Project

Respected sir/madam,

I have done writing the project in google document and then copy pasted it ,so I lost the attached images.I have also attached a pdf named "BAJA ATV model project.pdf" with this submission.Please do check that out.

Thankyou

SIMULINK FOR MECHANICAL AND ELECTRICAL ENGINEERS-PROJECT

BAJA ALL TERRAIN VEHICLE

Aim:

To carry out a system-level simulation of an all-terrain vehicle(ATV) and to study and analyse BAJA All Terrain Vehicle using simulink and to compare different models.

To prepare a technical report explaining the model properties & comments on the results.

To analyse and study the difference between all the models.

Different types of models studied:

• BAJA ATV model without dashboard(open loop configuration)
• BAJA ATV Model with dashboard(open loop configuration)
• BAJA ATV Model-Mapped look up table (closed loop configuration) without dashboard:
• BAJA ATV Model-Mapped look up table (closed loop configuration) with dashboard:

Introduction:

All Terrain Vehicles:

An all-terrain vehicle (ATV), also known as a light utility vehicle (LUV), a quad bike, or simply a quad, as defined by the American National Standards Institute (ANSI); is a vehicle that travels on low-pressure tires, with a seat that is straddled by the operator, along with handlebars for steering control. As the name implies, it is designed to handle a wider variety of terrain than most other vehicles. Although it is a street-legal vehicle in some countries, it is not street-legal within most states, territories and provinces of Australia, the United States or Canada.

By the current ANSI definition, ATVs are intended for use by a single operator, although some companies have developed ATVs intended for use by the operator and one passenger. These ATVs are referred to as tandem ATVs.

The rider sits on and operates these vehicles like a motorcycle, but the extra wheels give more stability at slower speeds. Although most are equipped with three or four wheels, six-wheel models exist and existed historically for specialised applications. Multiple-user analogues with side-by-side seating are called utility terrain vehicles (UTVs) or side-by-sides to distinguish the classes of vehicle. Both classes tend to have similar powertrain parts. Engine sizes of ATVs currently for sale in the United States (as of 2008 products) range from 49 to 1,000 cc (3.0 to 61 cu in).

In this project we are going to study and analyse the modelling of Continuously Variable Transmission (CVT) BAJA All Terrain Vehicle(ATV).This model is created by Team synergy of GL Bajaj Institute of Technology and Management.

The BAJA ATV is shown below:

The 3D CAD model of BAJA is shown below:

Continuously Variable Transmission (CVT)

A continuously variable transmission (CVT) is an automatic transmission that can change seamlessly through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant RPM while the vehicle moves at varying speeds.CVTs are used in automobiles, tractors, motor scooters, snowmobiles, bicycles and earthmoving equipment.The most common type of CVT uses two pulleys connected by a belt or chain; however, several other designs have also been used at times.

The variator connected to the primary pulley,which goes outward,variator of the secondary moves inwards such that the rpm of primary is less than that of the secondary.So speed reduction happens.

The variator of primary pulley moves inwards and the variator of secondary pulley moves outwards it will cause overdrive.that is primary rpm is greater than that of the secondary.

The input shaft inertia indicates primary pulley and the output shaft inertia indicates the secondary pulley.

Main Blocks used:

Generic Engine block:

This block represents a system-level model of spark-ignition and diesel engines suitable for use at initial stages of modelling when only the basic 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 demanded from the engine as a fraction of the maximum possible torque. If the engine speed falls below the Stall speed, the engine torque is blended to zero. If the engine speed exceeds the Maximum speed, the simulation stops and issues an error message.Connections F and B are mechanical rotational conserving ports associated with the engine crankshaft and engine block, respectively. Connections P and FC are physical signal output ports through which engine power and fuel consumption rate are reported.

Simple gear block:

To specify gear ratio we use a variable gear ratio block.In Order to connect the engine and CVt we have a gear ratio box also to reduce the speed.It represents a fixed-ratio gear or gear box. No inertia or compliance is modelled in this block. You can optionally include gear meshing, backlash, and viscous bearing losses.Connections B (base) and F (follower) are mechanical rotational conserving ports. Specify the relation between base and follower rotation directions with the Output shaft rotates parameter. Optionally include thermal effects and expose thermal conserving port H by setting Friction model to a temperature-dependent setting.

Variable Ratio Transmission block:

It represents a variable ratio gearbox such as implemented by mechanical belt CVT, electric, or hydraulic transmissions. 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 between base and follower rotation directions with the Output shaft rotates parameter.

Vehicle body block:

It is used to specify vehicle parameters like vehicle mass,number of wheels per axle,drag etc..

