Project

AIM : Here we study the reort on explaining how to build an ALL-TERRAIN VEHICLE(ATV) with CONTINUOUSLY VARIABLE TRANSMISSION(CVT) using BAJA ATV model.

OBJECTIVE :

.COMPONENTS OF BAJA ALL-TERRAIN VEHICLE(ATV)

. VEHICLE MODELLING

. DEFINING THE GEAR RATIO

. EFFECT OF PARAMETER VARIATION

. VEHICLE WEIGHT

. CVT RATIO

. INCORPARING CVT DATA IN TO THE MODEL

. OPEN LOOP MODEL

. CLOSED LOOP MODEL

TECHNICAL REPORT :

ALL TERRAIN VEHICLE(ATV) :

An all terrain vehicle (ATV) also known as quad,as defined by the american National standards institute(ANSI) is avehiclethat travels on low pressure tires,with a seat that is staddled by the operator,along with the handlebars for steering control.As the name implies is designed to handle the wider variety of terrain than most other vehicles.

BAJA ALL- TERRAIN VEHICLE (ATV) :

Baja is a collegiate design seriess competation run by the american standards institute.Teams of students from universities all over the world,design and build some cars.the cars all have an engine of some specifications

COMPONENTS OF BAJA ALL_TERRAIN VEHICLE (ATV) :

here the ATV model mainly consists of five parts they are tyre,suspension,vehicle body,engine,CVT.

TYPES OF BAJA ALL-TERRAIN VEHICLE (ATV) MODELS :

The BAJA ATV model consists of two types

. SIMULINK MODEL OF BAJA ATV WITH OPEN LOOP CVT MODEL

. SIMULINK MODEL OF BAJA ATV WITH CLOSED LOOP CVT MODEL

1.SIMULINK MODEL OF BAJA ATV WITH OPEN LOP CVT MODEL :

This is the diagram of a BAJA ATV with open loop CVT model

If we seen this diagram ATV is connected to the engine that named as generic engine,it represents a general internalcombustion engine.Engine types included are spark ignition and diesel, speed power and speed torque characterisations are to be provided.here T is a throttle and it represents a physical signalinput that specifies the normalized engine torqueand thwe connections F and B are mechanical rotational conserving portsassociatd with th engine crankshaft and block.

THROTTLE :

It is a mechanism by which fluid flow is managed by construction.An engines power can be increased or decreased by the restriction of inlet gases,but usually decreased.the throttle has to any mechanismby which the power or speedof an engine is regulated,sucha ascars accelerated pedal,particularly for jet -enginepowered aircraft,for a steam locomotivethe value which controls the steam known as regulator. if we given input conditions of the throttle

.it is the signal lies between zero to oneand specifies the torque demanded from the engineas a fraction of the maximum possible torque.

.If the engine speed falls belowthe stall speed,the engine torque is blended to zero

.If the engine speedexceeds the maximum speed,the simulationstops and issues an error message

her we can use the signal builder by giving the throttle and the brake inputs as shown in below figure

we seen the diagram first one showing the diagram of the brake input and second one shows the graph of throttle input, we see the throttle input affter some time velocity is incresased,throttle input is directly proportional to the velocity ie if the input is increased and the velocity is also be increased at that time, when if the velocity is increasing after a certain time, it is using the maximum velocity.

and we also discuss on speed and torque vector data. if the image is shown below in that image some values are given ,then that the values is to be changed in to data by using the grabbit file. it is a file exchanger that helps to support the data points from an image file.

VEHICLE BODY BLOCK :

The vehicle body is a two axle body in a longitudinal motion. the vehicle can hae the same or a different number of wheels on each axle,for example,two wheels on the front axle and two wheel on the rear axle.the vehicle also have a center of gravity that is at or below the plane of travel.The block accounts for the bodymass,aerodynamic drag,roadincline and weight distribution between axle due to acceleration and road profile. optionally include pitch and suspension dynamicsand the vehicle does not move vertically relative to the ground.

th block includes an externally defined mass and externally dfined inertia. the mass inertia and center of gravity of the vehiclebody can vary over the course of simulation in response to system changes.

the simulink of the vehicle body block is shown in below diagram

in this simulation of vehicle body is connected to two rear wheels and two front wheels.connection A refers that is the mechanical rotational conserving port for the wheel axle.connection H refers that is the mechanical translational conserving port for the wheel hubthrough which the thrust is developed by the tyre is applied to the vehicle,connection N represents that is a physical signal inputport that applies the normal force acting on the tyre,connection S is a physical signal outputthat reports the slip,connection V represents a physical signal output ports for vehiclevelocity,connection NF as a physical signal output ports for font normal wheel forces,connection NR states that physical signal output ports for rear normal wheel forces.here starting connection A is connected to the inertia output shaft.where inertia output shaft=Ie-1 and the double show brake block s tyre slip is connected to Awhich is the mechanicalrotational conserving port for the wheel axle.

