Project

                                                     PROJECT:

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

ANS:

AIM: to carry out a system level simulation of all-terrain vehicle and prepare a technical report vehicle and prepare a technical report explaining the model properties and results

ALL TERRAIN VEHICLE:

An all-terrain vehicle (ATV), also known as a light utility vehicle (LUV), a quad bike, or simply a quad, as defined by the American National Standards Institute (ANSI); is a vehicle that travels on low-pressure tires, with a seat that is straddled by the operator, along with handlebars for steering control. As the name implies, it is designed to handle a wider variety of terrain than most other vehicles. Although it is a street-legal vehicle in some countries, it is not street-legal within most states, territories, and provinces of Australia, the United States or Canada.

CVT: A continuously variable transmission (CVT) is an automatic transmission that can change seamlessly through a continuous range of gear ratios. 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.

CVTs are used in automobiles, tractors, motor scooters, snowmobiles, and earthmoving equipment.

Simulink model of BAJA All-Terrain Vehicle

The above model consists of

INPUT BLOCKS:  a) Brake Input. b) Throttle Input c) CVT Gear Ratio Block

GENRIC ENGINE: a) ENGINE Sensor b) Simple Gear

CVT (Continuously variable transmission): a) variable transmission b) inertia of rotating parts

VEHICLE BODY: a) physical body b) tire c) shoe brake

INPUT SYSTEM:

SIGNAL BUILDER BLOCK:

in input system we have brake and throttle are input parameters the inputs are provided to Simulink model by using signal builder block break input is 0 and throttle input is 0.3 for 20 seconds and 1 from 20 to 80 seconds as shown in the below figure

The Signal Builder block allows you to create interchangeable groups of piecewise linear signal sources and use them in a model. You can quickly switch the signal groups into and out of a model to facilitate testing. In the Signal Builder window, create signals and define the output waveforms. To open the window, double-click the block. See Signal Groups.

GENRIC ENGINE BLOCK:

The Generic Engine block represents a general internal combustion engine. This block is a suitable generic engine for spark-ignition and diesel. Speed-power and speed-torque parameterizations are provided. A throttle physical signal input specifies the normalized engine torque. Optional dynamic parameters include crankshaft inertia and response time lag. A physical signal port outputs the engine fuel consumption rate based on the fuel consumption model that you choose. Optional speed and redline controllers prevent engine stall and enable cruise control.

ENGINE PARAMETERS:

ENGINE SENSOR:

It consists of RPM Sensor block

he Ideal Rotational Motion Sensor block represents an ideal mechanical rotational motion sensor, that is, a device that converts an across variable measured between two mechanical rotational nodes into a control signal proportional to angular velocity or angle. You can specify the initial angular position (offset) as a block parameter.

The sensor is ideal since it does not account for inertia, friction, delays, energy consumption, and so on.

Connections R and C are mechanical rotational conserving ports that connect the block to the nodes whose motion is being monitored. Connections W and A are physical signal output ports for velocity and angular displacement, respectively

From the above rerults we can see engine Speed RPM increaes from 1600 RPM to 3780 RPM in 200 Seconds

 SIMPLE GEAR

It is used in simulation in power transmission from engine to driver pully for increasing and decreasing the speed

The Simple Gear block represents a gearbox that constrains the connected driveline axes of the base gear, B, and the follower gear, F, to corotate with a fixed ratio that you specify. You choose whether the follower axis rotates in the same or opposite direction as the base axis. If they rotate in the same direction, the angular velocity of the follower, ω_F, and the angular velocity of the base, ω_B, have the same sign. If they rotate in opposite directions, ω_F and ω_B have opposite signs.

CVT (Continuously Variable Transmission)

 There is input shaft inertia represents primary pully inertia and output shaft inertia represents secondary pully inertia.

The variable Ratio Gear used to continuaslly variable transmission

The Variable Ratio Transmission block represents a gearbox that dynamically transfers motion and torque between the two connected driveshaft axes, base and follower.

Ignoring the dynamics of transmission compliance, the driveshafts are constrained to corotate with a variable gear ratio that you control. You can choose whether the follower axis rotates in the same or opposite direction as the base axis. If they rotate in the same direction, ω_F and ω_B have the same sign. If they rotate in opposite directions, ω_F and ω_B have opposite signs.

