Assignment 6

EMBEDDED PROCESSORS AND
MICRO CONTROLLERS
Module Code
Module Name
Course
Department

ESD 530
Embedded Communication System
M.Sc in Real-Time Embedded Systems
Computer Engineering

Name of the Student

Bhargav Shah

Reg. No

CHB0911001

Batch

Full-Time 2011

Module Leader

Narsinhma murty

M.S.Ramaiah School of Advanced Studies
Postgraduate Engineering and Management Programmes(PEMP)
#470-P Peenya Industrial Area, 4th Phase, Peenya, Bengaluru-560 058
Tel; 080 4906 5555, website: www.msrsas.org

Wired & Wireless Embedded Networks

POSTGRADUATE ENGINEERING AND MANAGEMENT PROGRAMME – (PEMP)

MSRSAS - Postgraduate Engineering and Management Programme - PEMP

i

Declaration Sheet
Student Name

Bhargav Shah

Reg. No

CHB0911001

Course

Real Time Embedded System

Batch

FT-11

Module Code

ESD530

Module Title
Module Date

Embedded communication Syatem
to
10/10/2011
05/11/2011

Module Leader

Narsinhma Murty

Batch Full-Time 2011

Extension requests:
Extensions can only be granted by the Head of the Department in consultation with the module leader.
Extensions granted by any other person will not be accepted and hence the assignment will incur a penalty.
Extensions MUST be requested by using the ‘Extension Request Form’, which is available with the ARO.
A copy of the extension approval must be attached to the assignment submitted.

Penalty for late submission
Unless you have submitted proof of mitigating circumstances or have been granted an extension, the
penalties for a late submission of an assignment shall be as follows:
• Up to one week late:
Penalty of 5 marks
• One-Two weeks late:
Penalty of 10 marks
• More than Two weeks late:
Fail - 0% recorded (F)
All late assignments: must be submitted to Academic Records Office (ARO). It is your responsibility to
ensure that the receipt of a late assignment is recorded in the ARO. If an extension was agreed, the
authorization should be submitted to ARO during the submission of assignment.
To ensure assignment reports are written concisely, the length should be restricted to a limit
indicated in the assignment problem statement. Assignment reports greater than this length may
incur a penalty of one grade (5 marks). Each delegate is required to retain a copy of the
assignment report.

Declaration
The assignment submitted herewith is a result of my own investigations and that I have conformed to the
guidelines against plagiarism as laid out in the PEMP Student Handbook. All sections of the text and
results, which have been obtained from other sources, are fully referenced. I understand that cheating and
plagiarism constitute a breach of University regulations and will be dealt with accordingly.

Signature of the student

Shivaraj KM

Date

05/11/2011

Submission date stamp
(by ARO)

Signature of the Module Leader and date

Signature of Head of the Department and date

ii


Abstract
____________________________________________________________________________
In the past, electronic control units in automotive applications were connected by
individual signal wires. However, today, close to 100% of the ECUs are connected by bus
systems such as LIN, CAN and Flex Ray. This yields significant advantages, including
improved data availability, straightforward wiring and standardized interfaces. On the other
hand, all the control units connected to a bus must continuously monitor the traffic on the bus
and respond immediately in case of any messages that are relevant for them.
Another important area in automobile is DAS, which significantly improve road safety,
traffic flow. In the PART -A of the assignment, a general survey was carried out and a debate
was done on feasibility of driver assist systems in India and finally came out with conclusion
that DAS wont suit for Indian roadways became it is cost effective .
In the PART -B of the assignment, the functionality of a DAS, its block diagram that
represents the system being developed, different protocols used for communication

and

Criteria’s considered for choosing them. Finally the debate was done on use of suitable protocol
and sensors for DAS.
In the PART -C of the assignment, as a continuation of PART –B implementation and
simulation of DAS is done using CAN bus on Vector CANoe and concluded with the results
and the test cases of the system in the efficient working of the systems


iii

Contents
____________________________________________________________________________

Declaration Sheet ......................................................................................................................... ii
Abstract ....................................................................................................................................... iii
Contents ........................................................................................................................................iv
List of Tables .................................................................................................................................v
List of Figures ..............................................................................................................................vi
PART-A.........................................................................................................................................8
CHAPTER 1: Feasibility of autonomous vehicles for operating in India ....................................8
1.1Introduction ..........................................................................................................................8
1.2 Design and functioning of current autonomous vehicles ....................................................8
1.3 Major factors that would affect the design of autonomous vehicles for operating in India 9
1.4 From an embedded systems perspective major required changes .......................................9
1.5 Feasibility of widespread use of autonomous vehicles suited for Indian conditions ........10
1.6Conclusion ..........................................................................................................................10
PART-B .......................................................................................................................................11
CHAPTER 2 Design of driver assistant system ..........................................................................11
2.1 Introduction .......................................................................................................................11
2.2 Subsystem interaction and functionality ...........................................................................11
2.2.1 TCR Functionality ...................................................................................................11
2.2.2 ABS Functionality ......................................................................................................11
2.2.3 ESC Functionality ......................................................................................................13
2.3 Block diagrams and explanation .......................................................................................13
2.4 Considered input parameters & Decision making .............................................................16
2.4.1 Input parameter...........................................................................................................16
2.4.2 Control logic based on the input parameter................................................................17
2.5 List of sensor and actuators with position .........................................................................18
2.6 Choice of IVN protocol .....................................................................................................19
2.7 Conclusion .........................................................................................................................19
PART-C .......................................................................................................................................20
CHAPTER 3 Simulation of the integrated Driver Assistance System ........................................20
3.1 Introduction .......................................................................................................................20
3.2 Protocol Design .................................................................................................................20
3.3 Development of CAPL program ......................................................................................23
3.3.1 CAPL program for ABS Data node ...........................................................................24
3.3.2 CAPL program for ESU Data node ............................................................................24
3.3.3 CAPL program for TCR and main node ....................................................................25
3.4 Front panel designing ........................................................................................................29
3.5 Test cases ...........................................................................................................................30
3.6 Results ...............................................................................................................................31
3.7 Conclusion .........................................................................................................................36
CHAPTER 4 ................................................................................................................................37
Learning Outcomes .....................................................................................................................37
4.1 Module Learning Outcomes ..............................................................................................37

iv


List of Tables
____________________________________________________________________________

