Project

AIM:

• To prepare a technical report of simulation of an All-Terrain Vehicle (ATV) under different conditions.
• By giving break input ,throttle input through input block(Signal Builder,Step,Constant) and CVT ratio through (Signal Builder,LookUpTable) we should observe the velocity, displacement of vehicle and speed of engine(Driver Pulley) and speed of wheels(Driven Pulley).

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.

KEYWORDS: BAJA ATV(All-Terrain Vehicle), CVT (Continuously Variable Transmission),Lookup Table,Dashboard.

• 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.
• 

• Continous Variable Transmission: Transmission, which transmits the power from engine to the wheels through the shafts. 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.

• 
• LookUp Table : A lookup table block uses an array of data to map input values to output values, approximating a mathematical function. Given input values, Simulink performs a “lookup” operation to retrieve the corresponding output values from the table. If the lookup table does not define the input values, the block estimates the output values based on nearby table values.
• 
• Dashboard: The blocks in the Dashboard library help you control and visualize your model during simulation and while the simulation is paused.

STUDY #1:

CASE   #1:

Simulink model of CVT based BAJA ATV:

• Simulink model of CVT based BAJA ATV consists of Signal builder, generic engine, motion sensors, vehicle transmission, vehicle body,tyres and solver configuration blocks etc., as shown in figure-1.
• The CVT subsystem includes Transmission block, input and output shaft inertia and motion sensors as shown in figure-2.
• The vehicle body subsystem includes vehicle body block, double drum brake and tyres as shown in figure-3.
• The initial engine speed is given as 1750 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. Horizontal distance from CG to front axle is 1m, Horizontal distance from CG to rear axle is 0.35m and CG height above ground is 0.7m.

                                                                     Figure :1

                                                                   Figure :2

                                                                           Figure :3

INPUTS:

• The Simulink 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 0.5  for 20 Sec  and increases to 1 for above 20 Sec as shown in figure(4). 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 given to CVT through signal builder shown in figure(5).
• the engine torque and speed curve is given as input to engine as shown in figure(6).

                                                                         Figure : 4

                                                                          Figure :5 

                                                                               Figure :6

OUTPUTS:

• Variation of Velocity :

                                                                            Figure :7

• In the above figure (7), the brake is maintained as constant and increase in throttle which shows increase in velocity of the vehicle.
• The flow of fuel is increases when the throttle increases from 0.5 to 1, thus the power in the engine increases.
• The throttle(Accelerator) is incresed suddenly from 0.5 to 1 then velocity of the vehicle dosenot increase suddenlty, it increases gradually and after some time velocity become constant(60 kmhr).

• Variation of Shaft Speed:

                                                                          Figure :8 

• In the above figure(8),initial at t=0 Sec rotational speed of engine (Primary shaft) is 1750 rpm where rotational speed of axel/wheel (secondary shaft) is zero for break =0 and throttle = 0.5, and both the shaft speed increses up to 20 Sec.
• Now the throtlle value incresed 0.5 to 1 then both the shaft speeds increses. The rotational speed of the secondary shaft(wheel) is more i.e. 5434 rpm compared to the rotational speed of primary shaft (engine) i.e. 3810 rpm.

• Variation of Displacement:

                                                                         Figure :9

From the above figure(9), The displacent of the vehicle is gradually incresed.

CASE  #2:

Simulink model for BAJA ATV with CVT using DASHBOARD:

                                                                         Figure :10

• The above figure (10) 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.
• 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.
• By increasing the throttle, the velocity and speed of the engine & shaft increases.As the brake input varies from 0 - 0.5, the velocity and speed decreases accordingly.

OUTPUTS:

• Variation of Velocity :

                                                                           Figure :11

• In the above figure (11), initially the brake is maintained as constant(i.e. 0) and throttle input is at 0.5 then the output velocity maintain 53 km/hr.
• Now increase the throttle which shows increase in velocity of the vehicle.The throttle input varies from 0.5 to 1 then the velocity of the vehicle varies from 53 to 60 km/hr and maintain contsant velocity at 60 km/hr. 
• Now apply variable break input from 0 to 0.5 the velocity of vehicle decreases respectively. If we increase break and decrease the throttle value then at paticular point velocity of the vehicle become standstill(stop). 

