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Reaching New Heights in Multi-Agent Collective Construction

Martin Rameš, Pavel Surynek

TL;DR

The paper addresses multi-agent collective construction (MACC) by introducing ReRamp, a reversible ramp-based planning approach that trades a path-footprint for a tree-footprint to support higher structures within polynomial time. ReRamp defines ramps as central paths with reversible side ramps and uses the Ramp from Tree (RFT) primitive plus an add_edge operation to grow ramps and incorporate target columns, achieving scalable construction plans. Theoretical results establish NP-hardness for unrestricted ramp use via a Hamiltonian-circuit construction, but show that ReRamp attains a practical height bound of $\Omega(\sqrt{n})$ when reversibility and side ramps are employed, yielding polynomial-time planning. Empirical evaluations against exact MILP/CP solvers and 3D decomposition demonstrate substantial speedups while producing competitive plans, including a discretized single-story house built in under 4 hours with a 24-agent plan, illustrating real-world feasibility and potential for distributed multi-agent construction.

Abstract

We propose a new approach for multi-agent collective construction, based on the idea of reversible ramps. Our ReRamp algorithm utilizes reversible side-ramps to generate construction plans for ramped block structures higher and larger than was previously possible using state-of-the-art planning algorithms, given the same building area. We compare the ReRamp algorithm to similar state-of-the-art algorithms on a set of benchmark instances, where we demonstrate its superior computational speed. We also establish in our experiments that the ReRamp algorithm is capable of generating plans for a single-story house, an important milestone on the road to real-world multi-agent construction applications.

Reaching New Heights in Multi-Agent Collective Construction

TL;DR

The paper addresses multi-agent collective construction (MACC) by introducing ReRamp, a reversible ramp-based planning approach that trades a path-footprint for a tree-footprint to support higher structures within polynomial time. ReRamp defines ramps as central paths with reversible side ramps and uses the Ramp from Tree (RFT) primitive plus an add_edge operation to grow ramps and incorporate target columns, achieving scalable construction plans. Theoretical results establish NP-hardness for unrestricted ramp use via a Hamiltonian-circuit construction, but show that ReRamp attains a practical height bound of when reversibility and side ramps are employed, yielding polynomial-time planning. Empirical evaluations against exact MILP/CP solvers and 3D decomposition demonstrate substantial speedups while producing competitive plans, including a discretized single-story house built in under 4 hours with a 24-agent plan, illustrating real-world feasibility and potential for distributed multi-agent construction.

Abstract

We propose a new approach for multi-agent collective construction, based on the idea of reversible ramps. Our ReRamp algorithm utilizes reversible side-ramps to generate construction plans for ramped block structures higher and larger than was previously possible using state-of-the-art planning algorithms, given the same building area. We compare the ReRamp algorithm to similar state-of-the-art algorithms on a set of benchmark instances, where we demonstrate its superior computational speed. We also establish in our experiments that the ReRamp algorithm is capable of generating plans for a single-story house, an important milestone on the road to real-world multi-agent construction applications.
Paper Structure (8 sections, 8 theorems, 5 figures, 1 table, 3 algorithms)

This paper contains 8 sections, 8 theorems, 5 figures, 1 table, 3 algorithms.

Table of Contents

  1. Related work
  2. Multi-Agent Collective Construction
  3. MACC analysis
  4. Multi-Agent Collective Deconstruction
  5. MACC complexity
  6. ReRamp algorithm
  7. Experiments
  8. Conclusion

Key Result

Lemma 1

If there exists a simple ramp $s_r$ of length $n$, with nodes $v_0, \dots, v_n$, with $v_n$ next to a column $(x', y') \in \mathcal{N}_{v_n}$ of the target structure with height $m \leq n+1$, then the column at position $(x', y')$ is deconstructable.

Figures (5)

  • Figure 1: The TERMES robots and their Multi-Agent Collective Construction discretization. The left agent is carrying a block, the middle agent is placing a block and the right agent is moving without a block.
  • Figure 2: Order of block placement on a simple ramp.
  • Figure 3: Ramp with forward side ramp.
  • Figure 4: Ramp with reversed (backward) side ramp.
  • Figure 5: "Top view of the single-storey house." by Claire Richert, Hélène Boisgontier, and Frédéric Grelot is licensed under CC BY 4.0 (figure 1 of paper house).

Theorems & Definitions (22)

  • Definition 1
  • Lemma 1
  • proof
  • Lemma 2
  • proof
  • Lemma 3
  • proof
  • Lemma 4
  • proof
  • Lemma 5
  • ...and 12 more