Query: dexterous

title: Dexterous Tethered Space Robot: Design, Measurement, Control, and Experiment
abstract: In this paper, we systematically introduce a novel geostationary orbit (GEO) space debris removal system called dexterous tethered space robot (DTSR) The DTSR has three notable characteristics: dexterity, lightweight, and cost effectiveness. We first describe the system's design and a typical mission scenario, and then present its two core technologies (vision based pose measurement and coordinated controller design) in detail. Finally, we present the extensive simulations and ground semiphysical experiments to verify that the DTSR is a feasible solution to effectively remove the GEO space debris.

title: Optimal control with learned local models: Application to dexterous manipulation
abstract: We describe a method for learning dexterous manipulation skills with a pneumatically actuated tendon driven 24 DoF hand. The method combines iteratively refitted time varying linear models with trajectory optimization, and can be seen as an instance of model based reinforcement learning or as adaptive optimal control. Its appeal lies in the ability to handle challenging problems with surprisingly little data. We show that we can achieve sample efficient learning of tasks that involve intermittent contact dynamics and under actuation. Furthermore, we can control the hand directly at the level of the pneumatic valves, without the use of a prior model that describes the relationship between valve commands and joint torques. We compare results from learning in simulation and on the physical system. Even though the learned policies are local, they are able to control the system in the face of substantial variability in initial state.

title: Dynamic regrasping by in hand orienting of grasped objects using non dexterous robotic grippers
abstract: A method for in hand dynamic regrasping using a non dexterous gripper.Stochastic motion planning algorithm with trajectory optimization.The algorithm optimizes the initial pose of the regrasp and control gains.Simulations and experiments validate the proposed algorithm. Almost any task on an object requires regrasping of the object prior to performing an intended task by varying between grasp configurations. The human hand uses many methods to perform regrasping manipulations such as in hand sliding, finger gaiting, juggling, picking and placing, etc. The most complex and inspiring approach is the in hand orienting dynamic regrasping where an object is released into mid air and regrasped in a different orientation. This manipulation is useful in industrial robotics for rapid manufacturing and reducing the number of robotic arms in production lines. In this work, we present a novel approach for performing in hand orienting regrasping using computed torque control. To maintain an efficient and low cost approach, the regrasping is performed using a non dexterous two jaw gripper and by utilizing the robotic arms dynamics. We focus on the motion planning for the motion and propose a novel stochastic algorithm for performing an optimal manipulation satisfying the kinematic and dynamic constraints. The algorithm optimizes the initial pose of the arm and the control gains. Statistical analysis shows the probability for the algorithm to find a solution if such exists. Simulations on a KUKA arm and demonstration on a planar 3R arm validate the feasibility of the proposed regrasping approach and planning algorithm.

title: Design of a Variable Stiffness Soft Dexterous Gripper
abstract: This article presents the design of a variable stiffness, soft, three fingered dexterous gripper. The gripper uses two designs of McKibben muscles. Extensor muscles that increase in length when pressurized are used to form the fingers of the gripper. Contractor muscles that decrease in length when pressurized are then used to apply forces to the fingers through tendons, which cause flexion and extension of the fingers. The two types of muscles are arranged to act antagonistically and this means that by raising the pressure in all of the pneumatic muscles, the stiffness of the system can be increased without a resulting change in finger position. The article presents the design of the gripper, some basic kinematics to describe its function, and then experimental results demonstrating the ability to adjust the bending stiffness of the gripper's fingers. It has been demonstrated that the fingers' bending stiffness can be increased by more than 150% The article concludes by demonstrating that the fingers can be closed loop position controlled and are able to track step and sinusoidal inputs.

title: Kinematic Analysis, Prototypation and Control of a Novel Gripper for Dexterous Applications
abstract: Speed and flexibility are the primary concerns to whom a well designed industrial gripper should target. The first one leads to unquestionable pros in terms of production, while the second one to the ability of grasping and manipulating several payloads. However, these qualities are opposed to each other in terms of design requirements: speed requires a structure built of rigid bodies, flexibility would have to be favoured by the use of soft materials. As a common target, the human hand represents the most interesting inspiration source in this field, due to its natural dexterity and ability to perform in hand manipulations. Thus, many bio inspired or bio mimicked grippers have been developed in the last decades with the final aim of replicating the terrific capabilities offered by the human hand. In such panorama, this paper presents the kinematic synthesis of a novel, modular, reconfigurable gripper, which is capable to manipulate a plurality of objects, being dexterous at the same time. Instead of using soft materials to achieve in hand manipulation, the authors focused to use mechanisms to address the problem. The concept of manipulation is firstly evaluated in a multibody software environment, then a physical prototype was developed, and the necessary control laws were derived. Several experiments were conducted to test the effectiveness of the proposed structure. Results in terms of accuracy and repeatability are shown, and also the ability to address the three major tasks of grasp, in hand manipulation and release with appropriate posture have been demonstrated.

