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ABS 4 Presenters: Hong Jung, Binh Lai, Matthew Martin, Joe Mongiat, and Travis Ratcliff

Anti-Lock Braking System. ABS 4 Presenters: Hong Jung, Binh Lai, Matthew Martin, Joe Mongiat, and Travis Ratcliff. ABS. System Provides Anti-Lock Braking Wheels are prevented from locking up in hard braking situations where traction is low Motivation for ABS

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ABS 4 Presenters: Hong Jung, Binh Lai, Matthew Martin, Joe Mongiat, and Travis Ratcliff

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  1. Anti-Lock Braking System ABS 4 Presenters: Hong Jung, Binh Lai, Matthew Martin, Joe Mongiat, and Travis Ratcliff

  2. ABS • System Provides Anti-Lock Braking • Wheels are prevented from locking up in hard braking situations where traction is low • Motivation for ABS • Safety - Increased control of vehicle • A selling advantage over non-ABS Equipped Vehicles

  3. Wheel Speed Sensors Constantly evaluate the speed of each wheel Information is sent to the controller upon request ABS Controller Calculates the deceleration rate for each wheel Determines when to engage the ABS for each wheel independently Sends messages to other components to activate them Features • System Tests • Evaluate the system upon start-up and with each application of the brakes • Brake Fluid Reservoirs • Hold fluid that is diverted from main reservoir

  4. Overview of Requirements Analysis • Rapid Prototyping • Java applets • Peer review • Model Checking • Xspin • promela • UML Analysis • Dome

  5. UML Analysis

  6. Use Case Diagram

  7. Use case • Problems • Brakes in system or not • Technician interface and actor • Brake pressure valve actor name • Solutions • Brakes not in system • Added technician actor and reset use case • Proper naming for actor, consistent

  8. Class Model

  9. Class Diagram • Problems • Independent control of each wheel with one ABS controller • Is Brake a class in model? • How to model the pressure valve interface • Solutions • Methods have associated wheel • Brake is viewed as external signal • Simple interface, increase and decrease

  10. State Diagram

  11. State Diagram • Problems • Incorporating our concurrency ideas into model • Brake out/in model • Solutions • One concurrent state machine model • Brake is left out, viewed as a external signal

  12. Sequence Diagrams

  13. Power-Up/Power-Off

  14. Braking

  15. Model Checking

  16. Promela and XSpin • Model Analysis • Encoded State Diagram into Promela • Performed system simulation using XSpin

  17. XSpin Simulation Results • Power is turned On • Test is run and passes • Brake is applied • Test is run and passes again • Brake is released • Brake is applied again • Test runs and passes • ABS engages and then disengages • Brake is released • Brake is applied once again • Test runs and fails this time • Fail light is turned on • Then technician reset is issued • Power is turned on again • Test runs and passes • Etc…

  18. Critical Properties • Safety Properties • If the system has a failure it shall not engage until fixed by a technician • If the speed of the vehicle is below 15 MPH the system shall not engage • Liveness Properties • If wheel-lockup is imminent the ABS will eventually engage • If a failure occurs within the system the dashboard failure light will eventually be turned on

  19. Summary • What is ABS? • System Provides Anti-Lock Braking. • It’s embedded system. • UML Analysis • We tried to all diagrams simple and precise, but still making sure that we captured all requirements. • Dome is good, but sometimes difficult to manipulate. • Model Checking • Verification is coming.

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