1. Autonomous Control of a Scalextric Slot Car on a User-Defined Track Siddharth Kamath Souma Mondal Dhaval Patel School of Electrical and Computer Engineering Georgia Institute of Technology http://www.scalextric-usa.com/

2. What is Slot Car Racing? Electric Contacts Motor Powered Rails Resistor Handheld Controller Power Pack http://www.wikipedia.com

3. Project Overview Design a system that allows a car to autonomously race against a human player Design a system that allows a car to autonomously race against a human player Marketed toward existing Scalextric customers who cannot easily find opponents Marketed toward existing Scalextric customers who cannot easily find opponents The product will keep the user base active and boost the number of repeat customers The product will keep the user base active and boost the number of repeat customers The base station will cost $180 and each car will cost $50 The base station will cost $180 and each car will cost $50

4. Design Objectives Autonomously control car by: Autonomously control car by: Monitoring position of car around track in real-time Monitoring position of car around track in real-time Analyzing position data and applying appropriate voltage to track Analyzing position data and applying appropriate voltage to track Display last checkpoint passed if slot car falls off the track Display last checkpoint passed if slot car falls off the track Record performance metrics such as lap times and top speed Record performance metrics such as lap times and top speed

5. System Overview Position Data Digital In USB Analog Out Electric Contacts Motor Powered Rails Power Pack http://www.wikipedia.com

6. Main Subsystems Control Algorithm Data Transmission Position/Speed Detection

7. Position and Speed Detection Position – Increment counter per pair of reflective strips Position – Increment counter per pair of reflective strips Velocity – Obtain one velocity per checkpoint Velocity – Obtain one velocity per checkpoint 5V 0V Time Checkpoints Reflective Strips

8. Line Detector LOW HIGH IR LED Phototransistor Wireless Transmitter

9. Advantages of a Line Detector Inexpensive Inexpensive Easy to use Easy to use Digital output – convenient for wireless transmission Digital output – convenient for wireless transmission Continuous sensing – no polling necessary Continuous sensing – no polling necessary http://www.lynxmotion.com/

10. Data Transmission Data transmitted from car to PC Data transmitted from car to PC Wireless transfer from Slot Car using Linx Technologies HP3 wireless transmitter and receiver Wireless transfer from Slot Car using Linx Technologies HP3 wireless transmitter and receiver Data read in through NI USB DAQ into LabVIEW on PC Data read in through NI USB DAQ into LabVIEW on PC Voltage from PC to track Voltage from PC to track Control Voltage from LabVIEW output through NI USB DAQ Control Voltage from LabVIEW output through NI USB DAQ DAQ output voltage amplified to meet voltage specifications of track DAQ output voltage amplified to meet voltage specifications of track

11. Power Supply Selection CR2450 Li-MnO 2 Cell - Used to power the photo- interrupter and wireless modules on the car CR2450 Li-MnO 2 Cell - Used to power the photo- interrupter and wireless modules on the car Constraints Constraints Low weight (6gm) Low weight (6gm) Nominal voltage (3V) Nominal voltage (3V) High capacity (600mAh) High capacity (600mAh) Inexpensive Inexpensive Easily obtainable Easily obtainable http://www.wikipedia.com

12. Control Algorithm Get Upcoming Track Layout Position Speed Calculate Track Complexity Determine Optimal Track Voltage Desired Track Voltage Track Input by User

13. Calculating Complexity x – distance from the front of the car K – curvature of the track at that point 50cm – the horizon

14. The Mysterious Exponent c Multiplicative constants can be factored out and therefore do not work Multiplicative constants can be factored out and therefore do not work The exponent c therefore helps tune the importance of the curvature relative to the distance The exponent c therefore helps tune the importance of the curvature relative to the distance

15. Other Software Factors User selected difficulty – affects the aggressiveness and the top speed User selected difficulty – affects the aggressiveness and the top speed Learning from crashes – the complexity rating for that section of track is increased Learning from crashes – the complexity rating for that section of track is increased

16. Demonstration Plan System drives slot car around circuit without falling off track System drives slot car around circuit without falling off track Race the slot car against an experienced user on an arbitrary track Race the slot car against an experienced user on an arbitrary track Scale system’s performance depending on user’s difficulty setting Scale system’s performance depending on user’s difficulty setting In case of derailing, slot car can be placed onto last checkpoint and resume normal operation In case of derailing, slot car can be placed onto last checkpoint and resume normal operation

17. Problems and Issues Scaling voltage and power when connecting NI DAQ to track Scaling voltage and power when connecting NI DAQ to track Optimizing algorithm Optimizing algorithm Empirically determining the constant parameters Empirically determining the constant parameters Scaling performance based on difficulty levels Scaling performance based on difficulty levels

18. Project Schedule October October November November December December Hardware Testing and Software Development: Crash Tolerance, Control Parameters, Multiple Difficulty Levels Interfacing: Sensors, Control Unit and Race Track Power Supply, Wireless Transmission, NI-DAQ Additions: Optional Software Features Final Demo

19. Budget and Cost Analysis NI USB 6008 (DAQ)$150 NI USB 6008 (DAQ)$150 HP3 Series Receiver $30 HP3 Series Receiver $30 Base Station$180 HP3 Series Transmitter $25 HP3 Series Transmitter $25 Line Tracker $20 Line Tracker $20 Five 3V Coin Batteries$5 Five 3V Coin Batteries$5 Car$50 Total$230

20. Current Status Complete Complete Line tracker and NI-DAQ tested Line tracker and NI-DAQ tested Algorithm simulation Algorithm simulation Upcoming Milestones Upcoming Milestones Testing of wireless interface by Oct 25 th Testing of wireless interface by Oct 25 th Data transfer from car to PC to track by Oct 30 th Data transfer from car to PC to track by Oct 30 th

21. Questions?

22. Position Detection Sensor http://www.lynxmotion.com/

23. Spacing Requirements Max slot car speed = 1000 mm/s Max distance between checkpoints = 100 mm Max ping rate = 10 pings/sec Transmission rate = 56,000 pings/sec < 10cm Checkpoint n Checkpoint n+1