The block parameters entered are shown below:

It represents a two-axle vehicle body in longitudinal motion. The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. The vehicle can have the same or a different number of wheels on each axle. Optionally include pitch and suspension dynamics or additional variable mass and inertia. The vehicle does not move vertically relative to the ground.

Connection H is the mechanical translational conserving port associated with the horizontal motion of the vehicle body. The resulting traction motion developed by tires should be connected to this port. Connections V, NF, and NR are physical signal output ports for vehicle velocity and front and rear normal wheel forces, respectively. Wheel forces are considered positive if acting downwards. Connections W and beta are physical signal input ports corresponding to headwind speed and road inclination angle, respectively. If variable mass is modelled, the physical signal input ports CG and M are exposed. CG accepts a two- element vector representing the x and y distance offsets from vehicle CG to additional load mass CG. M represents the additional mass. If both variable mass and pitch dynamics are included, the physical signal port J accepts the inertia of the additional mass about its own CG.

We can use a simulation data inspector to compare the vehicle speed at different masses.

Double shoe brake block:

Block parameters entered are:

It represents a brake arranged as two pivoted rigid shoes symmetrically installed inside or outside a drum and operated by one actuator. The actuator force causes the shoes to exert a friction torque on a shaft connected to the drum.Connection S is a conserving rotational terminal associated with the drum shaft. Connection F is a physical signal port representing the force input to the actuator. Positive force creates friction torque that resists shaft rotation. Optionally include thermal effects and expose thermal conserving port H by setting Thermal port to Model.

Tire (magic formula) block:

The block parameters applied are:

It represents the longitudinal behaviour of a highway tire characterised by the tire Magic Formula. The block is built from Tire-Road Interaction (Magic Formula) and Simscape Foundation Library Wheel and Axle blocks. Optionally, the effects of tire inertia, stiffness, and damping can be included.Connection A is the mechanical rotational conserving port for the wheel axle. Connection H is the mechanical translational conserving port for the wheel hub through which the thrust developed by the tire is applied to the vehicle. Connection N is a physical signal input port that applies the normal force acting on the tire. The force is considered positive if it acts downwards. Connection S is a physical signal output port that reports the tire slip. Optionally expose physical signal port M by setting Parameterize by to Physical signal Magic Formula coefficients. Physical signal port M accepts a four element vector corresponding to the B, C, D, and E Magic Formula coefficients.

Engine sensor:

The rotational output from the generic engine is given to the RPM sensor and gives engines RPM in the scope.And this rotational energy is transferred to the CVT i.e the variable ratio gear,and the output of the CVT is given the simple gear,

The other blocks used are:

• Signal builder
• Scope
• Display
• Solver configuration
• Simulink to PS converter
• PS to Simulink converter
• Mechanical reference
• Rotational free end
• Inertia
• Rotational motion sensor
• PS terminator
• PS constant
• Custom measure gauge
• Knob
• Lookup table
• Step input
• Inclination
• Integrator
• PMC ports
• Output ports
• Gain ports..etc

BAJA ATV model without dashboard:

The filename is cvtmodel.slx

• The throttle signal is generated using signal builder block and it is given as input to the generic engine
• The speed and torque vectors are given through matlab workspace.This curve is given.This is characteristics of Speed and Torque curve of the engine,this is entered by the user,the data points can be extracted by using the file exchange called Grabit and it is fed to the generic engine.

• The engine starts running and it will generate the output RPM which can be taken out from the crankshaft output and this speed is given to the engine sensor (ideal rotational motion sensor block) to sense the output RPM.
• The output from the engine sensor is given to the CVT section where the variable ratio transmission is placed.
• The inputs like throttle input and brake inputs are inputted with the help of a signal builder.

• The desired CVT ratio is created using a signal builder and it is given as an input to the CVT.

Torque and speed Matlab workspace input:

The CVT ratio vs time plot is given below:

• Inside the CVT block there are two separate ideal rotational motion sensors for measuring the RPM of both primary pulley and secondary pulley.
• CVT output is connected to the simple gearbox to reduce the speed and improve the torque,the gear box’s gear ratio is set as 4 in this model.
• In the vehicle body the brake input is given through a gain block having a gain of 1000.
• The vehicle body gives output such as the vehicle velocity and from that velocity ,displacement output is also taken with the help of an integrator block.
• The outputs displayed in the scope are vehicle velocity,displacement,throttle input,brake input and CVT shaft speed i.e,both the primary and secondary pulley RPMs

The output plots are shown below:

As we can see as the throttle input increases the velocity and distance increases.