Table2. 1 List of sensors..............................................................................................................18
Table 3. 1 Messages associated with TCR .................................................................................21
Table 3. 2 Messages associated with ABS ..................................................................................22
Table 3. 3 Message associated with ECS ....................................................................................22
Table 3. 4 Test Cases ...................................................................................................................30


v


List of Figures
____________________________________________________________________________
Figure 1. 1 Components of autonomous navigation vehicles .......................................................8
Figure 2. 1 TCR system ...............................................................................................................12
Figure 2. 2 ABS system ...............................................................................................................12
Figure 2. 3 Block diagram of CAN network ...............................................................................14
Figure 2. 4 Law level block diagram for ABS ............................................................................14
Figure 2. 5 Low level diagram of ESC .......................................................................................15
Figure 2. 6 Low level block diagram of TCR .............................................................................16
Figure 2. 7 Decision making logic ..............................................................................................17
Figure 3.1 CAN network for ABS,TCR and ESU ......................................................................20
Figure 3.2 CAPL script for ABS .................................................................................................24
Figure 3.3 CAPL script for ESU .................................................................................................24
Figure 3.4 CAN Messages...........................................................................................................25
Figure 3.5 Environment Variable “env_ignition” .......................................................................25
Figure 3.6 Environmental variable “foult_fr_left”, “foult_fr_right”, “foult_r_left”
and“foult_r_right” .......................................................................................................................26
Figure 3. 7 Environmental variable “env_tcr” ............................................................................27
Figure 3.8 Environmental variable “env_ecu_left” .....................................................................28
Figure 3.9 Environmental variable “env_abs” ............................................................................28
Figure 3.10 Front panel design ....................................................................................................29
Figure 3.11 Results of test case 1 ................................................................................................31
Figure 3. 12 Results of test case 2 ...............................................................................................31
Figure 3. 13 Result of test case 3 at t=0 sec ................................................................................32
Figure 3. 14 Result of test case 3 at t=2 sec ................................................................................32
Figure 3. 15 Result of test case 4(1) ............................................................................................33
Figure 3. 16 Result of test case 4 (2) ...........................................................................................33
Figure 3. 20 Test case 6(1) ..........................................................................................................35
Figure 3. 21 Test case 6(2) ..........................................................................................................36


vi


Acronyms
____________________________________________________________________________

TCS
ABS
ESC
WSS
APPS
ADAS
GPS
PDA
RFID
ACC
VSC
EPAS
ARC
4WS
ECU
SPS
IVN

Traction Control System
Antilock Breaking System
Electronics stability Control
Wheel Speed Sensor
Acceleration Paddle Position Sensor
Automatic Driver assistant system
Global Positioning System
Personal Digital Assistant
Radio Frequency Identification
Adaptive Cruise Control
Vehicle Stability Control
Electric Power-assist Steering
Anti-Rollover Control
Four Wheel Steering
Electronics Control Unit
Steering Position Sensor
In Vehicle network


vii

PART-A
CHAPTER 1: Feasibility of autonomous vehicles for operating in
India
1.1Introduction
The research trend in the automotive domain is clearly moving from mechanically controlled
to computer assisted systems for both vehicle handling and comfort functions [1].As the part of the
computer assisted system for vehicle handling, intelligent algorithms are developed which takes the
input from couple of sensors. Handling decision of car is based on the real world quantities
measured by sensors. ADAS (Automatic Driver assistant system) is a part of computerized vehicle
handling system. Couples of sensors (camera, IR sensor, GPS) are used to detect and maintain the
exact movement, position and speed of car [2].

1.2 Design and functioning of current autonomous vehicles
An autonomously-driven vehicle is a true automobile, i.e., mobile on its own –self-propelled and navigated.
A semi-autonomous vehicle can use any navigational method, but the driver intervenes to determine the routing and
otherwise control the car. A person in a completely driver-controlled vehicle most often uses a map interfacing with
GPS or a handheld device, such as a personal digital assistant (PDA) that displays locations via GPS.
Routes ultimately are determined by the driver and may be charted by means such as on-board maps, web interface,
or PDAs.
There are three ways a car may be navigated: totally in autonomous mode – without any driver intervention,
semi-autonomously with some driver intervention, and completely driver controlled. A vehicle may be guided
autonomously by the Global Positioning System (GPS),cameras, laser detectors, radar, wires in or lines on the road, or
by transponders strategically located along a route. While road sensors or wires provide a more accurate navigation
there are practical limits to installing them, given the number of roads involved.

