Project

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

OBJECTIVE -

1. To check the speed of the vehicle for the given initial conditioin.
2. By applying the Brake and also changing the value of Throttle ,we have to compre the result.
3. To study the plot of CVT shaft speed,also the plots of Vehicle speed,Throttle and Brake w.r.t Time.

THEORY -

1. All terrain Vehicle(ATV) -An All Terrain Vehicle (ATV) is also known as Light Utility Vehicle (LUV) is defined as a vehicle that travels on low pressure tires,with a seat that is straddled by the operator, along with handlebars for steering control.

2.Continuously Variable Transmission (CVT) - CVT is an Automatic Transmission that can change seamlessly through a continuous range of gear ratio.

This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant RPM while the vehicle moves at varying speeds.

SIMULINK MODEL-

Simulink Model For BAJA ATV Model With Dashboard-

Block Used -

• Constant Block - To input the value of Brake and Throttle this block is used .

• Generic Engine Block - Represents a system-level model of spark-ignition and diesel engines suitable for use at initial stages of modeling when only the basic parameters are available.
• Engine Sensor Subsystem -

• Signal Builder Block -The Signal Builder Block allows us to create interchangeable groups of piecewise linear signal sources and use them in a model.
• CVT Subsystem -

• Input And Output Shaft Inertia -

  The block represents an ideal mechanical rotational inertia.

  The block has one or two mechanical rotational conserving ports. The difference is purely graphical, as the ports are rigidly linked. The block positive direction is from its port to the reference point. This means that the inertia torque is positive if the inertia is accelerated in the positive direction.

• Varable Ratio Gear -

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

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

• Ideal Rotational Motion Sensor -

  This block measures angular velocity or angle in a mechanical rotational network. The sensor is ideal since it does not account for inertia, friction, delays, energy consumption, and so on.

  The physical signal ports W and A report the angular velocity and angle, respectively, of port R relative to port C. The measured angular velocity is positive when the angular velocity at port R is greater than the angular velocity at port C.

• Simple Gear -

Represents a fixed-ratio gear or gear box. No inertia or compliance is modeled in this block. You can optionally include gear meshing and viscous bearing losses.

Connections B (base) and F (follower) are mechanical rotational conserving ports. Specify the relation between base and follower rotation directions with the Output shaft rotates parameter. Optionally include thermal effects and expose thermal conserving port H by setting Friction model to a temperature-dependent setting.

Vehicle Body Subsystem -

BLOCKS USED -

• Vehicle Body -

Represents a two-axle vehicle body in longitudinal motion. The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. The vehicle can have the same or a different number of wheels on each axle. Optionally include pitch and suspension dynamics or additional variable mass and inertia. The vehicle does not move vertically relative to the ground.

Connection H is the mechanical translational conserving port associated with the horizontal motion of the vehicle body. The resulting traction motion developed by tires should be connected to this port. Connections V, NF, and NR are physical signal output ports for vehicle velocity and front and rear normal wheel forces, respectively. Wheel forces are considered positive if acting downwards. Connections W and beta are physical signal input ports corresponding to headwind speed and road inclination angle, respectively. If variable mass is modeled, the physical signal input ports CG and M are exposed. CG accepts a two- element vector representing the x and y distance offsets from vehicle CG to additional load mass CG. M represents the additional mass. If both variable mass and pitch dynamics are included, the physical signal port J accepts the inertia of the additional mass about its own CG.

• TIRE -

  Represents the longitudinal behavior of a highway tire characterized by the tire Magic Formula. The block is built from Tire-Road Interaction (Magic Formula) and Simscape Foundation Library Wheel and Axle blocks. Optionally, the effects of tire inertia, stiffness, and damping can be included.

  Connection A is the mechanical rotational conserving port for the wheel axle. Connection H is the mechanical translational conserving port for the wheel hub through which the thrust developed by the tire is applied to the vehicle. Connection N is a physical signal input port that applies the normal force acting on the tire. The force is considered positive if it acts downwards. Connection S is a physical signal output port that reports the tire slip. Optionally expose physical signal port M by setting Parameterize by to Physical signal Magic Formula coefficients. Physical signal port M accepts a four element vector corresponding to the B, C, D, and E Magic Formula coefficients.

• Double Shoe Brake -

  Represents a brake arranged as two pivoted rigid shoes symmetrically installed inside or outside a drum and operated by one actuator. The actuator force causes the shoes to exert a friction torque on a shaft connected to the drum.

  Connection S is a conserving rotational terminal associated with the drum shaft. Connection F is a physical signal port representing the force input to the actuator. Positive force creates friction torque that resists shaft rotation. Optionally include thermal effects and expose thermal conserving port H by setting Thermal port to Model.

• P S Terminator -

  Use this block to terminate physical signal outputs. Unconnected physical signal output ports do not generate warnings, but connection to a PS Terminator can be used to indicate that the signal was not inadvertently left unconnected.

RESULT -

From the above figure the conclusion comes that with increasing the throttle the velocity increases, and by applying the brakes the velocity of vehicle decreases.

Conclusion Of CVT Shaft Speed -

when the variator of primary pulley goes outward and variator of secondary pulley goes inward it will lead to speed reduction , whereas variator of primary pulley goes outward and also the vriator of secondary pulley goes outwards then it will lead to overdrive.

Engine Torque Speed Curve -

Engine RPM Curve -

CVT Ratio Values Using Signal Builder Block -

From the above results Simulation of an All Terrain Vehicle Studied and conclusion were made.