Self-Contained Particulate Filter

Filter 3

Presenters: Ian Gray, Kyhia Bostic

Demo Given by: Nathan Sullivan

Unique Feature of System

• Sensor Checker

• Components of Sensor Checker:– Controls bypass valve– Monitors differential pressure of filter– Checks instantaneous RPMs of engine– Calculates engine revolutions elapsed

since previous cleaning cycle

What does Sensor Checker support?

• Opens bypass valve– Differential pressure exceeds 10 kPa– Differential pressure equals zero

• Sensor checker finds the differential pressure to be 11 kPa. It sets a variable to indicate a pressure warning and then opens the bypass valve.

Unique Feature of System

• Heater Elements

• Components of Heater Elements:– Self-contained– Monitors current– Monitors temperature– Mark itself not operational– Knows operational status

What does Heater Element support?

• Takes itself out of cleaning sequence– Current reaches 40 Amps or above– Temperature reaches 275° or above

• Controller tells Heater Element to increase current. Heater Element updates internal data value representing current and then increases current to actual heater element.

Two Key Models

• Sensor Checker State Diagram

• Class Diagram

Key Model

• Sensor Checker State Diagram

• Logic of system– How the system reacts to sensor data– Order of internal events of system– Reflects state of system, i.e. values of

variables in system

Model

Key Model

• Class Diagram

• Highly detailed– Details system operations– Reflects topology of system– Shows how real world objects are modeled

in the SCPF

Model

Critical Properties

• Safety Properties– Messages are sent to the driver if high

pressure is detected– High temperature will cause the element to

be taken out of the heating sequence– An electrical short will cause the cleaning

process to terminate

Critical Properties (cont.)

• Liveliness Properties– The cleaning process will begin when all

criteria are met– The cleaning process gradually increases

and decreases the power supplied to an element

– Every 1000ms a message is sent over the CAN to the engine controller

Promela and XSpin

• Results of analysis– Modeled the sensor checker– Made sure appropriate action was taken

according to the sensor readings

• Our sensor checker performed well

• Learned the importance of sensors

Bypass valve testing code In the pressure warning and fault states the bypass is opened by setting the bypass variable to true

Promela Testing

Elapsed Revolutions & Instantaneous RPMs testing code Instantaneous RPMs

Check– returns Low if < 700– returns OK if > 700

Elapsed Revolutions Check– returns Low if <

10000– returns OK if >

10000sets revs = true to start cleaning process

Promela Testing (cont.)

Demo of Prototype

• High-level features of User Interface:– Start/Stop engine– Control engine RPMs and filter pressure– Control operational status of individual

heater elements– Displays CAN communication information– Displays driver display information

Scenarios

• Normal Scenario– Turn on engine– Increase RPMs to above 700– Increase pressure to above 8 kPa– All operational heaters will turn on and ramp

up/down in sequence– When finished the system waits until 10,000

revolutions have occurred before starting cleaning sequence again

Scenarios (cont.)

• Non-operational heaters are skipped– Turn on engine– Uncheck the Operational box of a heater– Increase RPMs to above 700– Increase pressure to above 8 kPa– When a non-operational heater is reached,

it is skipped– Cleaning process continues with next

operational heater

Scenarios (cont.)

• Excessive pressure causes a message to be sent to the driver display– Turn on engine– Increase RPMs to above 700– Increase pressure to 12 kPa– A message appears in the driver display

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