Simulation of Antilock Braking System

8/2/2019 Simulation of Antilock Braking System

1/4

Simulation Of Antilock Braking System

Imdad A. Rizvi

Department of Electronics and Telecommunication Engineering,

Don Bosco Institute of Technology ,Mumbai.

( e-mail:[email protected] )

Dinesh ChawdeDon Bosco Institute of Technology ,Mumbai

( e-mail:[email protected] )

Department of Mechanical Engineering

Abstract-- This paper develops the anti-lock braking control

system integrated with active suspensions applied to a two

wheeler. In emergency, although the braking distance can be

reduced by the control torque, the braking time and distance can

be further improved if the normal force generated from active

suspension systems is considered simultaneously. Finally the

future developments on the ABS are dwelt on.

Keywords-- Anti-lock Braking System, Backstepping Design,

Lateral forces, longitudinal forces, friction, braking principles.

I. INTRODUCTION

Owing to advanced development of vehicular technology,

the requirement of safety for automobiles becomes more and

more important. The techniques applied for various vehicles

have already improved system stability and passenger safety

with the use of several significant control systems, such as

anti-lock braking systems (ABS) [1][2], active suspension

systems [4],traction control systems [3], and so forth,

popularly used in automobile industries. Recently, there are

some integrated studies which combine the previous

mentioned subsystems in order to control vehicle dynamic

states to reach better efficiency. For example, the concept of

integrating anti-lock braking systems with active suspensions

has been investigated in [1]. Many theories and design

methods for anti-lock braking systems and active suspension

systems have been proposed individually by several literatures

for decades. Various researchers have considered a slip-ratio

control of anti-lock braking systems in the use of sliding mode

control schemes [5].

When a driver of a vehicle hits a conventional brake hard

that is during panic braking, the wheels may lock causing the

vehicle to skid, especially on wet and slippery roads. Antilock

brake systems provide the capability for shorter stopping

distances and the ability to steer and to maintain control

during hard braking, especially on wet and slippery surfaces.

This system allows the driver to achieve the two main braking

advantages during maximum braking stops, one better lateral

stability control may be achieved by automatically pumping

the rear brake. This prevents continuous rear wheel lock-up

which is one cause of rear-end skidding and second shorter

stopping distances may be generally achieved by

automatically

providing the average rear brake pressure necessary for

maximum stopping force. These advantages are generally

achieved over a wide variety of road surfaces, weather

conditions, and driving situations. However, the extent of

the wheel lock control brake system advantages is determined

by many factors such as Road surfaces, weather conditions,

driver proficiency, vehicle speed, tire tread wear, tire inflation

brakes and suspension components.

The remainders of this paper are organized as follows.

In Section 2, the need of ABS is discussed. ABS for two

wheelers along with the program flowchart is discussed in

Section 3. In Section 4, Fabrication is highlighted. The

simulation results of the anti-lock braking system are

illustrated in Section 5. Finally, some concluding remarks

with future development are given in Section 6.

II.NEED OF ABS

Shortly hitting the brakes can be sufficient to cause

wheel lock-up even on a dry road. Locked-up wheels

cannot transfer lateral forces. The consequences: The

vehicle doesnt react to the drivers steering input. ABS

recognizes very early, if one or more wheels show a

Fig.1: Basic principles of braking

Fig. 1: Basic principles of braking.

tendency to lock-up while braking. In this case ABS

ensures that the braking pressure is kept on a constant

level or reduced. The wheels do not lock up and the

vehicle remains steer able. Thus the vehicle can be

decelerated quickly and safely and an obstacle can be

avoided. Above shows the basic principles of braking.

III. ABS FOR TWO WHEELERS

As two wheelers are more unstable in comparison with four

wheelers so there are more chances in bikes of getting skid on

slippery roads or there are chances of an accident during panic

braking. This can be avoided if the similar technology of


2/4

antilock braking system used in cars is used in bikes. To

achieve above in bikes , main aim is to reduce brake fluid

pressure inside disc brake caliper in the situation when the

bike is just going to skid (after applying brakes) ,as thepressure is reduced wheels will start rotating & just after a

few milliseconds the pressure is increased thereby locking the

wheels .This action of increasing & decreasing pressure will

respectively stop & rotate the wheels referring to figure 2.This

will built the necessary traction or grip between wheels &

road thereby giving the rider a steering control & thus saving

an accident. Therefore ABS can prove as a life saving guard.

