Project

AIM: To Study and Analyze the "BAJA all terrain vehicle(ATV)" model using Simulink

Objective: To Prepare Technical Report on 'Baja ATV model' with and without lookup table

Theory:

BAJA ATV:

The BAJA is an event(compitition) for the undergraduate students ,organised globally by the society of Automative engineers,USA. This event originated in the name of mini-BAJA,in the year 1976 at university of caroline.Since then the event has started in India too.The BAJA events give tasks to the student to design ,fabricare and validate a single seater four -wheeled off road vehicle totake part in series of event over a course of 3 days that test the vehicle for sound engineering practices that have gone in to it.

ALL TERRAIN VEHICLE:

An All-Terrain vehicle also known as light utility vehicle(LUV), a quad bike or simply quad as defined by American National Standards Institute(ANSI) ,it is a vehicle that travels on low-pressure tires,with a seat that straddled by the operartor ,along with handlebar for stearing control. As the name implies ,it is designed to handle a wider variety of terrain than other vehicles.

In this report we anlyse three models as below:

• BAJA ATV model without dashboard
• BAJA ATV model with dashboard
• BAJA ATV model -mapped lookup table with Dashboard

Main Model :

Major Component used:

1) Generic Engine:

Represesnts a system-level model of spark-igition and Diesel engines suitable for the use at initial stages of modelling when oly the basic parameters are available.The speed Torque and Speed power parameters are provided.

Ports:

B= Rotational conserving port representing engine block

F= rotational conserving port represesnting engine Crankshaft

T= physical signal input port specifying the normalised engine throttle level

P= Physical signal output port reporting the instantenious output power,in Watt(W)

FC = Physical signal input port reporting the fuel consumption rate in kg/s.

2)Simple Gear:

The Simple Gear block represent a gearbox that constrains the connected drivelineaxes of the base gear.B, and the Fololower gear,F, to corotate with a fixed ratio.The Gear ration is defined as

ports:

B= Base Gear or Driver Gear

F= Follower Gear or Driver Gear

3)CVT transmission:

In CVT( Continuous Variable Transmission) the variable diameter pulley plays a vital role in transmission.Variable- Diameter pulleys must alwys comes in pairs. One of them is known as drive pulley(or driving pulley) which is connected to crankshaft of engine.It also called as input pulley because it is the place where the energy from the engine enters the transmission.Second i.e.another pulley known as Driven pulley because the first pulley is turning it.As an output pulley ,Driven pulley transfers energy to the driveshaft.

The Distance between the center of the pulleys to where the belt makes contact in the groove is known as the pitch radius.When the pulleys are close together the belt rides higher and pitch radius increases.The ration of First( Driver) pulley and second (Driven ) pulley determines the gear when the pitch radius is small on Driver pulley and large on Driven pulley.,then the rotational speed of the Driven pulley decreases,resulting in lower gear.When the pitch radius is large on Driver pulley and small on driven pulley ,then rotational speeed of Driver pulley increases, resulting in a higher gear.

Ports:

B= Base or driver Pulley

F= Follower or Driven pulley

r= Variablr Transmission Ratio(Input)

4)Vehicle Body:

The vehicle body have Two-axle vehicle body in longitudinal motion.The vehicle can have same or a different number of wheels on each axle.For example,two wheels on the front axle and one wheel on the rear axle.The vehicle wheels are assumed identical in size.The vehicle ca also have a center of gravity(CG) that is at or below the plane of travel

Ports:

NR= Real axle Normal Force(N)

NF= Front Axle Normal Force(N)

Beta= Road Incline aAngle(rad)

V= Longitudinal velocity(m/s)

W= Head Wind Speed(m/s)

H = Horizontal Motion

5)Double Shoe Brake:

The Double-Shoe Brake block represents a frictional brake with two pivoted rigid shoes that press against a rotating drum to produce a braking action.The rigid shoes sit inside or outside the rotating drum in a diametrically opposed configuration. a positive actuating force causes the rigid shoes to press against the rotating drum.Viscous and cotact friction between the drum and the rigid shoe surfaces cause the rotating drum to decelerate.

Ports:

S= Rotational conserving port associated with rotating drum shaft

F= physical signal input port associated with applied associated force

6)Tire:

The Vehicle body is connected to 4 tires each per axle to move the vehicle according to the power input to the axle.

Ports:

N= Normal Force

S= Tire slip

A= Axle

H= Mechanical Translational Port associaed with the wheel hub that transmits the trust generated by the tire to the remainder of the vehicle.