Figure 1. 1 Components of autonomous navigation vehicles
Navigational software includes pre-programmed routes, driving rules (such as stopping for red lights and
lane changes), and user interfaces. Mechanical control is done by servo motors, relays, sensors, automated steering
and braking, throttle management, and so forth. List of available sensor, processing units and control systems are


shown in the above figure 1.1. With the improvement of automotive systems aided by computers and artificial
intelligence, it should not be surprising to see the emergence of vehicles that drive themselves.

1.3 Major factors that would affect the design of autonomous vehicles for
operating in India
•

There is less choice of routing and general control over the vehicle[3]

•

Even if the option exists of switching from autonomous driving to driving by a person, the problem arises of
integrating the switchover from a planned route to one that is determined by the driver and may not be
compatible[3]

•

There is the failure of systems and the consequences. One small disruption in a very large and integrated
system may have disastrous effects[3]

•

There is a continued dependence upon individual vehicles in face of looming constraints of diminishing
fuel supplies and congestion. A false security arises in thinking that the increased efficiency and
safety of autonomous systems is sufficient in overcoming these problems[3]

• The issue of hacking the software running [3]
1.4 From an embedded systems perspective major required changes
ESP/ESC (Electronic Stability Programme/Control)-- ESP stabilises the vehicle and prevent
skidding under all driving conditions and driving situation within the physical limits by active brake
intervention on one or more wheels and by intelligent engine torque management. A yaw-rate
sensor and a lateral acceleration sensor continuously monitor the movement of the vehicle about its
vertical axis and compare the actual value with the target value calculated on the basis of the
driver's steering input and the vehicle speed. The moment the car deviates from this ideal line, ESP
intervenes ESP systems combine the functions of ABS and TCS traction control and complement
them with directional stability assistance [4].
Blind spot monitoring-- Systems, which give information/warnings to the driver about relevant
obstacles in the blind spot around the vehicle, when the driver intends to change the lane. Systems
can use cameras or radar sensors to detect relevant objects.
Adaptive head lights-- Adaptive Head Lights improve night-time driving safety on twisty roads:
the headlamps follow the direction in which the driver is steering, thus extending the illumination
range in the relevant areas. In this way it is possible to spot pedestrians, cyclists and animals much
sooner.
Obstacle & collision warning--Systems detect obstacles and give warnings when collision is
imminent. Current solutions with limited performance are a separate feature of Adaptive Cruise


9


Control systems which use information obtained from radar sensors to give visual and acoustic
warnings. Future systems will optionally use near range radar sensors or LIDAR in addition to the
long range radar. The evolution of the function has been the following: 1) ACC without braking
capability, 2) ACC including braking capability but without taking care of fixed obstacles, 3) taking
care of some category of fixed obstacles i.e. those with a big equivalent surface to detection.
Lane departure warning-- Warning given to the driver in order to avoid leaving the lane
unintentionally. Video image processing is the most important technology. Warnings can be
acoustic, visual or haptic.

1.5 Feasibility of widespread use of autonomous vehicles suited for Indian
conditions
The technologies used in intelligent transport system are all new and they are very costly.
So the cost of investment on the components initially will be very high. Many of these devices will
be used to quick decongestion of the traffic hence there will be a constant saving over the fuel and
time by the road users which will become more than the initial cost if a time period of 20 to 25
years is considered. For example if dynamic traffic light system needs to be installed in a city the
cost of installing RFID to every vehicle will be very costly but in a long run the traffic congestion
will be reduced hence giving a better saving. Considering cities, the planning should be mainly to
ease the traffic congestion. The areas which are mainly causing congestion such as toll booths can
be made electronic allowing users to drive at normal speed even at the toll ways. The public
transport system such as buses and local trains can be synchronized so that the waiting period will
be reduced. By planning a dynamic traffic signaling system using RFID well in advance the traffic
congestion at the junctions can be addressed in a better way. The deployment of these intelligent
traffic systems can be difficult again due to the economic feasibility. So the most important once
can be deployed earlier by creating private public partnerships. Then with development the other
ITS systems can be deployed [4][5].

1.6Conclusion
Autonomous vehicles implemented on foreign roads do not have much complications where
road rules are followed good and roads are maintained in a well manner. In India all this cause
further implications as road rules are seldom followed in most places and roads are not maintained
good which is troublesome in automated cars. The cost deployment of such systems will be very
high which makes implementation of such vehicles much difficult as existing tolls and signals are
not readily supporting communication or sharing any information with a moving vehicle.


10


PART-B
CHAPTER 2 Design of driver assistant system
________________________________________________________________________________

2.1 Introduction
Many driver assistance systems were proposed over the last decade to enhance the comfort,
safety and efficiency of ground vehicles Examples include adaptive cruise control (ACC), vehicle
stability control (VSC) systems, electric power-assist steering (EPAS), anti-rollover control (ARC),
four wheel steering (4WS), etc. Some of these driver assistance systems were designed to relief
human drivers from certain (lower-level) driving tasks, and others were designed to work
collaboratively with human drivers. The collaboration of four such driver assistance systems like
ABS, Traction control, ESP, Driver Assistance systems offers greatest possible solution for vehicle
to be stable on slippery roads, skidding on less friction surfaces, sudden breaking and sudden turn .

