To fully explore the potential of robots for dexterous manipulation, this paper presents a whole dynamic grasping process to achieve fluent grasping of a target object by the robot end-effector. The process starts from the phase of approaching the object over the phases of colliding with the object and letting it roll about the colliding point to the final phase of catching it by the palm or grasping it by the fingers of the end-effector. We derive a unified model for this hybrid dynamic manipulation process embodied as approaching-colliding-rolling-catching/grasping from the spatial vector based articulated body dynamics. Then, the whole process is formulated as a free-terminal constrained multi-phase optimal control problem (OCP). We extend the traditional differential dynamic programming (DDP) to solving this free-terminal OCP, where the backward pass of DDP involves constrained quadratic programming (QP) problems and we solve them by the primal-dual Augmented Lagrangian (PDAL) method. Simulations and real experiments are conducted to show the effectiveness of the proposed method for robotic dynamic grasping.

This paper proposes a novel efficient multi-phase trajectory generation algorithm for dynamic dexterous manipulation tasks, such as throwing, catching, dynamic regrasping, and dynamic handover, which can be decomposed into multiple manipulation primitives, including sticking, rolling, approaching, separating, colliding, and grasping. Each manipulation primitive is formulate as a free-terminal optimal control problem (OCP), aimed at computing the optimal pose (position and orientation) trajectories of the object and the robot subject to the pose and force linkage constraints between them and the expected force maintenance at contact. A single-arm regrasping task and a dual-arm dynamic handover task are conducted to demonstrate the effectiveness of the proposed algorithm.

Intercepting an object in flight through nonpre-hensile manipulation is a challenging problem, which is aimed at catching and stopping a flying object using little contacts without completely restraining its relative motion to the robot. This paper presents a two-stage optimal trajectory generation method to tackle this problem. At the pre-catching stage, optimal position and attitude trajectories of the robot's end-effector to approach the object are generated by a variational method. At the post-catching stage, the end-effector's trajectories are generated to optimally eliminate the translational and rotational motion of the object and a convex-MPC algorithm combined with admittance control is used to realize the trajectory tracking. A series of simulations and experiments have been conducted to verify the effectiveness of the proposed method.

Research grants have played an important role in seeding and promoting fundamental research projects worldwide. There is a growing demand for developing and delivering scientific influence analysis as a service on research grant repositories. Such analysis can provide insight on how research grants help foster new research collaborations, encourage cross-organization collaborations, influence new research trends, and identify technical leadership. This article presents the design and development of a grant-based scientific influence analysis service, coined asGImpact. It takes a graph-theoretic approach to design and develop the scientific influence analysis algorithms over a real research-grant repository with three original contributions. First, we model the scientific influence analysis problem as a graph-based analysis problem by constructing heterogeneous graphs from the grants dataset, including mining the dataset to identify and extract important features and represent such features as a research grants information network. Second, we develop the scientific influence analysis algorithms over the research grants information network, which compute the overall scientific influence score by integrating self-influence score and multiple co-influence scores. The self-influence score reflects the grant-based research collaborations among institutions, and the co-influence scores reflect various types of cross-institution collaborations in terms of disciplines and keywords (subject areas). Third, we leverage the cluster analysis on the institution graph as an example application of scientific influence analysis service. By partitioning the institution graph into$K$clusters, with$K$as one of the service interface parameters, we show how different disciplines and different keywords are co-related through the grant-based influence analysis. We evaluateGImpactusing a real grants dataset, consisting of 2512 institutions and their grants received over a period of 14 years. Our experimental results show that theGImpactinfluence analysis approach can effectively identify the grant-based research collaboration groups and provide valuable insight on an in-depth understanding of the scientific influence of research grants on research programs, institution leadership, and future collaboration opportunities.