Project

AIM:

To prepare a technical report of simulation of BAJA All_terrain Vehicle (ATV) under different conditions

Objective:

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

ALL TERRAIN VEHICLE:

An all-terrain vehicle(AVT) 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

Study_1:

CASE1:

SIMULINK MODEL FOR BAJA ATV WITH CVT:

Major components in the model:

Continuosly Variable Transmission drive(CVT):

It is better to have more gears in a transmission, since it can optimize engine speed in a variety of driving conditions.that means low gears can provide better acceleration while higher gears can maximize fuel economy.CVTs differ from traditional automatic transmission in that they don't have gears that provide "steps" between low-and high-speed operations.Instead,the majority of them work via a pair of variable-diameter,cone-shaped pulleys connected by a steel or composite belt. The halves of each pulley are aligned with the pointed ends of the cones touching. These from A V-shaped groove in which the connecting cylinder. The cylinder can increase or decreasee the amount of space between the two sides of the pulley. This allow the belt ride to lower or higher along the walls of the pulley,depending on driving conditions,thereby changing the gear ratio

CVT Block:

VARIABLE TRANSMISSION RATIO:

Represent a variable ratio gearbox such as implemented by mechanical belt CVT,electric,or hydraulic tranmissions. The physical signal input r defines the ratio of input to output angular shaft velocities

Connections B(base) and F(follower) are mechanical rotational conserving ports.Specify the relation directions with the Output shaft rotates parameter.

ENGINE:

Represents a system-level model of spark-ignition and disel engines suitable for use at initial stages of modelling when only the basics parameters are available.Optional idle speed and red line controllers are included,The throttle input signal T lies between zero and one and specifies the torque demamded from the engine as a fracton of the maximum possible torque

connections F and B are mechanical rotational conserving ports associated with the engine crankshaft and engine block, respectively. Coneeections P and FC are physical signal output ports through which engine power and fuel consuption rate are reported

INPUT SIGNAL:

A Signal builder is used to create signal for brake and throttle.

CVT Gear Ratio Input:

Torque vs Engine Speed input:

VEHICLE BODY:

OUTPUT for CASE 1:

VEHICLE SPEED:

It is clear from the graph that the vehicle attains its maximum speed(V=55km/hr)

at the full throttle=1 after 30sec and then remains constant The brake input value is zero,hence it has no effect on velocity

CVT SHAFT RPM:

These graphs shows the variation in angular velocities of input and output shafts of the variable gear transmission system.These values differ with respect to the gear ratio.

STUDY-2:

CASE2:

SIMULINK MODEL FOR BAJA ATV WITH CVT USING DASHBOARD:

 

In  this model we have a  dashboard which contains knobs to control the inputs. In this case,the input-'Throttle'&'Brake' are not provided using signal builder. A knob is provided to control both the parameters in real-time for the user

OUTPUT for CASE2:

VEHICLE SPEED:

It can be observed from the graph that the velocity of the vehicle drastically from 0to50kmph when throttle value is 0.5 & brake input is 0. Once the braking value increase from 0.1 to 0.5, the velocity of the vehicle decrease tpo 0 at constant throttle value. This explains the direct relation of vehicle velocity with respect to throttle and brake inputs.

STUDY-2:

CASE1:

SIMULATION MODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE:

 

CVT BLOCK:

 

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.

STUDY2:

CASE2:

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.

OUTPUT for CASE2:

VEHICLE SPEED:

This graph is similar to that to cvt dashboard case. The variation in vehicle can be observed with change in throttle and brake inputs.with increase in braking value,the speed of vehicle decrease. 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.

CONCLUSION:

Thus we have successfully analysed 4 different models of BAJA ATV WITH CVT and recorded the outputs:-(Vehicle velocity & CVT shaft rpm) with respect to variations in input throttle and brake.