Energy-efficient Merging of Connected and Automated Vehicles using Control Barrier Functions

TL;DR

The paper tackles safety and efficiency challenges at highway merges by proposing an unstructured, centralized control framework based on Control Barrier Functions (CBFs). The Centralized-CBF Eco-merge controller computes actions for all vehicles in a control zone without enforcing a fixed passing order, using a safety-filter QP to achieve collision avoidance and cooperative coordination while promoting energy efficiency. Compared with a FIFO baseline, Monte Carlo simulations show substantial reductions in energy metrics (PaKE, BE, TEL) and improvements in merge time and average velocity, demonstrating the method's practical potential for CAV fleets. The approach integrates with existing longitudinal controllers and V2V communication with minimal changes to hardware, offering a scalable, continuous-control solution for energy-aware merge management.

Abstract

Highway merges present difficulties for human drivers and automated vehicles due to incomplete situational awareness and a need for a structured (precedence, order) environment, respectively. In this paper, an unstructured merge algorithm is presented for connected and automated vehicles. There is neither precedence nor established passing order through the merge point. The algorithm relies on Control Barrier Functions for safety (collision avoidance) and for coordination that arises from exponential instability of stall-equilibria in the inter-agent space. A Monte Carlo simulation comparison to a first-in-first-out approach shows improvement in traffic flow and a significant energy efficiency benefit.

Figures (4)

• Figure 1: Short merge scenario with communicating CAVs.
• Figure 2: Minimum barrier distance for 500 20-vehicle Monte Carlo simulations.
• Figure 3: Monte Carlo simulation results -- histograms of key evaluation metrics.
• Figure 4: Comparison of 20-vehicle velocity traces: FIFO and C-CBF Eco-merge approaches.