Physics-informed Temporal Difference Metric Learning for Robot Motion Planning
Ruiqi Ni, Zherong Pan, Ahmed H Qureshi

TL;DR
This paper introduces a novel self-supervised temporal difference metric learning method that improves robot motion planning by better solving the Eikonal equation, especially in complex and unseen environments.
Contribution
It proposes a new approach combining temporal difference learning with metric learning to accurately solve the Eikonal equation for robot motion planning.
Findings
Outperforms existing methods in complex environments
Generalizes well to unseen environments
Handles robot configurations from 2 to 12 DOF
Abstract
The motion planning problem involves finding a collision-free path from a robot's starting to its target configuration. Recently, self-supervised learning methods have emerged to tackle motion planning problems without requiring expensive expert demonstrations. They solve the Eikonal equation for training neural networks and lead to efficient solutions. However, these methods struggle in complex environments because they fail to maintain key properties of the Eikonal equation, such as optimal value functions and geodesic distances. To overcome these limitations, we propose a novel self-supervised temporal difference metric learning approach that solves the Eikonal equation more accurately and enhances performance in solving complex and unseen planning tasks. Our method enforces Bellman's principle of optimality over finite regions, using temporal difference learning to avoid spurious…
Peer Reviews
Decision·ICLR 2025 Poster
- The problem is well-motivated. - Very clear discussion about related works, including traditional motion planning methods, learning from experts, and self-supervised learning. - (Strength and also some weakness) I think the first improvement, using both continuous loss L_E from previous work and a novel TD loss is interesting. There is some discussion about the benefits of combining fine-grained and coarse-grained structures. The authors also used an example (Fig.1) to show that sometimes, onl
- I think the key weakness is that even though the various novel techniques improve NTFields, the empirical result does not seem to convey that impact. For example, in the ablation study (Fig.2 row 2), the errors discussed in line 403 convey that L_E, which was proposed in NTFields, is the most important component, and the other loss terms only provide small improvements (e.g., from 0.21 to 0.08 error). This makes me worry a bit about the effectiveness of the proposed techniques. In the real wor
- The method is significantly faster than sampling based motion planning. - Compared to other learning-based planning methods that require an expensive data collection phase, this method is self-supervised and hence removes that requirement.
- The proposed method has worse success rates than sampling-based planners. In particular, in the harder 7-DOF manipulator experiment, the proposed method is significantly worse (87%) than learning-free RRT-Connect (98%). - I am not convinced by the claim in the abstract that the method significantly outperforms existing methods, particularly in the more complex 7-dof domain. While it is much faster and has decent success rates, the results are more mixed. - The overall loss function h
- The paper tackles an important problem in robotics and does a good job of highlighting the challenges of performing motion planning in complex cluttered environments for high DOFs robots. - The authors provide a comprehensive literature review and the approach proposed is well positioned compared to prior work in traditional and neural motion planning. - The proposed method is well thought-out and well detailed in the paper. The design choices are sufficiently justified.
- The experimental methodology suffers from some weaknesses. First, the ablation study is conducted on a single 2D maze environment. While results highlight the importance of each loss and the chosen metric for this specific environment, they do not necessarily show that this importance/performance is maintained across different environments. Second, in the generalization to novel environments, both seen and unseen environments are used during testing, which in my opinion defeats the purpose of
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Taxonomy
TopicsRobotic Path Planning Algorithms · Robot Manipulation and Learning · Reinforcement Learning in Robotics
