Project
Aim:
To prepare a technical report of simulation of BAJA All-Terrain Vehicle (ATV) under different conditions.
Objectives:
Carry out a system -level simulation of an all -terrain vehicle and prepare a technical report explaining the model properties & comments on the results.
ALL TERRAIN VEHICLE:
An all-terrain vehicle(ATV) is defined as a monitorized off-highway vehicle designed to travel 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 components 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 variety of driving conditions.That means low gears can provide better acceleration while higher gears can maximize fueel economy .CTVs differ from traditional automatic transmissions in that theyy don't have gears that provide "steps" between low and high speed operations. Instead ,the majority of them work via a pair of variable diagram ,cone-shaped pulleys connected by a steel or composite belt.The halves of each pulley are aligned with the pointed ends of the cones touching .These form a V-shaped groove in which the connecting belt rides. One side of the pulley is fixed and the other side is movable ,actuated by a hydraulic cylinder .The cylinder can increase or decrease the amount of space between the two sides of the pulley .This allows the belt to ride lower or higher along the walls of the pulley,depending on driving conditions ,thereby changinig the "gear" ratio.
VARIABLE TRANSMISSION RATIO:
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.
ENGINE:
Represseents a system-level model of spark-ignition and diesel engines suitable for use at initial stages of modeling 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.
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.
INPUT SIGNAL:
A signal builder is used to create signals for brake and throttle.
CVT Gear ratio input:
Torque vs Engine speed input:
Vehicle body:
OUTPUT FOR CASE1
VEHICLE SPEED:
It is cleared from graph that the vehicle attains its maximum speed(V=55km/hr) at full throttle = 1 after 30 seconds and then remain constant.
CVT SHAFT RPM:
These graphs shows the variation in angular velocities of input and output shafts of the variable gear transmission system.these values differ wrt gearratio.
STUDYCASE2
SIMULINK MODEL FOR BAJA ATV WITH CVT USING DASHBOARD:
In this modal we have a dashboard which contains knobs to control the innputs in the case ,the inputs throttle,brake are not provided to control both the parameteers in real time for the user.
OUTPUT FOR CASE2:
VEHICLE SPEED:
It can be observed from the graph that the velocity of the vehicle increasess drastically from 0 to 50kmphr when throttle value is 0.5 and brake input 0 .once the breaking value increases from0. 1 to 0.5 ,thhe velocity of the vehicle decreasess to 0 at constant throttle .
CVT SHAFT RPM:
STUDYCASE2
SIMULINK MODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE:
CVT BLOCK:
The only differrence between this model and first model is that in this model,the gear ratio input to CVT is provided using a lookup table.
CVT GEAR RATIO:
LOOKUP TABLE VISUALISATION :
OUTPUT FOR CASE1
VEHICLE SPEED
CVT SHAFT RPM:
Both results are same as that of first case :SIMULINK MODEL FOR BAJA ATV WITH CVT since the inputt parameteers are same.
STUDYCASE2:
SIMULINKMODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE & DASHBOARD:
In this modal a dashboard is used to control the inputs-throttle &brake with knobs
OUTPUT FOR CASE2
VEHICLE SPEED
This graph is similar to that of cvt dashboard case.The variation in vehicle velocity can be observed with change in throttles and gear inputs.
CVT SHAFT RPM:
This graph indicates the variation in rpm of primary and secondary shafts wrt input parameters.
CONCLUSION:
Thus we have successfully analysed 4 differeent modals of BAJA ATV WITH CVT and recorded outputs(Vehicle velocity &CVT shaft rpm) wrt variations in input throttle and brake.