Blocks Used:

• Solver Configuration- To specify the solver parameters before starting the simulation.
• PS to simulink converter- To convert Simscape signal to simulink.
• Mechanical reference- To make sure all the components are clamped to the ground.
• Generic Engine- To run the engine with speed and torque values as input.
• Rotational motion sensor- To sense the rotational motion from the engine and give output as RPM.
• Variable Gear ratio- To vary the speed according to the gear ratios.
• PS Terminator- Terminator for unconnected physical signal outputs.
• Simulink to PS converter- To convert the simulink signal to Simscale.
• Signal Builder- To Input the brake,throttle and CVT ratio.
• Scope- to View the graph of the parameters.
• Custom Measure gauge- to measurethe brake and throttle input.
• Knob- To increase,decrease and vice-versa of throttle and brake input.
• Double shoe brake- To apply brake to the vehicle when needed.
• PS constants- Generate constant physical signal.
• Rotational Free end- for mechanical component.
• Vehicle Body- To represent the BAJA ATV model body.
• Lookup Table- To insert the CVT value from workspace.
• Display- To view the calculated engine power.
• Inertia- To represent the solid inertia.
• Tire- For transportation of vehicle.
• Step- To increase or decrease an input value for a defined time interval.

BAJA ATV Model Without Dashboard

Main Components used in above model are:

Engine Sensor:

This Block measures angular velocity or angle in a mechanical rotational network the sensor is ideal since it does not account for inertia,friction,delays,engine consumption etc.

The Physical signal port W reports the angular velocity and Port A reports angular displacement.Port R relative to port C. The measurement is positive when R is greater than motion at C.

CVT System:

Vehicle Body:

Simulation Process:

• The Throttle signal is generated by signal builder block and as an input to generic engine.Brake signal is generated from signal builder and applied to vehicle body for applying brake to axle.
• Here Throttle input given 0.5 and Brake input is 0
• The Torque and Speed is input from MATLAB workspace.

• The engine will generate output rpm which can be taken from the crankshaft output.The Speed will be given to Ideal Rotational Motion sensor to sense the output rpm.
• The same output will be given to simple gear mechanism to reduce the speed where gear ratio is 10.
• Then output will be given to CVT.
• CVT ratio is provided to CVT block through signal builder.

Output:

Torque- Speed Plot:

The torque speed inputted from MATLAB workspace and given to generic engine block to generate RPM. this plot is same for all model

• Engine Velocity and Distance Plot:

From above Graph we see that the brake in not applied during drive cycle(i.e.brake input=0) and throttle is constant at 1 .

Engine Spped plot:(CVT shaft spped)

BAJA ATV Model with Dashboard

Simulation Process:

Model work flow process is same as the process of ' BAJA ATV model without Dashboard' but the throttle and brake input are controlled by the user with the knob.also replaced signal builder with two constant blocks for Throttle and Brake input.

Output: Distance and Velocity Graph

• Here condition Throttle input= 0.78 and Brake input = 0.29 and Gear ratio =10
• Thses inputs controlled by user using knob

From the graph we observe that if brake input increases velocity decreases and if throttle input increases velocity increases.From duration 10 to14 ,brake input constant upto 11 it is at 0.22 and increases from 11and 12 it becomes constant at value 0.28. in the same duration velocity decreases

CVT shaft speed:

• Here condition Throttle input= 0.78 and Brake input = 0.29 and Gear ratio =10
• From above graph we observe that CVT primart is greater than CVT secondary i.e 4800> 3200
• Frpom duration 0 to 3.9, primary and secondary both are constant at 4800 and 3200 respectively.
• From Duration 4.8 to 11 primary and secondary both are constant and at 4500 and 3100 resp.
• From dDuration 12.1 onwords both are constant at 4100 and 2900 resp.

BAJA ATV Model- Mapped with Lookup Table

Dashboard:

Flow Process:

The Workflow process is same as process of BAJA ATV model with dashboard. Only the addithion is the CVT ratio and vehicle speed are extracted using 'To workspace' block.

Workspace Before Workspace after

Instead of signal builder block for CVT ratio ,the 2-D Lookup Table is used.The interpolation and Extrapolation methods are set to linear.

Right click on lookup table block click foundation library option and then plot option to visualise lookup table

Output:

Condition, Brake input 0.1 and Throttle input 0.8 .Given this input through controlling knob.

CVT ratio:

Vehicle Speed:

From above graph it observe that if Brake input increases velocity (vehicle speed)decreses and if throttle input increases velocity (vehicle speed)increases.

CVT shaft Speed:

From above Graph it observe that CVT primary RPM is graeter than secondary RPM after 3500.Throttle is applied and then kept constant then braking applied and finally brake is released so that engine speed is increased with the increase in throttle input.

Conclusion: All the three models are analysed and plotted output in report.