Project
CARRY OUT A SYSTEM LEVEL SIMULATION OF AN ALL-TERRAIN VEHICLE.
AIM:To prepare a technical report simulation of BAJA ALL Terrain vehicle under diferent conditions.
OBJECTIVE:
Carry out a system level simulation of an ALL terrain vehicle and prepare a technical report explaining the model properties and comments on the results.
ALL TERRAIN VEHICLE:
An All terrain vehicle ATV is defined as a motorized off highway vehicle designed to travel on four low-pressure or non-pneumatic tires having a seat designed to be straddled by the operation and handle bars for steering control.
COMPENENTS OF BAJA ATV;Vehicle body,suspension,tire,engine,and ctv.
PARTS USED IN SIMUALTION OF ATV:-
Signal builder
brake throttle as input
engine
engine sensor
solver
CVT
vehicle body
CVT ratio
gear
goto
scope
brake, etc.
MAJOR COMPONENTS IN THE MODEL:
Continuously varible transmission drive (CVT):
PARTS IN CVT;Primarypulley,Secondarypulley,Variator,Belt,Speedreduction Rp<Rs,overdrive Rp>Rs,decrease radius,increase radius.
If the primary pulley moves in the inwards than the secondary pulley moves in outwards direction the sceondary moves inward direction and the primary moves the outward direction.
According simulation model the CVT contains some blocks they are: inputshaft inertia,variable ratio gear, output shaft inertia,CVT primary rpm,CVT secondary rpm.
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 fuel economy CVTs differ from traditional automatic transmission in that they dont have gears that provide steps between low and high-speed operations.Instead the majority of them work via a pair of variable diameter cine shaped pulleys connected by a steel or composite belt. the havles of each pulley are aligned with the pointed ends of the cones 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,there by changing the gear ratio.
VARIBLE TRANSMISSION RATIO:
Represented a variable ratio gearbox such as implemented by mechanical belt CVT electric or hyderulic transmission they physical signal input are defined the ratio of input to output angular shaft velocities connections B(BASE) and F(Follower) are mechanical rotational base and follower rotational directions with the output shaft rotates parameter.
ENGINE:
Represented a system level model of spark ignition and diesel engine suitable for use at initial stages of modelling when only the basic parameter are available.Optional idel 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 crank shaft and engine block,respectively connections P and FC are physical signal output ports through which engine power and fuel consumption rate are reported.
INPUT SIGNALS: A Signal builder is used to create signals for brake and throttle are below uploaded.
CVT GEAR RATIO INPUT: the input of gear ratio is uploaded below.
TORQUE vs ENGINE SPEED INPUT: the torque vs engine speed input is uploaded below.
ENGINE RMP is uploaded below.
CASE:In this the lookup table is add inplace of cvt ratio.the terminal of cvt ratio is connected to the vehicle body velocity terminal.
OUTPUT:-
VEHICLE SPEED: It is clear from the graph that the vehicle attains its maximum speed (v=55km/hr) at full throttle=1 after 30seconds and then remains constant the brake input is zero.hence it has no effect on velocity.
CVT SHAFT RPM: These graph shows the variation in angular velocities of input and output shafts of the variables gear transmission system.these values differ with respect to the gear ratio.
CASE:2 SIMULINK MODEL FOR BAJA ATV WITH CTV DASHBOARD.
The output of ATV with dashboard with differenet velocity are uploaded in the below and output of CVT also uploaded below.
In this model we have a dashboard which conatins the inputs.In this case the inputs "throttle and brake" are not provided using signal block A knob is provided to control both the parameter in real-time for the user.
OUTPUT OBSERVATION: It can be observed from the graph that the velocity increase drastically from 0to50kmph when throttle value is 0.5 and brake input is 0.Once the braking value increase from 0.1 to0.5 the velocity of the vehicle decease to 0 at constant throttle value.this explains the direct relation of vehicle with respect to throttle and brake inputs.
CASE :in this the look up table also connected in the simulation, the lookup table is connected in the cvt block in this the only difference between this model and the first model is,In the model the gear ratio input to cvt is provided using a lookup table the vehicle velocity and shaft rpm outputs are same as before.
CONCLUSION:
In this the AVT model is explained in different cases with dashboard and without dashboard and with lookup table the BAJA ATV with CTV the output are uploaded below the output of vehicle velocity and ctv shaft rpm with respect to variations in inputs throttle and brake is done perfectly.