Design Factors and Unified Software Structure for ...

Main Design Factors and Unified Software Structure for Cable Puller and Caliper Integrated Type Electric Parking Brakes

J.S. Cheon, J.W. Jeon, H.M. Jung, I.U. Park, C.H. Park, T.-J. Yeo Oct. 13th, 2009 R&D Division, Hyundai MOBIS

Contents 1. Introduction 2 Actuator 2. A t t D Design i 3. Software Design h

EPB Functions

h

Software Structure

h

Target Performance Index

h

Variable Modules

4. Feedback Control 5. Results & Conclusions 2/19

Paper 2009-01-3022

▣ Introduction : EPB

Cable Puller EPB

Actuator / ECU Parking Brake

Conventional Parking

• Space • Safety • Comfort

Caliper Integrated EPB Actuator / Parking Brake

ECU

3/19

Paper 2009-01-3022

▣ Actuator Design : Type Cable Puller EPB

Caliper Integrated EPB

force sensor

screw gearbox

gearbox screw

motor piston

motor

parking cable

EPB

4/19

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▣ Actuator Design : Procedure Cable Puller EPB

System Design

Vehicle Specification

Target Braking Force

cable efficiency, DIH properties

Caliper Integrated EPB

Target Actuator Force

effective radius, friction pad

Actuator Specification

Actuator Detail Design

Electric

Mechanical

Motor

Gear

Screw

Capacity

Type

Lead

Current

Gear Ratio

Pitch Effective Radius

RPM / Torque

5/19

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▣ Actuator Design : Performance Cable Puller EPB Test

Caliper Integrated EPB

Results

Test

Results kgf 1,800 1,500 kgf

Actuator Force (Current)

1,500 1,430 kgf

120 kgf (15A)

Leakage Test

1500 kgf (OK)

1,200 900 EPB Apply 600 490 kgf

300 0

Hydraulic Apply

Curren t(A)

Response p Time

Response p Time

A l :1 Apply 1.0 0s

A l :0 Apply 0.7 7s Tim e(sec)

Force (kgf)

Current (A)

1400

30

1200

Max. Force / Cycle

25

1000 20

800

150,000 cycles

Durability

100,000 cycles

15 600

10 400

Max. Current / Cycle 5

200

0

0 199 2199 4199 6199 8199 10199 12199 14199 16199 18199 20199 22199 24199 26199 28199 30199 32199 34199 36199 38199 40199 42199 44199 46199 48199 50199 52199 54199 56199 58199 60199 62199 64199 66198 68198 70198 72198 74198 76198 78198 80198 82198 84198 86198 88198 90198 92198 94198 96198 98198

Durability

6/19

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▣ Software Design : EPB Functions z All EPB functions f ti based b d on three th main i functions f ti - Static Apply, Static Release, Dynamic Braking Function

Description

Static Apply

EPB application by switch

Static Release

EPB release by switch

Dynamic Braking

Emergency braking with EPB in case of service brake failure or brake pedal blockage

Auto Hold

Automatic application of EPB

Drive Away Release

Automatic release of EPB

High Temp. Re-Clamp

Re-clamping of EPB at high temperatures

Adaptive Clamping

Application of adaptive clamping according to hill slope angle

Key Out Apply

Automatic application with ignition off

Release Inhibit

Inhibition of EPB release depending on circumstances (eg. brake pedal off)

7/19

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▣ Software Design : Unified Structure z EPB Functions - Same fo for Cable P Puller lle & Calipe Caliper Integ Integrated ated EPBs

z Unified Software Structure - Fixed Modules

: need to be coded only once

- Variable Modules : adjusted for target vehicle application

8/19

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▣ Software Design : Fixed Modules z Fixed Modules : Input Commands, Functional Output

INPUT

Vehicle Status

Switch Status

EPB Status

COMMAND

Status Define PERFORM FUNCTION

Variable Module

(LOGIC)

FUNCTION OUTPUT

Static Apply

9/19

Static Release

Dynamic Parking

Paper 2009-01-3022

▣ Software Design : Variable Modules z Variable Modules : Main logic to perform functions INPUT

