Embedded Real-Time Control of a Distributed Trailer Propulsion System with Regenerative Braking for Net Neutral Load Towing

Towing significantly degrades vehicle efficiency, reducing battery-electric vehicle (BEV) range by up to 50% and increasing internal-combustion engine (ICE) fuel consumption by ~30%. To address this challenge, this paper presents a real-time embedded control architecture for a distributed trailer propulsion system that actively regulates drawbar force to achieve net neutral load towing while enabling regenerative braking. Unlike prior e-trailer concepts, this platform demonstrates a cost-effective, fully networked, model-based control implementation using commercial off-the-shelf components. The control system integrates dual Raspberry Pi controllers running ROS 2: one samples a hitch-mounted load cell at 100 Hz and the other processes OBD-II/CAN messages. Controllers designed in MATLAB/Simulink are deployed to a 5 kWh LiFePO₄ pack and a 5 kW traction motor, utilising embedded Linux for real-time scheduling and onboard data logging. Two operating modes are implemented: (i) PI regulation of filtered drawbar force and (ii) feedforward torque mapping from driver throttle. Both employ torque limiting, low-pass filtering, and a regenerative-braking governor to maintain stability and mitigate jackknifing. The development workflow combines desktop simulation, hardware-in-the-loop testing, and embedded deployment to support verification and validation. Preliminary field tests with ICE and BEV tow vehicles pulling 1,000‑lb trailers demonstrate 35–42% BEV range recovery, 14% ICE fuel savings, ~18% regenerative energy capture, and drawbar force regulation within ±50 N (≈5% of towing loads). Evaluation follows industry procedures referencing SAE J1321 (fuel economy), J1634 (BEV range), and J872 (drawbar performance). These results demonstrate a validated and scalable embedded control approach for trailer-assist systems that improve vehicle efficiency, extend range, and enable regenerative towing.