Project

Model Properties

The Baja ATV Simulink model consists of the following major components:

• Engine Model – Represents the power source with characteristics like torque-speed curve, throttle response, and fuel efficiency.
• CVT (Continuously Variable Transmission) System – Simulates the gear ratio variation for optimal power transfer.
• Drivetrain Model – Includes differentials, axles, and torque distribution mechanisms.
• Chassis and Suspension System – Models the dynamic response of the vehicle when interacting with different terrains.
• Tire and Terrain Interaction – Captures the effect of off-road conditions such as sand, mud, and rocky surfaces.
• Braking and Steering Control – Simulates user inputs for braking force and steering response.

ALL TERRAIN VEHICLE:

An all-terrain vehicle (ATV) is defined as a motorized off-highway vehicle designed to travel on four low-pressure or non-pneumatic tires, having a seat designed to be straddled by the operator and handlebars for steering control.

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.

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.

The only Difference between this model and the first model is that in this model, the gear ratio input to CVT is provided using a lookup table. The vehicle velocity and shaft rpm outputs are same as before.

Results:-

Study 3:-

CVT GEAR RATIO:

VEHICLE SPEED:

CVT SHAFT RPM:

Both results are same as that of the first case: - SIMULINK MODEL FOR BAJA ATV WITH CVT since the input parameters are same.

SIMULINK MODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE & DASHBOARD:

In this model a dashboard is used to control the inputs- ‘Throttle’ & ‘Brake’ with knobs.

VEHICLE SPEED:

This graph is similar to that of cvt dashboard case. The variation in vehicle velocity can be observed with change in throttle and brake inputs. With increase in braking value, the speed of vehicle decreases. On the other hand, increasing the throttle leads to increased vehicle velocity.

CVT SHAFT RPM:

This graph indicates the variation in rpm of primary and secondary shafts with respect to input parameters.

Results Analysis

After running the simulation, the key outputs observed include:

Ø Velocity and Acceleration Profile: The model accurately depicts how the ATV gains speed and stabilizes based on terrain resistance and engine power.

Ø CVT Performance: The CVT system efficiently adjusts the gear ratio to optimize engine performance for different loads and speeds.

Ø Suspension Response: The model demonstrates realistic vertical displacement and damping effects when the vehicle moves over obstacles.

Ø Wheel Slippage and Traction: Changes in traction depending on terrain type affect vehicle handling and stability.

CONCLUSION:

The Baja ATV Simulink model effectively captures the real-world behavior of an all-terrain vehicle in dynamic conditions. The simulation provides insights into engine efficiency, transmission performance, suspension dynamics, and vehicle control. The results confirm that the CVT transmission improves fuel efficiency and adaptability, while the suspension system plays a critical role in maintaining stability on rough terrains. This model is beneficial for engineers designing off-road vehicles, optimizing ATV powertrains, and testing different control strategies before real-world implementation. Future improvements can include terrain adaptability algorithms, advanced control strategies, and electric powertrain integration.