Project
Aim:
To prepare a technical report of simulation of BAJA ALL - Terrain vehicle (AVT) under different condition.
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 motorized 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 fuel economy. CVTs differ
from traditional automatic transmissions in that they don't have gears that provide "steps" between low- and high-
speed operations. Instead, the majority of them work via a pair of variable—diameter, 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 changing the "gear" ratio.
VARIABLE TRANSMlSSION 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:
Represents a system - level modeI 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.
Connections F and B are mechanical rotational conserving ports associated with the engine crankshaft and engine block,
respectively. Connections P ancl 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 signal for break and throttle.
CVT Gear Ratio Input:
Torque vs Engine speed input.
VEHICLE BODY:
OUTPUT OF CASE 1:
VEHICLE SPEED:
It is clear from the graph that the vehicle attains its maximum speed (V= 55km/hr) at full
throttle =1 after 30 seconds and then remains constant. The break input value is zero, hence
it has no effect on velocity.
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 with respect to the gear ratio.
STUDY #1:
CASE2:
SIMULINK MODEL FOR BAJA ATV WITH CVT USING DASHBOARD:
In this model we have a dashboard which contains knob to control the inputs. In this case, the inputs -
'Throttle' & 'Breake' are not provided using signal builder. A knob is provided to control both the parameters
in real -time for the user.
OUTPUT FOR CASE 2:
VEHICLE SPEED:
It can be observed from the graph that the velocity of the vehicle increases drastically from 0 to 50 Kmph when throttle
value is 0.5 & break input is 0. Once the breaking value increase from 0.1 to 0.5, the velocity of the vehicle decreases to
0 at constant throttle value. this exolains the direct relation of vehicle velocity with respect to throttle and brake inputs.
CVT SHAFT RPM:
STUDY #2:
CASE1:
SIMULINK MODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE:
CVT BLOCK
The only Difference between this model and the first model is that in this model, the gear ratio input to CVT is
provided using a lookup table. The vehicle velocity and shaft rpm outputs are same as before.
CVT GEAR RATIO:
LOOKUP TABLE VISUALISAION:
OUTPUT FOR CASE1:
VEHICLE SPEED:
CVT SHAFT RPM:
Both results are same as that of the first case:- SIMULINK MODEL FOR BAJA ATV WITH CVT since the input
parameters are same.
STUDY #2:
CASE2:
SIMULINK MODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE & DASHBOARD:
In this model a dashboard is used to control the inputs-'Throttle & Brake' with knobs.
OUTPUT FOR CASE 2:
VEHICLE SPEED:
This graph is similar to that of cvt dashboard case. The variation in vehicle velocity can be observed with change in
throttle and brake inputs. With increase in braking value, the speed of vehicle decrease. On the other hand,
increasing the throttle leads to increased vehicle velocity.
CVT SHAFT RPM:
This graph indicates the variation in rpm of primary and secondary shaft with respect to input parameters.
CONCLUSION:
Thus we have successfully analysed 4 different models of BAJA ATV WITH CVT and recorded the outputs:-
(vehicle velocity & CVT shaft rpm) with respect to variations in input throttle and brake.