Project

objectives:

carry out a system-level simulation of an all -terrain vehicle and prepare a techincal report explainning the model properties and comments on the results.

ALL TERRAIN VEHICLE:

An all-terrain vehicle (ATV)is defined as a motorised off highway vehicle designed to trvel 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 componets in the model:

continuously variable transmission drive(CVT):

It is better to have more gears in a transmission , since it can optimize engine speed in a varity of driving conditions.That means low gears can provide better accelerations while higher gears can maximize fuel economy.CVTs differs from tradtional automatic transmission in that they don't have gears that provides "step between low-and high speed operations.insted , the majority of them work via a pair of variable -diameter, cone-shaped pulleys connected byba steel or a composite belt. The halves of each pulleys are aligned with the pointed ends of the cones touching .The cylinder can increase and decrease the amount of space between the two sides of the pulley. This allows the belt to ride lower or higher along the wallls of the pulley,depending on driving conditions,there by changing the "gear" ratio.

CVT BLOCK:

VARIABLE TRANSMISSION RATIO:

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

Connection B(base) and F(follower) are mechanical rotational conserving ports.specify the relation between base and follwer rotation directions with the output shaft rotates parameter. 

ENGINE :

Represents a system-level model of spark-ignition and diesel engines suitable for use at intial stage of modelling ,when only the basic parameters are avaiable. optinal idle speed and red line controllers are included . The throttle input signal T lies between zero and one and specifies the torque demanded from the engine as a fraction of the maximumm possible torque.

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

INPUT SIGNAL:

The signal builder is used to create signals for brake and throttle.

CVT Gear ratio input:

Torque vs engine speed input:

VEHICLE BODY:

OUTPUT FOR CASE 1:

VEHICLE SPEED:

It is clear that the vehicle attains its maximum speed(v=55km/hr) at full throttle=1 after 30 seconds and then reamain constant . the brake input value is zero , it has no effect on velocity.

CVT SHAFT RPM:

These graph shows the variations in angular velocities of input and output shats of the variable gear transmission system. these values differ with respect to the gear ratio.

STUDY #1:

CASE 2:

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 inputs -'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 CASE 2:

VEHICLE SPEED:

 

It can be observed from the graph the velocity of the vehicle increases drastically from 0 to 50kmph when throttle value is 0.5 and brake input is 0. once the braking value increase from 0.1 to 0.5, the velocity of the vehicle decreases to 0 at constant throttle value.this explain the direct relation of the vehicle velocity with respect to throttle and brake inputs.

CVT SHAFT RPM:

STUDY#2:

CASE1:

SIMULINK 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.

CVT GEAR RATIO:

LOOKUP TABLE VISUALISATION:

OUTPUT FOR CASE1:

VEHICLE SPEED:

CVT SHAFT RPM:

Both result are same as that of first case 'SIMULINK MODEL FOR  BAJA ATV WITH CVT' since the input paramertes are same.

STUDY#2:

CASE 2:

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 CASE 2:

VEHICLE SPEED:

This graph is simliar to that of CVT dashboard case.The variation in vehicle velocity can be observed with change in throttle and brake inputs. with increases in braking value, the speed of vehicle decreses, on the other hand increasing the throttle leads. to increased vehicle velocity.

CVT SHAFT RPM :

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

CONCLUSION:

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