Project

Aim:

To prepare a technical report of Simulation of BAJA All-Terrain Vehicle (ATV) under different various conditions.

Objectives:

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 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 good to have more gears in a transmission, since it can control engine speed in a variety of driving conditions. That means low gears can provide better acceleration while higher gears can maximize fuel econom. 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.

CVT Block:

VARIABLE TRANSMISSION RATIO:

It Represents a variable ratio gearbox such as implemented by mechanical belt CVT, or hydraulic transmissions. The physical signal input are defines the ratio of input to output angular shaft velocities.

Connections B (base) and F (follower) are mechanical rotational conserving ports. The relation between base and follower is rotation directions with the Output shaft rotates parameter.

ENGINE:

It 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 present between zero and one and specifies the torque demanded from the engine as a fraction of the maximum torque.

The Connections F and B are mechanical rotational conserving ports associated with the engine crankshaft and engine block, respectively.The 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 CASE 1:

VEHICLE SPEED:

In this 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 brake input value is zero, hence it has no effect on velocity.

CVT SHAFT RPM:

In this 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:

We have a dashboard which contains knobs to control the inputs in this modeler. In this case, the inputs- ‘Throttle’ & ‘Brake’ are not provided using signal build. A knob is provided to control both the parameters in real-time for the user.

OUTPUT for CASE 2:

VEHICLE SPEED:

Here we can be observed from the graph that the velocity of the vehicle increases drastically from 0 to 50kmph when throttle value is 0.5 & brake input is 0. The braking value increases from 0.1 to 0.5, the velocity of the vehicle decreases to 0 at constant throttle value. This explains as their is direct relation of vehicle velocity with respect to throttle and brake inputs.

CVT SHAFT RPM:

STUDY 2:

CASE 1:

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.

LOOKUP TABLE VISUALISATION:

OUTPUT for CASE 1:

VEHICLE SPEED:

CVT SHAFT RPM:

Both results are same as that of the first case: - SIMULINK MODEL FOR BAJA ATV WITH CVT the input parameters are same.

STUDY 2:

CASE 2:

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 changes in throttle and brake inputs. With increase in braking value, the speed of vehicle decreases. 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 shafts with respect to input.

CONCLUSION:

Have we 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 of throttle and brake.