Intern Group Project Presentation #2

transcript

Intern Team Project #2A/D Modelling

Obi Michael, Nicholas Gill, and Frank Oh

-- Cummins Confidential --2

Outline

I. A/D Modelling Project Introduction/ Background

II. A/D Modelling Approach

III. AAD and RAD Simulink Diagrams

IV. Steady State and Transient Response Results

V. Test Cases and Simulation Results

VI. Tuning

VII. Challenges/References/ Resources

Outline

VI. Tuning

VII. Schedule/Challenges/References/ Resources

A/D Modelling Project Introduction/ Background

Definition– A/D (Analog-to-Digital) is an electronic conversion process in which an analog

signal is converted into a digital signal.

Goal– Design A/D circuits using Simulink similar to A/D pins on the ECM and also

design test cases which can be run on the models to understand the electrical characteristics of those pins.

Value– A/D Modelling simulates the internal circuitry of the ECM along with the sensor/

actuator to understand the electronic characteristics of the pin and/or the actuators/ sensors.

– A/D models could be used for tuning the out of range values for the sensors in software.

Outline

VI. Tuning

A/D Modelling Approach

Read specs on sensors to be modeled.– AAP (Ambient Air Pressure) Sensor– CT (Coolant Temperature) Sensor

Two sensor connection circuits were modeled in Simulink– RAD (Ratiometric Analog-Digital) Circuit

• Pressure sensor connection circuit.• Input is a variable voltage

– AAD (Absolute Analog-Digital) Circuit• Temperature sensor connection circuit.• Input is a variable resistance.

Outline

III. AAD and RAD Circuit & Simulink Diagrams

VI. Tuning

AAD Circuit (Confidential)

• CT Sensor Input• Variable Resistance

• Output Voltage• Input to ECM microcontroller

AAD Simulink Circuit • Function block: Matlab Code• Temperature Relationship• Loops through all temperatures

Function Block Code

AAD Temperature-Resistance relationship

TemperatureTolerance

Nominal Resistance

RAD Circuit (Confidential)

• AAP Sensor Input• Variable Voltage

• Output Voltage• Input to ECM Microcontroller

RAD Circuit Design Simulink• Function block: Matlab Code• Pressure Relationship• Loops through all Pressure

Pressure Relationship Function Block Code

• RAD Pressure – Voltage Relationship

• Tolerance

Outline

VI. Tuning

AAD (CT Sensor) Circuit Simulation Approach

Logged Input Resistance and Output Voltage using Simulink.– Output Voltage was converted to counts

– Counts was converted to temperature using calterm table (C_AIP_CT_Linear_Y).

Plotted Graph of Temperature vs. Resistance.– The graph was compared to original graph from CT sensor specification sheet

information.

AAD Steady State Specs sheet Vs. Simulation (Temp. - °C, Resistance - Ω)

RAD (AAP Sensor) Circuit Simulation Approach

Input Voltage and Output Voltage were logged using Simulink.– Output Voltage was converted to counts – Counts was converted to Pressure (kPa) using calterm table (C_AAP_SensorY).

Graph of Pressure Vs. Voltage was plotted.– The graph was compared to original graph from spec sheet information.

RAD Steady State Calculation Vs. Simulation

Transient Response Analysis (RAD)

• Unit Step Input Transient response.• It takes 2.2ms for output voltage to reach desired value.

Outline

VI. Tuning

Test Case 1: AAD Circuit (CT Sensor) – Voltage Supply Change Effect New ECMs would have a 5 V voltage supply.

– Old ECMs had a 5.175 V supply.

Simulation was done to see if there would be a major change in the output for a voltage supply change.

Voltage Supply

AAD Simulation

AAD Simulation Comments

5.175 V graph has different X,Y points than 5 V graph– For Example,

• corresponds to -25°C on 5 V graph• Ω corresponds to -48°C on 5.175 V graph

Voltage Supply change would result in change in the ECM software/calibration for the CT sensor.

Test Case 2: RAD Circuit (AAP Sensor) – Pull-down Resistor Effect Some ECM’s do not have the 47.5 KΩ resistor in the RAD

circuit for the pressure sensors. Simulation was done to see if this resistor actually affects

the output voltage of the RAD circuit.

Pull-down Resistor

RAD Circuit Simulation

RAD Circuit Simulation Comments

Although Simulation shows that the pull-down resistors do not affect the response of the circuit, it is still important.

Pull-down resistor prevents microcontroller from reading an unknown state when the AAP sensor input pin is floating.– Improves accuracy and reliability of readings.

Floating Sensor InputMicrocontroller Pin

Outline

VI. Tuning

Tuning

Tuning is adjusting certain parameters in an attempt to make certain features or hardware components perform optimally.– Proper tuning can prevent false failures from occurring and to

help us better catch failures when they do occur.

For this project we attempted to tune the OORL and OORH values for the AAP and CT sensors

Tuning (AAD)

AAD (Coolant Temperature Sensor)– Highest and lowest limits for resistance was calculated with

tolerances from spec sheet.– Resistances were corresponded with simulated graphs to derive

the temperatures.– Actual Out of Range Tuning values from calterm.

Calculated Temperature LimitsLower Limit -47°C 420,000 Ω Upper Limit 150°C 163 ΩCalterm Out-Of-Range Temperature Sensor CalibrationLower Limit -48.92°C Upper Limit 150°C

Tuning (RAD)

RAD (Ambient Air Pressure)– Highest and lowest limits for input voltage was calculated with

tolerances from spec sheet.– Input Voltage limits were corresponded with simulated graphs to

derive the temperatures– Actual Out of Range Tuning values from calterm

Calculated Pressure LimitsLower Limit 43.5 kPa 0.45 VUpper Limit 113.6 kPa 4.7 VCalterm Out-Of-Range Pressure Sensor CalibrationLower Limit 40.8 kPa Upper Limit 114.3 kPa

Outline

VI. Tuning

Challenges

Software version Differences– Frank (Matlab R2013b), Obi and Nick (Matlab R2010a)

Learn Simulink Balancing time for individual team projects and group

projects.

Special Thanks to…

Shashi Singh – HMLD Off-Highway Controls Customer Engineer.

Managers and Project Stakeholders. 2014 Group Intern Project Presentation. Mathworks.com

Intern Group Project Presentation #2

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