2.2 Subsystem interaction and functionality
2.2.1 TCR Functionality
An automobile can unexpectedly go into a skid on wet, slippery roads, not only when braking
but also when accelerating. Moreover, excessive slip of the driven wheels can occur during
acceleration on slippery road surfaces. The purpose of Traction control system is to prevent wheel
spin from occurring due to the acceleration. The maximum torque that can be transmitted to wheels
is determined by the co efficient of the friction generated between the road and the tires. If the
torque exceeds that level, the wheels are likely to spin. Conditions for Traction operation may
include loose gravel, slippery road surfaces. By the activation of the TCR system reduces engine
torque and drive wheel speed as necessary to bring the vehicle under control which improves the
vehicle stability when starting, accelerating or turning on sleepry road. Figure 2.1 shows the basic
connection diagram of TCS system. Four WSS (wheel speed sensor) and the throttle position sensor
is connected with the ECU which takes initiative on the occurrence of traction.
2.2.2 ABS Functionality
A vehicle braking system, including the tires, is most effective, i.e., produces the optimum
retarding force, when the wheel speeds are approximately 85 to 90% of the vehicle speed. The
difference (100% - 85% =15%) is called the percent slip of a particular wheel. The 10 to 15% slip
retarding force is greater than the locked wheel retarding force, so optimum braking is achieved
when the slip is 10 to 15% . Over-applying foundation brakes can cause wheels to lock (100% slip),
so a system that prevents this can improve braking effectiveness. Antilock braking systems (ABS)
have been developed to do this.
By monitoring the frequency output of each WSS, the ECU can decide if an individual

11


wheel slip exceeds a desired threshold. When such a threshold is exceeded at a particular wheel, the
ECU directs the hydraulic control unit to isolate that wheel and reduce hydraulic pressure at that
wheel, so that wheel can resume rotation. Once the wheel is again rotating at about optimum slip
(assuming the brakes are still applied) pressure is reapplied to that particular wheel. Typically, each
wheel control circuit is called a channel and the hydraulic control unit is typically called a hydraulic
modulator.

Figure 2. 1 TCR system

Figure 2. 2 ABS system


12


A schematic of such a feedback system is shown in Figure 2.2, where the controller is an
ECU, the controlled parameter is wheel cylinder pressure, and the feedback elements are individual
electronic wheel speed sensors (WSS).
2.2.3 ESC Functionality
Electronic stability control (ESC) is a vehicle control system comprising sensors, brakes,
engine control modules, and a microcomputer that continuously monitors how well the vehicle
responds to the driver’s steering input. The computer compares a driver’s commands to the actual
behavior of the vehicle. In general, when the sensors indicate the vehicle is leaving the intended
line of travel, ESC applies the brake pressure needed at each individual wheel to bring the vehicle
back on track. In some cases ESC also reduces the force exerted by the engine. The way ESC
systems are programmed to respond to the information from the sensors varies among vehicle
models. Some systems intervene sooner and take away more driver control of speed than others.
2.2.4 Subsystem Interaction
Since the primary function of both TCS and ABS is control of a wheel whose speed
significantly varies from the averaged speed of the other wheels (+ for TCS, – for ABS), where
both features are incorporated in a vehicle, these functions are usually combined into one hydraulic
control unit, sharing a common ECU. The main objective of both ABS and TCS is for them to
operate transparently to the consumer operator so as to provide enhanced vehicle tracking stability
under both braking and acceleration under adverse road surface conditions.
Combined ABS/TCS ECUs with the brake applied in ABS modes, if the speed of one wheel
drops significantly compared with the other wheels, the brake pressure on that wheel is
momentarily reduced to stop the wheel from locking. It is reapplied when the wheel speed is near
the average of the other wheel speeds. With no brake applied and under acceleration in TCS modes,
if the speed of one wheel increases significantly compared to the other wheels, that wheel brake is
momentarily applied to reduce that wheel speed. Braking is removed when that wheel speed returns
to near the average of the other wheel speeds.

2.3 Block diagrams and explanation
Figure 2.3 shows the high level block diagram of the DAS using CAN network. This
network is the medium of all sensors and controller of DAS. There are three node, named
TCR/Control node, ABS node and ESC node is sharing the network and transmit required signal on
bus. By triggering the ABS data ECU output is transmitted to the network to control ECU to take
control action. In the case of triggering of the data in Control ECU, wheel speed is continuously
measured by the speed sensor. Only when the ABS switch is ON, Lock Up switch is activated.


13


Combinational data of these events is transmitted on BUS. On receiving these data, based on the
lock up switch information, Control ECU controls the wheel speed. This low level working
phenomena of ABS is shown by Figure 2.4. As per the logic given, wheel speed decreases by 1
unit per two second.

Figure 2. 3 Block diagram of CAN network

Figure 2. 4 Law level block diagram for ABS


14


On the other side, By triggering the ESC data ECU output is transmitted to the network to
control ECU to take control action. In the case of triggering of the data in Control ECU, wheel
speed and movement of steering is continuously measured by the sensors. Only when the ESC
switch is ON, Lock Up switch is activated. Combinational data of these events is transmitted on BUS.
On receiving these data, based on the lock up switch information, Control ECU controls the stability of
the vehicle by varying the speed of wheels. To change wheels of speed ECS takes the breaking service
to the ABS control unit. This is graphically represented in Figure 2.5.

Figure 2. 5 Low level diagram of ESC
Here, in this network TCR node and control node is combined. By the triggering the TCS data,
output is transmitted to the network. Same node is receiving that message from the can bus. On the
triggering by data from the TCR functions, control functions will check the output of each wheel speed
sensor and acceleration paddle position sensor. After comparing both readings if the speed of the all
sensor (output of sensor) is same then there is no traction, but in other case if the speed of any of wheel
is different then acceleration paddle then there is a occurrence of traction. As an initiative of this
condition TCR control unit maintains the speed of the four wheels by applying the brakes to fast
moving wheels. For applying the brakes to particular wheel/wheels TCS node will take a service from
the ABS node by passing the Wheel ID and amount of speed to be reduced. This Low level
phenomenon is represented by the Figure 2.6.


