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Constraint Selection in Optimization-Based Controllers

Haejoon Lee, Panagiotis Rousseas, Dimitra Panagou

TL;DR

This paper addresses real-time constraint management in optimization-based controllers by solving a maxFS problem to maximize the number of satisfied constraints at each time step. It proposes a Lagrange-multiplier–informed heuristic that tests feasibility via a small dual LP, avoids slack-variable expansions, and uses past multipliers to iteratively discard soft constraints while allowing reintroduction. The approach yields significantly faster feasibility checks and scales well with the number of constraints, achieving performance comparable to state-of-the-art methods. The results demonstrate practical applicability to safe, efficient human-in-the-loop control in dynamic environments, with improved computational efficiency for real-time deployment.

Abstract

Human-machine collaboration often involves constrained optimization problems for decision-making processes. However, when the machine is a dynamical system with a continuously evolving state, infeasibility due to multiple conflicting constraints can lead to dangerous outcomes. In this work, we propose a heuristic-based method that resolves infeasibility at every time step by selectively disregarding a subset of soft constraints based on the past values of the Lagrange multipliers. Compared to existing approaches, our method requires the solution of a smaller optimization problem to determine feasibility, resulting in significantly faster computation. Through a series of simulations, we demonstrate that our algorithm achieves performance comparable to state-of-the-art methods while offering improved computational efficiency.

Constraint Selection in Optimization-Based Controllers

TL;DR

This paper addresses real-time constraint management in optimization-based controllers by solving a maxFS problem to maximize the number of satisfied constraints at each time step. It proposes a Lagrange-multiplier–informed heuristic that tests feasibility via a small dual LP, avoids slack-variable expansions, and uses past multipliers to iteratively discard soft constraints while allowing reintroduction. The approach yields significantly faster feasibility checks and scales well with the number of constraints, achieving performance comparable to state-of-the-art methods. The results demonstrate practical applicability to safe, efficient human-in-the-loop control in dynamic environments, with improved computational efficiency for real-time deployment.

Abstract

Human-machine collaboration often involves constrained optimization problems for decision-making processes. However, when the machine is a dynamical system with a continuously evolving state, infeasibility due to multiple conflicting constraints can lead to dangerous outcomes. In this work, we propose a heuristic-based method that resolves infeasibility at every time step by selectively disregarding a subset of soft constraints based on the past values of the Lagrange multipliers. Compared to existing approaches, our method requires the solution of a smaller optimization problem to determine feasibility, resulting in significantly faster computation. Through a series of simulations, we demonstrate that our algorithm achieves performance comparable to state-of-the-art methods while offering improved computational efficiency.
Paper Structure (12 sections, 1 theorem, 10 equations, 2 figures, 1 table, 1 algorithm)

This paper contains 12 sections, 1 theorem, 10 equations, 2 figures, 1 table, 1 algorithm.

Key Result

Theorem 1

The configuration $P_k \in \mathcal{C}$ in Problem eq:standard_form is a feasible configuration at time $t_k$ iff the following LP admits a bounded maximum, i.e, $d^\star < \infty$: where $P_k = \left[ P_k^1,\cdots,P_k^C\right]^\top\in\mathcal{C}$ and $\textrm{null}(\cdot)$ denotes the nullspace of a matrix.

Figures (2)

  • Figure 1: Simulation results over $50$ different runs with varying number of obstacles. (a) shows average (top) and maximum (bottom) running times of Alg. \ref{['alg:alg1']} and baseline algorithms with slacked LPs at each time step $t_k$. (b) visualizes average (top) and maximum (bottom) goal-reaching times for the robot with different algorithms. (c) displays average (top) and maximum (bottom) percentage of constraints disregarded for different algorithms at each $t_k$.
  • Figure 2: Histograms showing the distribution of the percentage of soft constraints disregarded (out of $50$) at each time instance across $50$ simulations for each algorithm. Frequency (in log-scale) indicates the total number of time instances at which the corresponding percentages of constraints are disregarded across $50$ different simulations.

Theorems & Definitions (6)

  • Definition 1
  • Definition 2
  • Definition 3
  • Remark 1
  • Theorem 1
  • Remark 2