Project

AIM :

To carry out a system-level simulation of an all-terrain vehicle and prepare a technical report explaining the model properties & comments on the results.

By Downloading the model from the given link:

https://www.mathworks.com/matlabcentral/fileexchange/70576-baja-all-terrain-vehicle-atv-model

So, it is clearly observed by dowloading the model that there are totally four case studies and they can be listed as follows:

1. Study of the Baja ATV model without dashboard

2. Study of the Baja ATV model with dashboard

3. Study of the Baja ATV model using the lookup table without dashboard

4. Study of the Baja ATV model using the lookup table with dashboard

INTRODUCTION:

The transmission system which transmits the power from the engine to the wheels through the shafts and it consists of four type mainly and they are :

1. Manual transmission

2. Continuous variable transmission

3. Semi- automatic transmission

4. Automatic Transmission

ATV All terrain Vehicle :

A continuously variable transmission or the 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 the traditional automatic transmissions

Now the same can be understood by using the simulink of Baja Atv model as follows:

By using simulink model of CVT consists of Signal builder, generic engine, motion sensors, vehicle transmission, vehicle body,tyres and solver configuration blocks etc

The CVT subsystem includes Transmission block, input and output shaft inertia and motion sensors as shown in second diagram

The vehicle body subsystem includes vehicle body block, double drum brake and tyres as shown in the third and the initial engine speed is given as 2100 rpm and the mechanical rotation of driven pulley and the driving pulley is 0.8 and 0.7 respectively and the mass of the vehicle is as 250kg and two axles which connects four wheels

BAJA ATV model :

CVT subsystem:

Vehicle Body Subsystem:

The signal builder block is used as input for brake, throttle and gear ratio and the brake input is maintained as 0 for overall simulation. The throttle input is given as 0.3 for 20 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 the below diagram:

below are the signal builder blocks used in the simulation

Graph 2 :

Case Study 2 :

Baja ATV with Dashboard Model :

Simulink diagram for reference:

The below diagram represents '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 dashboard. 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 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.

CASE STUDY 3:

BAJA ATV Model using look up chart

By using simulink model of the CVT which consists of step time, generic engine, motion sensors, vehicle transmission, vehicle body,tyres and solver configuration block etc.. abd the CVT subsystem includes look up table, Transmission block, input and output shaft inertia motion sensors. The vehicle body subsystem includes vehicle body block, double drum brake and tyres as shown in 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 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 and a 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 values, simulink can estimate an output value using interpolation, extrapolation, or rounding and where:

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

CVT Subsystem:

Vehicle body subsystem :

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 rēsult 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 which is an approximate value

CASE STUDY 4:

BAJA ATV Model using Dashboard with lookup table :

The below diagram shows Baja ATV with dashboard model using lookup table which consists of throttle meter and brake input in the dash board and indicated as constant block and rest of the blocks and subsystems are very common in the baja ATV model Without dash board. The main concept Of using dashboard 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 and simulink the input value from the lookup table and obtain the result according to the table As the brake input varies frorn 0 to 0.5 and the velocity and speed decreases accordingly which inturn the gear ratio also decreasing in this and by the throttle, the velocity and of the engine & shaft increases. The transrnission as primary pulley and secondary pulley. in which the radius of primary pulley increases by compacting and the radius of the pulley decreases totally

Case study 1 : variation of the velocity and the shaft speed

Case study 3 : variation of the velocity and the shaft speed

Case study 4 : variation of the velocity and the shaft speed

In the above graph 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 and to the secondary shaft The radius Of the primary shaft as rnore than the secondary shaft and that 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.so we can get any particular value for input.

Conclusions :

Now some of conclusions can be discussed as follows briefly as follows:

1. As the throttle increases, the velocity also increases which also makes the power in the engine to increase

In the above diagram or graph at the starting stage the speed is reducing because of the gear ratio and the torque output increases

2. Mainly as the braking input increases the velocity decreases and the engine power also will decrease and similarly at a particular input value the engine may go to OFF state when there is no power input and therefore the engine power which is inversely proportional to the brake input as shown in the below diagram:

3. As the gear ratio increases then the torque increases and which will decrease the velocity

as it's shown or represented in the below diagram , the Torque is increasing with the increase in the engine speed and at a at particular point the torque is decreasing when the gear ratio increases in order to achieve maximum velocity.

Now in the below diagram the velocity is varying with respect to the gear ratio and for High gear ratio the torque is more which decreases the velocity and now by changing the gear to high the gear ratio becomes less parallel to Torque and also less which can give the high velocity.

4. With the help of the lookup table we can vary any input values and also get the output values by using the interpolation and extrapolation method with the simulink link can solve by its own.

Gdrive Link for easy access :

Alternatively all the above with images and models work can be viewed by clicking the below

G-Drive Link :

https://drive.google.com/drive/folders/1Mw7ra902qNDQ_LY-7cUVQmdhYVcRmPuk