15


Figure 2. 6 Low level block diagram of TCR

2.4 Considered input parameters & Decision making
2.4.1 Input parameter
•

Ignition state sensor: Input of the Ignition state sensor is given to the control node. There are
two expected (either ignition ON or ignition OFF) values are given as the output of this
sensor. Based on the value given by the Main node can decide wither car is on or off.

•

WSS: Input of the WSS (wheel speed sensor) is given to the control node. The value of this
input is carrying the speed of the individual wheel. On each wheel one WSS is placed to
provide the speed of particular wheel to the main ECU that helps main ECU to make
decision of traction condition.

•

APPS: Input of the APP (Acceleration paddle position sensor) is given to control node.
Based on the position acceleration wheels speed id being changed. Also this position is the
desired/required speed by the user. This is used by TCS.

•

SPS: Input of SPS (steering position sensor) is given to the main node. Output of SPS is the
angular displacement of the steering provided by the user. Based on the steering angular
displacement and time taken to achieve that displacement, stability decisions are made.


16


•

TCR switch sensor: Input of the TCR switch sensor is given to main node .Output of this
sensor is carrying the two value(TCR is ON or OFF).Traction control unit comes in active
when the TCR switch is on.

•

ECS switch sensor: Input of the ECS switch sensor is given to main node .Output of this
sensor is carrying the two value(TCR is ON or OFF).Electronic stability control unit comes
in active state when the ECS switch is on.

•

ABS switch sensor: Input of the ABS switch sensor is given to main node .Output of this
sensor is carrying the two value(TCR is ON or OFF).ABS control unit comes in active state
when the ECS switch is on.

2.4.2 Control logic based on the input parameter

Figure 2. 7 Decision making logic


17


Decisions of autonomous cars are under many bounded conditions. It works on artificial
intelligence where in the decision is made quickly within a matter of seconds and then the car is out
of danger in time of accident situation. These functions are mainly done by sensors where the
respective sensors sense their surroundings and send messages to its processors to process further
functions. The figure 2.7 shows the flow chart of advanced systems like ABS, ESC, and TCR.
Initially the successful ignition leads to the application of sensors in turn leading to the display of
wheel speed sensors sensing the speed of the vehicle. Then if ESC is considered the steering
position sensor changes the speed of the vehicle giving information to reduce the speed of the rear
wheel. After some delay it also reduces the speeds of the front wheel in order attain a uniformity of
both the wheels. Second consideration is the traction control. Here a comparison is done with the
speed of Acceleration Pedal Position sensor is leading to reduce the speed of fast moving vehicles.
Lastly the consideration of an important system called the anti-lock braking system. If it is forced
into use then it reduces the speed of wheels in a periodic manner i.e., the brake shoes catches and
leaves periodically.

2.5 List of sensor and actuators with position
Sensors are the pillars of any autonomous vehicle. Use of correct sensor at the correct
location can change decisive accuracy and efficiency of the vehicle. Table 2.1 shows the list of
sensors and the function of the sensors associated with designed DAS.
Table2. 1 List of sensors
Sensors
Wheel speed sensor

Position

Purpose

This is a magnetic sensor. One The main purpose of this
magnet is mounted on the sensor

is

to

measure

the

rotating the wheel. On the other accurate wheel speed.
fixed side receiver is counting
the number of timer magnet
passed by.
Acceleration paddle position The
acceleration
position As its name suggests, this
sensor
sensor location is generally sensor continuously monitors
near throttle body and can be throttle position and sends
easily located on either its right feedback to the ECU.
or left hand side under the car
hood[7].
Steering position sensor

The steering position sensor is The sensor’s basic function is


18


located with the power steering to monitor the driver’s steering
unit[7].

inputs. This includes the angle
of the steering wheel and/or the
rate at which the driver is
turning the wheel[8].

Break paddle Position sensor

Break paddle position sensor is This
situated near the break paddle.

sensor

continuously

monitors break position and
sends feedback to the ECU.

2.6 Choice of IVN protocol
Now days modern cares include high precision sensors and actuators. To communicate with
sensors and actuators efficient communication protocol is required. As the solution of this, Robot
Bocsh invented CAN protocol. CAN is the standard in automotive networks. For growing the need
of IVN, CAN is not seen as a solution for implementing the most recent advances in automotive
electronics field. In CAN, nodes can create asynchronous messages on their own, due to this eventdriven model, there is no way to know in advance the exact time a given message will be sent. In
case of bus overload, it can even lead to some messages missing their intended deadlines. The
maximum allowed bit rate is only 1 Mb/s and the network can stretch for 40m at most.
On the other side Flex-ray has features of the synchronous time-triggered protocols and the
asynchronous Protocols. Flex-ray can provide spatial redundancy and higher bandwidth by the use
of duel channel. ). This feature increases the robustness of the whole system in the condition of
broken down links. . Different bit rates are allowed and a maximum of 10 Mb/s will be supported
by the first generation components. Based on the above debate, I can conclude that Flex ray can
take position of CAN.

2.7 Conclusion
Driver Assistance System containing all the four systems can provide greatest extent of
safety to a driver and reducing the accidents due to slipping of wheels. Survey of such systems
proved Driver Assistance System reduces accidents to 1/3 of annual rate. All the functionalities
required are developed and a design of systems using high level and low level block diagrams and
proper I/O sensors using event triggered CAN protocol and CAPL program is developed. Proper
design simulation is done using CANoE simulator and it can be further interfaced with relevant
hardware configuration to fully implement this design.


