Motion Planning under Uncertainty: Integrating Learning-Based Multi-Modal Predictors into Branch Model Predictive Control

In complex traffic environments, autonomous vehicles face multi-modal uncertainty about other agents' future behavior. To address this, recent advancements in learningbased motion predictors output multi-modal predictions. We present our novel framework that leverages Branch Model Predictive Control(BMPC) to account for these predictions. The framework includes an online scenario-selection process guided by topology and collision risk criteria. This efficiently selects a minimal set of predictions, rendering the BMPC realtime capable. Additionally, we introduce an adaptive decision postponing strategy that delays the planner's commitment to a single scenario until the uncertainty is resolved. Our comprehensive evaluations in traffic intersection and random highway merging scenarios demonstrate enhanced comfort and safety through our method.

Learning-Aided Warmstart of Model Predictive Control in Uncertain Fast-Changing Traffic

Model Predictive Control lacks the ability to escape local minima in nonconvex problems. Furthermore, in fast-changing, uncertain environments, the conventional warmstart, using the optimal trajectory from the last timestep, often falls short of providing an adequately close initial guess for the current optimal trajectory. This can potentially result in convergence failures and safety issues. Therefore, this paper proposes a framework for learning-aided warmstarts of Model Predictive Control algorithms. Our method leverages a neural network based multimodal predictor to generate multiple trajectory proposals for the autonomous vehicle, which are further refined by a sampling-based technique. This combined approach enables us to identify multiple distinct local minima and provide an improved initial guess. We validate our approach with Monte Carlo simulations of traffic scenarios.

An Empirical Bayes Analysis of Vehicle Trajectory Models

We present an in-depth empirical analysis of the trade-off between model complexity and representation error in modelling vehicle trajectories. Analyzing several large public datasets, we show that simple linear models do represent realworld trajectories with high fidelity over relevant time scales at very moderate model complexity. This finding allows the formulation of trajectory tracking and prediction as a Bayesian filtering problem. Using an Empirical Bayes approach, we estimate prior distributions over model parameters from the data that inform the motion models necessary in the trajectory tracking problem and that can help regularize prediction models. We argue for the use of linear models in trajectory prediction tasks as their representation error is much smaller than the typical epistemic uncertainty in this task.