FLIP : Flow-Centric Generative Planning for General-Purpose Manipulation Tasks

Chongkai Gao1, Haozhuo Zhang2, Zhixuan Xu1, Zhehao Cai1, Lin Shao1,
1National University of Singapore, 2Peking University
arXiv Code

Abstract

We aim to develop a model-based planning framework for world models that can be scaled with increasing model and data budgets for general-purpose manipulation tasks with only language and vision inputs.

To this end, we present FLow centrIc generative Planning (FLIP), a model-based planning algorithm on visual space that features three key modules: 1. a multi-modal flow generation model as the general-purpose action proposal module; 2. a flow-conditioned video generation model as the dynamics module; and 3. a vision-language representation learning model as the value module. Given an initial image and language instruction as the goal, FLIP can progressively search for long-horizon flow and video plans that maximize the discounted return to accomplish the task. FLIP is able to synthesize long-horizon plans across objects, robots, and tasks with image flows as the general action representation, and the dense flow information also provides rich guidance for long-horizon video generation. In addition, the synthesized flow and video plans can guide the training of low-level control policies for robot execution.

Experiments on diverse benchmarks demonstrate that FLIP can improve both the success rates and quality of long-horizon video plan synthesis and has the interactive world model property, opening up wider applications for future works.

Three Modules of FLIP

Action, Dynamics, and Value modules of FLIP.
Left: the tokenizing process of different modalities in training data.
Middle Left: we use a Conditional VAE to generate flows as actions. It separately generates the delta scale and directions on each query point for flow reconstruction.
Middle Right: we use a DiT model with the spatial-temporal attention mechanism for flow-conditioned video generation. Flows (and observation history) are conditioned with cross attention, while languages and timestep are conditioned with AdaLN-zero.
Right: The value module of FLIP. We follow the idea of LIV and use time-contrastive learning for the visual-language representation, but we treat each video clip (rather than each frame) as a state. The fine-tuned value curves of LIV and ours are shown at bottom.

LIBERO-LONG Planing Results

We train FLIP on LIBERO-LONG, a suite of long-horizon tabletop manipulation tasks with 50 demonstrations for each task.
The flows, videos, and value curves are all generated by FLIP.

LIBERO-LONG Low-Level Policy Results

We use the flow and video plans from FLIP to train a low-level conditional diffusion policy on the LIBERO-LONG tasks, and achieve better results than previous methods. Among them, Ours-FV achieves the best results, showing the advantages of using both flow and video conditions.

Low level policy results

Real World Policy Results: Tea Scooping

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Real World Policy Results: Cloth Unfolding

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Interactive World Model Results

We manually specify image flows for several LIBERO-LONG tasks to demonstrate the interactive property of FLIP.
Note the flows are different with the flows in the training dataset.

Resist Visual Distractions

We show how will FLIP perfrom if we add visual distractions on the initial image. In the two cases, we manually add an image of apple as the visual distraction. If the apple is on the target obejct (left case), the model-based planning will fall in several steps; however, if the apple is on the background (right case), the model-based planning can successfully continue for a long time, showing our model can resist kinds of visual distractions.
It is worth noting that the generated flows are stabler than the generated videos, showing the advantages of using flows as the action representation.

Failure Cases

We show the failure cases of FLIP. These are caused by the accumulated error during the planning.

Aloha Real Results

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Aloha Sim Results

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FMB Benchmark Results

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Cube Results

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Egg Peeling Results

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Folding Results

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Unfolding Results

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Pen Spin Results

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Tying Plastic Bag Results

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Fruit Peel Results

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BibTeX


      @article{flip,
        author = {Gao, Chongkai and Zhang, Haozhuo and Xu, Zhixuan and Cai, Zhehao and Shao, Lin},
        title = {FLIP: Flow-Centric Generative Planning for General-Purpose Manipulation Tasks},
        journal = {arXiv preprint arXiv:2412.08261},
        year = {2024},
        url = {https://arxiv.org/abs/2412.08261},
      }