1. P07521 BRDF Imaging Platform
Concept Review
19 Jan 2007

2. Team Members

3. Project Description

4. Needs Assessment

5. Specification Table

6. Function Generation (brainstorming)

7. Function Decomposition (our flow chart)

8. Benchmarking
TASE system

9. Benchmarking
Askman AP system

10. Camera Stabilization System

11. Customer Needs 15x15 pixel area on target at all times
50-70 degree angle from horizontal on target
Keep the system nearly level while imaging
Robust enough to prevent damage of equipment

12. Concept Generation Active Gyro Passive Gyro Dampened Joint
Model Airplane Gyro
Floating Compass System
Model Airplane Gyro/Dampened Joint

13. Pugh’s Matrix

14. Askman AP system

15. Kenyon Labs Passive Gyro

16. Model Airplane Gyro

17. Concept Selection Dampened Joint with airplane gyro is preferred
Airplane gyro will be purchased if budget allows

18. Data Storage System

19. Customer Needs Store images as .TIFF files
Log GPS coordinates with each picture taken
Time stamp on pictures to know when it was taken

20. Concept Generation
Serial RS-232
Compact Flash
Flashdisk

21. Pugh’s Matrix

22. Pictures
Compact Flash
Flashdisk
Serial RS232 to USB

23. Concept Selection Customer prefers both options
Will add removable media if budget allows
Customer has a serial to USB converter if removable media is too expensive

24. Batteries

25. Customer Needs Self contained power Battery life = flight time
Easy access to battery

26. Specifications Battery current Battery voltage
System to withstand temperatures

27. Concept Generation Concepts Solar Battery – only feasible choice Wind
Nuclear
Fuel
Fuel Cell

28. Pugh’s Matrix

29. Concept Selection NiCd used as reference – most common
NiMH cheaper and as good as NiCd
Size and discharge rate were issues
Li-Ion better power, lifespan, performance
Higher cost
Li-Polymer very small size and weight
Lead Acid is unstable and friggin huge

30. Pictures
Ni-Cd
Li-Ion
Li-Poly
NiMH
Lead Acid

31. Pan Tilt Assembly Motor Selection

32. Motor Selection Pan Tilt Assembly
Evaluated four different types of motors:
AC Motors
DC Motors
Servo Motors
Stepper motors
Each was evaluated for the specific criterion of this project
Torque available
Speed
Reliability
Repeatability of results

33. Pugh’s Matrix

34. AC Motors Pros: Cons: Very rugged and simple
Wound – rotor AC motors have controllable speed and torque
Cons:
Don’t have AC current available for UAV
Do not have the longevity and reputation of DC motors in precision/positioning applications
Good for constant speed applications

35. DC Motors Pros: Cons: Very easy to control
Very high torque is possible
Very high speeds are possible
Cons:
Most efficient as high speeds so a gearbox is needed
Brushes can and will wear out after time
Switched DC motor can be jerky at low speeds and do not have the torque of standard DC motors

36. Servo Motors Pros: Cons: Excellent for high dynamic requirements
Continuous duty for high speed and torque requirements
Delivers continuous power at high speeds (12000 RPM)
Cons:
Requires a feedback loop
Without and encoder inertia can carry the rotation beyond what is desired
Expensive and can be complex

37. Stepper Motors Pros: Cons: Require no position feedback
Small in size and highly accurate
Easy to program
High torque low speed applications under 2000 RPM
Cost effective and economical
Cons:
Can skip steps when overloaded
Can become bulky at high torque

38. Pictures
DC Motor
AC Motor
Servo
Stepper

39. Motor Selection A Stepper motor will best fit this project
Excellent positioning accuracy
Two members of the group have previous experience with this application
Can be easily interfaced with the existing hardware
Is a highly cost effective solution
Will produce the necessary skew rate
Will not “skip” steps if proper motor selection is used
Stepper will be controlled by a Basic STAMP to the PC104+ board

40. Sketch

41. Future Work