2. Robotics Intensive: Day 3 Gui Cavalcanti 1/17/2012

3. Class Goals 1.Discuss open loop vs. closed loop control 2.Discuss PID 3.Review control project goals 4.Work on control systems 5.Demo control systems!

4. Open Loop vs. Closed Loop Control

5. Open Loop Control Issuing commands based on how you think a system will react, without taking into consideration how it is actually reacting Common examples: – Sprinkler Systems – Washing Machines – 3pi spelling your name

6. Open Loop Pitfalls Easy to develop, and thus easy to assume it’s a good solution You have no idea what’s actually happening, or even if the robot is successful

7. Closed Loop Control Issuing commands based on both how you think a system will react and the current state of the system Common examples – Aircraft Autopilot – Car Cruise Control – 3pi following a line

8. Cruise Control System Parts: – Microcontroller – Speed Sensor – Engine Control Actuator Decision-Making: – Microcontroller says “I want 50 MPH” – Speed Sensor says “We’re driving 45 MPH” – Microcontroller says “Actuator, make us go faster”

9. Cruise Control 50 mph 45 mph 5 mph TOO SLOW! GO FASTER! Increase Throttle Repeat again and again.

10. PID Control

11. Most common type of closed loop control, commonly used in robotics PID: – Proportional – Integral – Derivative What you control around matters!

12. Proportional Control Equivalent to a big spring. Amount system responds is proportional to how large the error is.

13. Integral Control Equivalent to filling a bucket over time. Amount system responds is proportional to how long the error has existed.

14. Derivative Control Equivalent to running through water. Amount system responds is proportional to how fast the system is moving.

15. Controls Project Goals

16. The Mission

17. Project Description 1.Implement the basic line following algorithm from the mbed Cookbook. 2.Implement the PID line following algorithm from the mbed Cookbook. 3.Demonstrate identification of and use of intersections. 4.Demonstrate travel to every branch of the map.

18. Bonus Points Fastest time Ability to travel to a specific intersection Ability to travel to a specific intersection by more than one route Demonstrate (software-based) object detection

19. Work on demos!