title: Mechanical Model of Dexterous Continuum Manipulators With Compliant Joints and Tendon/External Force Interactions
abstract: Dexterous continuum manipulators (DCMs) have been widely adopted for minimally and less invasive surgery. During the operation, these DCMs interact with surrounding anatomy actively or passively. The interaction force will inevitably affect the tip position and shape of DCMs, leading to potentially inaccurate control near critical anatomy. In this paper, we demonstrated a two dimensional mechanical model for a tendon actuated, notched DCM with compliant joints. The model predicted deformation of the DCM accurately in the presence of tendon force, friction force, and external force. A partition approach was proposed to describe the DCM as a series of interconnected rigid and flexible links. Beam mechanics, taking into consideration tendon interaction and external force on the tip and the body, was applied to obtain the deformation of each flexible link of the DCM. The model results were compared with experiments for free bending as well as bending in the presence of external forces acting at either the tip or body of the DCM. The overall mean error of tip position between model predictions and all of the experimental results was 0.62 0.41 mm. The results suggest that the proposed model can effectively predict the shape of the DCM.

title: The SSSA MyHand: A Dexterous Lightweight Myoelectric Hand Prosthesis
abstract: The replacement of a missing hand by a prosthesis is one of the most fascinating challenges in rehabilitation engineering. State of art prostheses are curtailed by the physical features of the hand, like poor functionality and excessive weight. Here we present a new multi grasp hand aimed at overcoming such limitations. The SSSA MyHand builds around a novel transmission mechanism that implements a semi independent actuation of the abduction/adduction of the thumb and of the flexion/extension of the index, by means of a single actuator. Thus, with only three electric motors the hand is capable to perform most of the grasps and gestures useful in activities of daily living, akin commercial prostheses with up to six actuators, albeit it is as lightweight as conventional 1 Degrees of Freedom prostheses. The hand integrates position and force sensors and an embedded controller that implements automatic grasps and allows inter operability with different human machine interfaces. We present the requirements, the design rationale of the first prototype and the evaluation of its performance. The weight (478 g) force (31 N maximum force at the thumb fingertip) and speed of the hand (closing time: <370 ms) make this new design an interesting alternative to clinically available multi grasp prostheses.

title: Dexterous Aerial Robots Mobile Manipulation Using Unmanned Aerial Systems
abstract: In this paper, we present selected benchmark aerial manipulation tasks using an aerial vehicle endowed with multi degree of freedom manipulators. The proposed tasks analyze environmental coupling and are broken into three general categories: momentary, loose, and strong coupling. A classical control structure is derived, tuned, and verified through experiments, conducted for benchmarking purposes to include pick and place, insertion, and valve turning tasks. Although other nonlinear controllers may prove more effective, the classical control approach has been selected in order to analyze contact stability and provide benchmark results for future reference. An analysis of system stability is conducted and implemented into the controller. A vision based high level controller fuses motion tracking data in order to provide control of both the aircraft and the manipulators, allowing the system to become coupled to the environment and perform the required operation. We present recent results validating our framework using the proposed aircraft arm system.

title: KITECH Hand: A Highly Dexterous and Modularized Robotic Hand
abstract: This paper presents an anthropomorphic robotic hand named "KITECH Hand," along with its kinematic analysis and detailed mechanical features. From a kinematic perspective, the authors particularly focus on the structure of the metacarpophalangeal (MCP) joints of the fingers. The KITECH Hand adopts a new "roll pitch" type MCP structure to replace conventional "yaw pitch" structures. The proposed structure provides benefits such as enhanced kinematic performance and ease of the mechanical design. Through the kinematic analysis, it is shown that the KITECH Hand shows remarkably high dexterity, well surpassing that of existing robotic hands with conventional MCP joints. The unique MCP structure also helps modularize the robot at the joint level, which simplifies its mechanical structure and enables the production cost to be reduced. The performance of the KITECH Hand, including its dexterity feature, was experimentally verified through a series of experiments, which included object in hand manipulation and a Cutkosky taxonomy test.

title: The JamHand: Dexterous Manipulation with Minimal Actuation
abstract: From using chopsticks to grab items off a plate, to snapping together two LEGO bricks in one hand, common manipulation tasks are easy for humans. However, grasping and dexterous manipulation still rank among the principal grand challenges in robotics. A key challenge is the complex interaction between hand biomechanics and motor control, leading to humanoid hands that remain too complex and costly for use in daily tasks. Here, we bypass this challenge by offering an alternative approach based on multi finger material phase transition effects. By limiting our focus to dexterous manipulation, we are able to design a robotic hand that can achieve six fundamental dexterous manipulations as well as precision and power grasps, all with only two actuators. We further demonstrate our system on a range of real world grasping and manipulation challenges. Besides practical application, these results suggest that leveraging the phase transition of granular materials is a viable technique for reducing the han.