Project

AIM: To study the system-level simulation of an all-terrain vehicle.

KEYWORDS: CVT, lookup table, dashboard, Baja ATV.

SOFTWARE: Matlab, Simulink.

OBJECTIVE:-

1. Study-1, The Baja ATV model without a dashboard.
2. Study-2, The Baja ATV model with the dashboard.
3. Study-3, The Baja ATV model using a lookup table without the dashboard.
4. Study-4, The Baja ATV model using a lookup table with a dashboard

INTRODUCTION:-

Transmission transmits the engine's power 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, provides more usable 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 in 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 several benefits including extremely smooth shifts and exceptional fuel economy. A CVT draws top engine power from a small engine, which gives drives 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.

STUDY-1:-

The Baja ATV model without a dashboard.

Using the Simulink model of CVT consists of singal builder, generic engine, motion sensors, vehicle transmission, vehicle body, tyers, and solver configuration blocks, etc., as shown in the fig-1. The CVT subsystem includes transmission block, input and output shaft inertia, and motion sensors as shown in fig-2. The vehicle body subsystem includes vehicle body block, double drum brake, and tyers as shown in fig-3. The initial engine speed is given as 2100rpm, mechanical rotation for driven pulley and driver pulley as 0.8 & 0.7 respectively. The mass of the vehicle is 250kg and 2 axles which connects 4 wheels accordingly.

FIG-01:-

FIG-02:-

FIG-03:-

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 for 20sec and increases to 1 for the overall simulation. the throttle valve mainly controls that flow or amount of fuel increases to the IC engine which in turn 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 fig(4-5)

FIG-04:-

FIG-05:-

STUDY-2:-

The Baja ATV model with the dashboard.

The above fig shows Baja ATV with dashboard model which consists of throttle meter and brake input in the dashboard instead of giving output through the signal builder. The rest of the blocks and subsystems are common in the above Baja ATV model without a dashboard as shown in fig 2&3.THe main concept of using the dashboard is to 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 fig 5. As the brake input varies from 0-0.5, the velocity and speed decrease accordingly.By increasing the throttle, the velocity, and speed of the engine & shaft increase.

FIG-06:-

STUDY-3:-

The Baja ATV model using a lookup table without the dashboard.

By using the Simulink model of CVT consists of stop time, generic engine, motion sensoe=rs, vehicle transmission, velocity body, tire and solver configuration blocks, etc., as shown in fig-7. The CVT subsystem includes a lookup table, Transmission block, input and output shaft inertia, and motion sensors as shown in fig-8. The vehicle body subsystem includes vehicle body block, double drum brake, and tires as shown in the fig-9. The initial engine speed is given as 2100 rpm, mechanical rotation for driven pulley as 0.8 & 0.7 respectively. The mass of the vehicle is 250kg and 2 axles which connect the four-wheel accordingly.

A lookup table is an array of data that maps input values to output values, thereby approximating a mathematical function. Given a set of input values, a lookup operation retrieves the corresponding output values from the table. If the lookup table does not explicitly define the input values, Simulink can estimate an output value using interpolation, extrapolation, or rounding, where:

• An interpolation is a process for estimating values that lie between known data points.
• An extrapolation is a process for estimating values that lie beyond the range of know data points.
• A rounding is a process for approximating a value by altering its digits according to a known rule.

FIG-07:-

FIG-08:-

FIG-09:-

The brake input and throttle input is given by step time, which depends on the run time and varies accordingly. By using a 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 a certain speed and very easy to achieve greater velocity and engine speed. It works as a closed-loop when the input is given by a lookup table. The Simulink het the input value from a 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 in terms of velocity. The maximum velocity reached 57kmph approximately.

WORKSPACE:-

FIG-10:-

STUDY-4:-

The Baja ATV model using a lookup table with a dashboard

FIG-11:-

FIG-12:-

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

FIG-13:-

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

STUDY-2:-Variation of velocity & shaft speed

FIG-14:-

In the above fig, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 varying by increasing the value of the throttle which increases the velocity of the vehicle. By increasing the brake input, the velocity of the vehicle decreases accordingly which is shown in fig-14.

FIG-15:-

In the above fig, 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 is 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:-Variation of velocity & shaft speed

FIG-16:-

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

FIG-17:-

In the above fig, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 varying by increasing the value of the throttle which increases the velocity of the vehicle. By increasing the brake input, the velocity of the vehicle decreases accordingly which is shown in fig-14.

STUDY-4:-Variation of velocity & shaft speed

FIG-18:-

In the above fig, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 varying by increasing the value of the throttle which increases the velocity of the vehicle. By increasing the brake input, the velocity of the vehicle decreases accordingly which is shown in fig-18. By using a lookup table, it works as a 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 a lookup table.

FIG-19:-

In the above fig, 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 is 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 valve and brake input value can be varying in the dashboard, so we can get any particular value for the input.

CONCLUSION:-

1. As the throttle increases, the velocity also increases which in turn the power in the engine also increases.

FIG-20:-

In the above fig, a the beginning the speed reduces because of gear ratio and torque output. When the gear ratio increases, the torque increases.

2. As the brake input increases, the velocity decrease, and engine power also decrease. at a certain brake input value the engine may shut down and there is no power output. That engine power is inversely proportional to the brake input.

FIG-21:-

3. As the gear ratio increases, torque increases which in turn velocity decreases.

FIG-22:-

In the above fig, the torque is increasing by an increase in engine speed. At a particular point, the torque is decreasing when the gear ratio increases to achieve max velocity.

FIG-23:-

In the above fig, the velocity is varying wrt the gear ratio. For the high gear ratio, the torque is more which decreases the velocity. By changing to high gear, the gear ratio becomes less parallelly the torque also less which can get high velocity. With help of the lookup table, we can vary any input value and also get the output value by using interpolation and extrapolation method which the Simulink can solve.