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 VEHICLE:
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.
STUDY 1 -CASE 1
SIMULINK MODEL OF BAJAJ ATV WITH CVT :
Major model components:
CVT (Continuously Variable Transmission); having more gears in a transmission is beneficial since it can optimise engine speed in a range of driving scenarios.
Low gears will provide better acceleration, while higher ratios will maximise fuel economy. CVTs are distinguished from standard automatic gearboxes by the absence of gears that offer "steps" between low and high speeds. Instead, the bulk of them use a steel or composite belt to connect a pair of variable-diameter cone-shaped pulleys.
The connecting belt rides in a V-shaped groove formed by them. The pulley has a fixed side and a moveable side that is controlled by a hydraulic cylinder. The cylinder has the ability to change the distance between the two sides of the pulley. Depending on driving circumstances, this permits the belt to ride lower or higher along the walls of the pulley, modifying the "gear" ratio.
VARIABLE TRANSMISSION RATIO:
A variable ratio gearbox, such as a mechanical belt CVT, an electric transmission, or a hydraulic transmission. The angular shaft velocities input to output ratio is defined by the physical signal input r.
Mechanical rotational conserving ports are connections B (base) and F (follower). With the Output shaft rotates parameter, you can specify the relationship between base and follower rotation directions.
ENGINE:
Represents a system-level model of spark-ignition and diesel engines that can be used when only the fundamental parameters are available in the early phases of modelling. Idle speed and red line controllers are available as options. The torque needed from the engine is specified as a fraction of the maximum attainable torque via the throttle input signal T, which ranges from zero to one.
Mechanical rotational conserving ports F and B are connected to the engine crankshaft and engine block, respectively. Engine power and fuel consumption rate are represented by connections P and FC, which are physical signal output ports.
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 OF CASE 1
VEHICLE SPEED
It is clear from the graph that the vehicle attains its maximum = 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 VARIATION IN ANGULAR VELOCITIES OF INPUT AND OUTPUT SHAFTS OF THE VARIABLE GEAR TRANSMISSION SYSTEM.
STUDY 1 CASE 2
SIMULINK MODEL FOR BAJA ATV WITH CVT USING DASHBOARD:
In this case we have a dashboard which contains knobs to control the input. In this case, the inputs - Throttle and brake are not provided using signal builder. A knob is provided to control both the parameter in real -time for the user.
OUTPUT OF CASE 2
VEHICLE SPEED
The graph shows that when the throttle value is 0.5 and the brake input is 0, the vehicle's velocity increases dramatically from 0 to 50kmph. When the brake value is increased from 0.1 to 0.5, the vehicle's velocity drops to zero at continuous throttle. This explains why vehicle velocity is directly proportional to throttle and brake inputs.
CVT SHAFT RPM
STUDY 2
CASE 1
SIMULINK MODEL FOR BAJA ATV WITH CTV WITH LOOKUP TABLE
CVT BLOCK
The only Difference between this model and the first model is that in this model, the gear ratio input to CVT is
provided using a lookup table. The vehicle velocity and shaft rpm outputs are same as before.
CVT GEAR RATIO
LOOK UP TABLE VISUALIZATION
OUTPUT OF CASE 1
VEHICLE SPEED
CVT SHAFT RPM
STUDY 2 CASE 2
SIMULINK MODEL OF BAJA ATV WITH CVT WITH LOOKUPTABLE AND DASHBOARD
OUTPUT OF CASE 2
VEHICLE SPEED
This graph is similar to that of CVT dashboard case.The variation in vehicle velocity can be observed with change in throttle and brake inputs.As brake values increases, the speed decreases.
CVT SHAFT RPM
This graph depicts the relationship between primary and secondary shaft rpm and input parameters.
CONCLUSION :
Thus, we successfully analysed four distinct models of BAJA ATV WITH CVT and recorded the following outputs: - (vehicle velocity & CVT shaft rpm) in response to input throttle and brake variations.
