Analysis of Stability and Performance of Economic Model Predictive Control with State-Independent Costs
Pith reviewed 2026-05-08 02:38 UTC · model grok-4.3
The pith
Under strict dissipativity, EMPC with input-only costs drives closed-loop trajectories to the set of optimal steady states.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
For EMPC schemes whose stage cost depends solely on the control input, a strict dissipativity assumption with respect to the set of optimal steady states guarantees that closed-loop trajectories converge asymptotically to this set and that the economic cost converges to the optimal steady-state cost. A modified stage cost is proposed that preserves the optimal input while guaranteeing asymptotic stability of one specific equilibrium point, accepting a slight performance loss. The framework is extended to periodic EMPC for a class of linear systems by lifting the problem to a multi-step formulation.
What carries the argument
The strict dissipativity assumption defined with respect to the set of optimal steady states, which supplies the decrease condition needed for asymptotic convergence of both trajectories and economic cost.
If this is right
- Closed-loop economic cost converges to the optimal steady-state cost.
- The modified stage cost yields asymptotic stability of a chosen equilibrium while keeping the same optimal input.
- Lifting to multi-step EMPC extends the results to linear systems with periodic costs and disturbances.
- The water-distribution-network example confirms both asymptotic convergence and the stabilizing modification in a realistic setting.
Where Pith is reading between the lines
- The input-only cost structure may simplify controller design in systems where full state measurement is costly or unavailable.
- Similar dissipativity-based arguments could apply to other networked control problems that naturally produce input-dependent objectives.
- Quantifying the exact performance loss introduced by the stabilizing modification would allow explicit trade-off analysis in applications.
Load-bearing premise
The strict dissipativity assumption with respect to the set of optimal steady states must hold for the convergence claim to be valid.
What would settle it
A concrete dynamical system satisfying the strict dissipativity condition for which closed-loop trajectories under the EMPC law fail to approach the set of optimal steady states.
Figures
read the original abstract
This paper studies economic model predictive Control (EMPC) schemes, where the stage cost depends only on control inputs. Such problems arise in applications like water distribution networks and differ from standard EMPC since multiple steady states can correspond to the unique optimal steady input. We show that, under a strict dissipativity assumption related to the set of optimal steady states, the closed-loop trajectories converge asymptotically to this set, ensuring convergence of the economic cost to the optimal steady state cost. To enhance Lyapunov stability, we propose a modified stage cost that preserves the optimal input while guaranteeing asymptotic stability of a specific equilibrium with a slight performance loss. The approach is further extended to EMPC of a class of linear systems with periodic costs and disturbances by lifting it to a multi-step EMPC problem for periodic operations. A case study with a water distribution network demonstrates the effectiveness of the proposed methods in achieving both asymptotic convergence and stability.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper analyzes EMPC with state-independent stage costs (depending only on u), where multiple steady states may share the same optimal input. Under a strict dissipativity assumption w.r.t. the set of optimal steady states, it proves asymptotic convergence of closed-loop trajectories to this set (hence economic cost convergence to the optimum). It introduces a modified stage cost to achieve Lyapunov stability of a chosen equilibrium with minor performance degradation, extends the framework to linear systems with periodic costs/disturbances via multi-step lifting, and illustrates the methods on a water distribution network example.
Significance. If the dissipativity assumption is satisfied, the results offer a useful extension of EMPC theory to input-only costs, which arise in applications such as water networks. The stability modification and periodic extension are practical additions, and the case study provides concrete evidence of convergence behavior. These contributions are solid when the assumption holds, but their broader utility depends on the ease of verifying the key hypothesis.
major comments (2)
- [Dissipativity assumption and main convergence result] The central convergence theorem (asymptotic convergence of trajectories to the optimal steady-state set) rests entirely on the strict dissipativity assumption w.r.t. that set. The manuscript states the assumption but supplies neither general sufficient conditions on the dynamics and input-dependent cost that guarantee dissipativity for a non-singleton set, nor any checkable test or numerical verification for the water-network example. This renders the implication from assumption to closed-loop behavior formally correct yet difficult to apply or falsify in practice.
