ARCHIVED - SG2007 Electrohydraulic Braking

Chassis/Safety
Electrohydraulic Braking
Overview
Electrohydraulic braking (EHB) systems are
designed to allow electronic control of
vehicle braking while retaining a reduced
hydraulic system. The hydraulic system
functions as a reserve in the event of a
failure in the electronic control.
The EHB control unit receives inputs from
sensors connected to the brake pedal. In
normal operation, a backup valve is closed
and the controller activates the brakes of
the wheel through an electric motor driven
hydraulic pump. When the controller goes
into a fail-safe mode, the backup valve is
opened, which allows the brakes to be
controlled through a conventional hydraulic
circuit.
> Uses software updates to
simplify the calibration
process by adjusting brake
response and pedal feel
ELECTROHYDRAULIC BRAKING BLOCK DIAGRAM
Pedal Sensor
Hydraulic Pump
EHB Control Unit
· MCU
· Output Driver Hardware
Accumulator
Key Benefits
> Reuses hydraulic system
technology while
incrementally building on the
development of advanced
electronic systems, such as
electronic stability programs
(ESP), traction control, and
brake assist
> Improves connectivity with
other emerging systems,
such as adaptive cruise
control
> Removes the large vacuum
servo to allow flexible
installation
> Features an anti-lock braking
system (ABS) without
feedback from the pedal
Backup Valve
Hydraulic Brake Actuators
Freescale Ordering Information1
Part Number
Product Highlights
Additional Information
MPC500
32-bit microcontrollers
www.freescale.com2
SMARTMOS
Integrated circuits
www.freescale.com/analog
Notes:
1. Contact your Freescale Semiconductor sales representative for complete information about existing products and custom solutions.
2. Search on the listed part number.
Design Challenges
Electrohydraulic braking is based on
existing ABS systems with the addition
of several enhancements. The inclusion
of analog electrohydraulic valves
requires closed-loop, current-controlled
pulse width modulation (PWM) outputs
from the electronic control unit (ECU).
Freescale Semiconductor Solution
An EHB system requires mid-range
performance MPC500 microcontrollers
for system control with SMARTMOS
companion chips for functions such as
load driving, sensor interfacing, voltage
regulation, and system watchdog
operation.
An EHB system is required to
incorporate a fail-safe state in the event
of a fault occurring. To correctly initiate
the fail-safe state, the system relies on
its electronic components to provide a
high level of operational fault coverage.
Freescale Semiconductor has gained
experience developing many of the
specific aspects required for the
implementation of an EHB system.
Because of its extensive experience in
the development of fail-safe
microcontrollers, braking-specific
modules such as the wheel speed timer,
and a software center including drivers,
tools, and operating systems, Freescale
Semiconductor has proven its ability to
develop the right solutions in
collaboration with its customers.
Development Tools
Vendor
MPC555
MPC561
MPC562
MPC563
MPC564
MPC565
MPC566
CodeWarrior for Embedded PowerPC ISA
!
!
!
!
!
!
!
CodeWarrior for OSEK RTOS
!
!
!
!
!
!
!
CodeWarrior Development Systems
!
OSEKturbo (RTOS)
!
TPU
Metrowerks
!
!
!
!
TPU Low-Level Driver Library
!
Flash Programming —
CodeWarrior for Embedded PowerPC ISA
!
!
!
!
!
Flash Programming —
CodeWarrior for OSEK RTOS
!
!
!
!
!
Wind River Systems
BDM Debugger — SingleStep
!
!
!
!
BDM Debugger — SingleStep with Vision
!
!
!
!
Flash Programming — SingleStep
!
!
!
BDM Debugger — VisionCLICK
!
!
!
!
!
!
!
!
!
!
Nexus Debugger — VisionCLICK
Nexus Debugger — SingleStep with Vision
Flash Programming — VisionCLICK
!
Compiler — DiabData
!
!
MATRIXX
!
!
Simulator — SingleStep
!
!
SG2007-2
!
!
!
!
!
!
!
!
!
!
!
!
!
!
Development Tools (continued)
Vendor
MPC555
MPC561
MPC562
MPC563
MPC564
MPC565
MPC566
TPU
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
Lauterbach
BDM Debugger Trace32
Nexus Debugger Trace32
Code Trace (with Bus access)
!
!
!
!
!
!
!
Code Trace (Nexus)
!
!
!
!
!
!
!
Low-Cost Evaluation Board
!
!
Mid-Range Evaluation Board
!
!
Full-Feature Evaluation Board
!
!
!
!
!
!
!
!
!
!
!
!
!
!
Axiom Manufacturing
Ashling Microsystems
BDM Debugger — Opella, Genia, and Vitra
Nexus Debugger — Vitra (w/trace)
!
!
!
Nexus Debugger — Opella, Genia
!
!
!
!
Green Hills Software
IDE, Debugger — Multi
!
!
!
!
Compiler — C/C++/EC++
!
!
!
!
Low-Cost Debugger
!
!
!
!
Flash Programming Tools
!
!
!
!
!
P&E Microcomputer Systems
GNU
Compiler/Debugger
!
!
ASH WARE
TPU Simulator
!
ETAS
ErCOSEK
!
!
!
!
Calibration Tools (ETK)
!
!
!
!
Calibration Tools (ETK) Nexus
!
!
!
!
!
!
!
!
!
!
!
!
Logic Analyzer
!
!
!
!
Inverse Assembler, Source Correlation
!
!
!
!
Emulation Probe (BDV)
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
dSPACE
TargetLink
dli
Logic Analyzer
Agilent Technologies
Tektronix
Logic Analyzer
Abatron AG
BDM Support
Accelerated Technology
Nucleus (RTOS)
SG2007-3
Third Party Support
Vendor
Contact Information
Metrowerks
800-377-5416 (www.metrowerks.com)
Axiom Manufacturing
972-926-9303 (www.axman.com)
Wind River Systems
800-872-4977 (www.windriver.com)
Green Hills Software
805-965-6044 (www.ghs.com)
Lauterbach
508-303-6812 (www.lauterbach.com)
Accelerated Technology
800-468-6853 (www.acceleratedtechnology.com)
Ashling Microsystems
408-732-6490 (www.ashling.com)
ASH WARE
503-533-0271 (www.ashware.com)
GNU
617-542-5942 (www.gnu.org)
ETAS
888-382-7462 (www.etasinc.com)
dSPACE
248-567-1300 (www.dspace.com)
P&E Microcomputer Systems
617-353-9206 (www.pemicro.com)
Online Topics
Description
Location
MPC500
www.freescale.com
Analog and Mixed Signal
www.freescale.com
32-Bit Development Tools
www.freescale.com
Related Product
Product Number
Product Name
Contact Information
MPXV6115V
High temperature accuracy integrated silicon pressure
sensor — small outline package
www.freescale.comNote
Note: Search on the listed part number.
Learn More: Contact the Technical Information Center at +1-800-521-6247 or +1-480-768-2130.
For more information about Freescale products, please visit www.freescale.com.
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
All other product or service names are the property of their respective owners.
© Freescale Semiconductor, Inc. 2004. All rights reserved.
SG2007
REV 1
12/2004
December2004