Project
AIM:-
To study and analyze the BAJA All Terrain Vehicle (ATV) model using Simulink and compare between different models.
OBJECTIVES :-
1. To Prepare a technical report explaining the functions of the subsystems & blocks used for preparing the model.
2. To Explain in detail all the differences between all the five models provided.
3. To undertand and comment on the results.
TYPES OF MODEL studied:-
1. BAJA ATV model without Dashboard(cvtModel)
2. BAJA ATV model - Data Extraction (cvtModel_data) 3. BAJA ATV model with
Dashboard (cvtModel_dashboard)
4. BAJA ATV model - Mapped Lookup Table without
Dashboard (cvtModel_mapped)
5. BAJA ATV model – Mapped Lookup Table with Dashboard (cvtModel_dashboard_mapped)
INTRODUCTION:-
MAIB BLOCKS USED:-
Generic Engine Block:-
The Generic Engine block represents a general internal combustion engine. Engine types include 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 engine fuel consumption rate based on choice of fuel consumption model. Optional speed and redline controllers prevent engine stall and enable cruise control.
Main ports:
1. B Rotational Conserving Port :representing the Engine Block(should be connected to rotational motion reference)
2. F-Rotational Conserving Port :representing the Engine Crankshaft
3. T- Physical signal input port :specifying the normalized engine throttle level
4. P- Physical signal output port: reporting the instantaneous engine power, in W
5. FC - Physical signal output port: reporting the fuel consumption rate, in kg/s
SIMPLE GEAR:-
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 is specified.
The follower-base gear ratio is
gFB =rf/rB=NF/NB
where:
Ng is the number of teeth in the base gear
NBF is the number of teeth in the follower gear
Main Ports:
B-Base: Rotational mechanical conserving port associated with the base, or input, shaft.
F - Follower: Rotational mechanical conserving port associated with the follower, or output, shaft.
Variable Ratio Transmission block:-
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 control 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, WF and we have the same sign. If they rotate in opposite directions, WF and we have opposite signs.
Transmission compliance introduces internal time delay between the axis motions. Therefore, unlike a gear, a variable transmission does not act as a kinematic constraint. You can also control torque loss caused by transmission and viscous losses.
Main ports:
1. B-Base Pulley or Drive Pulley
2. F- Follower Pulley or Driven Pulley
3. r-Variable Transmission Ratio (Input)
Vehicle Body block:-
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.
10:25
EZ D.
15%
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.
Limitations:
The Vehicle Body block lets you model only longitudinal dynamics, parallel to the ground and oriented along the direction of motion. The vehicle is assumed to be in pitch and normal equilibrium. The block does not model pitch or vertical movement. As such, the equations assume that the wheels never lose contact. This constraint can result in negative normal forces.
Input ports:
1. Beta - Road Incline Angle (rad):physical signal input
port for road incline angle 2. W - Head Wind Speed (m/s):physical signal input
port for road incline angle
3. CG-center of gravity(m):physical signal input port of externally defined mass relative to the cg of vehicle(only available with externally defined additional mass is set to on)
1. M-mass(kg):physical signal input port for mass of the externally defined mass(only available with externally defined additional mass is set to on)
1. J-Externally defined moment of inertia(in kg*m^2):physical signal input port of the externally defined mass
Output ports:
1. NR - Rear Axle Normal Force (N): physical signal output port for the rear axle which is considered positive acting downward
2. NF-Front Axle Normal Force (N):physical signal output port for the front axle which is considered positive acting downward
2. NF- Front Axle Normal Force (N):physical signal output port for the front axle which is considered positive acting downward
3. V-Longitudinal Velocity (m/s):physical output signal of vehicle velocity
Conserving ports:
H- Horizontal Motion: conserving port related to the horizontal motion of vehicle body(tyres should be connected to this port)
Double shoe brake Block:
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 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.
Limitations:
Contact angles smaller than 45° produce less accurate results.
The brake uses the long-shoe approximation.
The brake geometry does not self-lock.
The model does not account for actuator flow consumption.
Input ports:
F - Physical signal input port associated with the applied actuating force
Conserving ports:
S- Rotational conserving port associated with the rotating drum shaft
Tire (magic formula) block:
The Tire (Magic Formula) block models a tire with longitudinal behavior given by the Magic Formula, 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 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.
Other Blocks used:-
1. Solver Configuration - To specify the solver parameters before starting the simulation.
2. Signal Builder - To input the Brake, Throttle and CVT Ratio
3. Simulink to PS Converter - To convert the Simulink signal to Simscape environment
4. PS to Simulink Converter - To convert Simscape signal to Simulink environment
5. Mechanical Reference - To make sure all the components are clamped to the ground
6. Rotational free end: The Rotational Free End block represents a mechanical rotational port that rotates freely, without torque.
7. Scope - To display different graphs
8. Display-To view the calculated engine power
9. Inertia - To represent the solid inertia
10. Rotational Motion Sensor - To sense the rotational motion from the engine and give output as rpm
11. PS Terminator - Terminator for unconnected physical signal outputs
12. PS Constant - Generate constant physical signal
13. Rotational Free End - For mechanical component (Tire)
14. Custom Measure Gauge - To measure the brake and throttle input
15. Knob - To increase, decrease and vice-versa of throttle and brake inputs 16. Lookup Table - To insert the CVT values from the workspace
17. Step - To increase or decrease an input value for a defined time interval
BAJA ATV MODEL WITH DASHBOARD:
SEPS:-
The model workflow process is same as the process of 'BAJA ATV model without Dashboard' but the throttle and brake inputs are controlled by the user with knobs.
RESULTS:-
When inputs are given as Break input is 0, Throttle input is 0.5 and Then velocity increases and speed also increases.
When inputs are given as Break input is 0.3, Throttle input is 0.8 and Then velocity decreases and speed also decreases.
When inputs are given as Break input is 0, Throttle input is 0.8 and Then velocity increases and speed also increases.
These are the results in my observation.