Introduction and future application - SVEA FORDON · Introduction and future application 1 High Performance Pneumatic Actuator for Commercial Vehicles and Controllability Impact of

Innovative Vehicle SolutionsInnovative Vehicle Solutions

FABV and Controllability impact of Autonomous SystemsIntroduction and future application

High Performance Pneumatic Actuator for Commercial Vehicles and Controllability Impact of Automous Systems1

Jim Crawley Haldex Brake Products Ltd.

Innovative Vehicle Solutions

Presentation Content

Contents Introduction to the Fast Acting brake valve

Conventional system theory FABV Principle System performance and results

FABV and integration into future vehicle systems FABV and Autonomous Systems



Current Situation

Conventional ABS

Time [s]

Spee

d [m

/s]

Vehicle speed (dashed)

Wheel speed (solid)

Free-wheeling

Brake Pressure Reduced Here

Current Conventional Pneumatic ABS Theory Provide short stopping distances Maintain Vehicle stability and steer ability Cycling pressure to avoid wheel lock Free wheeling


(Henderson et al, 2016)


Conventional ABS slip Curve Theory

Optimum braking occurs at between 10-20% If the wheel speed and vehicle speed are the same wheel slip -0% A locked wheel will have a wheel slippage of 100%

Longitudinal slip, λ (unitless)

Nor

mal

ised

forc

e (u

nitle

ss)Longitudinal tyre force, Fx

ABSRange of Fx

max Fx

min Fx

Slip Ratio

Coef

ficie

nt o

f fric

tion

betw

een

tire

and

road

sur

face

Provide short stopping distances

Maintain Vehicle stability and steer ability

Definition

Slip ratio = [Vehicle speed – Wheel speed]/Vehicle speed x 100%

When slip ratio is 0%, the vehicle speed corresponds exactly to the wheel speed. When it is 100%, the wheels are completely locked [rotating at a zero speed] while the vehicle is moving.





ABS

Longitudinal tyre force, Fx

Lateral tyre force, Fy


Nor

mal

ised

forc

e (u

nitle

ss)

Range of Fy

max Fy

min Fy

Range of Fx

Optimum braking occurs at between 10-20% If the wheel speed and vehicle speed are the same wheel slip -0% A locked wheel will have a wheel slippage of 100%

Slip Ratio

Coef

ficie

nt o

f fric

tion

betw

een

tire

and

road

sur

face

Provide short stopping distances

Maintain Vehicle stability and steer ability

Definition







Slip control


Nor

mal

ised

forc

e (u

nitle

ss)

Longitudinal tyre force, Fx

Lateral tyre force, Fy

λdem

Range of Fx

Range of Fy

Providing Slip control provides optimum use of friction coefficients Minimising stopping distances whilst maintaining stability

Slip Ratio

Coef

ficie

nt o

f fric

tion

betw

een

tire

and

road

sur

faceDefinition






Slip control Comparison

Conventional ABS

Slip Control

Time [s]

Spee

d [m

/s]

Main requirements for slip control implementationHigh-bandwidth control of brake chamber pressure requiredKnown parameters1. Vehicle speed2. Adhesion force at the wheel3. Approximate slip curve peak

Vehicle speed (dashed)

Wheel speed (solid)

Comparison Theory Slip control allows optimum use of the slip corridor Maximum utilisation of adhesion Shorter stopping distances




Fast Acting Brake Valve Principle

Joint development between Haldex, Cambridge and Chalmers

Direct acting reduces the pneumatic delays in conventional valves

High speed – valve can change state very quickly

High flow – sufficient for a single brake chamber

A conventional ABS valve operates much slower



Fast Acting Brake Valve Technology

Conventional Trailer ABS/EBS Valves

Prototype Valves Gen 2

(Henderson, 2013)

System Performance Eliminates system time

delays Fast Response than

conventional Systems Shorter stopping distances Lower air consumption



2015 Test Vehicle System trial

Valve block

Slip controller electronics

Prototype System 1 Test Installation with prototype system


Prototype System Performance Test carried on wet basalt tile at MIRA, UK

Laden bobtail

Tractor-semitrailer (BBC)