Fig 2: ABS in two wheeler

For working of ABS we will consider two cases,

Case 1:

This case is regarding normal braking operation of bike

that is when there is no skid of bike. When brake lever is

pressed, the fluid pressure inside the hose pipe connecting

master cylinder with brake caliper through solenoid valve

increases to about 8 bars .The pressure so produced is enough

to bring friction pads of disc brake in contact with rotating

disc thus stopping the bike. During this process sensors

continuously send their output signals to micro controller.

Micro controller checks for the condition of skidding that is

whether rpm1 is equal to rpm2 or rpm1 is less than rpm2. Asthis case is of normal braking operation rpm1 will be equal to

rpm2 hence it does not give any output signal. Due to this

solenoid valve & solenoid actuator remains OFF.

Case 2:

In this case the actual working of ABS system takes

place. As we know the rpm sensed by front & rear wheel

sensors are continuously supplied to micro controller. Now if

found that rpm1 is lesser than rpm2 which is the condition for

skidding of bike then micro controller will first trigger the

relay which is connected to solenoid valve. Soon after few

milliseconds second relay connected to solenoid actuator gets

triggered. As soon as first relay gets triggered current flows

from battery to solenoid valve .Due to this solenoid valve gets

energized disconnecting hydraulic connection between master

cylinder & brake caliper & makes hydraulic connection

between brake caliper & injection cylinder. After a delay of

few seconds that is after triggering first relay, second relaygets triggered thus energizing solenoid actuator the solenoid

actuator would pull master cylinder piston thus sucking in the

fluid .The expansion caused in the line will decrease the brake

fluid pressure. This is turn would give some motion to the

locked wheel. Soon after microcontroller switch Offs the

second relay thereby disconnecting the supply from battery to

solenoid actuator. Solenoid actuator will no more have power

to hold the shaft & thus due to spring action shaft which is

connected with piston of master cylinder will move towards

left thereby increasing the pressure of fluid thus locking the

wheels. Thus this increase & decrease in pressure will buit

enough traction between wheels & roads. This traction will

help the driver to take bike to safer position. This process arerepeated till micro controller finds the condition rpm1 equal to

rpm2.As soon as this condition is encountered microcontroller

will first switch OFF solenoid actuator & then solenoid valve

thus bringing every thing into normal state.

PROGRAMING FLOWCHART

Fig 3: Programming Flowchart

IV. FABRICATION

The first step was to replace the original front wheel drum

brake by disc brake kit. The next step consists of fabricating and

assembling various components of the hydraulic circuit like single

acting cylinder, 3/2 valve, solenoid actuator, threaded rod, spring,

sensor holder, battery stand, hoses etc. A m.s. flat was cut to the

required size and three holes were drilled in it. It was then fasten

to the body of solenoid linear actuator by using three metal


3/4

screws. One end of the threaded rod was screwed with the plunger

of solenoid linear actuator. Other end of the threaded rod was

screwed with the piston of the single acting cylinder. Two

m.s. flats were cut to the required length and then welded with

the m.s. flat which was fastened to the solenoid linear

actuator. Thus the frame structure was formed. The sub

assembly consisting of frame, single acting cylinder, solenoid

actuator, threaded rod was then mounted on to the chassis of

the bike to ensure whether it fits properly. After ensuring thatthe sub assembly was fitting properly we disassembled it,

fitted spring, nut and locknut to it and then mounted the

assembly again on to the bike. The 3/2 solenoid valve holder

was made from M.S flat by bending it to the required shape &

drilling two holes in it. The holder was then fitted on to the

chassis through one of the holes & 3/2 solenoid valve was

then mounted on it through the second hole using nut bolts.