19


PART-C
CHAPTER 3 Simulation of the integrated Driver Assistance System
________________________________________________________________________________

3.1 Introduction
Anti-Lock Brake System (ABS) allows the driver to maintain steering control of the vehicle
while in hard braking situations. Traction control system (TCR) allows is used to avoid the traction
and maintain the speed of four wheels on the sleepy surface. In sharp turning condition, stability of
the car is the essential. To achieve the stability in the conditions electronics stability module (ESU)
is used .By changing the speed of the respected wheels stability of the car is gained. In this part of
the CAN network is created for ABS, TCR and ESU using CANoe.

3.2 Protocol Design
Figure 3.1 shows the CAN network for ABS, TCR and ESU systems. In the network three
nodes are developed. One is TCR, second is ECU and the third is ABS. In the condition of the
sleepry surfaces synchronization of the speed of four wheels is lost. As a result of this condition
front thrust of car is disturbed. To avoide this condition TCR unit contain speed sensor on the four
wheels of the car. This continuously measures the speed of the four wheels. At the movement, when
speed of the any of the wheels is decreased TCR control maintains the speed of the four motor by
breaking down the fast rotating wheels. As the result of TCR speed of four wheels maintains same
and front thrust is not disturbed. In this simulation, individual switch is used to provide the traction
on each wheel and A single switch named TCR is used to powered traction control system. A track
bar is used to accelerate the engine.

Figure 3.1 CAN network for ABS,TCR and ESU


20


Messages and signals associated with TCR are shown in table 3.1.
Table 3. 1 Messages associated with TCR
Message

Signal

Values of signal

Transmitter

Ignition

Ignition_stat

0 or 1

tcr

M_button

S_button

0 to 16

tcr

Foult_fr_left

Foult_fr_left

0 or 1

tcr

Foult_fr_right

Sig_f_right

0 or 1

tcr

Foult_r_right

Sig_r_right

0 or 1

tcr

Foult_r_left

Foult_r_left

0 or 1

tcr

tcr

Sig_tcr

0 or 1

tcr

m_timer

s_timer

0 or 1

tcr

Purpose
This message is used to
sense the ignition status of
the simulation process.
sense
the
acceleration
provided by user.
This message is responsible
of producing the traction
fault in front left wheel.
fault in front right wheel.
fault in rear right wheel
fault in rear left wheel.
describe state of tcr system.
This message is the timer
message .when the timer is
overflowing with given
value this message will
occur. After switching of
the TCR system, response
of TCR system can be
obtained after 5 seconds.

Normal break may produce skidding while it suddenly pressed on the high speed. To avoid
this skidding ABS is used .While pressing the sudden break ABS will sense the speed of the wheel
and according to the speed it will provide breaks in busty manner. As a result of this skidding can
be avoided. In simulation dedicated node named ABS is used to send the message regarding to ABS
system. Track bar named break is used to see simulate performance of the normal break. A switch
named ABS is used to see the performance of the ABS. Speed of each wheels is shown by meter.
Recursion of the timer is used in the ABS. After sending the over flow message timer itself call
same timer with some value. After completion of given time signal value of the timer message is
incremented by 1. By the arrival of incremented value of timer signal, speed of the wheels should
be decreased by some factor of total speed. That will produce the breaking in the busty manner.


21


Here in the simulation process at every two seconds speed of the wheels is decreasing by two
seconds. Messages and signals associated with ABS are shown in table 3.2
Table 3. 2 Messages associated with ABS
Message
M_abs

Signal
S_break

Values of signal
0 or 1

Transmitter
abs

Purpose
describe the state of ABS
system.

M_break

S_break

0 to 16

abs

describe the state of the
normal break.0 to 16 values
are used to describe the
position of the break paddle.

m_timer2

S_timer2

0 to 16

tcr

message. it is sent by tcr
when timer exceeds from
the given value . Increments
the signal value after every
2 seconds.

In the cases of sudden turn if the speed of four wheels remains same that cause the usability
in the car. Depend upon the steering position change in speed of individual wheel can be beneficial
to obtain stability while turning. Electronic stability control unit is used to obtain the stability in the
sudden tuning condition. In simulation dedicated node named ECU is used to send the message
regarding to ECU system. Movement of the steering is represented by the two track bars. One
represents left movement and another represent the right movement of steering. Movement of
steering is divided in to five integers. Change in speed of the wheels can be seen in the meters.
Messages and signals associated with TCR are shown in table 3.3

Table 3. 3 Message associated with ECS
Message
M_ecu_left

Signal
S_ecu_left

Values of signal
0 to 5

Transmitter
abs

Purpose
This

message

is

used

to

describe position of steering
towards


left

side.

After

22


receiving this speed of the rear
left wheel is decreased.
M_ecu_right

S_ecu_right

0 t0 5

abs

This

message

is

used

to

describe position of steering
towards right side. After getting
this message speed of the right
rare wheel is decreased.
m_t3

S_t3

0 or 1

tcr

message. it is sent by tcr when
timer

exceeds

from

the

2

seconds .After receiving this
message the speed of the front
right wheel is decreased for 3
seconds.
m_t4

S_t4

0 or 1

Tcr

message. it is sent by tcr when
timer

exceeds

from

the

3

seconds. After receiving this
message speed of the four
wheels will be equal.

