Overview

The Master Control Unit (MCU) acts to unite all of the electronic subcomponents of the car, communicating by using the CAN bus protocol, which is the de facto standard communication protocol in the automotive industry. These subcomponents include the pedal box sensors, the shutdown circuit, the battery management system, and the motor controller, among others.

The MCU can be thought of as the electronic brain of the car. It receives data from sensors around the car, and uses that data to make decisions, if needed. The most obvious example is when the driver presses the accelerator. Sensors measure the pedal position and send the position information to the MCU, which then processes this data, and sends a reference signal to the motor controller based on this, which in turn regulates the amount of current supplied to the motor.

Figure 1: the National Instruments cRIO-9033 used as the Master Control Unit. Contains various CAN communication units along with a switching relay.

The benefit of having the control unit in-between the two components, is that we can control exactly how we want the pedal to affect motor output. Transitioning to a more advanced drivetrain with dedicated engines for every wheel will also be easier, as torque vectoring can be implemented purely using the controller software.

Figure 2: LabVIEW front panel showing data received via CAN from the pedal box of the car, using a graphic interface. LabVIEW is the programming language used to code the MCU.

Status

The MCU team is currently hard at work making sure all systems are up and talking to each other. At the current point in time all major subsystems have been successfully set up and are communicating properly with the MCU. Next step is to connect them all to the same CAN network, where it will be important to make sure that the bandwidth of the network is not exceeded, by sending an excessive amount of CAN messages. This could potentially result in loss of data, which is less than ideal.

An important goal of the MCU team this year is to create a foundation from which people working on future iterations of the car will be able to build upon. As such, we hope to be able to develop the MCU so that it is easily configurable while still being completely tailored to the car.

Stay tuned and thanks for reading!

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