Vibration-Based In-Hand Manipulation for Full Reconfiguration Control of Thin Objects

Active Surface-Driven

Force-Sensitive Underactuated Three-Finger Robot Hand

This paper presents a prototype of a novel three-finger underactuated robot hand with force sensing. It is an electrically-driven high-power gripper with a large grasping force, yet capable of handling both rigid and fragile objects of various shapes and sizes. Its grasp configuration is adaptable to the shape of the object, thanks to its specific linkage-driven power transmission system and the combination of actively and passively (spring-loaded) actuated joints. The hand has 10 degrees of freedom in total, actuated by 4 motors. The novelty of the hand design is reflected in the following aspects: (i) original design and prototype of a three-finger robot hand as a complex mechatronic device, (ii) force sensing based on a custom-designed force sensor integrated into soft fingertips, and (iii) bus communication system with cable-less signal transmission in robot fingers. Signal transmission is based on custom-designed slip ring technology integrated into finger joints, while the bus communication system provides a modular, reconfigurable sensory system.

Active Surface-Driven Reconfigurable Gripper: Robust Grasping and Sequential Manipulation of Thin Objects

Robotic grippers face substantial challenges in grasping and manipulating thin objects. Most existing grippers rely on highly precise approach and grasp motions, which limits robustness and reduces applicability. This paper explores thin-object grasping using books as a representative example. Here, we propose a novel solution that integrates an active surface with underactuated compliance to achieve stable grasping of thin objects without complex control. First, an underactuated gripper with an active surface is designed. The active-surface thumb performs in-hand repositioning of the target book without requiring adjustments of the robot arm or the other fingers, while the underactuated fingers establish compliant contact conditions with the environment, and the reconfigurable structure enables reliable grasping of books under different configurations. Second, we establish a kinematic model of the gripper, and determine the initial grasp postures for two representative scenarios (books lying flat on a desktop and books vertically packed in a shelf). Third, by analyzing the physical model of a book lying on a table and its interaction with the gripper and the environment, we systematically optimize the structural parameters and grasping strategy. Finally, extensive experiments validate the effectiveness of the proposed gripper and strategy. The results demonstrate strong robustness and adaptability when grasping thin objects placed flat (including books, paper, fabric, plastic film, and mouse pad), as well as a high success rate when grasping vertically packed books. Moreover, the proposed gripper can reliably complete long sequential"grasp-place"tasks.

Design of a soft gripper with a changeable adapter for enhanced grasping and manipulation

: Soft grippers utilize compliant materials to achieve adaptable grasping, yet they often face challenges in accommodating objects with widely varying dimensions due to their fixed kinematic structures. This paper presents the design, fabrication, modeling, and control of a novel soft gripper featuring a rigid-flexible coupled variable range adapter. By integrating a motorized crank-slider mechanism with soft pneumatic fingers, the gripper achieves a dynamic volumetric workspace capable of manipulating objects ranging from compact to large geometries. Theoretical modeling and experimental characterization reveal that the adapter serves a dual purpose: it not only expands the effective workspace but also functions as a mechanical force amplifier, capable of exponentially boosting the contact force through kinematic reconfiguration. Furthermore, an intuitive Human-in-the-Loop (HITL) teleoperation strategy is established using wearable flex sensors. This control framework maps human gestures to robotic actuation, leveraging human visual feedback as a high-level perception loop to validate the open-loop response of the soft actuators. Experimental results demonstrate that this integrated system significantly improves adaptability and payload stability for diverse object geometries compared to fixed-base counterparts.

G-raph Hand: A Reconfigurable Anthropomorphic Hand With Hybrid Control and Lightweight Closure-Guided In-Hand Manipulation

Underactuated robotic hands offer high adaptability and control simplicity, yet limited dexterity often constrains their manipulation capabilities. To address this limitation, this article presents the G-raph hand, a reconfigurable anthropomorphic robotic hand designed for stable in-hand manipulation while maintaining control simplicity. Inspired by human manipulation, the design integrates underactuated fingers with a reconfigurable palm featuring a central compliant mechanism. This biomimetic architecture enables both active reconfiguration and passive adaptation by modulating finger-base distribution. Furthermore, a hybrid control scheme of in-hand manipulation is developed, combining position and force-feedback control with a lightweight gait planning strategy based on rapid closure property evaluations. By integrating motion intent and system stability, the proposed framework facilitates stable grasping and significant object reorientation. Kinematic workspace analysis and extensive multifinger manipulation experiments demonstrate that the G-raph hand and its associated control framework achieve reliable, flexible, and anthropomorphic performance in complex tasks.

Grasping and Stabilizing Tumbling Objects With Rotating-Base Multiarm Space Manipulators

This article presents an innovative guidance and control method for a space manipulator that actively maneuvers its base to hold a tumbling object stationary relative to the base during proximity operations. This simplifies motion planning, reduces collision risk, and enables impact-free capture using single- or multiarm configurations, with or without predefined grasping interfaces. The proposed approach involves two phases. In the pregrasping phase, a synchronization control aligns the target's center of mass with the system's, virtually rigidizing the target–servicer system to keep the object stationary for reliable grasping. In the postgrasping phase, a control strategy based on Hamiltonian dynamics and optimal control stabilizes the combined system by minimizing time, fuel, or energy, while respecting base torque limits and multiple grasping constraints. For structured targets, applied forces and torques stay within their bounds; for unstructured ones, friction constraints prevent slipping. A case study demonstrates the method's effectiveness in enabling both the subsequent grasping and detumbling phases.