Navigating Clutter: A Smarter Way for Robots to Manipulate Objects

Author: Denis Avetisyan


A new motion planning framework empowers robots to deftly handle elongated objects in complex, crowded spaces.

Through varied scenarios—including part delivery, ceiling installation, rebar assembly, rescue operations amidst unstable rock formations, and beam transportation—the system demonstrates a capacity for navigating complex environments, indicated by the swept volume of robotic manipulation as it transitions from initial to goal configurations.
Through varied scenarios—including part delivery, ceiling installation, rebar assembly, rescue operations amidst unstable rock formations, and beam transportation—the system demonstrates a capacity for navigating complex environments, indicated by the swept volume of robotic manipulation as it transitions from initial to goal configurations.

This research introduces TAPOM, a hierarchical planning system that utilizes task-space topology and keyframe sampling for efficient robot manipulation in constrained environments.

Despite advances in robotic manipulation, navigating cluttered environments with elongated objects remains a challenge due to limitations in planning algorithms susceptible to local minima and inefficient sampling. This paper introduces TAPOM: Task-Space Topology-Guided Motion Planning for Manipulating Elongated Object in Cluttered Environments, a novel hierarchical framework that addresses these issues by incorporating task-space topological analysis to guide keyframe generation. Experimental results demonstrate that TAPOM significantly improves success rates and efficiency compared to state-of-the-art methods in low-clearance manipulation tasks. Could this approach unlock more robust and adaptable robotic systems for complex real-world applications?


Navigating Complexity: The Essence of Robotic Motion

Complex environments pose significant challenges for robot motion planning, demanding efficient algorithms to identify feasible paths. Traditional approaches often struggle with computational demands in high-dimensional spaces and intricate obstacle configurations. The ‘Narrow Passage Problem’ exemplifies this, requiring precise alignment of elongated objects within constricted spaces – a task exceeding standard pathfinding techniques.

Figure 1:A typical manipulation task. A robot needs to manipulate an elongated object (a rebar beam) through a narrow passage (free sapces in a scaffold). Because translational motion is restricted, this robot needs to align object with the passage to pass through.
Figure 1:A typical manipulation task. A robot needs to manipulate an elongated object (a rebar beam) through a narrow passage (free sapces in a scaffold). Because translational motion is restricted, this robot needs to align object with the passage to pass through.

A robot’s ability to navigate such passages depends on understanding systemic vulnerabilities – for systems break along invisible boundaries, and foresight is paramount.

Deconstructing the Problem: A Topology-Aware Planner

The Topology-Aware Path Optimization Method (TAPOM) addresses computational complexity by decomposing the environment based on topological structure through ‘Topology Analysis’. This identifies critical obstructions and navigable free space, simplifying the planning problem. TAPOM represents this as a ‘Channel Graph’, where nodes represent channels and edges denote transitions, enabling efficient exploration of the configuration space.