EFFECT OF PARAMETER VARIATION :

VEHICLE WEIGHT : if every change in velocity in vehicle mass the linearly increases and becomes the constant velocity.

CVT - CONTINUOUSLY VARAIBLE TRANSMISSION :

A continuously variable transmission (CVT) is an automatic transmission that can change seamlessly through a continuos range of gear ratios.this contrasts with othe rtransmisssionsthat provides a limited number of gear ratios in fixed steps. the flexibility of a CVT with suitable control may allow th engine to operate at a constant RPM while the vehicle moves at varying speeds.

genrally cvt is used in tractors,motor scooters,snowmobilesand earthing equipment. The most common type of CVT uses two pulleys connected by belt and chain.

Mainly CVT consists of primary pulley,variator,belt,secondary pulley

the variator which is connected to the primary pulley,when it goes outward,the variator of secondary pulley will move inward,such that the radius of the secondary pulley will be more tha that of the radius of primary pulley.so that will lead to speed reduction

if the variator which is connected to the primary pulley when it goes inward,the variator of secondary pulley will move outward.such that the radius of the secondary pulley wil be less than over the radius of the primary pulley,soo that will lead to the over drive.

1.CVT MODEL WITH OPEN LOOP :

BLOCK DIAGRAM OF THE CVT MODEL WITH OPEN LOOP IS SHOWN BELOW

the CVT block consists of

.connection B is connected to inut shaft inertia which is a primary pulley

.connection F is connected to output shaft inertia which is a secondary pulley

.where connection B and F are mechanical rotational conserving ports.specify the relation between base and follower rotational directions with the output shaft rotates parameter.

.To specify the CVT ratio we use the variableratio gear

.we get CVT primary RPM from input shaft inertia and base to the ideal rotational motion sensor-1

.we get CVT secondary RPM from output shaft inertia and a follower to the ideal rotational motion sensor-2.

EFFECT OF PARAMETER VARIATION :

CVT RATIO :

.The range of the CVT ratio if from 0.50 to 0.35,but we know that the range is given to the CVT ratio is around 0.40 to3.

.By taking the value of CVT ratio from 0.5 to 3, the CVTprimary RPM and CVT secondary RPM varies.

.when the CVT ratio is less than 1, the RPM of the primary CVT is greater than the CVT secondary RPM,when it becomes less thanone the secondary RPM than the primary RPM.

the variation of the vehicle velocity curve and CVT secondary Pulley is almost the same because the secondary pulley is connected to the rear wheel .

SIMULINK DASHBOARD MODEL OF BAJA ATV WITH OPEN LOOP CV MODEL :

. Taking the intiaql condition for brake at 0 and throttle input at 0.3 the engine RPM and the velocity are in running condition.

.when the throttle inputis gradually increaseed from 0.3 to 1, the engine RPMand velocity values are increased gradually.similarly, when the throttle input is decreased from 1 to 0.3 the engine RPM and velocity decreases gradually.

.when the brake input is at 0.1 ansd throttle intial condition at 0.3,the engine RPM and velocity are going to stop suddenly.

.when the throttle input at a maximum which is at 1 and brake is applied gradually from 0 to 0.5, the engine RPM and the velocity gradually coming to rest position or stops.

LIMITATIONS :

In the starting condition of the vehicle,when the Engine RPM and velocity are in running,it stops the engine RPM and velocity applying by bvrakes.

In openloop CVT the problem of facing is stopping or comes to rest quickly

It is not realistic because the CVT ratio has to be depending upon the vehicle velocity,but we taken the Random CVT values.

LOOK UP TABLE VISUALIZATION PLOT :

The valie of the lookuptable is taken from the CVT and the vehicle speeddata to a plotwe get from the open loop model of CVT

CVT CLOSED LOOP MODEL :

Here Taking the intial condition for brake at 0 and throttle input at 0.3 the engine RPM and velocity are in running condition

when the throttle inputis gradually increased from 0.3-1,the Engine rpm and the velocity increases gradually.similarlly when the throttle input is gradually decreased from 1 to 0.3. the engine RPM and velocity values are decreased.

when the brake input is gradually increased from 0 to 0.5, the engine rpm and velocity values are decreasing gradually.similarlly,when the brake input is gradually increasedfrom 0.5 to 0. the engine rpm and velocity values are increased gradually.

when the throttle input at maximum which is at 1 and brake is applied gradually from 0-0.5,the engine rpm and the velocityvalues are decreasedcompared to intial condition but it wont be in stopping condition.

RESULT :

we discuss the results in two models.

1.OPEN LOOP MODEL :

this model has a problem that whenever we apply the brakes in running condition the engine stops wbich RPM isat zero and velocity is also at zero,because it is not realistic because the CVT ratio has to be depending up on the vehcle velocity,but we taken the random CVT values.

2.OPEN LOOP MODEL :

the model rectify the problemof brakes which are in running condiionby using the data by depending up on the vehicle velocity,so the model is to applicable to all running conditions of the vehicle.