Transmission compliance introduces internal time delay between the axis motions. Therefore, unlike a gear, a variable ratio transmission does not act as a kinematic constraint. You can also control torque loss caused by transmission and viscous losses. For model details, see Variable Ratio Transmission Model.

Ports

B and F are rotational conserving ports representing, respectively, the base and follower driveshafts.

You specify the unitless variable gear ratio g_FB(t) as a function of time at the physical signal input at port r. If the signal value becomes zero or negative, the simulation stops with an error.

CVT Gear Ratio Given as Input to CVT: -

VEHICLE BODY:

Vehicle body consists of a) vehicle body b) Double Shoe break c) Tires d) inertia

MAIN VEHICLE BODY:

It is Two-axle vehicle with longitudinal dynamics and motion and adjustable mass, geometry, and drag properties

The Vehicle Body block represents a two-axle vehicle body in longitudinal motion. The vehicle can have the same or a different number of wheels on each axle. For example, two wheels on the front axle and one wheel on the rear axle. The vehicle wheels are assumed identical in size. The vehicle can also have a center of gravity (CG) that is at or below the plane of travel.

The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. Optionally include pitch and suspension dynamics. 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.

The block has an option to include an externally-defined mass and an externally-defined inertia. The mass, inertia, and center of gravity of the vehicle body can vary over the course of simulation in response to system changes. As shown in below figure

TYRE:

The Tire (Magic Formula) block models a tire with longitudinal behavior given by the Magic Formula [1], an empirical equation based on four fitting coefficients. The block can model tire dynamics under constant or variable pavement conditions.

The longitudinal direction of the tire is the same as its direction of motion as it rolls on pavement. This block is a structural component based on the Tire-Road Interaction (Magic Formula) block.

To increase the fidelity of the tire model, you can specify properties such as tire compliance, inertia, and rolling resistance. However, these properties increase the complexity of the tire model and can slow down simulation. Consider ignoring tire compliance and inertia if simulating the model in real time or if preparing the model for hardware-in-the-loop (HIL) simulation.

From the above figure we change the parameters of the Tyre

Double Shoe Brake: -

The Double-Shoe Brake block represents a frictional brake with two pivoted rigid shoes that press against a rotating drum to produce a braking action. The rigid shoes sit inside or outside the rotating drum in a diametrically opposed configuration. A positive actuating force causes the rigid shoes to press against the rotating drum. Viscous and contact friction between the drum and the rigid shoe surfaces cause the rotating drum to decelerate.

Double-shoe brakes provide high braking torque with small actuator deflections in applications that include motor vehicles and some heavy machinery. The model employs a simple parameterization with readily accessible brake geometry and friction parameters.

You can also enable faulting. When faulting occurs, the belt will exert a user-specified force. Faults can occur at a specified time or due to an external trigger at port T.

INERTIA: -

The Inertia block represents an ideal mechanical translational inertia

DOING SIMUALATION WITH DEFAULT PARAMETERS:

OUTPUT OF VEHICLE SPEED, THROTTLE AND BRAKE OUPUTS:

From the above graph we can observe that vehicle speed increases when the throttle value increses 0.3 to 1 and brake output position is constant zero position

OUTPUT OF SHAFT SPEEDS:

We can clearly observe that the output of secondary CVT is higher than the primary CVT, nearly after 30secs time duration secondary shaft rpm has crossed primary shaft rpm

WHEN WE CHANGE THE CVT GEAR RATIO:

OUTPUT OF SHAFT SPEEDS:

Here secondry shaft is greater than primary but after 98 seconds of time duration is secondary shaft is got decreased than primary shaft due change in the CVT gear ratio

Baja ATV Dashboard Model:-

Baja ATV Dashboard model is similar to CVT model here input signal builder block is replaced by constant blocks here in this model the control knobs are used as inputs for vary brake input and throttle inputs

BAJA ATV CLOSED LOOP MODEL:

Here in the above model there is a feed back signal to CVT block from vehicle body block here CVT block does not any gear ratio as input

Here look up table is the data between the CVT Gear ratio and vehicle speed.

COCLUSION:

We have succesfully analysed 3 different models of BAJA ATV WITH CVT