Usage of CAN and CAN-FD for High-Definition Headlight Systemss3.eu-central-1.amazonaws.com/cancia-de/documents/... · 2015. 11. 13. · Gennady Benderman | EEK4 25/26 • Transfer

CiA-Presentation.pptx Gennady Benderman | EEK4 1/26

Usage of CAN and CAN-FD for High-Definition Headlight Systems


Introduction


• Development of Light Sources: − Candle − Gas burner (Acetylene) − Electric headlamp „Bosch Light“ − Bilux lamp − Halogen lamp − Xenon gas lamp − Led − Laser

Introduction

Robert Bosch GmbH Osram Licht AG


• Main light distributions: Low beam with a kink in the light-dark

border • Isolux diagrams:

Bird‘s eye perspective of low beam:

Bird‘s eye perspective of high beam:

Introduction

The Optical Society Hella KGaA Hueck & Co. ZKW Group GmbH


Development of intelligent light functions

• Use of stepper motors for: − Beam height control − Curve light − Adaptive Front-lighting System (AFS)

• Camera based Advanced Driver Assistance System:

− Adaptive cut-off line − Glare-free high beam (vertical cut-off line) − Matrix light

Lead to higher safety on the road at night

Introduction

Hella KGaA Hueck & Co.


Masked out region by Matrix Beam

Introduction


Masked out persons by Matrix Beam

Introduction

Audi AG


E/E-Architecture


Control of intelligent headlamps via CAN

E/E-Architecture

Headlight control via a general CAN bus

Headlight control via a separate AFS-CAN bus

CiA-Presentation.pptx Gennady Benderman | EEK4 10/26 E/E-Architecture


Bus-Load


• CAN is a well-known and economical communication standard • Calculation of the bus-load

[Bitsum] = bit [Cycletime] = s [Bitrate] = kbit/s

• Messages usually transmitted with cycle time tc1, at changes switch to faster tc2 • Stuffing bits additional increase of bus-load

Bus-Load


• Advantages of CAN-FD: Longer data field of up to 64 Bytes Higher allowed data rate

• ISO-CAN-FD Frame with CRC bit stuffing counter

• The marked bits can transmitted with a higher CAN-FD specific bit rate

Bus-Load

Fast Transmission

Holger Zellwanger; CAN FD verbessert; www.elektroniknet.de, 2015


• Calculation of the average CAN-FD bitrate • Calculation of the busload per message

[Bitsum] = bit [Cycletime] = s [Bitrate] = kbit/s

Bus-Load


• Pixelwise transmission via 500kbit/s CAN

• Worst case bus load (incl. stuffing bits) at max. 50%

• Today’s exemplary bus load of the front-lighting CAN

Bus-Load

90 pixels, 6 bit CAN 500 kbit/s

CAN-FD 2 Mbit/s

CAN-FD 8 Mbit/s

best case/ no bit stuffing 30.83 % 10.98 % 4.62 %

best case/ with stuffing 36.37 % 12.96 % 5.45 %

worst case/ no bit stuffing 38.33 % 15.03 % 6.49 %

worst case/ bit stuffing 45.22 % 17.72 % 7.64 %


Calculation of possible pixel number per headlamp • Number of pixels per 64 Byte data frame for highest average data rate:

• Collecting of CAN messages in new CAN-FD messages

Bus-Load

Bus Load <50% CAN-FD 2 Mbit/s

CAN-FD 5 Mbit/s

CAN-FD 8 Mbit/s

Number of Pixels/HL ~1500 ~3500 ~4700


Matrix Light


• 90 pixel matrix (30 by 30) • Overlap of neighbored segments

• Limited resolution overhead angle = open angle – object width

Matrix Light

CiA-Presentation.pptx Gennady Benderman | EEK4 19/26 Matrix Light

• Oncoming traffic relative speed of 200 km/h starting at 300 m


• 1548 (86 by 18) pixel matrix with typical aspect ratio

Matrix Light


• More relatively small switching steps of pixels by using a higher horizontal resolution

More comfortable for driver

Matrix Light


• A smoother increase of switched off pixel by using a higher horizontal resolution

Matrix Light


• Reduction of the overhead angle by using a higher horizontal resolution

Matrix Light


Alternative Pixel Control


• Transfer of object information from a central Light ECU to the headlamp ECUs

Data fusion in the Light ECU

Calculation effort because of the parallax effect

Object type, position, distance or object information for both coordinate systems

Image processing in both headlamps computationally intensive tasks in the headlamp ECUs

Alternative Pixel Control

Sascha Saralajew; Berechnungen der Fehlstellungen eines Scheinwerfersys-tems, 2014


Thank you!

Documents

Usage of CAN and CAN-FD for High-Definition Headlight Systemss3.eu-central-1.amazonaws.com/cancia-de/documents/... · 2015. 11. 13. · Gennady Benderman | EEK4 25/26 • Transfer