FABV



Results from 2015 System Trial


Tractor Steer Axle Tractor Drive Axle Trailer axles

Axle load (static) 6.1 tonne 9.8 tonne 5.1 tonne

Coefficient of adhesion 0.106 0.106 0.117*

Surface:Wet basalt tile, MIRA, UK

System Results System testing performed by CVDC at MIRA Combination system tested on Wet Basalt Improvements in Air usage and stopping

distances

Total combination weight: 31 tonne


2015 Test Vehicle System trialPrototype System 1


Tractor-semitrailer (BBC) (Henderson et al, 2016)


Future System IntegrationIntegration into Vehicle Motion Management (VMM) systems The FABV with its improved controllability of individual brake torques is an

enabling technology for advanced ‘full vehicle control’ systems Motion devices controlled (using Control Allocation theory) by a single

Vehicle Motion Management controller. As described in Laine, 2007 VMM communicates directly with all devices All devices broadcast capability to the VMM, VMM uses live information in optimised

control allocation calculations The VMM transmits individual ‘requests’ to

each actuator Conventional EBS have a central global

braking controller. Allowing the VMM to communicate and

directly control brake torque reduces communication delays.

(Henderson et al, 2016)High Performance Pneumatic Actuator for Commercial Vehicles and Controllability Impact of Automous Systems13


Future heavy vehicle braking

Levels of automation for on-road vehicles defined by SAE J3016


(SAE, 2014)


Future heavy vehicle brakingLevels of automation for on-road vehicles defined by SAE J3016

Level 4 to 5 High to Full Automation SAE levels 4 and 5 the vehicle control system can no longer rely on a

human driver to intervene in the event of a system fault. Conventional EBS with pneumatic back up unsuitable for fully

autonomous driving due to human intervention A vehicle control system with dual, independent electrical power

sources (batteries) and communication networks required for level 4/5.


(SAE, 2014)


Future heavy vehicle brakingLevels of automation for on-road vehicles defined by SAE J3016

Level 5 Full Automation Level 5 - full-time performance by an automated driving system of

all aspects of the dynamic driving task under all roadway and environmental conditions that can be managed by a human driver”

This cannot be realized without live, accurate knowledge of the tyre-road characteristics, in all driving modes. FABV can enable this

(SAE, 2014)



ConclusionsSummary FABV provides improved controllability of wheel torques and

longitudinal slip Stopping distance reduction achieved on prototype system

FABV constant Monitoring of tyre and road conditions is an enabler for future full vehicle motion management systems Reduction in communication delays Improved controllability

FABV System enables compliance to SAE standard for “Fully automated Vehicle control systems” by supporting:- The automated driving system must perform a dynamic driving

task under all road and environmental conditions. The automated driving system must perform all-aspects of a

dynamic driving task even if a human driver does not respond appropriately



ReferencesHenderson, L., Cebon, D., & Laine, L. (2016). Brake system design for future heavy goods vehicles. The 14th International Symposium on Heavy Vehicle Transport Technology. Rotorua, New Zealand.

Henderson, L. (2013). Improving emergency braking performance of heavy goods vehicles (PhD thesis), Cambridge University Engineering Department.

Laine, L. (2007). Reconfigurable Motion Control Systems for Over-Actuated Road Vehicles (Ph.D. Thesis). Chalmers University of Technology.

Society of Automotive Engineers (SAE). (2014). J1306: Taxonomy and Definitions for Terms Related to On-Road Motor Vehicle Automated Driving Systems.



Contact Details


Jim Crawley MSOE, MIRTEHomologation Engineer

Mobile: +44 7780958452Direct: +44 2476 400334E-mail: [email protected]://www.haldex.com

Haldex Brake Products LtdMIRA Technology ParkLindleyWarwickshireCV13 6DEUnited Kingdom

Documents

Introduction and future application - SVEA FORDON · Introduction and future application 1 High Performance Pneumatic Actuator for Commercial Vehicles and Controllability Impact of