Project

EV BATCH-17

1. Carry out a system-level simulation of an all-terrain vehicle.

Download the model from the given link:

https://www.mathworks.com/matlabcentral/fileexchange/70576-baja-all-terrain-vehicle-atv-model

Prepare a technical report explaining the model properties & comments on the results.

AIM:

To Carry out a system-level simulation of an all-terrain vehicle

KEYWORDS: CVT, lookup table, Dashboard, baja ATV

SOFTWARE: Matlab, Simulink

OBJECTIVE:

1. Study the baja ATV model without dashboard.
2. Study the baja ATV model with dashboard.
3. Study the baja ATV model using lookup table without dashboard.
4. Study the baja ATV model using lookup table with dashboard.

THEORY:

Transmission, which transmits the power from engine to the wheels through the shafts. It consists of 4 types mainly,

• Manual transmission
• Continous variable transmission
• Semi-automatic transmission
• Automatic transmission

A continuously variable transmission, or CVT, is a type of automatic transmission that provides more useable power, better fuel economy and a smoother driving experience than a traditional automatic transmission. The CVT is a system that makes it possible to vary stepless the transmission ratio without interruption of the torque flow. Therefore an infinite number of ratios (between a minimum and maximum value) are possible. It is an automatic, single speed. and gearless transmission that can shift through an infinite number of gear ratios.

• This ability to seamlessly shift through these different gears provides a number of benefits including extremely smooth shifts and exceptional fuel economy.
• A CVT draws top engine power from a small engine, which gives drivers quicker acceleration than standard automatic transmissions.
• Because of their greater ability to control the engine speed range, CVTS produce fewer emissions. CVTS are also lighter weight than traditional automatic transmissions.

EXPLANATION:

## Study-1:

• By using simulink model of CVT consists of Signal builder, generic engine, motion sensors, vehicle transmission, vehicle body,tyres and solver configuration blocks etc., as shown in above figure.

>> CVT model:

• The CVT subsystem includes Transmission block, input and output shaft inertia and motion sensors as shown in Above figure.
• The meaning of the abbreviation CVT is Continuously Variable Transmission, and it's a type of single-speed automatic gearbox.
• The CVT gearbox has been used in a variety of cars, but you'll usually find it fitted to a small car. Its compact size and simplicity of construction means it's more cost-effective to use in a small car than a conventional automatic gearbox.
• If you compared them back-to-back, the manual model would have better claimed fuel economy, too. But again, that's the same as you'll find with a regular auto 'box.

>> Vehicle Body:

• The vehicle body subsystem includes vehicle body block, double drum brake and tyres as shown in above figure. The initial engine speed is given as 2100 rpm, mechanical rotation for driven pulley and driver pulley as 0.8 & 0.7 respectively.
• The mass of the vehicle as 250kg and 2 axles which connects 4 wheel accordingly.
• Vehicle Body is Two-axle vehicle with longitudinal dynamics and motion and adjustable mass,geometry and drag properties. The vehicle can have the same or a different number of wheels on each axle
• The Vehice Body contains given below terminals

> NR- Rear axle normal force

> NF- Front axle normal force

> beta- Road incline angle

> V- Longitudinal velocity

> W- Head wind speed

> H- Horizontal motion

>> Simple Gear:

• The most common use is in motor vehicles, where the transmission adapts the output of the internal combustion engine to the drive wheels.
• Such engines need to operate at a relatively high rotational speed, which is inappropriate for starting, stopping, and slower travel.
• The transmission reduces the higher engine speed to the slower wheel speed, increasing torque in the process. Transmissions are also used on pedal bicycles, fixed machines, and where different rotational speeds and torques are adapted.

>> Generic Engine:

The Generic Engine block represents a general internal combustion (IC) engine which is a type of Spark Ingition (SI-Petrol) or Compression Ignition (CI-Diesel). The speed torque and speed power parameters = provided.

• B - Rotational conserving port representing the Engine Block level.

• F - Rotational conserving port representing the Engine Crankshaft.

• T - Physical signal input port specifying the normalized engine throttle.

• P - Physical signal output port reporting the instantaneous engine power in W.

• FC - Physical signal output port reporting the fuel consumption rate, in kg/s.

>> Signal Builder:

• The signal builder is used as input for brake, throttle and gear ratio. Brake input is maintained as 0 for overall simulation. The throttle input is given as 0.3 for20 secs and increases to 1 for overall simulatuion.
• The throttle valve is mainly to control the flow or amount of fuel into the engine, if the throttle value increases the flow of fuel increases to the IC engine which inturn increases the power of the engine.
• The gear ratio is maintained as 2.3 for 5 secs and linearly decreases to 1.8 and maintained constant for overall simulation as shown in figure (4-5).

## Results:

>> Variation of Velocity and shaft Speed:

• In the above figure, the brake is maintained as constant and increase in throttle which shows increase in velocity. The flow of fuel is increses when the throttle increases from 0.3 to 1, thus the power in the engine increases.
• The torque reaches approximately 7N-m at 1.8 gear ratio, which defines that gear ratio is directly proportional to the torque. By this gear ratio, the speed & velocity can achieve maximum.

