Project

AIM:Carrying out a system-level simulation of an all-terrain vehicle.

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

INTRODUCTION: There are mainly 4 types of transmissions.They are:

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

A manual transmission (MT), also known as manual gearbox, standard transmission  or stick shift is a multi-speed Motor vehicle Transmission system, where gear changes require the driver to manually select the gears by operating a gear stick and clutch (which is usually a foot pedal for cars or a hand lever for motorcycles).

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.

A semi-automatic transmission is a multiple-speed transmission where part of its operation is automated (typically the actuation of the clutch), but the driver's input is still required to launch the vehicle from a standstill and to manually change gears. Most semi-automatic transmissions used in cars and motorcycles are based on conventional manual transmissions or sequencial manual transmissions, but use an automatic clutch system. However, some semi-automatic transmissions have also been based on standard hydraullic automatic transmission system with torque converters converters and planetary gearsets.

An automatic transmission (sometimes abbreviated to auto or AT) is a multi-speed transmission used in Internal combustion engine -based Motor vehicles that does not require any driver input to change forward gears under normal driving conditions. It typically includes a transmission, axle, and differential in one integrated assembly, thus technically becoming a transaxle.

STUDY - I

As illustrated in the figure 1, the CVT model created with Simulink comprises of Signal builder, a generic engine, motion sensors, the vehicle transmission, the vehicle body, the tyres, and solver configuration blocks. As indicated in figure 2, the CVT subsystem consists of the transmission block, input and output shaft inertia, and motion sensors. According to figure 3, the vehicle body subsystem consists of the vehicle body block, the double drum brake, and the tyres. The initial engine speed is listed as 2100 rpm, with mechanical rotations of 0.8 for the driven pulley and 0.7 for the driver pulley. The vehicle has two axles that link four wheels and a mass of 250 kg.

                                                                      figure 1

                                                                            figure 2

                                                                                  figure 3

Brake, throttle, and gear ratio inputs are all derived from the signal builder. Brake input is kept at 0 for the duration of the simulation. The throttle input starts at 0.3 for 20 seconds and rises to 1 for the duration of the entire simulation. The throttle valve's primary function is to regulate the amount of fuel that enters the engine; as the throttle value rises, more fuel enters the IC engine, increasing its power. As illustrated in figure, the gear ratio is held at 2.3 for 5 seconds before decreasing linearly to 1.8 and remaining constant throughout the simulation.

                                 figure 4

                                         figure 5

STUDY - II

                                                       figure 6

The model of "Baja ATV with dashboard" depicted in the above picture has a throttle metre and brake inputs rather of giving input through a signal builder. The remaining blocks and subsystems in the abovementioned baja ATV type without a dash board are similar, as can be seen in figures 2 and 3. The basic idea behind employing a dash board is to observe the results of altering the brake and throttle inputs, which demonstrate the engine's velocity and speed. According to figure 5, the gear ratio is held at 2.3 for 5 seconds before decreasing linearly to 1.8 and remaining constant throughout the experiment.

STUDY - III

As shown in the figure 7, the CVT model created with Simulink consists of step time, a generic engine, motion sensors, the vehicle transmission, the vehicle body, the tyres, and solver configuration blocks. According to figure 8, the CVT subsystem consists of the look-up table, the transmission block, the input and output shaft inertia, and motion sensors. According to figure 9, the vehicle body subsystem consists of the vehicle body block, the double drum brake, and the tyres. The initial engine speed is listed as 2100 rpm, with mechanical rotations of 0.8 for the driven pulley and 0.7 for the driver pulley. The vehicle has two axles that link four wheels and a mass of 250 kg.

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 known data points.
• A rounding is a process for approximating a value by altering its digits according to a known rule.

                                      figure 7

                                               figure 8

                                             figure 9

Step time, which is based on run time and varies correspondingly, provides the brake and throttle input. utilising a gear ratio lookup table that serves as the CVT's input, works in accordance with the input gear ratio, and produces the output. This technique is particularly efficient since it makes it simple to increase engine speed and velocity while avoiding exceptional torque at a particular speed. When the input is provided through a lookup table, it operates as a closed loop. The simulink uses a lookup table to acquire the input value and then calculates the outcome based on the input values for the gear ratio. As velocity is taken into account for both the input and output, the gear ratio ranges from 2.3 to 1.8. The maximum velocity reached as 57 kmph approximately.

