1. Gimbal Control and Design for Tracking of a Solar Eclipse
Matthew Plewa and Brent Scharlau

2. Introduction Two part system Gimbal Flight characteristics Pointer
Two methods commonly used
Mathematical method
Imaging method

3. Gimbal What is the typical motion of balloons? Pendulum motion
Rotation
What is required to compensate for this motion?

4. Gimbal Requirements 3 axis are required Pitch ± 90 degrees Roll Yaw
Due to rotation this axis needs as much freedom as possible

5. Electronics Gimbal controller storm32-BGC Compact
Contains brushless motor controllers
Variety of input pins
Closed source firmware causes issues for modifications

6. Electronics
RFD-900
Needed a way to send Sun’s current azimuth and zenith angle
The gimbal controller allows for PWM input for setting values
RFD-900 acts as a serial port and using a chipkit allows the string to be converted and then transmitted using PWM

7. Pointing Analytic Developed for solar array pointing
Angles can then be transmitted via RFD- 900 link

8. Pointing Imaging Using a low resolution camera
Filter required to prevent sensor damage
Look for the brightest object
Even during an eclipse arcs of the Sun will still be present
It is possible using simple geometry to find the center of an arc.
Point toward the center of the circle or arc

9. Manufacturing Mostly off the shelf parts
It was necessary to manufacture the adapter plates between of the shelf components and the gimbal motors

10. Testing
RFD-900 link testing to verify strings where being decoded properly
Axis rotation had to be tested
Yaw axis was limited due to the large number of wiring going to the camera
Would be necessary to unwind the cables periodically

11. Flight Cables led to more issues
Since it was a cold spring day the cables were incredibly stiff
This meant that the motors had to work harder to compensate for this stiffness.
During the flight this caused the gimbal controller to time out since the requested angles were not achievable

12. Future Work (Gimbal) Cable management Yaw location change
It may be possible to make the yaw axis not have to compensate for the cables
Using a “Weather vane” to limit the amount of rotation (Hopefully eliminating the rotation)

13. Future Work (Pointer) Hybrid system
Instead of using an imaging or analytic method by itself using them together can eliminate many of the issues
This will also help to eliminate any error that accumulates in the gimbal controller
A fully automatic system is possible through a hybrid system

14. Questions? Matthew Plewa