BAJA All Terrain Vehicle (ATV)

Aim of the project :- To carry out a system-level simulation of an all terrain vehicle. or To run simulation and analyze the result.

Objective :- To run the simulation and make report.

This is a BAJA All Terrain Vehicle (ATV) Model.

• Small open motor vehicle with one seat and three or more wheels fitted with large tyres, designed for use on rough ground.

• Baja SAE is an Collegiate Design Series competition run by the Society of Automotive Engineers International (SAE International). Teams of students from universities all over the world design and build small off-road cars. The cars all have engines of the same specifications. As of 2018 the engine has been an unmodified Briggs & Stratton Model 19 Vanguard engine single-cylinder with a displacement of 305cc and power output of approximately 10 bhp (7.5 kW).

• The goal in Baja SAE racing is to design, build and race off-road vehicles that can withstand the harshest elements of rough terrain. The vehicles used in Baja SAE racing are often similar in appearance to dune buggies. Before 2007, the events were called "Mini Baja."

• The all-terrain vehicle also called a light utility vehicle 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. The rider sits on and operates these vehicles like a motorcycle, but the extra wheels give more stability at slower speeds. Although most are equipped with three or four wheels, six-wheel models exist for specialized applications.

• CVT BAJA ATV :-
• There are main two models
  • BAJA ATV Model
    • cvtModel_dashboard
    • cvtModel
  • BAJA ATV Model with lookup table
    • cvtModel_mapped
    • cvtModel_data
    • cvtModel_dashboard_mapped
    • cvtModel_cvtratio_rpm
• Some minor changes between these all simulink models and here, I'll take cvtModel_dashboard.

• This is a simulink model of cvtModel_dashboard for All Terrain Vehicle (ATV).
  • In this model we have a two input signals. Those are Brake Input and Throttle Input.
  • You can see input value of Brake and throttle as a nobe in dashboard and also you can see RPM meter and velocity indicates meter.
  • In the simscape model you can see whole Baja ATV Drivetrain.
  • Here, Input value of brake and throttle are just like driver foot pedal input.This input is give to the Generic Engine and output power of Generic Engine is supply for Engine Sensor and CVT Subsystem. Output power pass through the Simple Gear to the Vehicle Body and finally we got the answer.
  • The simulation output is get from last simulink area box. There are two scope, one is give information about velocity(or vehicle speed), distance, throttle and brake output. Second is give information about CVT Shaft Speed.

• Generic Engine :-
  • Internal combustion engine with throttle and rotational inertia and time lag
  • 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.
  • 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. Optional idle speed and red line controllers are included.
  • The throttle input signal T lies between zero and one and specifies the torque demanded from the engine as a fraction of the maximum possible torque. If the engine speed falls below the Stall speed, the engine torque is blended to zero. If the engine speed exceeds the Maximum speed, the simulation stops and issues an error message.
  • Connections F and B are mechanical rotational conserving ports associated with the engine crankshaft and engine block, respectively. Connections P and FC are physical signal output ports through which engine power and fuel consumption rate are reported.
  • To improve simulation performance, set the Dynamics > Time Constant parameter to No time constant - Suitable for HIL simulation.

• Simple Gear
  • Simple gear of base and follower wheels with adjustable gear ratio, friction losses, and triggered faults.
  • 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.
  • 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.

• CVT Ratio :- Signal builder input you can see in below.

• This is an Engine Sensor subsystem.

• RPM Sensor :- (Ideal Rotational Motion Sensor)
  • The 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.
  • 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.

• Subsystem of CVT :-

• Inertia block :-
  • 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.
  • The Inertia block represents an ideal mechanical translational inertia that is described with the following equation:

    T=J*(dω/dt)

    where:

    • T is inertia torque.

    • J is inertia.

    • ω is angular velocity.

    • t is time.

• Variable Ratio Transmission :-
  • Dynamic gearbox with variable and controllable gear ratio, transmission compliance, and friction losses.
  • 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.
  • 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.

• This is a Subsystem of Vehicle Body.

• Double-Shoe Brake :-
• Frictional brake with two pivoted shoes diametrically positioned about a rotating drum with triggered faulting.
• 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.
• 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.

• Vehicle Body :-
  • Two-axle vehicle with longitudinal dynamics and motion and adjustable mass, geometry, and drag properties.
  • 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.
  • 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.
  • 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.

• Tire (Magic Formula) :-
  • Tire with longitudinal behavior given by Magic Formula coefficients
  • 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.
  • 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.

• All configurations will work the same. So, one model is chosen & the input parameters such as throttle & Brake in that model are changed. In order to view, How
  the results vary. So, The "BAJA ATV model with Dashboard" is taken. This appears in the Simulink GUI as shown in below fig. This model is simulated for three
  cases. They are explained below.

• Case 1 :- This is a default case in which brake and throttle input is applied by default.
  • Here, Throttle input is 0.5 and Brake input is zero it means no braking condition is applied and the simulation run time is 30 second.

• The simulation output is get from last simulink area box. There are two scope, one is give information about velocity(or vehicle speed), distance, throttle and brake output. Second is give information about CVT Shaft Speed.
• Here, Vehicle move more than 300m in 30sec. with max velocity of vehicle is nearly 52km/hr. RPM and Velocity is gradually increase with respect to time.

• Case 2 :- In this case, Throttle input is maximum and Brake input is also maximum it means full braking and acceleration condition is applied and the simulation run time is 30 second.

• The simulation output is get from last simulink area box. There are two scope, one is give information about velocity(or vehicle speed), distance, throttle and brake output. Second is give information about CVT Shaft Speed.
• Here, Vehicle move nearly 225m in 30sec. with max velocity of vehicle is nearly 30km/hr. Velocity is gradually increase at starting point and than it make constant (at 30km/hr) with respect to time.

• Case 3 :-In this case, Throttle input is maximum and Brake input is zero it means no braking condition is applied and full acceleration condition is applied and the simulation run time is 10 second.

• The simulation output is get from last simulink area box. There are two scope, one is give information about velocity(or vehicle speed), distance, throttle and brake output. Second is give information about CVT Shaft Speed.
• Here, Vehicle move more than 100m in 10sec. with max velocity of vehicle is closer to 60km/hr. RPM and Velocity is gradually increase with respect to time.

• This is a same case like case no. 1. Here, simulation is decrease three times.
• Case 4 :- This is a default case in which brake and throttle input is applied by default.
  • Here, Throttle input is 0.5 and Brake input is zero it means no braking condition is applied and the simulation run time is 10 second.

• The simulation output is get from last simulink area box. There are two scope, one is give information about velocity(or vehicle speed), distance, throttle and brake output. Second is give information about CVT Shaft Speed.
• Here, Vehicle move less than 70m in 10sec. with max velocity of vehicle is nearly 35 km/hr. RPM and Velocity is gradually increase with respect to time.

• This is Engine torque-speed curve.

• This is a same case like case no. 2. Here, simulation is decrease three times.
• Case 5 :- In this case, Throttle input is maximum and Brake input is also maximum it means full braking and acceleration condition is applied and the simulation run time is 10 second.

• The simulation output is get from last simulink area box. There are two scope, one is give information about velocity(or vehicle speed), distance, throttle and brake output. Second is give information about CVT Shaft Speed.
• Here, Vehicle more than 65m in 10sec. with max velocity of vehicle is nearly 28 km/hr. Velocity is gradually increase at starting point and than it make constant (at 28km/hr) with respect to time.