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 1:-
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 subsystem includes vehicle body block, double drum brake and tyres as
shown in figure-3. 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.

figure 1:

figure 2:

figure 3:

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).
Fi

figure 4:

figure 5:

study 2:

figure 6:

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.
A rounding is a process for approximating a value by altering its digits according to a known rule.

figure 7:

figure 8:

figure 9:

The brake input and throttle input is given by step time, which depends on the run time and varies accordingly. By using Lookup table
for gear ratio which takes as input to the CVT and works according to the input gear ratio and obtained the output. This method is
very effective which can avoid the unusual torque at the certain speed and very easy to achieve greater velocity & engine speed. It
works as closed loop when the input is given by lookup table. The simulink get the input value from lookup table and obtain the result
according to the input values of gear ratio. The gear ratio varies from 2.3 to 1.8 as taken as input and output interms of velocity. The maximum velocity reached as 57 kmph approximately.

figure 10:

study 4:

figure 11:

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: Variation of velocity & Shaft speed

In the above figure, the brake is maintained as constant and increase in throttle which shows increase in velocity. The flow of fuel is
increses when the throttle increases from 0.3 to 1, thus the power in the engine increases. The torque reaches approximately 7N-m at
1.8 gear ratio, which defines that gear ratio is directly proportional to the torque. By this gear ratio, the speed & velocity can achieve maximum.

In the above figure, the primary shaft reaches high speed and secondary shaft as low rotational speed because the radius of the
primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the radius increases
the speed of the shaft also increases.

study 2: variation of velovity and shaft speed

In the above figure, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 and varying by increasing
the value of throttle which increases the velocity of vehicle. By increasing the brake input, the velocity of the vehicle decreasing

In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which
defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft.
The radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the
radius increases the speed of the shaft also increases.

study 3:variation of velocity and shaft speed

In the above figure, the brake is maintained as constant and increase in throttle which shows increase in velocity. The flow of fuel is
increses when the throttle increases from 0.3 to 1, thus the power in the engine increases. The torque reaches approximately 7N-m at
1.8 gear ratio, which defines that gear ratio is directly proportional to the torque. By this gear ratio, the speed & velocity can achieve maximum. The gear ratio is assigned in lookup table and given as input to the simulink which reads every input value and obtain the
result according to the input.

In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which
defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft.
The radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the
radius increases the speed of the shaft also increases.

Study 4:- Variation of velocity & Shaft speed

In the above figure, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 and varying by increasing
the value of throttle which increases the velocity of vehicle. By increasing the brake input, the velocity of the vehicle decreasing
accordingly which shown in figure18. By using lookup table, it works as closed loop by recording the velocity value and we can get at
any particular value of gear ratio which is beyond the range or any random value within the range by using extrapolation and
interpolation by lookup table.

In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which
defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft.
The radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the
radius increases the speed of the shaft also increases. The throttle value and brake input value can be varying in dashboard

In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which
defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft.
The radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the
radius increases the speed of the shaft also increases. The throttle value and brake input value can be varying in dashboard

CONCLUSION:
1. As the throttle increases, the velocity also increases which inturn the power in the engine also increases.
2. As the brake input increases, the velocity decreases and engine power also decreases. At a certain brake input value the engine may shut down and there is no power output. The engine power is inversly proportional to the brake input.
3. As the gear ratio increases, torque increases which inturn the velocity decreases.
gear ratio increases inorder to achieve maximum velocity.By
changing to high gear, the gear ratio become less paralelly the torque also less which can get high velocity.
4. With help of lookup table, we can vary any input value and also get the output value by using interpolation and extrapolation nethod which simulation can solve.