BAJA All-Terrain Vehicle model with Continuously Variable Transmission

Aim: To perform the simulation of BAJA All-Terrain vehicle model and observe the vehicle speed and CVT shaft speed output graph by changing break and throttle inputs.

Description:

Figure below shows the BAJA All-Terrain vehicle model with continuously variable transmission

Figure below shows the Speed-torque curve of the engine

Blocks used in the Simscape model are as follows:

a). Generic Engine- It represents the general internal combustion engine.

b). Engine sensor- It is a subsystem which has a RPM sensor to calculate the RPM of the engine. Figure below shows its subsystem

Figure shows the RPM output observed in the scope

By the observation we can say that at initial conditions the engine runs at 2021 RPM.

c). Continuosly variable transmission(CVT): It is an automatic transmission that can change seamlessly through a continuous range of gear ratios. In this model it is used as a subsystem and it is as shown below

Here we can see that a variable ratio gear is used, one input shaft inertia and one output shaft inertia which are primary and secondary pulleys respectively, one CVT primary RPM sensor and one CVT secondary RPM sensor used to measure the primary and secondary pulleys rotations, and two goto blocks.

d). CVT ratio- It is signal builder block used to give the input signal to the main CVT system. Figure below shows the input given by it

e). Simple gear- It represents a fixed-ratio gear or gear box.

f). Vehicle body- It is the actual body of the vehicle. Figure below shows the subsytem of the vehicle body

Here we can see that an inertia output shaft is used which is actually a secondary pulley of the CVT, a double-shoe brake with a gain, left-right front and rear tires where the rear tires are connected with the double-shoe brake and the CVT secondary pulley and front tires are rotating at free end, and the vehicle body block which considers wind velocity and inclination that are kept as constants.

g). Scope- It is used to observe the output results of vehicle speed and CVT shaft speed.

h). Goto, From, constants used for brake and throttle inputs and a solver configuration are the miscellaneous blocks used in this Simscape model.

Figure below shows the model after it is simulated at initial conditions

At initial conditions when brake input=0 and throttle input=0.3, we can observe that approx. 2040 RPM and 35.4 km/hr velocity is achieved as seen from the dashboard.

Figure below shows the vehicle speed output at initial conditions

We can observe from here that the velocity of vehicle is 35.4 km/hr.

Figure below shows the CVT shaft speed output at initial conditions

We can observe from here that the RPM of primary and secondary pulleys of the CVT is 2022 and 4044 RPM respectively.

Figure below shows the model after it is simulated when the brake input is changed to 0.3

When the brake input is changed to 0.3, we can observe that approx. 350 RPM and 6.2 km/hr velocity is achieved as seen from the dashboard.

Figure below shows the vehicle speed output when the brake input is changed to 0.3

We can observe from here that the velocity of vehicle is 6.2 km/hr.

Figure below shows the CVT shaft speed output when the brake input is changed to 0.3

We can observe from here that the RPM of primary and secondary pulleys of the CVT is 352 and 705 RPM respectively.

Figure below shows the model when the throttle input is changed to 1

When the throttle input is changed to 1, we can observe that approx. 3640 RPM and 63.5 km/hr velocity is achieved as seen from the dashboard.

Figure below shows the vehicle speed output when the throttle input is changed to 1

We can observe from here that the velocity of vehicle is 63.5 km/hr.

Figure below shows the CVT shaft speed output when the throttle input is changed to 1

We can observe from here that the RPM of primary and secondary pulleys of the CVT is 3644 and 7288 RPM respectively.

Results:

Brake input	Throttle input	Velocity (km/hr)	Primary shaft speed (RPM)	Secondary shaft speed (RPM)
0	0.3	35.4	2022	4044
0.3	0.3	6.2	352	705
0	1	63.5	3644	7288