- [Case study section] In the water distribution network case study, the effectiveness demonstration assumes the dissipativity condition without providing any explicit verification, parameter values, or simulation check that the storage function and class-K function exist for the given f and l(u). This leaves the applicability of the convergence claim unconfirmed for the motivating example.
minor comments (2)
- [Introduction] The introduction could more clearly distinguish the set of optimal steady states from the unique optimal input early on, to avoid potential confusion for readers unfamiliar with multi-steady-state EMPC.
- [Periodic extension] In the periodic extension, the performance loss incurred by the modified cost is described qualitatively; a brief bound or comparison relative to the original economic cost would strengthen the claim of 'slight' degradation.
Simulated Author's Rebuttal
We thank the referee for their constructive and detailed comments on the manuscript. We address each major comment point by point below, indicating where we will revise the paper to improve clarity and practical applicability while preserving the core theoretical contributions.
read point-by-point responses
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Referee: [Dissipativity assumption and main convergence result] The central convergence theorem (asymptotic convergence of trajectories to the optimal steady-state set) rests entirely on the strict dissipativity assumption w.r.t. that set. The manuscript states the assumption but supplies neither general sufficient conditions on the dynamics and input-dependent cost that guarantee dissipativity for a non-singleton set, nor any checkable test or numerical verification for the water-network example. This renders the implication from assumption to closed-loop behavior formally correct yet difficult to apply or falsify in practice.
Authors: The convergence theorem is rigorously established under the stated strict dissipativity assumption with respect to the set of optimal steady states, which is the natural extension of standard dissipativity-based EMPC results to the case of state-independent costs. We do not supply general sufficient conditions for dissipativity on non-singleton sets, as these are typically system-dependent and their derivation would require a separate, substantial research effort beyond the scope of the present analysis. This is consistent with the broader EMPC literature, where dissipativity is posited as an assumption and verified on a case-by-case basis. To address the practical concern, we will revise the manuscript to include a discussion of numerical verification procedures and apply them explicitly to the water-network example. revision: partial
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Referee: [Case study section] In the water distribution network case study, the effectiveness demonstration assumes the dissipativity condition without providing any explicit verification, parameter values, or simulation check that the storage function and class-K function exist for the given f and l(u). This leaves the applicability of the convergence claim unconfirmed for the motivating example.
Authors: We agree that the case study would benefit from explicit verification to confirm applicability. In the revised version, we will add the specific parameter values employed for the water distribution network, propose a candidate storage function, and include simulation results or direct checks demonstrating that the strict dissipativity inequality holds with a suitable class-K function for the given system dynamics and input-dependent cost. revision: yes
- General sufficient conditions on the dynamics and input-dependent cost that guarantee dissipativity for a non-singleton set
Circularity Check
No circularity: results are conditional theorems under external assumptions
full rationale
The paper states its central convergence result as a theorem that holds under a strict dissipativity assumption with respect to the optimal steady-state set; this assumption is imported from the broader EMPC literature rather than being derived from or equivalent to the paper's own conclusions or fitted quantities. The subsequent construction of a modified stage cost is an explicit design choice that trades a small performance loss for Lyapunov stability of a chosen equilibrium, without any reduction of the claimed properties back to the inputs by definition. The periodic extension and water-network case study are presented as applications, not as self-referential verifications. No load-bearing step reduces by construction to a self-citation, a fitted parameter renamed as prediction, or an ansatz smuggled via prior work by the same authors.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption strict dissipativity assumption related to the set of optimal steady states
Reference graph
Works this paper leans on
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[4]
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[5]
Appendix A Lifted Dynamical System Iterating the dynamical system in (24) overTsteps yields xkT+i =AixkT + i−1X j=0 Ai−1−jB ukT+j + i−1X j=0 Ai−1−jBd dj, i= 1, . . . , T. 13 Stacking theseTstate equations yields xkT+1 xkT+2 ... x(k+1)T = 0 0· · ·0A 0 0· · ·0A 2 ... ... ... ... 0 0· · ·0A T | {z } ˜A x(k−1)T+1 x...
2012
discussion (0)
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