3.3 Development of CAPL program
Communication Application Programming Language is a C-like program. CAPL program
are created for measurement and simulation setup. CAPL is an event-based programming language.
The environment variables are described by events and states of the system environment. In this
assignment note environment variables are associated to ignition switch, TCR switch, speed of
wheels etc. To work with environment variable in CAPL, an event procedure of the type – ‗on
envVar <react to the change in environment variable>‘ is used. CAPL program also counts
messages that are generated in CANoe simulation setup. To work with messages in CAPL, a event
procedure of the type – on message <react to message event>‘ is used. Corresponding message
variables are declared. CAPL functions – getValue () and putValue () are used to read and write
environment variables.


23


3.3.1 CAPL program for ABS Data node
As the purpose of this network node is to collect the event triggering variables like Normal
breaking paddle positing and ABS switch. After getting the event it sends the corresponding signal
on the bus. In the case of the normal break, variable is holding the position of the break paddle.
CAPL code is written for their respective environment variables are shown by figure 3.2.

Figure 3.2 CAPL script for ABS

3.3.2 CAPL program for ESU Data node
As the purpose of this network node is to collect the event triggering variables associated
with position of steering.

Figure 3.3 CAPL script for ESU


24


After getting the event it sends the corresponding signal on the bus. The position of steering
is divided in to five positions. For each position there is one value. Signal is
Carrying the value on the bus.
3.3.3 CAPL program for TCR and main node
This is controlling node of the network. As the purpose of this network node is to collect the
event triggering variables associated with TCR, ignition and provide dedicated action on the
occurrence of the event. Figure 3.4 shows the message variables are declared. They are the CAN
messages to be transmitted by the nodes.

Figure 3.4 CAN Messages

Figure 3.5 Environment Variable “env_ignition”


25


The figure 3.5 shows the behavior of environment variable “env_ignition”. On occurrence
of change in the state of this variable, initial speed of the four wheels has been set to 1.state variable
named “env_fr_left”, “env_fr_right”, “env_r_right” and “env_r_left” are associated with the speed
of four wheels.
The figure 3.6 shows the behavior of environment variable “foult_fr_left”,”
foult_fr_right”,” foult_r_left” and “foult_r_right”. These environment variables are associated with
the four switches, which is used to produce the virtual traction on the individual wheel. On
occurrence of change in the state of this variable, speed of the related wheel is increased by w=2.

Figure 3.6 Environmental variable “foult_fr_left”, “foult_fr_right”, “foult_r_left”
and“foult_r_right”
The figure 3.7 shows the behavior of environment variable “env_tcr”.This environment
variable is associated with the switch, which is used to switch on the TCR. On occurrence of
change in the state of this environmental variable, time named myTimer activates for 5000 ms. At
the end of given timing interval timer sends a message named m_timer. After receiving this
message if the ignition is on and tcr control is on the speed of the all wheels is set to the given
acceleration value which is stored as variable a. Purpose of this work id to provide 5 second delay
between TCR is switched on and response of TCR on wheels speed. After functioning this all
myTimer is cancelled.


26


Figure 3. 7 Environmental variable “env_tcr”

The figure 3.8 shows the behavior of environment variable “env_ecu_left”.This
environment variable is associated with the track bar, which is used to provide left turning
sharpness (position of steering) via message of “m_env_left”. On occurrence of change in the state
of this environmental variable, initially speed of rear left wheel is decreased by turning factor. After
decreasing the speed timer t1 is initiated. At the time of overflow time will send message named
“m_t3”.On the occurrence of this message speed of the front left wheel is decreased and again timer
t4 will be initiated.”m_t4” message is sent by the timer t4 on the time of ever flow. At the
occurrence of the timer this message speed of both wheels are set to the original acceleration speed.
The same phenomena for right turns are applied on the right wheels.
The figure 3.9 shows the behavior of environment variable “env_abs”.This environment
variable is associated with the switch, which is used to provide ON/OFF function to the ABS
system. On the occurrence of this event timer t3 is initialized with 2 second. Message “m_timer 2”
is sent by the timer .After sending the message timer is re initiated by itself. And again it send same
message but the value of the signal is increased by the 1.This functionality of the timer is used to
simulate ABS. After every message of the timer speed of the four wheels is decreased by one. This
will function like a small amount breaking with the delay of 2 second.


27


Figure 3.8 Environmental variable “env_ecu_left”

Figure 3.9 Environmental variable “env_abs”


28


3.4 Front panel designing
Panel represents the I/O interface between the user and the simulated network node in CANoe
simulation setup. Every element on the panel is associated with the environment variables. Environment
variables are used to model the functional behavior of the network nodes.

Env
_ved
io2

env_ignition

env_tct

env_abs
Env_ved
io

env_fr_left

env_fr_right

Env_break
Env_num

button
env_ecu_right
env_r_left

Env_r_right

env_ecu_left
Figure 3.10 Front panel design

Figure 3.10 shows the front panel of the ADAS system. A switch indicator is used change
the ignition statue, TCR control status and ABS status and virtually producing traction in wheels.
Track bar is used to change the acceleration paddle status, normal break paddle status and turning
position of steering. Digital meter is showing the speed of car. Meter gauge is used to represent the
RPM of the individual wheels. In figure caption shows the environmental variable attached with
each component. In the simulator, two video windows are shown. On the arrival of the env_tct
environmental variable one video regarding to “what is TCR ?” plays as same On the occurrence of
the env_abs vedio regarding to “what is ABS?” plays. Which provide the batter idea about TCR and
ABS to user.


