Project
>Introduction:-
>An all-terain vehicle(ATV), also known as a quad(cycle), three-wheeler, four-track, four-wheeler or quadri-cycle as defined the American Ntional Standard Institute(ANSI) is vehicle that travells on low pressure tires, with a seat that is stradeled by the operator, along with handle bars for steering control.It's designed to handle awider varity of terrain than most other vehicles.
>Baja SAE is an iter-polligiate design competeton run by the SOciet Of Automotive Engineer(SAE).
>Teams of students from universities all over the design and build samll off-road cars, the cars all have engines of the same specifications.
>As of 2009, the engine has been an unmodified capital briggs & Straton Intek 20 single-cylinder with a displacement of 30 cc and a power output of approximetly 10 bhp(7.5kw).
>MAjor And Crucial Compenets:-
(1)CVT:
>The meaning of the abbrivation CVT is continously Variable Transmission, and it is atype of a single-speed automatic gear box. The CVT gear box is used in lot of cars, but you will usually find it fitted to a small car. It's compact sixe and simplicty of construction is more cost effective to use in a small car than a conventional gear box.
(2)Vehicle Body:
>A Baja ATv of two axle type vehcile with longitudnal dynamics and motion, has adjustable mass, geometry, drag and drag properties. The vehicle may have the same or a different no. of wheels on each axle. For ex, two wheels on the front axle and one wheel on the rear axle. The vehicle wheels are assumed identical in size. The vehicle can also have centre of gravity(CG) i.e. oer below the plane of travel so the vitigates the chances of rolling over.
where,
NR- Rear Axle Normal Force(N),
Beta- Road Incline Angle(rad),
V- Logitudnal velocity(m/s),
W- Head Wind Speed(m/s)&
H- Horizontal motion
(3)Genric Engine:
>A generic engine block represents a general Internal Cumbustion (IC) engine which is a type of compression Ignition Engine (CI-diesel) or Spark Ignition(SI) petrol. The speed torque and speed power parameters are provided by the design
where,
B- Rotational Conserving Port represtaing the engine block
F- Rotational Conserving Port represtaing the engine crank shaft.
T- Physical signal input port specifying the normalized engine throttle level.
P- Physical signal output port reporting the instantaneous engine power, in W.
Fc- Physical signal output port repoting the fuel consuption rate, in kg/s
(4)Simple Gear:
>A simple gear is combination of a driver and a driven gear whee the speed is reduced by the gear ratio. The gear ratio is defined as:
Gear ratio= Follower gear speed/base gear speed
where,
B- Base gear or driver gear
F- Follower gear or driven gear
(5)Tires and brakes:
>The vehicle body is connected to four tires each per code to move give vehicle according to power input to the axle.
where,
N- Normal force
s- Tire snip
A- Axle
H- Mechanical Translation pot associated with wheel hub that transmits the thrust generated by the btire to the remainde rof the vehicle.
>Study Of the Baja ATV model with a Dashboard:-
Simulink Model:
>In this model, a dashboard with knobs is used to controlboth the inputs that are Throttle & Brake.
>The visualiztion of CVT with the lookup table and overallmodification of the CVT blocks are shown.
Inputs:
>One signal builder block is used to create signal for brake and throttle and another one is used to create the required CVT ratio.
Outputs:
>The graph shows that the input were given manually to obsereve the desired varriations and the vehicle's speed respone to that.
>The throttle is increased fro 0.3 to 1 value in an increasing staircase manner and the brake was applied at different points of time after the throttle gets value 1. Increasing throttle increases speed over time and settle at 55km/hr.
>But, after that instance where the brake was applied, there is a decrese in the vehicle velocity.
>The brake value of 0.4 was the highest, so the graph properly justifies the vehicle behavior.
CVT Primary and Secondary Speed:
>Here we have both CVT primary and secondary RPMs; The initial increase and settlrement were for throttle value 0.3 when there is no brake applied yet.
>After that, the behaviur is the result in variation in both the inputs.
>After the time when throttle is having value of 1, all the variation bascially result from the application of the bake.
>The downsteps are when the brake is applied and the immediate upsteps are the result of the releasing the brake.