Searcharxiv⌕ Search

arXiv subjects

Allan Andre do Nascimento

Publications and source records attributed to Allan Andre do Nascimento.

2 recordsLinked to original sources

Model Predictive Control with Multiple Constraint Horizons

We propose a Model Predictive Control (MPC) formulation for nonlinear systems without terminal penalty or dedicated stabilizing terminal set, in which state constraints are enforced heterogeneously along the prediction horizon. In this setting a control-invariant set certifies near-term safety, while a less restrictive set constrains later predictions. This structure is motivated by safety-critical formulations, such as Control Barrier Function (CBF) based MPC, collision avoidance, and robotic receding-horizon planning, where near-term predictions must be certified safe and later predictions can be re-certified in future updates. We develop a value-function-difference analysis separating the effects of constraint-set selection and prediction-horizon length on closed-loop performance bounds, yielding implicit suboptimality certificates. Assuming cost-controllability, we further propose an upper-bound certificate which accounts explicitly for distinct constraint sets, their associated decay rates, and horizons. We also provide a lower-bound certificate for the closed-loop cost beyond the finite-horizon open-loop cost, which, for the admissible parameter range, is not weaker than the standard finite-horizon bound. Simulations on linear and nonlinear safety-critical systems demonstrate the proposed certificates \textit{a priori} and \textit{a posteriori}.

eess.SY↗

Probabilistically safe controllers based on control barrier functions and scenario model predictive control

Control barrier functions (CBFs) offer an efficient framework for designing real-time safe controllers. However, CBF-based controllers can be short-sighted, resulting in poor performance, a behaviour which is aggravated in uncertain conditions. This motivated research on safety filters based on model predictive control (MPC) and its stochastic variant. MPC deals with safety constraints in a direct manner, however, its computational demands grow with the prediction horizon length. We propose a safety formulation that solves a finite horizon optimization problem at each time instance like MPC, but rather than explicitly imposing constraints along the prediction horizon, we enforce probabilistic safety constraints by means of CBFs only at the first step of the horizon. The probabilistic CBF constraints are transformed in a finite number of deterministic CBF constraints via the scenario based methodology. Capitalizing on results on scenario based MPC, we provide distribution-free, \emph{a priori} guarantees on the system's closed loop expected safety violation frequency. We demonstrate our results through a case study on unmanned aerial vehicle collision-free position swapping, and provide a numerical comparison with recent stochastic CBF formulations.

eess.SY↗