Figure 2:Overview of the proposed planner.(a)Obstacles are manually segmented into some sub-obstacles like boxes, cylinders, and spheres. Contact points between sub-obstacles are identified as red dots.(b)Connectivity graph𝒪seg\mathcal{O}\_{\text{seg}}is represented by nodes (red dots) and edges (black line). Simple loops (shaded areas, light red indicates invalid loops) are detected in this graph, representing potential channels. Arrows are several candidate channel paths with different feasibility.(c)Channel extraction: planeΠ\Piis fitted to loop contact points{p1,…,pm}\{p\_{1},\dots,p\_{m}\}via least-squares. Channel area (white) derived from convex hull onΠ\Pi, thickness from perpendicular clearance.(d)Edge weights in channel graphGchG\_{\text{ch}}: edge weightswei​jw\_{e\_{ij}}indicate transition feasibility. Additionally, optimal high-level path𝒫∗\mathcal{P}^{\<i>}is highlighted in red.(e)Channel connectivity graphGchG\_{\text{ch}}: nodes (blue dots) represent channels and edges represent feasible transitions between them. Channel paths in(b)are generated in this graph.(f)Generation of keyframes from the optimal high-level path𝒫∗\mathcal{P}^{\</>}in task space.(g)Growing and merging trees within keyframe regions.” style=”background:#FFFFFF” /><figcaption>Figure 2:Overview of the proposed planner.(a)Obstacles are manually segmented into some sub-obstacles like boxes, cylinders, and spheres. Contact points between sub-obstacles are identified as red dots.(b)Connectivity graph𝒪seg\mathcal{O}\_{\text{seg}}is represented by nodes (red dots) and edges (black line). Simple loops (shaded areas, light red indicates invalid loops) are detected in this graph, representing potential channels. Arrows are several candidate channel paths with different feasibility.(c)Channel extraction: planeΠ\Piis fitted to loop contact points{p1,…,pm}\{p\_{1},\dots,p\_{m}\}via least-squares. Channel area (white) derived from convex hull onΠ\Pi, thickness from perpendicular clearance.(d)Edge weights in channel graphGchG\_{\text{ch}}: edge weightswei​jw\_{e\_{ij}}indicate transition feasibility. Additionally, optimal high-level path𝒫∗\mathcal{P}^{\<i>}is highlighted in red.(e)Channel connectivity graphGchG\_{\text{ch}}: nodes (blue dots) represent channels and edges represent feasible transitions between them. Channel paths in(b)are generated in this graph.(f)Generation of keyframes from the optimal high-level path𝒫∗\mathcal{P}^{\</>}in task space.(g)Growing and merging trees within keyframe regions.</figcaption></figure><p>‘Keyframe Guidance’ further enhances efficiency by focusing sampling within strategically identified regions derived from the optimal high-level path, optimizing performance for algorithms like Rapidly-exploring Random Trees (RRT).</p><h2>From Topology to Trajectory: Refinement and Execution</h2><p>TAPOM employs a hierarchical approach. Following high-level planning, ‘Low-Level Planning’ refines the coarse path into a detailed, executable trajectory, ensuring dynamic feasibility and adherence to robot constraints. Efficient search algorithms, including ‘AIT’ and ‘EIT’, identify ‘Feasible Paths’ leveraging ‘Obstacle Segmentation’ and analysis of ‘Free Space’. These algorithms employ heuristic estimates to optimize path length and execution time.</p><p>TAPOM achieves a 100% success rate in Beam Transportation (BT) and Rescue scenarios, and 90% in Part Delivery (PD) and Ceiling Installation (CI) scenarios, with average planning times of 71.62s (BT) and 224.96s (PD), demonstrating robust performance.</p><h2>Implications and the Future of Robotic Navigation</h2><p>TAPOM presents a novel approach to motion planning, prioritizing computational efficiency through topology-aware search. This framework reduces complexity in challenging environments, a common limitation of existing systems, and allows for rapid adaptation to dynamic environments and evolving tasks.</p><p>In the Rebar Assembly (RA) scenario, the system achieved an 80% success rate with an average planning time of 325.99s. Average planning times of 287.07s (CI) and 173.09s (Rescue) further demonstrate consistent performance across diverse applications.</p><p>Future development will explore multi-robot coordination and integration with learning-based planning algorithms. This promises to unlock the potential for robots to execute increasingly complex manipulation tasks, broadening their operational scope. Efficient navigation isn’t merely about reaching a destination, but about sculpting possibility from space.</p><p>The presented framework, TAPOM, embodies a principle of structured problem-solving, dissecting complex manipulation into manageable topological segments. This aligns with the belief that structure dictates behavior; by analyzing the task-space topology, the system isn’t merely reacting to the environment, but proactively understanding it. The efficiency gained through keyframe sampling isn’t simply about computational speed, but about distilling the problem to its essential elements. As G. H. Hardy observed, “The essence of mathematics lies in its elegance and simplicity.” TAPOM demonstrates this; a seemingly complex task—manipulating elongated objects in cluttered spaces—is addressed not through brute force, but through a carefully considered hierarchy and topological understanding, showcasing how simplicity scales where overly complex solutions would falter.</p><h2>What’s Next?</h2><p>The presented framework, while demonstrating proficiency in navigating the predictable difficulties of cluttered environments, merely scratches the surface of truly robust manipulation. If the system looks clever, it’s probably fragile. The reliance on pre-defined keyframes, for example, introduces a sensitivity to initial conditions that belies any claim of generalizability. One suspects that a slightly perturbed environment, or a novel object geometry, will quickly expose the limitations of this approach. The elegance of topology-guided planning is apparent, but topology alone does not grant intelligence.</p><p>Future work must address the inherent rigidity of keyframe selection. Perhaps a learned, adaptive keyframe generation strategy – one that anticipates environmental variation – could offer a path forward. More fundamentally, the field needs to confront the fact that manipulation isn’t merely about path planning. It’s about <i>force</i>. Ignoring the dynamics of contact – the subtle interplay between object and manipulator – is akin to designing a bridge without considering gravity. The architecture is, after all, the art of choosing what to sacrifice.</p><p>Ultimately, the true challenge lies in moving beyond geometric solutions towards a more holistic understanding of manipulation as a coupled perception-action-dynamics problem. The current work provides a useful, if limited, stepping stone. However, a truly intelligent system will require a deeper engagement with the messy, unpredictable reality of the physical world.</p><hr><p><em>Original article: <a href='https://arxiv.org/pdf/2511.05052.pdf'>https://arxiv.org/pdf/2511.05052.pdf</a></em></p><p><em>Contact the author: <a href='https://www.linkedin.com/in/avetisyan/'>https://www.linkedin.com/in/avetisyan/</a></em></p><h2>See also:</h2><ul class=
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  • 2025-11-11 03:00