Grounding Language Plans in Demonstrations Through Counterfactual Perturbations

Grounding the common-sense reasoning of Large Language Models in physical domains remains a pivotal yet unsolved problem for embodied AI. Whereas prior works have focused on leveraging LLMs directly for planning in symbolic spaces, this work uses LLMs to guide the search of task structures and constraints implicit in multi-step demonstrations. Specifically, we borrow from manipulation planning literature the concept of mode families, which group robot configurations by specific motion constraints, to serve as an abstraction layer between the high-level language representations of an LLM and the low-level physical trajectories of a robot. By replaying a few human demonstrations with synthetic perturbations, we generate coverage over the demonstrations' state space with additional successful executions as well as counterfactuals that fail the task. Our explanation-based learning framework trains an end-to-end differentiable neural network to predict successful trajectories from failures and as a by-product learns classifiers that ground low-level states and images in mode families without dense labeling. The learned grounding classifiers can further be used to translate language plans into reactive policies in the physical domain in an interpretable manner. We show our approach improves the interpretability and reactivity of imitation learning through 2D navigation and simulated and real robot manipulation tasks. Website: https://sites.google.com/view/grounding-plans

Human-Machine Cooperative Multimodal Learning Method for Cross-subject Olfactory Preference Recognition

Odor sensory evaluation has a broad application in food, clothing, cosmetics, and other fields. Traditional artificial sensory evaluation has poor repeatability, and the machine olfaction represented by the electronic nose (E-nose) is difficult to reflect human feelings. Olfactory electroencephalogram (EEG) contains odor and individual features associated with human olfactory preference, which has unique advantages in odor sensory evaluation. However, the difficulty of cross-subject olfactory EEG recognition greatly limits its application. It is worth noting that E-nose and olfactory EEG are more advantageous in representing odor information and individual emotions, respectively. In this paper, an E-nose and olfactory EEG multimodal learning method is proposed for cross-subject olfactory preference recognition. Firstly, the olfactory EEG and E-nose multimodal data acquisition and preprocessing paradigms are established. Secondly, a complementary multimodal data mining strategy is proposed to effectively mine the common features of multimodal data representing odor information and the individual features in olfactory EEG representing individual emotional information. Finally, the cross-subject olfactory preference recognition is achieved in 24 subjects by fusing the extracted common and individual features, and the recognition effect is superior to the state-of-the-art recognition methods. Furthermore, the advantages of the proposed method in cross-subject olfactory preference recognition indicate its potential for practical odor evaluation applications.

Dr. LLaMA: Improving Small Language Models on PubMedQA via Generative Data Augmentation

Large Language Models (LLMs) have made remarkable strides in natural language processing, but their expanding size poses challenges in terms of computational expense and inefficiency. Conversely, Small Language Models (SLMs) are known for their efficiency but often encounter difficulties in tasks with limited capacity and training data, particularly in domain-specific scenarios. In this paper, we introduce Dr. LLaMA, a method that improves SLMs in the medical domain through generative data augmentation utilizing LLMs. The objective is to develop more efficient and capable models tailored for specialized applications. Our preliminary results on the PubMedQA dataset demonstrate that LLMs effectively refine and diversify existing question-answer pairs, leading to improved performance of a significantly smaller model after fine-tuning. The best SLM surpasses few-shot GPT-4 with under 1.6 billion parameters on the PubMedQA. Our code and generated data are publicly available to facilitate further explorations.

Visual Pre-training for Navigation: What Can We Learn from Noise?

A powerful paradigm for sensorimotor control is to predict actions from observations directly. Training such an end-to-end system allows representations that are useful for the downstream tasks to emerge automatically. In visual navigation, an agent can learn to navigate without any manual designs by correlating how its views change with the actions being taken. However, the lack of inductive bias makes this system data-inefficient and impractical in scenarios like search and rescue, where interacting with the environment to collect data is costly. We hypothesize a sufficient representation of the current view and the goal view for a navigation policy can be learned by predicting the location and size of a crop of the current view that corresponds to the goal. We further show that training such random crop prediction in a self-supervised fashion purely on random noise images transfers well to natural home images. The learned representation can then be bootstrapped to learn a navigation policy efficiently with little interaction data. Code is available at https://github.com/yanweiw/noise2ptz.

Temporal Logic Imitation: Learning Plan-Satisficing Motion Policies from Demonstrations

Learning from demonstration (LfD) methods have shown promise for solving multi-step tasks; however, these approaches do not guarantee successful reproduction of the task given disturbances. In this work, we identify the roots of such a challenge as the failure of the learned continuous policy to satisfy the discrete plan implicit in the demonstration. By utilizing modes (rather than subgoals) as the discrete abstraction and motion policies with both mode invariance and goal reachability properties, we prove our learned continuous policy can simulate any discrete plan specified by a Linear Temporal Logic (LTL) formula. Consequently, the imitator is robust to both task- and motion-level disturbances and guaranteed to achieve task success. Project page: https://sites.google.com/view/ltl-ds