Cable Type

Caliper Type

One-Motor Drive

F Force Control C t l Cable Connection

Two-Motor Drive Target Performance Index

DIH / Drum

Current Control Direct Connection Caliper

OUTPUT 10/19

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▣ Software Design : Variable Modules z Variable modules for each type of EPB are independent - Cable puller EPB vs. Caliper integrated EPB

z Share Common Target Performance Indices - Conceptual module linking the two variable modules

Required Target g Performance Defined

Cable Type Variable Module Caliper Type Variable Module

11/19

Required Target g Performance Satisfied

Paper 2009-01-3022

▣ Software Design : Target Indices Function

Static Apply

Static Release

Dynamic g Braking

Target Index

Goal

Application Time

Short Time

Application Current

Low Current

Noise Quality

Low Frequency

Noise Level

Low Decibel

Release Time

Short Time

Noise Quality

Low Frequency

Noise Level

Low Decibel

Wheel Lock D Deceleration l ti

Effect increase parking stability • decrease sensitivity to noise •

use efficient motor range • decrease capacity of ECU •

•

improve emotional quality (customer satisfaction)

improve operation efficiency • decrease d sensitivity iti it to t noise i •

•

improve emotional quality (customer satisfaction)

Prevention

•

improve braking stability

Hi h Deceleration High D l ti

•

i improve braking b ki performance f

12/19

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▣ Feedback Control : Type Cable Puller EPB Switch Status Motor Duty Control

Vehicle Status

S Sensor

Error

+-

S Screw

Target Force

Gear

Control Logic

M Motor

EPB Status

Cable

DIH

Measured Force

Caliper Integrated EPB Measured Current Screw Screw

Duty

Motor

Control Current - Error Motor +Logic Control

Piston / Caliper

Gear

Target

EPB Status

Gear

Duty

Motor

Switch Status

Piston / Caliper

Vehicle Status Measured Current

13/19

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▣ Feedback Control : Duty Ratio z Duty ratio : representative of input voltage to motor - PWM (Pulse Width Modulation) w2 w1

12 V 0V

Duty Ratio =

w1 w2

Average Motor Voltage = 12V × Duty Ratio

z Key control parameter determining performance - Logic og c in variable a ab e modules odu es sets app appropriate op ate duty ratio at o 14/19

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▣ Feedback Control : Characteristic Curve z Appropriate duty ratio to be determined depending on function request and target performance : control logic must make compromises between various targets No Load Position

Speed (N)

N3

N

i2

2

i1 N

1

Duty Ratio 1

Tmot1

Duty Ratio 2

Tmot2

Duty Ratio 3

Stall Torque Position

Torque (Tmot) 15/19

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▣ Software Design : Overall Structure Fixed Module

Vehicle Status

Switch Status

Variable Module

EPB Status

INPUT COMMAND

Status Define Cable Type

Caliper Type

One-Motor Drive

Two-Motor Drive

PERFORM FUNCTION (LOGIC)

Target Performance Index

Force Control Cable Connection DIH / Drum

Current Control Direct Connection Caliper

FUNCTION OUTPUT

Static Stat c Apply pp y

Static Stat c Release e ease

16/19

Dynamic y a c Braking a g

Paper 2009-01-3022

▣ Results : Static Function

Static Test

Cable EPB

Caliper EPB

Apply Time

0.75 sec

0.74 sec

Power Consumption

300 W

156 W

Cable Puller EPB

Caliper Integrated EPB Right Actuator Current

Cable Force Left Actuator Current

17/19

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▣ Results : Dynamic Function

Dynamic D i Test

Cable EPB

Caliper EPB

Wet Asphalt

0.24 g

0.33 g

Snow

0.12 g

0.16 g

Cable Puller EPB

Caliper Integrated EPB

Vehicle Speed Vehicle Speed

Operation Current (Left / Right)

Operation Force

18/19

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▣ Conclusions z Actuator Design of Cable Puller / Caliper Integrated EPBs z Same Functions for Both Types of EPBs z Unified Software Structure for EPB Development - Fixed Modules and Variable Modules - Target Performance Indices

z Feedback Control and Duty Ratio z Vehicle Test Results

19/19

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