A Robot powered by a Raspberry Pi, is built and used as a dynamic moving projector for Appearance Editing work.
This was developed at the CGVLab at Purdue University for ongoing Appearance Editing research.
GBSN - Microbiology (Unit 7) Microbiology in Everyday Life
Robotic Platform for Appearance Editing
1. Robotic Platform for Appearance
Editing
C. D. Tharindu Mathew
Advisor: Prof. Daniel Aliaga
2. Appearance Editing
● Illuminate an object using digital projectors, so that its
appearance is visually altered
Source: http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:virtual_restoration
3. Setup Details - Robots
Wheeled mobile robots equipped with
● Raspberry Pi with HDMI output and wifi dongle
● Micro Projector
● Infrared LED pattern on top
● Control circuit to drive motors
4. Setup Details - Control Table
● Table with checkerboard pattern
● Overhead camera with infrared filter
5. Setup Details - Control Program
● Receives input from overhead camera
● Issues commands and pose information to robots
● Calibration of camera and projector
6. Contribution
● Robots, Control table - Luis Rodrigo, Control Program -
Prof. Aliaga
● Robot control program existed, written in Python
● Re-wrote the robot control program in a more structured
manner with reliable execution
7. wiringPi
● C Library that allows to control GPIO pins
● Allows to generate software based PWM signals
● High performance in benchmarks - Possible to generate
6.9 MHz signal
Source: http://codeandlife.com/2012/07/03/benchmarking-raspberry-pi-gpio-speed/
8. Development Environment
● Raspberry Pi runs Raspbian 32-bit
● Eclipse allows to configure different compilers
● Windows Batch script to deploy into robots
9. Initial Attempt
● Wrote a control loop that does the following:
o Rotate towards destination point
o Move at constant speed for 2s
o Repeat
10. Video - Initial Attempt
https://www.youtube.com/watch?v=iLXbehabnwY
15. Video - Attempt after integration of PID Controller
https://www.youtube.com/watch?v=iLXbehabnwY
16. Velocity cut offs
● Maximum velocity operates at 30%
● Minimum velocity is 10%
● Ratio between vl and vr are considered when one value
hits maximum
17. Tuning the PID Controller
● To accommodate the table size, more rotation is
needed compared to translation
● Use 66x more Kp and Ki values for output ϴ (0.3 vs 200)
18. Video 3 - Tuned PID Controller
https://www.youtube.com/watch?v=RjGPhbkbHsQ
19. Projector Calibration
● Uses overhead camera to calibrate Projector using
Tsai’s method
● Then, create image to project based on the
image→world coordinates