BAJA All-Terrain Vehicle (ATV) Model- STUDY & ANALYSIS
BAJA All-Terrain Vehicle (ATV) Model- STUDY & ANALYSIS
Aim:-
To make a clear study and analysis on the ATV model with the help of the Simulink model and to prepare a technical report.
Basic structure of the project:-
This report contains the explaination that includes BAJA ATV model with Continuously Variable Transmission(CVT).
These models show how to build an ATV with CVT which is mostly used in BAJA competitions. Simscape and Simscape Driveline have been used to complete the system. The engine data used in the model is provided as an image which shows the Engine Speed (RPM) Vs Torque curve.
Main components of ATV :-
CVT ( Continous variable transmission ):-
CVT is one of the main components used for the ATV baja vehicle.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. The CVT for the ATV will look as follows:-
1) BAJA ATV model without Dashboard:-
Main blocks used for this general layout:-
1) Signal builder block:-
The signal builder block is used to provide the input signals to the whole model which will be in the form of Throttle. The Brake signl will be fiixed as zero. So the input signal throttle is provided as the main input for the Engine block used. Let us visualise the input datas in the graph form by double clicking the signal builder block as follows:-
Throttle input:-
A constant throttle of 0.3 is maintained upto 20 seconds and then the throttle is raised for 1 and its maintained throught the stimulation.
Brake input:-
The brake input is maintained as Zero throught the stimulation.
Both the throttle and brake inputs are connected to the generic engine block through the Simulink to ps converter.
Generic engine block:-
By default, the Generic Engine block uses a programmed relationship between torque and speed that is modulated by the throttle signal. T & B ports represents the throttle and brake input ports. The output signal from the generic engine block is then fed into the engine sensor block.
Engine Sensor block:-
When you double click the Engine sensor block, the above sub block will get opened. It consists of the RMP sensor, connected along with the rotational reference and will calculate the RPM of the engine for the given throttle input.
Gear block:-
The gear block represents the gear ratios provided for the CVT. By defining the gear ratios throough the simple gear block, the output speeds can be varied. We can provide the gear ratio by double clicking the simple gear block. B represents the base gear & F represents the follower gear. And hence the gear ratios can be defined by NF/NB. Here NF represents the number of teeths in the follower gear & NB represents the number of teeths in the base gear.
CVT Subsystem:-
This is how thw subsystem of the CVT block appears, when you double click the CVT block. It's subsystem appears. In the subsystem, we can witness that two input and output shaft inertia blocks are connected to the variable gear ratio block.
The variable gear ratio represents the gearbox which is get connected by belts between two gears , which are represented above. Here also, the B represents the base gear and F represents the followe gear. As we notices clearly both the input and output signal ends are connected to the primary and secondary rpm sensors respectively. The speeds of both the primary and the secondary rpm depends upon the gear ratio provided to the variable gear ratio block.
Input for CVT block:-
A signal builder is connected to the CVT main block, which provides the input signals to the subsystem connected. And the output signals from the CVT block is connected to the Vehicle body.
Vehicle Body subsystem:-
The vehicle body consists of the whole setup for the ATV which is going to get designed. All the specifications including, how much will be the effect of wind velocity to the tyre specifications will be specified in this vehicle body block. This block mainly consists of the mass, aerodynamic properties, weight distribution between the axels etc. Depending upon our design we can specify our own number of tyres required for the vehicle. The tyre block is represented as follows:-
The brake specifications and the brake inputs are connected to all the foure tyres which are connected to the exle of the vehicle. It represents the behaviour of the tire using the tyre magic formula. This is an prebuild block, avilable in the simscape library . We can also include the inertia , damping conditions and stiffness conditions also.
2) BAJA ATV model with Dashboard:-
There is no major chanes done in between these two simulink models , except a dashboard setup is connected from the simscape library to the blocks. And hence we can vary the throttle speed manually from the dashboard and we can witness the velocity values clearly. Initially in the above block, the throttle is not actuated and hence we can see the needle of the velocities of the dashboard as zero. we can change the throttle as follows:-
As we can clearly see, when the throttle value is adjusted in the dashboard we can see the velocity needle moving and provides the velocity as well as the speed values.
Output:-
Study 2:-
BAJA ATV model with Look up table:-
When comparing with the previous study 1, we can witness that the inputs are provided with thw look up tables, insted for signal builder. when we open up the CVT subsystem,
We can see that the input from the V-look up table is given as the input for the cvt subsystem. And all the remaining parameters are same as that of the above discussions.
This is only the major change which is made to this block and hence the inputs can be taken from the look up table which are provided and hence the signal builder block can be neglected.
Look up table visualization:-
And hence all the tecnical aspects of an ATV vehicle design is studied and their result a intrepreted.