Project

AIM: To study the system level simulation of an all terrain vehicle.
KEYWORDS: CVT, lookup table, Dashboard, baja ATV

SOFTWARE: Matlab, Simulink

OBJECTIVE:

1. Study the baja ATV model without dashboard.

2. Study the baja ATV model with dashboard.

3. Study the baja ATV model using lookup table without dashboard.
4, Study the baja ATV model using lookup table with dashboard.

INTRODUCTION:

Transmission, which transmits the power from engine to the wheels through the shafts. It consists of 4 types mainly,

* Manual transmission

* Continous variable transmission
* Semi-automatic transmission

* Automatic transmission

A continuously variable transmission, or CVT, is a type of automatic transmission that provides more useable power,
better fuel economy and a smoother driving experience than a traditional automatic transmission. The CVT is a
system that makes it possible to vary stepless the transmission ratio without interruption of the torque flow. Therefore
an infinite number of ratios (between a minimum and maximum value) are possible. It is an automatic, single speed,
and gearless transmission that can shift through an infinite number of gear ratios. This ability to seamlessly shift
through these different gears provides a number of benefits including extremely smooth shifts and exceptional fuel
economy. A CVT draws top engine power from a small engine, which gives drivers quicker acceleration than
standard automatic transmissions, Because of their greater ability to control the engine speed range, CVTs produce
fewer emissions. CVTs are also lighter weight than traditional automatic transmissions.

STUDY I:

By using simulink model of CVT consists of Signal builder, generic engine, motion sensors, vehicle transmission,
vehicle body,tyres and solver configuration blocks etc, as shown in figure-1. The CVT subsystem includes
Transmission block, input and output shaft inertia and motion sensors as shown in figure-2. The vehicle body

CVT SUBSYSTEM MODEL:

VEHICLE BODY SUBSYSTEM:

The signal builder is used as input for brake, throttle and gear ratio. Brake input is maintained as 0 for overall
simulation. The throttle input is given as 0.3 for20 secs and increases to 1 for overall simulatuion. The throttle valve is
mainly to control the flow or amount of fuel into the engine, if the throttle value increases the flow of fuel increases to
the IC engine which inturn increases the power of the engine. The gear ratio is maintained as 2.3 for 5 secs and
linearly decreases to 1.8 and maintained constant for overall simulation as shown in figure (4 - 5).

STUDY 2:-

The above figure shows ‘Baja ATV with dashboard’ model which consists throttle meter and brake input in the dash
board instead of giving input through signal builder. Rest of the blocks and subsystems are common in the above
baja ATV model without dash board as shown in figure 2 & figure 3. The main concept of using dash board is study
the result by varying the input of brake and throttle, which shows that the velocity and speed of the engine. The gear
ratio is maintained as 2.3 for 5 secs and linearly decreases to 1.8 and maintained constant for overall simulation as
shown in figure 5. As the brake input varies from 0 - 0.5, the velocity and speed decreases accordingly. By increasing
the throttle, the velocity and speed of the engine & shaft increases.

STUDY 3:-

By using simulink model of CVT consists of step time, generic engine, motion sensors, vehicle transmission, vehicle
body,tyres and solver configuration blocks etc, as shown in figure-7. The CVT subsystem includes look up table,
Transmission block, input and output shaft inertia and motion sensors as shown in figure-8. The vehicle body
subsystem includes vehicle body block, double drum brake and tyres as shown in figure-9. The initial engine speed is
given as 2100 rpm, mechanical rotation for driven pulley and driver pulley as 0.8 & 0.7 respectively. The mass of the
vehicle as 250kg and 2 axles which connects 4 wheel accordingly.

A lookup table is an array of data that maps input values to output values, thereby approximating a mathematical
function. Given a set of input values, a lookup operation retrieves the corresponding output values from the table. If
the lookup table does not explicitly define the input values, simulink can estimate an output value using interpolation,
extrapolation, or rounding, where:

* An interpolation is a process for estimating values that lie between known data points.
* An extrapolation is a process for estimating values that lie beyond the range of known data points.
* Arounding is a process for approximating a value by altering its digits according to a known rule.

STUDY 4:-

The above figure shows ‘Baja ATV with dashboard’ model using lookup table which consists throttle meter and brake
input in the dash board and indicated as constant block. Rest of the blocks and subsystems are common in the
above baja ATV model without dash board as shown in figure 8 & figure 9. The main concept of using dash board is
study the result by varying the input of brake and throttle, which shows that the variation of velocity and speed of the
engine. The gear ratio is given by lookup table, simulink get the input value from the lookup table and obtain the
result according to the lookup table. As the brake input varies from 0 - 0.5, the velocity and speed decreases
accordingly which inturn the gear ratio also decreasing. By increasing the throttle, the velocity and speed of the
engine & shaft increases. The transmission as primary pulley and secondary pulley, in which the radius of primary
pulley increses by compacting and the radius of secondary pulley decreases. As the gear ratio varies, the torque also
varies. Gear ratio is directly proportional to the torque, which increases by increasing the gear ratio. At the max
torque, the speed and velocity is decreases.

OUTPUT:

Study 1:- varation of velocity & shaft speed