1. Construction and Motion control of a mobile robot using Visual Roadmap
By: Harshad Sawhney
Guide: Dr. Amitabha Mukerjee

2. Objective
Source
Destination

3. Introduction Inspiration From Human Brain.
The roadmap approach, captures connectivity of robot’s free space.
3-DOF mobile robot constructed.

4. Construction Of Robot Major Components: Receives Data
UART communication
Lithium-Ion battery
Wireless module Xbee
Microcontroller Arduino
2 DC motors
Motor driver
Image Source: robokits.co.in

5. Flow Chart of Robot Navigation
Camera Input
Image Processing
Wireless data transfer
Microcontroller receives command
µC sends output
Robot Advances
Destination Reached NO
YES
Stop

6. Few images from dataset
Image Pre-processing
10k images taken.
Background subtraction performed.
Parameters extracted - robot navigation.
Few images from dataset

7. Background subtraction
Initial Image
Background subtraction

8. Distance Metric Computation
L2-norm expansion method.
Dist(X, Y) = sqrt(||X||2 + ||Y||2 - 2*||Y’X||)

9. Graph generation k-nearest neighbours calculated.
Robot location as nodes.
k=6 taken.
k=10 ; robot jumps larger distance.

10. Nearest nodes to some vertices

11. Shortest path calculation
Without Obstacles:
Dijkstra’s algorithm used.
Shortest Path Graph

12. Shortest path calculation
With obstacles:
Obstacles image extracted.
Compared the image with the dataset.
Nodes and edges removed.
Reduced to no obstacles case.

13. Obstacle Image Image of environment with obstacles
Obstacle image extraction

14. Shortest path calculation
Shortest Path Graph with obstacles in the environment

15. Robot Motion Control Feed the nodes.
Camera: Negative closed loop feedback mechanism.
Reach till destination.
Real Time.

16. Algorithm for controlling robot
(x, y, Ɵ): Robot current parameters
(x’, y’, Ɵ’): Node parameters
Ɵ : Robot vector angle.
Ɵ1 : Position of robot and node vector angle.
Step1: Ƒ = | Ɵ - Ɵ1 |
Rotate till | Ƒ | < ɛ
Step 2: Move till | (x-x’)2+ (y-y’)2|< ɛ1

17. Algorithm for controlling robot
Step 3: Align till | Ɵ - Ɵ’| < ɛ2
Steps executed in increasing order of priority.
Thus, the camera provides negative feedback closed loop system.

18. Results Robot accurately navigates.
Videos demonstrating robot navigation.

19. Challenges Distance metric computation: limits sampling density.
Real time motion: possibly leading to collisions.

20. Future Work Dynamic obstacle avoidance
Update graph first time; use relative changes in image for future considerations.

21. References
[1] Amitabha Mukerjee, M Seetha Ramaiah, Sadbodh Sharma, Arindam Chakraborty, “The Baby at One Month: Visuo-motor discovery in the infant robot". [2] Joshua B. Tenenbaum, Vin de Silva, John C. Langford, “A Global Geometric Framework for Nonlinear Dimensionality Reduction", [3] Jean-Claude Latombe, "Robot Motion Planning”, Edition en anglais. Springer, [4] Choset, Howie, Principles of robot motion: theory, algorithms, and implementations. MIT press, [5] Seth Hutchinson, Gregory D Hager, and Peter I Corke. A tutorial on visual servo control. Robotics and Automation, IEEE Transactions on, 12(5):651{670, 1996.