Monte Carlo tree search (MCTS) has been successful in a variety of domains, but faces challenges with long-horizon exploration when compared to sampling-based motion planning algorithms like Rapidly-Exploring Random Trees. To address these limitations of MCTS, we derive a tree search algorithm based on policy optimization with state-occupancy measure regularization, which we call Volume-MCTS. We show that count-based exploration and sampling-based motion planning can be derived as approximate solutions to this state-occupancy measure regularized objective. We test our method on several robot navigation problems, and find that Volume-MCTS outperforms AlphaZero and displays significantly better long-horizon exploration properties.

Solving storage problems—where objects must be accurately placed into containers with precise orientations and positions—presents a distinct challenge that extends beyond traditional rearrangement tasks. These challenges are primarily due to the need for fine-grained 6D manipulation and the inherent multi-modality of solution spaces, where multiple viable goal configurations exist for the same storage container. We present a novel Diffusion-based Affordance Prediction (DAP) pipeline for the multi-modal object storage problem. DAP leverages a two-step approach, initially identifying a placeable region on the container and then precisely computing the relative pose between the object and that region. Existing methods either struggle with multi-modality issues or computation-intensive training. Our experiments demonstrate DAP’s superior performance and training efficiency over the current state-of-the-art RPDiff, achieving remarkable results on the RPDiff benchmark. Additionally, our experiments showcase DAP’s data efficiency in real-world applications, an advancement over existing simulation-driven approaches. Our contribution fills a gap in robotic manipulation research by offering a solution that is both computationally efficient and capable of handling real-world variability. Code and supplementary material can be found at: https://github.com/changhaonan/DPS.git.

Optimal motion planning is a long-studied problem with a wide range of applications in robotics, from grasping to navigation. While sampling-based motion planning methods have made solving such problems significantly more feasible, these methods still often struggle in high-dimensional spaces wherein exploration is computationally costly. In this paper, we propose a new motion planning algorithm that reduces the computational burden of the exploration process. The proposed algorithm utilizes a guidance policy acquired offline through model-free reinforcement learning. The guidance policy is used to bias the exploration process in motion planning and to guide it toward promising regions of the state space. Moreover, we show that the gradients of the corresponding learned value function can be used to locally fine-tune the sampled states. We empirically demonstrate that the proposed approach can significantly reduce planning time and improve success rate and path quality.

Transfer learning is a popular approach to bypassing data limitations in one domain by leveraging data from another domain. This is especially useful in robotics, as it allows practitioners to reduce data collection with physical robots, which can be time-consuming and cause wear and tear. The most common way of doing this with neural networks is to take an existing neural network, and simply train it more with new data. However, we show that in some situations this can lead to significantly worse performance than simply using the transferred model without adaptation. We find that a major cause of these problems is that models trained on small amounts of data can have chaotic or divergent behavior in some regions. We derive an upper bound on the Lyapunov exponent of a trained transition model, and demonstrate two approaches that make use of this insight. Both show significant improvement over traditional fine-tuning. Experiments performed on real underactuated soft robotic hands clearly demonstrate the capability to transfer a dynamic model from one hand to another.

Automatic program repair offers the promise of significant reduction in debugging time, but still faces challenges in making the process efficient, accurate, and generalizable enough for practical application. Recent efforts such as Prophet demonstrate that machine learning can be used to develop heuristics about which patches are likely to be correct, reducing overfitting problems and improving speed of repair. SearchRepair takes a different approach to accuracy, using blocks of human-written code as patches to better constrain repairs and avoid overfitting. This project combines Prophet's learning techniques with SearchRepair's larger block size to create a method that is both fast and accurate, leading to higher-quality repairs. We propose a novel first-pass filter to substantially reduce the number of candidate patches in SearchRepair and demonstrate 85% reduction in runtime over standard SearchRepair on the IntroClass dataset.