Ken Chisholm

Viridis – Intelligent Electric Bicycle Trailer

Introduction

To reduce the reliance on internal combustion engine (ICE) motor vehicles for towing purposes, a motorized bicycle trailer design was proposed. It incorporates an electric propulsion, braking, and a central control system to account for its own weight, providing towing capability while imparting minimal force onto the rider.

Engineering Challenges

• Minimizing control system runtime to account for real-time operating constraints
• Integrating 10+ sensors with a STM32 microcontroller, leveraging I2C and SPI communication protocols and analog, digital, and PWM I/O
• Implementing electrical isolation between high-power components and low-power sensors and control hardware to prevent noise propagation

Results and Learnings

• Achieved a 93% reduction in force felt by the rider
• Implemented control loop on 100Hz interrupt timer, ensuring that the system has a known and consistent response time
• Leveraged DMA capabilities of microcontroller to facilitate memory transfer from sensors while reducing control loop runtime