Combined mechanical and electronic image stabilization

1. A system comprising:

an image sensor configured to capture an image;

one or more motion sensors configured to detect motion of the image sensor;

a mechanical stabilization system, including gimbals and motors, configured to control an orientation of the image sensor;

an electronic image stabilization module configured to correct images for rotations of the image sensor; and

a processing apparatus that is configured to:

determine a sequence of orientation estimates based on sensor data from the one or more motion sensors;

based on the sequence of orientation estimates, invoke the mechanical stabilization system to reject motions occurring within a first operating bandwidth with an upper cutoff frequency;

receive the image from the image sensor;

based on the sequence of orientation estimates, invoke the electronic image stabilization module to correct the image for rotations of the image sensor occurring within a second operating bandwidth with a lower cutoff frequency to obtain a stabilized image, wherein the lower cutoff frequency is greater than the upper cutoff frequency, wherein the first operating bandwidth and the second operating bandwidth are substantially non-overlapping; and

store, display, or transmit an output image based on the stabilized image.

2. The system of claim 1 , comprising a drone that is coupled to a housing of the image sensor by the gimbals of the mechanical stabilization system.

3. The system of claim 1 , in which the processing apparatus is configured to:

apply a first filter with a pass band matching the first operating bandwidth to the sequence of orientation estimates to obtain data that is input to the mechanical stabilization system; and

apply a second filter with a pass band matching the second operating bandwidth to the sequence of orientation estimates to obtain data that is input to the electronic image stabilization module.

4. The system of claim 1 , in which the processing apparatus is configured to:

adjust the first operating bandwidth and the second operating bandwidth in a complimentary manner by adjusting the upper cutoff frequency and the lower cutoff frequency by a same amount.

5. The system of claim 4 , in which the processing apparatus is configured to:

determine a temperature of the motors of the mechanical stabilization system; and

wherein the upper cutoff frequency and the lower cutoff frequency are adjusted based on the temperature.

6. The system of claim 5 , in which determining the temperature comprises:

receiving measurements of current drawn by the motors of the mechanical stabilization system; and

estimating the temperature based on the measurements of current.

7. The system of claim 5 , in which the upper cutoff frequency and the lower cutoff frequency are adjusted based on a difference between the temperature and a maximum rated temperature for the motors of the mechanical stabilization system.

8. The system of claim 4 , comprising a user interface, and in which the processing apparatus is configured to:

receive a mode selection input from the user interface; and

wherein the upper cutoff frequency and the lower cutoff frequency are adjusted based on the mode selection input.

9. The system of claim 4 , comprising a battery, and in which the processing apparatus is configured to:

determine a state of charge of the battery; and

wherein the upper cutoff frequency and the lower cutoff frequency are adjusted based on the state of charge.

10. The system of claim 4 , in which the processing apparatus is configured to:

detect a condition selected from the group consisting of low light, high motion, high noise, and high contrast; and

wherein the upper cutoff frequency and the lower cutoff frequency are adjusted based on the condition.

11. The system of claim 1 , in which the mechanical stabilization system comprises a proportional integral derivative controller with coefficients tuned to enforce the first operating bandwidth.

12. The system of claim 1 , in which the electronic image stabilization module is implemented by software executed by the processing apparatus.

13. A method comprising:

determining a sequence of orientation estimates based on sensor data from one or more motion sensors;

based on the sequence of orientation estimates, invoking a mechanical stabilization system to reject motions of an image sensor occurring within a first operating bandwidth with an upper cutoff frequency;

receiving an image from the image sensor;

based on the sequence of orientation estimates, invoking an electronic image stabilization module to correct the image for rotations of the image sensor occurring within a second operating bandwidth with a lower cutoff frequency to obtain a stabilized image, wherein the lower cutoff frequency is greater than the upper cutoff frequency, wherein the first operating bandwidth and the second operating bandwidth are substantially non-overlapping; and

storing, displaying, or transmitting an output image based on the stabilized image.

14. The method of claim 13 , comprising:

adjusting the first operating bandwidth and the second operating bandwidth in a complimentary manner by adjusting the upper cutoff frequency and the lower cutoff frequency by a same amount.

15. The method of claim 14 , comprising:

determining a temperature of motors of the mechanical stabilization system; and

wherein the upper cutoff frequency and the lower cutoff frequency are adjusted based on the temperature.

16. The method of claim 14 , comprising:

determining a state of charge of a battery; and

wherein the upper cutoff frequency and the lower cutoff frequency are adjusted based on the state of charge.

17. The method of claim 13 , in which the mechanical stabilization system includes gimbals and motors controlled by proportional integral derivative controllers.

18. A system comprising:

an image sensor configured to capture an image;

a mechanical stabilization system, including motors, configured to control an orientation of the image sensor to reject motions occurring within a first operating bandwidth with an upper cutoff frequency; and

an electronic image stabilization module configured to correct images for rotations of the image sensor occurring within a second operating bandwidth with a lower cutoff frequency to obtain a stabilized image, wherein the lower cutoff frequency is greater than the upper cutoff frequency, wherein the first operating bandwidth and the second operating bandwidth are substantially non-overlapping.

19. The system of claim 18 , comprising a drone that is coupled to a housing of the image sensor by the mechanical stabilization system.

20. The system of claim 18 , comprising:

a motion tracking module including one or more motion sensors configured to detect motion of the image sensor and determine a sequence of orientation estimates for the image sensor;

a first filter module configured to apply a first filter with a pass band matching the first operating bandwidth to the sequence of orientation estimates to obtain data that is input to mechanical stabilization system; and

a second filter module configured to apply a second filter with a pass band matching the second operating bandwidth to the sequence of orientation estimates to obtain data that is input to electronic image stabilization module.