• Variation of Shaft Speed:

                                                                           Figure : 12

• From the above figure(12), similarly as break input increses from 0 to 0.5 then the speed of the engine (primary shaft) and speed of the wheel(secondary shaft) of the CVT are decreases respectively.
• Here the speed of the wheel (secondary shaft) of CVT is high as compared to speed of the engine (primary shaft).
• Variation of Displacement:

                                                                          Figure :13

• From the above figure(13), similarly as break input increses from 0 to 0.5 then then slope of the time to displacement is slightly down means distance traveled by vehicle decrease compared to without break.

STUDY #2:

CASE #1:

Simulink model for BAJA ATV with CVT using LookUp Table:

                                                                      Figure :14

                                                                   Figure :15                                                         

• 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:

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

• 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.

OUTPUT:

• Variation of Velocity :

                                                                          Figure :17

• In the above figure (17), the brake is maintained as constant and increase in throttle which shows increase in velocity of the vehicle. The flow of fuel is increases when the throttle increases from 0.5 to 1, thus the power in the engine increases. The throttle(Accelerator) is incresed suddenly from 0.5 to 1 then velocity of the vehicle dosenot increase suddenlty, it increases gradually and after some time velocity become constant(65 kmhr).

• Variation of Shaft Speed:

                                                                           Figure :18

• In the above figure(18),initial at t=0 Sec rotational speed of engine (Primary shaft) is 1750 rpm where rotational speed of axel/wheel (secondary shaft) is zero for break =0 and throttle = 0.5, and both the shaft speed increses up to 20 Sec. Now the throtlle value incresed 0.5 to 1 then both the shaft speeds increses. The rotational speed of the secondary shaft(wheel) is more i.e. 7570 rpm compared to the rotational speed of primary shaft (engine) i.e. 3785 rpm.

• CVT Ratio:

                                                                         Figure : 19

• In the above figure(19),initial at t=0 Sec CVT ratio is 3.5 and simulation time increases the gear ration decreases gradually upto 0.5. then this gear ratio is remaine same for overall simulation.

CASE #2:

Simulink model for BAJA ATV with CVT using LookUp Table and DASHBOARD:

                                                                      Figure :20

• The above figure(20),shows ' Simulation model for Baja ATV with CVT using LookUp Table and Dashboard' 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 dashboard .
• The main concept of using dash board is study the result by varying the input of brake and throttle, which shows that the variation of velocity and 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 speed 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.

OUTPUT:

• Variation of Velocity :

                                                                          Figure :21

• In the above figure (21), initially the brake is maintained as constant(i.e. 0) and throttle input is at 0.5 then the output velocity maintain 56 km/hr.
• Now increase the throttle which shows increase in velocity of the vehicle.The throttle input varies from 0.5 to 1 then the velocity of the vehicle varies from 56 to 66 km/hr and maintain contsant velocity at 66 km/hr. 
• Now apply variable break input from 0 to 0.5 the velocity of vehicle decreases respectively. If we increase break and decrease the throttle value then at paticular point velocity of the vehicle become standstill(stop)

• Variation of Shaft Speed:

                                                                          Figure : 22

• From the above figure(22), by increasing throttle input 0.5 to 1 then the the speed of the engine (primary shaft) and speed of the wheel(secondary shaft) of the CVT are Increases respectively.
• similarly as break input increses from 0 to 0.5 then the speed of the engine (primary shaft) and speed of the wheel(secondary shaft) of the CVT are decreases respectively.
• Here the speed of the wheel (secondary shaft) of CVT is high as compared to speed of the engine (primary shaft).
• If we decrease the throttle input less than break input then the the speed of the engine (primary shaft) overcome  the speed of the wheel(secondary shaft) of the CVT . so that vehicle velocity become very less.

• CVT Ratio:

                                                                           Figure : 23

• In the above figure(19),initial at t=0 Sec CVT ratio is 3.5 and simulation time increases the gear ration decreases gradually upto 0.5. if we increase the break value upto 0.5 then the value of gear ratio increases(LOWER GEAR) i.e.  velocity of vehicle and wheel speed decreases.
• But if we decreased the throttle value upto 0.3 and break value incresed upto 0.5 then the velocity of the vehicle become 20 km/hr , and gear ratio become very high (LOWER GEAR) then the speed of the engine  (Primay shaft) overcome the speed of the wheel (secondary shaft) i.e. vehicle speed become very less.

Conclusion:

• prepared a technical report of simulation of an All-Terrain Vehicle (ATV) under different conditions.
• In all Conditions the throttle input increases, the velocity also increases which inturn the power in the engine also increases.
• 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.
• 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.
• 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.