Dashboard

Our 2024 Dashboard provides in-depth vehicle information to the driver in real time. Two seven-segment displays show the driver the current speed of the vehicle, and an array of LEDs shows the current fuel level. The dashboard also flaunts two full-color LCDs which provide the engine RPM, CVT speed ratio, current time, and 2WD/4WD status. Lastly, four status LEDs provide valuable information such as CVT temperature, data logging status, and low battery warnings. 

CAN Bus System

When deciding how to transmit data from point to point in the vehicle, there were many factors to consider. Most notably, the system had to be durable and compact. One option could have been a spoke-hub distribution, where each subsystem would have its own wiring to transmit data back to a central data acquisition system. However, this wiring would be very complex, and it would limit the access of information between subsystems. Therefore, we implemented a CAN-Bus communication system. CAN-Bus is a two-wire differential voltage protocol, making it extremely compact and resistant to electrical noise. It also allows every node in the system to have access to all information transmitted over the system. 

We standardized all of our subsystems to use ESP32 microcontrollers, which have a CAN-Bus controller built in. Adafruit's TJA1051T CAN transceiver modules were also used via the built-in CAN controller. Because of the speed requirements for these subsystems, we were also able to take advantage of the ESP32's dual cores. One core of each subsystem is dedicated to solely transmitting and receiving CAN data, while the other is used to update displays, read sensors, and other related tasks.

A CVT, or Continuously Variable Transmission, is used in Baja SAE vehicles to eliminate the need for a standard geared transmission. As the vehicle speeds up, the gear ratio between the primary (left) and secondary (right) changes. The primary is directly connected to the engine, and therefore spins at the same RPM as the output shaft. The secondary is connected to a gearbox, which then connects to the wheels, making it have a fixed proportion to the wheel speed. 

Using both of these concepts, we designed an Infrared Transmitter and Receiver pair to count each revolution. This data is then used to calculate vehicle speed, engine RPM, and CVT speed ratio. Additionally, we implemented a TMP36 temperature sensor into the design that communicates the ambient internal CVT temperature to the rest of the vehicle.

Harnessing driver input data is essential to our data logging. With all of our data being transmitted over CAN-Bus to the data acquisition logger, we can sync driver inputs to the pedals with the data about how the vehicle reacts. For example, the position of the accelerator pedal can be mapped to the vehicle's acceleration and speed.

The Data Acquisition Logger is essential to batching all of the vehicle's data and saving it to an SD card. Onboard the logger is a GPS module, providing latitude, longitude, altitude, velocity, heading, and GPS time. Additionally, an accelerometer and gyroscope module is able to capture all of the vehicle's movement. Together with the rest of the data from the CVT Tachometer, pedal sensors, and other subsystems, the logger saves all of the timestamped data to an SD card for later viewing. Because of the CAN-Bus implementation, upgrading and adding subsystems with additional data requirements is very straightforward.

Strict fuel system regulations have made sensing the vehicle's fuel level a challenge. Baja's rules require that the tank itself remains unmodified and that the fuel capacity is not increased. This eliminates many conventional fuel level measurement methods, such as floats, capacitive sensors, and other sensors that require access to the interior of the tank. As a result, our team decided to implement a fuel flow-rate sensor, which is placed in line with the fuel line and measures the volume that passes by it. Because the fuel tank is a fixed volume, we can subtract the used fuel from the total capacity to find the remaining fuel. Our DAQ also gives us access to nonvolatile memory, allowing the tank to access its last-known capacity when the vehicle is powered up.  

2WD/4WD Engagement Switch