1. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 1
Bi-Directional Cooperative
Obstacle Avoidance for
Heterogeneous Unmanned
Vehicles
By: Jonathan Lwowski
The University of Texas at San Antonio
Department of Electrical and Computer Engineering
Advisor: Dr. Daniel Pack
B.S. Computer Engineering

2. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 2
Overview
• Motivation
• Significance of Methods
• Obstacle Avoidance Algorithm
• Door Entering Algorithm
• Simulation Results
• Conclusion
• Future Work
• REEF Projects

3. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 3
Motivation
• Reactive Bearing
Angle Only Obstacle
Avoidance System for
Unmanned Ground
Vehicles
• Global Vs. Local Path
Planning
• Visual Electro-Optic
Sensors

4. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 4
Significance of Methods
• First reported bi-directional heterogeneous system
using only cameras.
• Allows the UGV to incorporate obstacle avoidance
into global path plan

5. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 5
Flow Diagram

6. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 6
Obstacle Avoidance Algorithm
• Doorway is not detected
• UGV Tracking
• Directional Path Calculation
• Criteria for Ending Obstacle Avoidance Procedure
• Communication to UGV
• UGV Controller

7. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 7
UGV Tracking
• Color Thresholding
• PD Controllers

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Directional Path Calculation
• Detect Obstacles
• Create Nodes

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Directional Path Calculation
• Calculate Shortest Path Using Dijkstra's Algorithm
• Convert Path to Directional Information

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Criteria for Ending Obstacle Avoidance
Procedure
• Determine if UGV has passed the obstacle
• Acute Angle
• Obstacle Passed
• Obtuse Angle
• Obstacle Not Passed

11. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 11
Communication to UGV
• Direction Sent Check
• Directional Path
• Obstacle Passed

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UGV Controller
• Uses the bearing angle as
the only input
• Directional path determines
which direction to avoid the
obstacle

13. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 13
Simulation Results

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Doorway Entering Algorithm
• Doorway is detected
• Door Entering Using PD Controller
• MAV and Doorway Tracking
• Homography Decomposition

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Door Entering Using PD Controller
• PD Controller
• Centroid of Doorway

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Simulation Results

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MAV and Doorway Tracking
• Create four feature
points on door and MAV
• Find the centroid of
each feature point in the
reference frame
• Find the centroid of
each feature point in the
current frame

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Homography Decomposition
• Calculate homography matrix using feature points
• Four feature points from reference frame
• Four feature points from current frame
• Decompose homography matrix to find camera
rotation and translation matrix
• Homography Matrix
• Camera Calibration Matrix

19. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 19
Conclusion
• First reported bi-directional heterogeneous system
using only cameras.
• Allows the UGV to plan a long term path
• No requirement of GPS signals
• Effectiveness of system demonstrated using
software simulations

20. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 20
Future Work
• Finish homography based door entering
• Implement system on to hardware

21. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 21
REEF Projects
• Topological Map Merging
• Calculate Elevation Map

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REEF Projects
• Calculate Elevation Map using 20 Loops
• Calculate Elevation Map using 200 Loops
• Combine Elevation Maps

23. The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 23
Acknowledgments
• AFRL Munitions Directorate
• OSD & The Privileged Sensing ARPI
• Mathematical Modeling and Optimization Institute
• Dr. Emily Doucette
• Dr. Will Curtis
Questions?