THE CYBER-PHYSICAL BIKE: A STEP TOWARDS SAFER GREEN TRANSPORTATION S. Smaldone C. Tonde V. K. Ananthanarayanan A. Elgammal L. Iftode Summarized by Yuki

Outline Analysis Design Implementation Evaluation Conclusion

Analysis Problem A biker must spend cognitive and physical ability to periodically scan for a rear-approaching vehicle. As a result, the biker can not maintain continual awareness for the forward situation. Solution The Cyber-Physical bicycle system continuously monitors the environment behind the biker, automatically detects rear- approaching vehicles, and alerts the biker prior to the approach.

Design Roadway segmentation analysis using optical flow Reduces computational load

Design Vehicle tracking Determines if each vehicle passes the biker in either a safe or unsafe manner

Implementation Development environment C/C++ NVIDIA CUDA library (v2.3) Open source optical flow library [1] Bike computer - HP Mini 311 notebook Intel Atom N GHz CPU 3 GB RAM NVIDIA ION GPU (16 CUDA cores and 256 MB memory) 80 GB SSD hard disk 3.26 pounds / 1.48 kilograms (the worst case with peripherals) 1. WERLBERGER, M., TROBIN, W., POCK, T., WEDEL, A., CREMERS, D., AND BISCHOF, H. Anisotropic Huber-L1 optical flow. In BMVC’09 (London, UK, 2009).

Implementation (cont.) Rear-facing video camera - Sony DCR-SX40 Over 3 hours of video recordings of real-world roadway cycling traces (repeatability of experiment) Every interaction between the biker and a vehicle (approaching and departing) are manually annotated using the timestamps Ordinary road bicycle - Trek FX7.5

Evaluation How accurate are video-based techniques in detecting rear-approaching vehicles? Accuracy = TP / (TP + FP + FN) = 19 / ( ) = 73.1% A vehicle hidden by another biker A sudden vibration caused by uneven roadway

Evaluation (cont.) Can detection be performed timely? Alerting to occur an average of 3.5 seconds prior to a vehicle encounter at reduced frame rates (3 FPS) 3.5 seconds is 92% of the potential time (the difference between the first appearance of the vehicle and the time it passes the cyclist)

Conclusion The Cyber-Physical bicycle is a system that augments normal bicycles with video processing capabilities for automated rear-approaching vehicle detection. This system directly improves the safety of bikers by reducing their cognitive overheads of continuously probing for rear-approaching vehicles. The prototype can perform rear-vehicle detection with good accuracy at full frame rates (30 FPS), and can operate in real-time at reduced frame rates (3 FPS).