1. Mini-commercial vehicle EPAS
development and DTC errors
mitigation
Awate Durgesh R.
14MEA0043
Dr. K Ganesan
Director, TI-FAC
CORE
VIT University, Vellore
Mr. Senthil Arumugam
Head, engineering
Robert Bosch Automotive
Steering,Pune
Guided By

2. Objective
• Development of EPAS in Indian OEM
Mini-commercial vehicle, which is
replacement of older rack and pinion
Mechanical Steering System.
• Advantage of improved fuel efficiency.
• Elimination of need for harmful
hydraulic steering fluid.

3. Objective
 Less space and are more durable
compared to older one.
 Less complicated build and
mechanism.
 No maintenance compared to fluid
leakage of hydraulic system.

4. Introduction
 The older rack and pinion system was
directly coupled to rack and pinion
mechanically whereas EPAS is
electrically coupled.
 During engine ON only, motor gives
assist otherwise mechanical assist.
 Motor gives assist by receiving torque
sensor, rotor position sensor signals
and also vehicle speed.

5. Introduction
 Compared to Hydraulic steering EPAS
takes current only when motor starts
to give assist.
 Increased driving feel by reducing
torque requirement by driver to rotate
wheel.
 It gives quick assist of motor directly
compared to hydraulic fluid increasing
safety percentage.

6. Introduction
 Three types of EPAS systems
depending on volume of vehicle,
column, dual pinion, parallel axis
activated.
 Column type for small volume, dual
pinion for medium volume and parallel
axis activated are for upper medium.

7. Literature Survey
 Mini-commercial vehicle has a rack
and pinion steering system.
 No CAN network is available.
 No other ECUs in the car (e.g. no
electronic Brake System, digital
cluster).
 No other sensors to get vehicle speed
or engine running status.

8. Literature Survey
 As no electronic and electrical part in
older system, no diagnosis possible.
 EPAS comprises of ECU, motor and
sensors hence diagnosis is possible.
 With the help of diagnosis easy to
detect error.
 Maintenance problem of fluid in older
system.

9. Block Diagram of column type
EPAS

10. General Diagnosis procedure
 After complete assembly of EPAS,
system can be diagnosed on the
vehicle and Off the vehicle.
 After EOL, system can be diagnosed
by Bosch software green studio Off
line.
 On vehicle Diagnostic Engineering
Tool is used for testing .

13. Methodology or
Implementation
 It is carry-over of car power steering.
 No changes in electrical components (ECU,
Motor, TIS, RPS)
 No support for different communication
interface (K-Line, Flexray, etc.) only CAN.
 Mechanical adaptations, Like tuning of steering
column with mechanical steering gear.
 Mechanical steering gear of commercial
vehicle.

14. Methodology or
Implementation
 Installed digital cluster and
communicated with EPAS ECU for
vehicle speed signal.
 Engine’s dynamic or static condition
simulated
 After assembly, OFF vehicle diagnosis
and ON vehicle diagnosis.

15. Testing
 CAN analyser to test steering ON
vehicle condition.
 Green Studio to diagnose DTC errors
and EPAS ECU signal communication.

16. Power supply handling of EPAS ECU.
KL30

17. Results
EPAS and Digital Instrument cluster installation

18. Application
 For growing mini-commercial vehicle
market in India, EPAS offers great
advantages like increased fuel
efficiency, drive-ability, durability and
less maintenance.

19. Future Scope
 In 2020 there would be vehicles on
road with automated power steering
systems with lane keeping assistance.
 The power steering with lane keeping
assistance would warn driver about
lane changing and if driver doesn’t do
action system itself takes the control.