Design and Implementation of a Semi-Autonomous Battery-Powered Electric Vehicle Controller Using an Arduino Microcontroller

The world's roads are crowded with vehicles that burn fossil fuels, releasing gases that warm the planet and pollute the air we breathe. In response, engineers are turning to electric vehicles, machines that run on stored electricity rather than burning gasoline or diesel. These vehicles offer a cleaner path forward, but they rely on complex systems to manage their power. At the heart of an electric car is a battery that stores energy and a motor that turns that energy into motion. To make the car move, stop, or change direction, a controller acts as the brain, deciding exactly how much power to send to the motor at any given moment. For these systems to be practical, especially in developing regions where cost is a major barrier, the controllers must be affordable, reliable, and easy to build using parts that are readily available in local markets.

Researchers at the University of Rwanda have designed and tested a controller for a small, battery-powered electric vehicle that aims to meet these needs. Their work focuses on creating a system that is both semi-autonomous, meaning it can manage its own basic driving functions, and inexpensive enough for local communities to adopt. The team built a digital model of their design using simulation software, allowing them to test how the vehicle would behave without needing to construct a physical prototype first. They focused on a specific setup: a 600-watt electric motor powered by a 24-volt battery, all managed by a small, low-cost computer chip known as a microcontroller. This chip, which serves as the vehicle's brain, was programmed to handle the delicate task of controlling the motor's speed and direction while keeping a close watch on the battery's health.

The core of their design is a circuit that acts like a traffic director for electricity. To make the motor spin forward or backward, the current flowing through it must be reversed. The researchers used a configuration of electronic switches, arranged in a specific pattern, to flip the direction of the electricity instantly. These switches are made from a type of component called a MOSFET, which is chosen for its ability to handle power efficiently without wasting too much energy as heat. To control the speed of the motor, the system does not simply turn the power on or off; instead, it switches the electricity on and off so rapidly that the motor feels a smooth, average voltage. By changing how long the power stays on during each tiny cycle, the system can make the motor spin slowly or quickly, much like dimming a light by flicking a switch very fast. This method, known as pulse-width modulation, allows for precise speed control without the energy losses found in older, resistive methods.

A critical part of the system is its ability to monitor the battery. As the vehicle drives, the battery loses charge, and if it is drained too deeply, it can be permanently damaged. The researchers programmed the controller to constantly check the battery's voltage, which serves as a proxy for how much energy remains. If the battery drops below a safe level, the system automatically stops the motor to prevent damage, displaying a warning on a screen for the driver. This screen also shows the current speed and the driving mode, giving the operator a clear view of what the vehicle is doing. The entire system was tested in a virtual environment that mimics the behavior of real electronic components. The simulation showed that the controller could successfully drive the motor forward, reverse it, and bring it to a halt using a braking technique that short-circuits the motor; while this setup theoretically permits kinetic energy recovery, the authors note that such recovery would require additional external circuitry not implemented in this specific prototype.

The results of the simulation confirmed that the design works as intended. The virtual tests showed the motor reaching speeds of 1,500 revolutions per minute in both forward and reverse directions, with the controller maintaining a steady pace based on the driver's input. The battery monitoring system proved effective, correctly identifying the charge level and inhibiting the motor when the power was low. The researchers found that the electronic switches operated with high efficiency, and the speed control remained smooth and responsive. While the study was limited to a computer simulation and did not include a physical road test, the data suggests that the design is sound and ready for the next stage of development. The team noted that their approach uses components that are cheap and easy to find in Rwanda, making the technology accessible for local innovation.

This work demonstrates that complex electric vehicle systems can be built using open-source tools and affordable parts. The researchers have shown that a simple microcontroller can effectively manage a powerful motor, protect a battery from damage, and provide clear feedback to a driver. While the current design relies on a simulation to verify its performance, the successful results provide a strong foundation for building a real-world prototype. Future work will involve constructing the physical vehicle, testing it on actual roads, and refining the battery monitoring system to be even more accurate. By proving that a low-cost, locally sourced controller can function effectively, this research offers a practical step toward making electric mobility a reality for developing economies.