The main hose line was cut in to two halves & their ends were

connected to the normally open ports of 3/2 solenoid valve

through hose connectors. The third port was connected to the

auxiliary hose which connects the single acting cylinder. The

sensor holders were made from M.S flat by bending it to the

required shape & drilling two holes in it. The holders werethen fitted on to the front & rear fork. Then sensors were fitted

on it.

V. RESULTS:

Threaded rod is modeled for the first iteration by following

considerations; Length of the threaded rod is known since it is

equal to the free length of the spring which has already been

designed. i.e. L = 200mm, referring to figure 4.

Nominal diameter of the external threads is initially assumedas 15mm.

The FE Model is then assigned with Aluminum as the

material. Boundary conditions are then substituted which

consists of following constraints and restraint sets:

1. An axial force of 100 N on the internal threads on actuator

side.

2. A restraint at the internal threads on piston rod side

The FE Model is then meshed using 4 node non-uniform

tetrahedral solid elements.

The refined mesh is then checked for any errors

2. Stress (Von Mises)

The results are displayed using the visualizer which shows the

above quantities graphically using a spectrum of colour.

And the CAD model is then updated to reflect the changes as

shown below:


4/4

The ABS on the Two wheeler looks like this :

VI. FUTURE DEVELOPMENT

One of very prominent development required in ABS is to

have a good program that will be fed in to micro controller

,the program that will check for the condition of skidding of

bike & soon as the condition is satisfied to send signal to

appropriate components.In case of 8031 or 8051 there are only two timer ,

from which we use one timer to count no of pulses &

other to calculate seconds. Hence both two timer are

required for detection of one wheel speed. If we used

8032, then there are three timer & the codes are very

much similar as that in case of 8031. from those 3

timer, one can be used for counting seconds & other two

can be used for counting no of pulses. Instead of

displaying these frequencies on the circuit we can used

them for further operations i.e. Say timer T1 and T2 are

used as counter in mode 01 and timer T0 is used as a

timer for enabling the counter for counting the no of

pulses in 1 sec duration. Let f1 be the no of pulses

counted by timer 1 per sec. & f2 be the no of pulses

counted by timer 2. If f1 - f2 is not = to zero . Then 5v

d.c output should be given to appropriate terminals as to

switch on the hydraulic circuit. Another development thatcould still improve the efficiency of ABS is to have

mechanical components with very high responses.

REFERENCES

[1] A. Alleyne, Improved vehicle performance usingcombined suspension and braking forces, Vehicle

System Dynamics, 1997, Vol.27. pp.235-265.

[2] L. Alvarez, J. Yi, X. Claeys and R. HorowitzEmergency braking control with an observer-based

dynamic tire/toad friction model and wheel angular

velocity measurement, Vehicle System Dynamics, 2003,Vol.39, No.2, pp. 81-97

[3] S.V. Drakunov, B. Ashrafi, and A. Rosiglioni, Yawcontrol algorithm via sliding mode control, Proceedings

of the American Control Conference,Chicago, Illinois,

June 2000, Vol.1, pp. 580-583.

[4] E.-S Kim. Nonlinear indirect adaptive control of aquarter car active suspension, Proceedings of the 1996

IEEE International Conference on Control Applications,

Dearborn, MI, September, 1996, pp.61-66.

[5] S.V. Drakunov, U. Ozguner, P. Dix and B. Ashrafi,ABS control using optimum search via sliding modes,

IEEE Transactions on Control SystemsTechnology,

Volume: 3, Issue: 1, March 1995, Pages: 79-85.[6] BOSCH AG, GERMANY (Dvd-rom ,Cd-rom,Brouchers).

Imdad Rizvi is holding M.E. (Electronics) degree from

University of Mumbai. He is currently working as a lecturer in

Don Bosco Institute of Technology, Kurla , Mumbai. His area

of interest includes Embedded systems, Image processing and

Wavelets.

Dinesh Chawde is holding M.E. (Mechanical) degree from

University of Mumbai. He is currently working as a lecturer inDon Bosco Institute of Technology, Kurla , Mumbai. His area

of interest includes Machine design, FEA and ABS.

Simulation of Antilock Braking System

Documents

Transcript of Simulation of Antilock Braking System