This document summarizes the history and types of electronic power steering systems. It discusses the early developments of power steering in vehicles in the late 19th century. Hydraulic power steering became common starting in the 1950s using hydraulic fluid and actuators to augment steering effort. More recently, electro-hydraulic and electronic power steering have been developed using electric motors and control units instead of hydraulic pumps and fluid. Electronic power steering systems provide variable assistance based on driving conditions and are more energy efficient than hydraulic systems. Future developments may include fully electronic "steer-by-wire" systems without any mechanical linkages between the steering wheel and wheels.

1. ELECTRONIC
POWER
STEERING
By
GAURAV MANOHAR RAIKAR
Goa University

2. CONTENTS
 Introduction
 History
 Types of power steering
 Hydraulic power steering
 Electro-hydraulic power steering
 Electronic power steering
 Future developments

3. INTRODUCTION
• Power Steering helps drivers steer vehicles by augmenting steering
effort of the steering wheel.
• Hydraulic and electric actuators add controlled energy to the steering
mechanism, so the driver needs to provide only modest effort regardless
of conditions.
• Hydraulic power steering systems for cars augment steering
effort via an actuator, a hydraulic cylinder that is part of
a servo system. These systems have a direct mechanical
connection between the steering wheel and the linkage that
steers the wheels. This means that power-steering system
failure still permits the vehicle to be steered using manual
effort alone.
• Electric power steering systems use electric motors to
provide the assistance instead of hydraulic systems.

4. • The first power steering system was
apparently installed in 1876 by Fitts.
• In 1926,Engineer Francis W. Davis of the
truck division of Pierce Arrow invented and
demonstrated the first practical power
steering.
• Interest in power steering increased during
World War II, as it facilitated manoeuvres
for large military vehicles.
HISTORY
Francis W. Davis

5. • In 1951,Chrysler
Corporation introduced the
first commercially available
passenger car power steering
system on the 1951 Chrysler
Imperial under the name
"Hydraguide".
HISTORY
1951 Chrysler 1st Power Hydraulic Steering Hydraguide

6. TYPES OF POWER STEERING SYSTEMS
1. Hydraulic power steering system(HPS)
2. Electro-hydraulic power steering system(EHPS)
3. Electronic power system(EPS)
(HPS) (EHPS) (EPS)

7. HYDRAULIC POWER SYSTEM BLOCK
RESERVOIR PUMP
CONTROL VALVE Relief valve
POWER CYLINDER

8. HYDRAULIC POWER SYSTEM COMPONANTS

9. ROTARY VANE PUMP
• Pump = Belt Driven by the Engine crankshaft. It creates fluid flow within the system and provides the
force required to operate the steering gear. It transfers the fluid from reservoir to relief valve and than to
the control valve under pressure.

10. POWER CYLINDERCONTROL VALVE
Control valve = It directs the fluid to the Power
Cylinder. It is also called heart of hydraulic system.
Relief valve = It provides an escape to the fluid
back to the reservoir.
Power cylinder = It converts Hydraulic System into
mechanical force, which in turn activates Pinion and Rack
to give linear motion.

11. Rack and pinion
The rack and pinion steering gear translates driver steering input into movement of the front wheels for
turning. In this system, a pinion gear is connected to the steering shaft i.e. its basically using the rotational
motion of the steering wheel, then converting that rotational motion into linear motion, which is required to
turn the wheels.

12. STEERING MOVEMENT
• When the driver starts rotating the steering
wheel, the hydraulic pump driven by the
engine starts pumping the highly compressed
hydraulic fluid through lines.
• The hydraulic pressure from the pump enters
the hydraulic cylinder through control valve
which in turn applies pressure over the
cylinder’s piston.
• The piston which is under high pressure starts
moving from one end to the another. With this
movement of piston the input force applied by
the driver is multiplied several times.
• This high pressure fluid sent by the hydraulic
cylinder then applies the pressure to the
attached pinion through the coupling
mechanism which in turn applies high force to
the rack gear and the steering action in the
front wheels takes place.

13. ELECTRO-HYDRAULIC POWER SYSTEM BLOCK
Electro-hydraulic power steering systems, sometimes abbreviated EHPS, and also sometimes
called "hybrid" systems, use the same hydraulic assist technology as standard systems, but
the hydraulic pressure comes from a pump driven by an electric motor instead of a drive belt
at the engine.

14. ELECTRO-HYDRAULIC POWER SYSTEM COMPONANTS
MOTOR & GEAR PUMP

15. Steering torque: The sensor records the torsion bar angle that is required for the steering movement.
Steering torque sensor
• Hall-type sensors monitor the twist of the torsion bar
by measuring the change in magnetic flux generated
by its position .
• When the rotor moves, a change in magnetic flux will
produce a signal to an analog sensing integrated
circuit (ASIC) that will process the signal and send the
information to the controller’s assist algorithm.
2 types of torque sensors
• Non-Contact sensors
• Contact sensors

16. Steering angle: The sensor measures the angle and speed of change in the position of the steering wheel.
Steering Angle sensor

17. Electronic control unit (ECU)
An Electronic Control Unit (ECU) is any embedded system in automotive electronics
that controls one or more of the electrical systems or subsystems in a vehicle. It reads
signal coming from sensors from different components of the car and depending on this
information controls various units within the car.

18. ELECTRONIC POWER STEERING (EPS)
• Electronic power steering is electronically controlled steering mechanism that
provides steering assistance in terms of torque to improve the driver’s comfort
and to provide overall efficient performance of steering system.
• EPS eliminates many HPS components such as the pump, hoses, fluid and other
mechanical components. For this reason, electric steering systems tend to be
smaller and lighter than hydraulic systems.
• EPS systems have variable power assist, which provides more assistance at
lower vehicle speeds and less assistance at higher speeds. They do not require
any significant power to operate when no steering assistance is required.
For this reason, they are more energy efficient than hydraulic systems.
• The first electric power steering system appeared on the Suzuki
Cervo in 1988.

19. ELECTRONIC POWER SYSTEM BLOCK

20. COMPONANTS OF EPS

21. WORKING OF EPS
• The EPS electronic control unit
(ECU) calculates the assisting
power needed based on the
torque being applied to the
steering wheel by the driver, the
steering wheel position and the
vehicle’s speed.
• The EPS motor rotates a steering
gear with an applied force that
reduces the torque required from
the driver.

22. WORKING OF EPS

23. FORMS OF EPS
There are four forms of EPS based on the position of the assist motor.
• The column assist type (C-EPS).
• The pinion assist type (P-EPS).
• The dual pinion type (D-EPS) .
• The rack assist type (R-EPS).

24. Future developments
The next step in electronic steering is to remove the mechanical linkage to the steering wheel and convert
to pure electronically controlled steering, which is referred to as steer-by-wire.

25. • This kind of system will provide
steering control to a car with fewer
mechanical components/linkages
between the steering wheel and the
wheels. The control of the wheels'
direction will be established
through electric motor(s) which are
actuated by electronic control units
monitoring the steering wheel
inputs from the driver.
• The first production vehicle to
implement this commercially was
the Infiniti Q50.
• The Swedish start-up Uniti will
release the Uniti all electric car in
2019 with an in-house designed
steer-by-wire system and will
entirely replace the steering wheel.
STEER-BY-WIRE
Infinity Q50
Uniti

26. THANK
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