May 19, 2010

Managing Software Interfaces of

On-Board Automotive Controllers

Anthony Tsakiris

Ford Motor Company

atsakiri@ford.com

May 19, 2010

Introduction

Today’s cars rely heavily on software-intensive

electronic controllers that share information.

A typical Ford vehicle has

20 controllers. Our high-end

vehicles have about 40

controllers.

Increasingly, controllers must cooperate to deliver

functions none can provide alone.

Vehicle Network

May 19, 2010

Hybrid Electric Power Pack

Engine + Controller

Motor + Generator + Gear Set + Controller

High Voltage Battery + Controller

May 19, 2010

Business Goals

• Avoid duplication of engineering work

• Easily deploy new features and technologies

• Be quicker to market

• Reduce product and development cost

May 19, 2010

Scenario 1

Offer different

power packs in a

single vehicle

May 19, 2010

Scenario 2

Reuse a power

pack in different

vehicles

May 19, 2010

The Problem

We tried to reuse the hybrid electric power pack of a

North American SUV in a European sedan that original

had a conventional power pack. (scenario 2)

• Many unanticipated interface mismatches

• Lots of re-engineering

• Slow progress

• Project eventually cancelled

Two big causes:

• Interface variations

• Organizational constraints Square peg, round hole!

May 19, 2010

Cause 1 - Variation

Optional features across large product line

FOCUS SEDAN FOCUS COUPE FUSION MUSTANG TAURUS FUSION HYBRID ESCAPE HYBRID EDGE FLEX

RANGER F-150 TRANSIT CONNECT SUPER DUTY E-SERIES ESCAPE SPORT TRAC EXPLORER EXPEDITION

KA FIESTA C-MAX MONDEO S-MAX KUGA GALAXY

Legacy designs from many brands

Ford Mercury Lincoln Mazda Volvo Jaguar Land Rover

May 19, 2010

Cause 2 - Organizational Constraints

We were not architecturally driven.

• Non-functional requirements have low priority

• Decisions often driven by immediate needs of an individual project

• Incremental change favored to reduce risk

• Collective mental model of system overwhelmingly focused on hardware view

• Different brands have different business models

May 19, 2010

The Solution

A new project ... to eliminate the problems that caused the first project’s failure ...

• Six workstreams, one devoted to control architecture and interfaces

• A committed team of subject matter experts who can make change happen

• A new framework to guide our thinking

• Commonized control architecture and signal interfaces

May 19, 2010

Solution - A New Framework - Hardware

TM

ECA

CM

E

ASM

RM

Vehicle

Speed

Controller

Traction

Force

Request

Speed

Limit

Cruise

Control

Required

Crankshaft

Torque

Brake

&

Stability

Limitation

Anti-Jerk

Control

Crankshaft

Traction

Force

Arbitration

Speed

Control

Logic Actual

Traction

Force

Actual

Torque

Ratio

Engine

Speed

Control

Torque

Coordination

&

Shuffle

Control

Crankshaft

Torque

Arbitration

SC

AC

ALC

MC

Adaptive

Cruise

Control

BM

Drivetrain

Mode

Manager

Wheel Torque

Distribution

Anti-Jerk

Control

Motor

FB

FWC

Wheel

Torque

Arbitration

Clutch

Contrtol

EA

Powertrain

Mode

Manager

Energy

Management

GC

EC

Shift

Control

Calculate

Friction

Torques

Battery

Maintenance

Management

Regenerative

Brake

Torque

Request

Brake

Coordinator

ARB

Stability Control

Axle

Stability

Limitation

Base YC,

RC, TC

City

Safety CMbB

Brake

Torque

Request

Brake

Torque

Requests

Arbitration

Shift

StrategyState

Management

EPB

DE

DA

VMC

DTC

DE DA VMC

VMC

RM TC

DA

Battery Management

Motor Control

Electrical Acc. Control

Generator Control

Engine Control

Steering Pump Control

AC Comp. Control

Alternator Control

Transmission Control

Drivetrain Control

Vehicle Motion Control

Driver

Assist

Driver

Eval

Driver

Eval

Driver

Assist

Driver

Assist Vehicle Motion Control

Vehicle Motion

Control

Parking Brake Control

Brake Control

Controller 1

Controller 2(not always present)

Controller 3

Controller 4

Controller 5(not always present)

= function(s)

= data flow(s)Internal details not shown for confidentiality reasons.

May 19, 2010

Solution - A New Framework - Function

Vehicle Control Functions

Subsystem Control Functions

Internal details not shown for confidentiality reasons.= data flow(s)

= function(s)

May 19, 2010

Solution - Interface Commonization

1160 interface signals collected from legacy designs

We created three categories:standardized for common, long-term use restricted for short-term use only prohibited to eliminate variation

• id• name• description• range• resolution• enumerated values

• update rate• initial value• aliases• transmitters• receivers• etc.

May 19, 2010

Results

393 redundant or undesirable signals eliminated

100%1160Total

24%276TBD*

34%393Prohibited

8%99Restricted

34%392Standardized

Fraction of All Signals

Number of Signals

Signal Category

* Note: We have since addressed the TBD signals.

May 19, 2010

Results

Established corporate data dictionary for allnetwork interface signals, not just those affecting the power pack

That means about 800 more signals

100%2017Total

25%506Prohibited

15%311Restricted

60%1200Standardized

Fraction of All Signals

Number of Signals

Signal Category

May 19, 2010

The Lessons Learned

#1 Illuminate the entire product line constantly.Establish a framework for thinking about the system that covers the entire product line. Make it the basis for integrating new features. This helps balance new features and old features.

#2 Keep the team.A permanent cross-functional team can provide continuous attention to non-functional quality attributes. Do not disband the team unless other mechanisms are established to take its place.

May 19, 2010

The Lessons Learned

# 3 Evolution works too.Many organizational habits are deeply rooted. It is far more effective to evolve existing work products and processes instead of trying to revolutionize them.

#4 Do not wait for a complete architecture description.A multi-view architecture description makes great sense but is difficult to establish in an organization that is not architecture-driven. Add value incrementally by working from implementation to architecture.

May 19, 2010

The Lessons Learned

#5 Educate.Plan time and resources for education about architecture. Most of the engineering community does not think in terms of quality attributes, stakeholder concerns, architectural strategies, and multiple views.

#6 Be persistent; have patience.Some changes take a very long time. Keep at it. Light pressure is better than no pressure.