• In the above figure, the primary shaft reaches high speed and secondary shaft as low rotational speed because the radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the radius increases the speed of the shaft also increases.

## Study-2:

>> Study the baja ATV model with dashboard.

• The above figure shows 'Baja ATV with dashboard' model which consists throttle meter and brake input in the dash board instead of giving input through signal builder.
• Rest of the blocks and subsystems are common in the above baja ATV model without dash board as shown in figure 2 & figure 3.
• The main concept of using dash board is study the result by varying the input of brake and throttle, which shows that the velocity and speed of the engine.
• The gear ratio is maintained as 2.3 for 5 secs and linearly decreases to 1.8 and maintained constant for overall simulation as shown in figure.
• As the brake input varies from 0-0.5, the velocity and speed decreases accordingly. By increasing the throttle, the velocity and speed of the engine & shaft increases.

Results:

Dashboard:

While observing the above shown figure when the simulation of 50sec stop time then the RPM and velocity will increase it shown in above fig

>> Output 1:

output graph represents the response of the velocity ,current ,throtle, break with respect to sample time.

• In the above figure, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 and varying by increasing the value of throttle which increases the velocity of vehicle.
• By increasing the brake input, the velocity of the vehicle decreasing accordingly which shown in above figure

>> Output 2:

The graph represents the shaft spped vs CVT primary RPM and CVT secondary rpm.

• In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft.
• The radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the radius increases the speed of the shaft also increases

## Study-3:

The baja ATV model using lookup table without dashboard.

• The brake input and throttle input is given by step time, which depends on the run time and varies accordingly. By using Lookup table for gear ratio which takes as input to the CVT and works according to the input gear ratio and obtained the output.
• This method is very effective which can avoid the unusual torque at the certain speed and very easy to achieve greater velocity & engine speed. It works as closed loop when the input is given by lookup table.

• The simulink get the input value from lookup table and obtain the result according to the input values of gear ratio. The gear ratio varies from 2.3 to 1.8 as taken as input and output interms of velocity.
• The maximum velocity reached as 57 kmph approximately.

Results:

>> Output 1:

The graph represents the charaterstics of vehilce speed vs velocity,trottel,break input.

• In the above figure, the brake is maintained as constant and increase in throttle which shows increase in velocity. The flow of fuel is increses when the throttle increases from 0.3 to 1, thus the power in the engine increases.
• The torque reaches approximately 7N-m at 1.8 gear ratio, which defines that gear ratio is directly proportional to the torque.
• By this gear ratio, the speed & velocity can achieve maximum. The gear ratio is assigned in lookup table and given as input to the simulink which reads every input value and obtain the result according to the input.

>> Output 2:

The graph represents the shaft spped vs CVT primary RPM and CVT secondary rpm.

• In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing bre input value, which defines that the throttle can flow more amount of fuel which increases the power of the eng and similar to the secondary shaft.
• The radius of the primary shaft as more than the secondary shaft, the spee is directly proportional to the radius of the shaft. As the radius increases the speed of the shaft also increases.

## Study4:

Study the baja ATV model using lookup table with dashboard.

• The above figure shows 'Baja ATV with dashboard' model using lookup table which consists throttle meter and brake input in the dash board and indicated as constant block. Rest of the blocks and subsystems are common in the above baja ATV model without dash board as shown in above figures.
• The main concept of using das board is study the result by varying the input of brake and throttle, which shows that the variation of velocity anc speed of the engine.
• The gear ratio is given by lookup table, simulink get the input value from the lookup table and obtain the result according to the lookup table. As the brake input varies from 0-0.5, the velocity and speec decreases accordingly which inturn the gear ratio also decreasing.
• By increasing the throttle, the velocity and speed of the engine & shaft increases. The transmission as primary pulley and secondary pulley, in which the radius of primary pulley increses by compacting and the radius of secondary pulley decreases.
• As the gear ratio varies, the torque also varies. Gear ratio is directly proportional to the torque, which increases by increasing the gear ratio. At the max torque, the speed and velocity is decreases.

Results:

>> Output1:

The graph represents the charaterstics between the speed vs velocity and throtle and break input.

• In the above figure, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 and varying by increasing the value of throttle which increases the velocity of vehicle.
• By increasing the brake input, the velocity of the vehicle decreasing accordingly which shown in above figure.
• By using lookup table, it works as closed loop by recording the velocity value and we can get at any particular value of gear ratio which is beyond the range or any random value within the range by using extrapolation and interpolation by lookup table.

>> Output2:

The below graph represents the charaterstics between the shaft speed vs CVT primary and secondary rpm

• In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft.
• The radius of the primary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the radius increases the speed of the shaft also increases.
• The throttle value and brake input value can be varying in dashboard, so we can get any particular value for input.