                                        figure 10

STUDY - IV 

                                                figure 11

The above graphic displays a lookup table-based model of a "Baja ATV with dashboard" that includes a throttle metre and brake input on the dash board and is denoted as a constant block. The remaining blocks and subsystems in the aforementioned baja ATV type without a dash board are similar, as seen in figures 8 and 9. The primary goal of employing a dash board is to analyse the results of changing the brake and throttle inputs, which reveal changes in the engine's velocity and speed. The gear ratio is provided via a lookup table, which Simulink uses to retrieve the input value and produce results in accordance with the lookup table.The velocity and speed decrease in direct proportion to the brake input, which ranges from 0 to 0.5, and the gear ratio follows suit. The engine and shaft's velocity and speed increase as the throttle is opened wider. The transmission has a primary pulley and a secondary pulley, and the primary pulley's radius increases by compacting while the secondary pulley's radius shrinks. The torque fluctuates along with the gear ratio. The torque is exactly proportional to the gear ratio, and the gear ratio rises as the torque does. The speed and velocity decrease as the torque increases.

OUTPUTS:

Study 1:- Variation of velocity & Shaft speed

                                                 figure 12

 

The brake is kept at a steady setting while the throttle is increased to illustrate an increase in velocity. When the throttle is turned up from 0.3 to 1, the fuel flow increases and the engine's power rises as a result. At 1.8 gear ratio, the torque reaches about 7N-m, demonstrating that the gear ratio is directly proportional to the torque. This gear ratio allows for the most speed and velocity.

                                              figure 13

Because the primary shaft has a larger radius than the secondary shaft in the above illustration and because speed is directly related to radius, the primary shaft rotates at a high speed and the secondary shaft at a low speed. The speed of the shaft also increases as the radius does.

Study 2:- Variation of velocity & Shaft speed

                               figure 14

In the picture above, the vehicle's velocity is kept constant at a constant throttle value of 0.3 and varied by raising the value of the throttle, which raises the vehicle's velocity. As the brake input is increased, the vehicle's velocity decreases as seen in figure 14.

                                          figure 15

The primary shaft speed in the preceding diagram increases with increased throttle and decreases with increased brake input value, indicating that the throttle can flow more fuel, boosting the engine's power and acting similarly to the secondary shaft. The speed is directly proportional to the shaft radius, with the major shaft's radius being greater than the secondary shaft's. The speed of the shaft also increases as the radius does.

Study 3:- Variation of velocity & Shaft speed

                                   figure 16

The brake is kept at a steady setting while the throttle is increased to illustrate an increase in velocity. When the throttle is turned up from 0.3 to 1, the fuel flow increases and the engine's power rises as a result. At 1.8 gear ratio, the torque reaches about 7N-m, demonstrating that the gear ratio is directly proportional to the torque. This gear ratio allows for the most speed and velocity. The gear ratio is entered into a lookup table and provided to the simulator, which examines each input value and produces a result based on it.

                                      figure 17

The primary shaft speed in the preceding diagram increases with increased throttle and decreases with increased brake input value, indicating that the throttle can flow more fuel, boosting the engine's power and acting similarly to the secondary shaft. The speed is directly proportional to the shaft radius, with the major shaft's radius being greater than the secondary shaft's. The speed of the shaft also increases as the radius does.

Study 4:- Variation of velocity & Shaft speed

                                        figure 18

In the illustration above, the vehicle's velocity is kept constant at a constant throttle value of 0.3 and varied by raising the value of the throttle, which raises the vehicle's velocity. As the brake input is increased, the vehicle's velocity decreases as seen in figure 18. We can obtain any specific gear ratio value that is outside the range or any random value within the range by applying extrapolation and interpolation using lookup table. The lookup table functions as a closed loop by recording the velocity value.

                               figure 19

The primary shaft speed in the preceding diagram increases with increased throttle and decreases with increased brake input value, indicating that the throttle can flow more fuel, boosting the engine's power and acting similarly to the secondary shaft. The speed is directly proportional to the shaft radius, with the major shaft's radius being greater than the secondary shaft's. The speed of the shaft also increases as the radius does. We can acquire any specific value for input by adjusting the throttle and brake input values in the dashboard.

CONCLUSION:

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

                            figure 20

In the above figure, at the begining the speed reducing because of gear ratio and torque output. When the gear ratio increases, the torque increases.

2. As the brake input increases, the velocity decreases and engine power also decreases. At a certain brake input value the engine may shut down and there is no power output. The engine power is inversly proportional to the brake input.

                           figure 21

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

                             figure 22

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

                                   figure 23

In the above figure, the velocity is varying wrt the gear ratio. For the high gear ratio, the torque is more which decrease the velocity. By changing to high gear, the gear ratio become less paralelly the torque also less which can get high velocity.

4. With help of 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.