Can robots mold soft plastic materials by shaping depth images? The short answer is no: current day robots can not. In this article, we address the problem of shaping plastic material with an anthropomorphic arm/hand robot, which observes the material with a fixed depth camera. Robots capable of molding could assist humans in many tasks, such as cooking, scooping, or gardening. Yet, the problem is complex, due to its high-dimensionality at both perception and control levels. To address it, we design three alternative data-based methods for predicting the effect of robot actions on the material. Then, the robot can plan the sequence of actions and their positions, to mold the material into a desired shape. To make the prediction problem tractable, we rely on two original ideas. First, we prove that under reasonable assumptions, the shaping problem can be mapped from point cloud to depth image space, with many benefits (simpler processing, no need for registration, lower computation time, and memory requirements). Second, we design a novel, simple metric for quickly measuring the distance between two depth images. The metric is based on the inherent point cloud representation of depth images, which enables direct and consistent comparison of image pairs through a nonuniform scaling approach, and therefore opens promising perspectives for designingdepth image-basedrobot controllers. We assess our approach in a series of unprecedented experiments, where a robotic arm/hand molds flour from initial to final shapes, either with its own dataset, or by transfer learning from a human dataset. We conclude the article by discussing the limitations of our framework and those of current day hardware, which make human-like robot molding a challenging open research problem.

In this paper, we adapt the Continuous Collision Detection (CCD) method proposed in [1] to efficiently handle the case of spherical and two revolute joints, this kind of joints is very common in modern robotic systems. The new formulations provide more tight motion bounds, thus increase the success rate of checking collision-free paths. We also propose an extension to get the minimum distance to obstacles along a path, this information is primordial as it allows sampling-based motion planning techniques to sort collision-free paths according to their minimum clearance. We have integrated our implementation into a sampling-based motion planning technique and validated it through simulation and on the real Baxter research robot. The experiments revealed that the method not only does not miss any collision between the robot and the obstacles, but also the minimum distance extension provides the path with the maximum clearance at no additional computational cost.

To make production lines more flexible, dual-arm robots are good candidates to be deployed in autonomous assembly units. In this paper, we propose a sparse kinematic control strategy, that minimizes the number of joints actuated for a coordinated task between two arms. The control strategy is based on a hierarchical sparse QP architecture. We present experimental results that highlight the capability of this architecture to produce sparser motions (for an assembly task) than those obtained with standard controllers.