Innovative E-Bike Lighting Systems for Enhanced Safety and Comfort

Abstract

As society transitions towards more sustainable modes of transport, E-bikes play a key role by increasing the accessibility of cycling to a broader range of users. However, their growing adoption introduces new safety challenges. This thesis presents a proof of concept for an intelligent rear-brake light system designed by repurposing a Melexis automotive-grade LED driver. The resulting demonstrator showcases how existing advanced semiconductor technologies can be adapted to support cycling safety and contribute to Melexis' strategic goal of expanding into the alternative mobility market.

A detailed review of existing bicycle lighting solutions, as well as relevant cycling regulations was conducted to identify opportunities for innovation and guide the design strategy. The resulting system integrates an accelerometer alongside an advanced Melexis LED driver, leveraging its internal microcontroller for embedded signal processing. To reliably detect braking events within noisy accelerometer data, both low-pass and Kalman filtering approaches were explored. A constant jerk Kalman filter was ultimately selected, achieving a robust trade-off between responsiveness and noise suppression. Braking events in this project are detected using a threshold-based approach, with the LED brightness being proportional to the measured deceleration intensity. The project also investigated a novel magnetic force sensing concept using a magnet embedded in an elastomer gel, which offers a promising opportunity to build a fully integrated chip containing the LED driver and acceleration sensing.

A custom printed circuit board was designed and assembled to implement the demonstrator, which performed reliably under testing conditions. To further support the evaluation, a competitive analysis of the Supernova TL3 PRO rear light was conducted. This offered a component overview and functional insights on the product that helped contextualise the performance of the demonstrator system. Overall, the prototype confirms the feasibility of using Melexis components in intelligent bicycle lighting applications and serves as a concrete example of how automotive-grade semiconductor technologies can be effectively repurposed for sustainable alternative mobility solutions.