Project
Aim:
To prepare a technical report of simulation of BAJA All- Terrain Vehicle (ATV) under different conditions.
Objectives:
Carry out a system-level simulation of an all-terrain vehicle and prepare a technical report explaining the model properties & comments on the results.
All-terrain Vehicles:
An all-terrain vehicle (ATV) is defined as a motorized off- highway vehicle designed to travel on four low -pressure or non- pneumatic tires, having a seat designed to be straddled by the operator and handlebars for steering control.
Study1:
Case1: Simulink model for BAJA ATV with CVT:
Continuously Variable Transmission Drive(CVT):
It is better to have more gears in a transmission, since it can optimize engine speed in a variety of driving conditions. That means low gears can provide better acceleration while higher gears can maximize fuel economy. CVTs differ from traditional automatic transmissions in that they don’t have gears that provide “steps” between low-speed and high speed operations. Instead, the majority of them work via a pair of variable-diameter, cone-shaped pulleys connected by a steal or composite belt.
CVT block:
Variable Transmission Ratio:
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 vehicles.
Engine:
Connection 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.
Input signal:
A signal builder is used to create signals for brake and throttle.
CVT Gear Ratio Input:
Torque vs Engine speed input:
Vehicle Body:
Output for case 1:
Vehicle speed:
It is clear from the graph that the vehicles attains its maximum speed (V=55km/hr) at full throttle=1 after 30 seconds and then remains constant. The brake input value is zero , hence it has no effect on velocity.
CVT Shaft RPM:
These graphs shows the variations in angular velocities of input and outputs of the variable gear transmission system. These values differ w.r.t to the gear ratio.
Study 1:
Case 2: Simulink model for BAJA ATV with CVT using dashboard:
In this model we have a dashboard which contains knobs to control the inputs. In this, case the inputs ‘throttle’ & Brake are not provided using signal builder. A knob is provided to control both the parameters in real time for the user.
Output for case 2:
Vehicle speed :
It can be observed that from the graph that the velocity of the vehicle increases drastically from 0 to 50kmph when throttle value is 0.5 & brake input is 0. Once the braking value increases from 0.1 to 0.5, the velocity of the vehicle decreases to 0 at constant throttle value .
CVT shaft RPM:
Study 2:
Case 1: Simulink model for BAJA ATV with CVT using lookup table:
CVT block:
The only difference between this module and previous model is that the gear ratio input to CVT is provided using a lookup table. The vehicle velocity and shaft rpm output are same as before.
CVT gear ratio:
Lookup table visualization:
Output for case 1:
Vehicle speed:
CVT shaft RPM:
Both results are same as that of the first case.
Study 2:
Case 2: Simulink model for BAJA ATV with CVT using Look up table & dashboard:
In this model a dashboard is used to control the inputs- “ throttle” & “ Brake” with knobs.
Output for case 2:
Vehicle speed :
This graph is similar to that of CVT dashboard case. The variations in vehicle velocity can be observed with change in throttle and brake inputs. With increase in braking value, the speed of vehicle decreases.
CVT shaft rpm:
This graph indicates the variation in rpm of primary and secondary shafts w.r.t. input parameters.
Conclusion:
Thus, we have successfully analysed 4 different models of BAJA ATV with CVT and recorded the outputs (vehicle velocity and cvt shaft rpm) w.r.t variations in input throttle and brake.