Anti-lock Brake System Group 2 Presenters: Christan Balnius, Zain Kazim, Mark Pulver Demo Given by: Brian Lawnichak

Unique Feature: Distributed Control System (DCS) Enhances modularity of system Components of DCS –Manager –Wheel Monitors –Wheel Cylinder Gnomes

What DCS Supports Functionality of DCS –Computes, recognizes, and responds to rapid deceleration –Encapsulates per-wheel activity Sample scenario description –Manager receives brake signal –Manager signals Wheel Monitors –Wheel Monitors compute deceleration –Wheel Monitors signal Gnome

Key Model: State Diagram High-level state diagram showing concurrent processes It is key because –Shows the major components of system –Highlights concurrency We will decompose this further…

High-level State Diagram

Key Model Revisited Now focusing on the Manager, which is the top level of the DCS Manager is key because –Handles error testing –Responds to signals from vehicle –Sends signals to wheel monitors as appropriate State diagram highlights this behavior

Manager State Diagram

Critical Properties Safety properties –If ABS fails, mechanical braking still works –ABS activity never leads to spins Liveness properties –If the car speed drops below 15 mph while braking, ABS becomes idle –If a skid is detected above 15 mph, pressure is modulated on the wheel

Promela and XSpin Verification Technique –Modeled our state diagram in Promela –Verified safety and liveness properties through use of LTL invariants –Assertion and reachability tests were also performed

Safety Property Verification If ABS fails, mechanical braking still works [](Error -> (Power Off | Brake Not Pressed | <>(Main Brake Valves Open, Relief Valves Closed))) XSpin verified that this property holds

Liveness Property Verification If the car speed drops below 15 mph while braking, ABS becomes idle [](Below Activation Speed -> <>(Wheel Monitors Idle)) XSpin verified that this property holds

Demo of Prototype High-level features of User Interface: –Independent control of wheel speed and acceleration –Changeable environmental factors –Feedback on system-wide conditions with indicator lights –Per-wheel information readout

Scenario 1 Single-wheel skid –Press ignition button to start engine –Increase system speed to 30 m/s –Press brake button –Decrease the speed on wheel 3 to 20 m/s

Scenario 2 Change-of-surface skid –Press ignition button to start engine –Increase system speed to 30 m/s –Press brake button –Initiate a panic brake by increasing system brake pressure to 200 kg –Change road type from “Pavement” to “Gravel”