actuator activity selected from the group and the second actuator activity is different from the first actuator activity.

6. The method of claim 1 :

wherein the first sensor of the robot actuator is configured to sense a first modality, and

wherein the second sensor of the robot actuator is configured to sense a second modality that is different from the first modality.

7. The method of claim 6 :

wherein the first modality comprises an angular position, and

wherein the second modality comprises a tension.

8. The method of claim 6 :

wherein the first modality comprises a first modality selected from the group consisting of: an angular position, a tension, a velocity, a voltage, a current, and a temperature, and

wherein the second modality comprises a second modality selected from the group and the second modality is different from the first modality.

9. The method of claim 1 , wherein the robot actuator comprises a torque controlled actuator.

10. The method of claim 9 , wherein the torque controlled actuator comprises:

a frame, and

one or more timing belt stages coupled in serial on the frame, wherein the one or more timing belt stages include an input stage for coupling to a motor and an output stage for coupling to a load, wherein the one or more timing belt stages couple rotation of the motor to rotation of an output of the output stage.

11. The method of claim 1 , wherein the internal state of the robot actuator comprises an internal state selected from the group consisting of: a belt tension, an output position, a belt phase, an output torque, a winding temperature, a winding voltage, a winding current, and a motor encoder phase.

12. The method of claim 1 , wherein the output is indicative of a potential fault of the first sensor or the second sensor.

13. The method of claim 1 , wherein the output is indicative of a potential fault of a component of the robot actuator.

14. The method of claim 1 , further comprising providing the output and a log of data from the first sensor and the second sensor to a remote server.

15. The method of claim 1 , further comprising storing the output and a log of data from the first sensor and the second sensor in a memory coupled to the robot actuator.

16. The method of claim 1 , further comprising:

receiving a log of sensor data acquired using multiple sensors of one or more robot actuators;

identifying a relationship between results of the first sensor and results of the second sensor using a machine learning process and the log of sensor data; and

determining the normalization function based on the identified relationship.

17. A computing device, comprising:

one or more processors; and

a computer-readable medium, configured to store instructions, that when executed by the one or more processors, cause the computing device to perform functions comprising:

receiving a first result of an actuation of a robot actuator from a first sensor of the robot actuator,

receiving a second result of the actuation of the robot actuator from a second sensor of the robot actuator,

determining a first estimate of an internal state of the robot actuator using the first result of the actuation,

determining a second estimate of the internal state of the robot actuator using the second result of the actuation and a normalization function, wherein the normalization function normalizes the second result of the actuation for comparison with the first estimate of the internal state of the robot actuator,

determining whether a difference between the first estimate of the internal state of the robot actuator and the second estimate of the internal state of the robot actuator satisfies an error threshold, and

in response to determining that the difference does not satisfy the error threshold, providing an output indicative of a potential fault of the robot actuator.

18. The computing device of claim 17 :

wherein the first result of the actuation comprises data indicative of actuator activity of a first component of the robot actuator, and

wherein the second result of the actuation comprises data indicative of actuator activity of a second component of the robot actuator.

19. The computing device of claim 17 :

wherein the first sensor of the robot actuator is configured to sense a first modality, and

wherein the second sensor of the robot actuator is configured to sense a second modality that is different from the first modality.

20. A system, comprising:

a robot actuator;

at least two sensors configured to measure actuator activity of the robot actuator; and

a computer-based controller configured to:

receive a first result of an actuation of the robot actuator from a first sensor of the at least two sensors,

receive a second result of the actuation of the robot actuator from a second sensor of the at least two sensors,

determine a first estimate of an internal state of the robot actuator using the first result of the actuation,

determine a second estimate of the internal state of the robot actuator using the second result of the actuation and a normalization function, wherein the normalization function normalizes the second result of the actuation for comparison with the first estimate of the internal state of the robot actuator,

determine whether a difference between the first estimate of the internal state of the robot actuator and the second estimate of the internal state of the robot actuator satisfies an error threshold, and

in response to determining that the difference does not satisfy the error threshold, provide an output indicative of a potential fault of the robot actuator.

21. The system of claim 20 :

wherein the first result of the actuation comprises data indicative of actuator activity of a first component of the robot actuator, and

wherein the second result of the actuation comprises data indicative of actuator activity of a second component of the robot actuator.

22. The system of claim 20 :

wherein the first sensor of the robot actuator is configured to sense a first modality, and

wherein the second sensor of the robot actuator is configured to sense a second modality that is different from the first modality.

23. The system of claim 20 , wherein the robot actuator comprises a torque controlled actuator, the torque controlled actuator comprising:

a frame, and

one or more timing belt stages coupled in serial on the frame, wherein the one or more timing belt stages include an input stage for coupling to a motor and an output stage for coupling to a load, wherein the one or more timing belt stages couple rotation of the motor to rotation of an output of the output stage.