The CVT shaft speed output plot is given below:

As we can see from the shaft output plot the primary shaft RPM gradually increases to 3300 RPM and remains constant.And the secondary shaft RPM gradually increases to 4800 RPM and remains constant .

BAJA ATV Model with dashboard:

The file name is cvtModel_dashboard.Here dashboard showing velocity,RPM,brake input and throttle input is present.The initial condition to run the simulation is to fix the brake input as 0 and throttle input as 0.5.

At the initial condition the dashboard looks like this:

As the throttle input rises the velocity increases.The brake input and the throttle input can be adjusted directly by using the knob in the dashboard.

The throttle input is given as input to the generic engine block.

The rotational motion from the generic engine is given to the engine sensor.The engine sensor is shown:

The engine sensor contains RPM sensor which measures the engine RPM.The rotational motion is now given to the CVT block.The CVT contains:

It contains variable ratio gear and two rotational sensors to measure the primary pulley RPM as well as the secondary pulley RPM. CVT ratio input is given to CVT with the help of signal builder.

CVT ratio to time plot is shown:

The CVT output is given to the simple gear ratio block to reduce the speed and to increase torque.

The velocity plot,distance plot,Throttle input,Brake input all are shown below:

The CVT primary and secondary shaft output is shown below:

As we can see the secondary shaft RPM remains constant at 4925 RPM and the primary shaft RPM remains constant at 3445 RPM.

BAJA ATV Model-Mapped look up table (closed loop configuration) without dashboard:

The filename is cvtModel_mapped.The model is shown below:

The model workflow is same as the BAJA ATV model without dashboard except that it used signal builder block for throttle input and brake input here it is using step input block.After 20s time the throttle input increases to 1 from 0.3 and remains 1 throughout.The step time for brake input is 35s.

CVT sub block:

The CVT sub block is same as the previous model BAJA ATV model without dashboard instead of the signal builder block for CVT ratio here a 2D lookup table is used.The interpolations and extrapolation methods are set to linear.It needs to be fed in the workspace having the filename ‘lookuptable_data.mat’.

What is a Lookup table?

A lookup table is an array of data that maps input values to the output values thereby approximating a mathematical function.Given a set of input values, a lookup table does explicitly define the input values.The processes: Extrapolation,Interpolation,Rounding.This block represents a physical signal converter whose input-output relationship is specified by a lookup table. The table grid must be in strictly ascending or strictly descending order, but the spacing can be non uniform.Right-click on the block and select Foundation Library > Plot Table to visualise the table data based on the selected interpolation and extrapolation methods.

Here the vehicle speed output is given as the feedback to the 2D lookup table so that we can verify that the velocity of the vehicle is changing perfectly when the CVT ratio is changing.Here the speed of the vehicle is converted to m/s from kmph.

CVT ratio vs vehicle speed plot: Lookup table visualisation

For 0 to 8 kmph the CVT ratio is 3.5 then from 10 to 38kmph it gradually decreased to 0.5 and then remains constant .

CVT ratio plot: CVT ratio vs time

As we can see the CVT ratio remains the same for 3.5 from 0 to 4sec.And then decreases to 0.5 at 35 sec and remains constant for 200 sec.

The velocity plot,throttle input,brake input plots:

As we can see from the velocity plot ,the velocity gradually increases from 4 to 38kmph within 35 sec.And then gradually increases to 66kmph.

As said earlier the throttle input remains 0.3 for 20sec and stepped to 1 for remaining time.

The brake input is 0 for all the time.

CVT shaft output plot:

BAJA ATV model mapped lookup table (closed loop configuration) with dashboard:

The filename is cvtModel_dashboard_mapped.The model is shown below:

The model workflow process is the same as the process of BAJA ATV model mapped lookup table without dashboard.Here the throttle and brake inputs are controlled by the user with knob present in the dashboard.

CVT ratio plot:

In this ATV model the engine is preset to run at 3300 rpm with the throttle value of 0.3 at the velocity of 45kmph.As we can see when the throttle input increases and the CVT ratio also increases simultaneously and when the ratio reaches 1.8 the engine speed is maximum.

Engine speed plot and Throttle input,Brake input plot is shown:

As we can see we can infer that the vehicle was running at minimum rpm of 3300rpm and then the brake is applied so it slows down and then throttle applied so the speed increases.It is clear in that plot.

CVT shaft speed plot:

As we can see from the above graph at first the shaft speed was constant and when brake applied the shaft speed decreased then throttle applied so the shaft speed increases.The blue line shows Primary shaft output and red one shows the secondary pulley rpm.