29


3.5 Test cases
Table 3. 4 Test Cases
Tc No

Test condition
By

1

pressing

the

Input
ignition Ignition button

button speed of wheels

Expected Output
Initially at the starting, wheels
RPM should be 10.
If ignition is on, according to the

2

By changing the acceleration
from the track bar

position of the track bar speed of
Acceleration

wheels

is

changed

and

by

changing the speed of wheel
speed of car is changed
At any speed pressing the ABS
3

At any speed by pressing ABS button

button , speed of the wheels/car

ABS button speed

should be decreased in busty
manner with delay of 2 sec
At any speed by pressing traction

4

In the condition of the traction TCR Button,

button virtual traction should be

TCR is on

created

Traction button

in

the

associated

wheel.after that by pressing TCR
button Traction should be avoided
By taking sharp turn to left side
5

In the condition of steering is Left turn track bar

speed of the rear left wheel is

tilted to extreme left

decreased first after that speed of
the front left wheel is decreased
and after 2 second both wheels
speed should be set to original
speed.

6

ABS is pressed when traction ABS Button,TCR In the condition of the traction
is present

Button

when the ABS is pressed,as the
first approach traction should be
recovered

and then breaking

should be applied.


30


3.6 Results
In this part of assignment all the test cases, which are developed in section 3.6 has been tested and
the results has been documented.Figure 3.11 shows that by switching off the simulator initially the
speed of the wheels is set to the 10 rpm.

Figure 3.11 Results of test case 1

Figure 3. 12 Results of test case 2
Figure 3.12 shows the changing of the speed of the wheels and car according to the
position of the acceleration bar.
Figure 3.13 shows the speed of the car and wheels at the time of pressing ABS. Assume that
at time t=0 ABS is pressed. At t=0 speed of four wheels are 10 unit. At t=2 second speed of four


31


wheels is decreased by 1.Which is shown by Figure 3.14.This provides the breaking in busty
manner. By pressing the ABS, simulator plays video associated with ABS switch.

Figure 3. 13 Result of test case 3 at t=0 sec

Figure 3. 14 Result of test case 3 at t=2 sec
Figure 3.15 shows virtual traction created by the switch named traction. Speed of the
front left wheel is increased by the 2.Figure 3.16 shows TCR switch is on. By pressing the TCR
switch by deference in the speed of wheels are avoided.


32


Figure 3. 15 Result of test case 4(1)

Figure 3. 16 Result of test case 4 (2)

On the sudden turning towards left side first Stability control unit reduced the speed of the
back left wheel. The amount of the reduced speed is depending upon the sharpness of the turn. This


33


phenomenon is shown by Figure 3.17. After 3 second of this event, Stability control unit decreased
the speed of front left wheel by 4 units to achieve the best possible stability. Snapshot of this event
is shown by figure 3.18.


After getting stable position in the other lane(on the left side in this case) Stability Control
unit reads the APPS output based on that it provides the same speed to the wheels to produce
forwad thrust .This behavior is shown in Figure 3.19.


34



Figure 3. 20 Test case 6(1)
Test case 6 is basically a integration type of the testing. In the condition of the traction, ABS is
pressed by the user. In such condition first it is necessary to reduce the traction to avoid the crash.
After that breaking will take place .Figure 3.20 shows that the traction is created in the wheel. At


35


time ABS is pressed. First system is reducing the traction after that its indulging to breaking
function. This is shown by figure 3.21.

Figure 3. 21 Test case 6(2)

3.7 Conclusion
CANoe is tool which used to development, test and analysis environment for CAN bus
systems.. ABS Data, ESC Data and TCS Control/Control ECU‘s share the network and transmits
the signal on to the BUS. The triggering data which ABS Data, ESC Data ECU outputs on the bus
is transmitted to the Control EUC for the control action. The behavior of network nodes with regard
to input and output signals is described with the help of environment variables. The control panels
provide a user-friendly interface to the environment variables. The required output is observed on
the panel.


36


CHAPTER 4
Learning Outcomes
________________________________________________________________________________

4.1 Module Learning Outcomes
•

This module helped in understanding of the concept of embedded network systems and OSI
stack structure and functionalities of each layer as a foundation for embedded network
system

•

Wired Embedded networking protocols such as SPI, I2C, CAN and LIN, and wireless
Embedded networking protocols such as Bluetooth, Zig-bee, were taught in the class

•

Assignment helped to get expertise on the CANoe tool and to write CAPL programming

•

The socket programming given the basic knowledge of how exactly communication takes
place through TCP sockets. Since its all wireless communications, the security aspects and
how to achieve security with different algorithms were taught in the class


37


References
________________________________________________________________________________

[1]http://www.electricalelectronics.jotoexplorer.com/electrical-engineering/sensor-actuatorsupported-implicit-interaction-in-driver-assistance-systems-free-pdf/
[2] http://www.ectri.org/YRS07/Papiers/Session-5/Tapani.pdf
[3]http://www.scribd.com/doc/63977741/Autonomous-Vehicle-Navigation
[4]http://www.scribd.com/doc/19385577/Technical-Feasibility-of-Advanced-Driver-AssistanceSystems-ADAS-for-Road-Traffic-Safety-Lu-Et-Al
[5]http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=627420&fileOId=627431
[6] BOSCH---- Driving stability systems, The Bosch Yellow Jackets, edition 2005
[7] http://www.buzzle.com/articles/throttle-position-sensor.html
[8] CANoe/DENoe- CAN.LIN.MOST.FlexRay, Manual version 4.1, Vector Informatik


38

Bibliography
________________________________________________________________________________
[1]Www.vactor.com
[2]www.google.com

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