Dexterous Robot Research Articles

掌にカメラを装着した4指12自由度ハンドによるボルトおよび治具の組立の研究

In industrial sectors of the mechanical work, it is advancing the introduction of robots for the purpose of enhancing production efficiency and reducing labor costs. To improve the dexterity of industrial robots, we investigate robotic assembly of fixtures used in the production lines. To assemble the fixtures, we use a 4-finger 12 d.o.f. hand with a camera on the palm. In this paper, we investigate a grasp and insertion task of a bolt to a screw hole. And we investigate a grasp and insertion task of a slide unit to another slide unit. In these tasks, uncertainty of grasping by the hand occurs. To overcome the problem, we utilize the information of a 6-axis force sensor equipped in the robot wrist and the camera image.

多指ロボットハンドによる折り紙動作のためのスプライン関数を用いた軌道生成

One of recent important topics of dexterous manipulation is to manipulate flexible objects such as rope, cloth, or paper. We have also developed a dexterous robot hand system that can achieve Origami tasks. In this study, its trajectory generation method is improved so as to speed up the operation. The trajectory is generated with spline functions and its coefficient parameters are determined using a constrained nonlinear optimization. The optimization is executed with considering the torques of joints and the collision between the robot hand and obstacles. As a result, the time of operation has been shortened to 43% of the time in the previous method.

指の正確な関節構造に基づく筋骨格モデルによる日常動作での筋長変化の評価

Essential understanding of human hand dexterity is very important to make a dexterous robot hand like human hand. In this paper, we focus on the human thumb which can make the movement of opposition. The widely known musculoskeletal model of human thumb uses moment arms which were estimated from the measurements of a specimen. However, the moment arms were derived with an assumption that its joint structure can be approximated by the universal-joint model. However, universal-joint is not appropriate for modeling the real joint structure. In this paper, we evaluate a musculoskeletal model of human thumb in in daily performance which we constructed based on its real joint structure so that we can annualize muscle-skeletal activities more accurately. It is shown that the estimated muscle length with the conventional thumb model has larger error than than the one with the proposed model.

Intelligent Computation in Grasping Control of Dexterous Robot Hand

Dexterous robot hand is an important integrated product of bionics and robotics. In modern life, it has gradually become the focus and hot spot. This paper introduces various types of famous dexterous robot hand and its development. The intelligent computation of robot hand also improves to adapt the more complicated using environment. The paper focuses on the study of the theoretical calculation in grasping control. The theoretical characteristics of intelligent computation are analyzed. In the end, the conclusion of grasping control is summarized.

Extra-Planetary Digital Cultures

Extra-Planetary Digital Cultures

Control-Oriented Design and Robust Decentralized Control of the CEA Dexterous Robot Hand

This study presents the optimized design and robust control strategies for the CEA dexterous hand. A key design feature relies on integrated modular units, for which the tendon routing minimizes kinematic and static coupling between the different finger axes in the motor-to-joint transmissions. Using single-input/single-output control schemes for the mechanically quasi-decoupled system is particularly relevant when considering practical implementation of controllers for systems with a high number of inputs and outputs. Consequently, analysis of the relative gain array puts forward interesting properties in terms of axes decoupling. In particular, stability conditions are easily respected due to the generalized diagonally dominant property of the resulting plant. Decentralized controllers for both flexion/extension and abduction/adduction motions of one finger unit have been successfully embedded into one single DSP board. The controllers are synthesized using two-degree-of-freedom $H_{\infty}$ structure with both feedforward and feedback actions. They have guaranteed high levels of precision and robustness, which, in turn, helps to improve dexterous manipulation skills of robotic hands.

Tactile sensing in dexterous robot hands — Review

Tactile sensing is an essential element of autonomous dexterous robot hand manipulation. It provides information about forces of interaction and surface properties at points of contact between the robot fingers and the objects. Recent advancements in robot tactile sensing led to development of many computational techniques that exploit this important sensory channel. This paper reviews current state-of-the-art of manipulation and grasping applications that involve artificial sense of touch and discusses pros and cons of each technique. The main issues of artificial tactile sensing are addressed. General requirements of a tactile sensor are briefly discussed and the main transduction technologies are analyzed. Twenty eight various tactile sensors, each integrated into a robot hand, are classified in accordance with their transduction types and applications. Previously issued reviews are focused on hardware part of tactile sensors, whereas we present an overview of algorithms and tactile feedback-based control systems that exploit signals from the sensors. The applications of these algorithms include grasp stability estimation, tactile object recognition, tactile servoing and force control. Drawing from advancements in tactile sensing technology and taking into consideration its drawbacks, this paper outlines possible new directions of research in dexterous manipulation.

IRIS: Integrated Robotic Intraocular Snake.

Retinal surgery is one of the most technically challenging surgical disciplines. Many robotic systems have been developed to enhance the surgical capabilities. However, very few of them provide the surgeon the dexterity within the patient's eye to enable more flexible, more advanced surgical procedures. This paper presents a sub-millimeter intraocular dexterous robot, the Integrated Robotic Intraocular Snake (IRIS). The variable neutral-line mechanism is used to provide very high dexterity with a very small form factor. The IRIS distal dexterous unit is 0.9 mm in diameter and about 3 mm in length. It enables two rotational degrees of freedom at the distal end of the ophthalmic instruments. The analysis on contact mechanics provides a reference for the adjustment of the wire pretension. Redundant actuation is implemented by using one motor for each wire. A motion scaling transmission is developed to overcome the suboptimal resolution of the motors. A scale-up model of the IRIS is built for initial experimental evaluation. Preliminary results show that the scale-up IRIS can provide large range of motion. For given bending angle, the kinematic model can estimate the desired wire translation when the friction is not significant. The first prototype of the actual-scale IRIS is assembled and tested.

Impact of laparoscopic experience on virtual robotic simulator dexterity.

BACKGROUND:Different skills are required for robotic surgery and laparoscopic surgery. We hypothesized that the laparoscopic experience would not affect the performance with the da Vinci® system. A virtual robotic simulator was used to estimate the operator's robotic dexterity.MATERIALS AND METHODS:The performance of 11 surgical fellows with laparoscopic experience and 14 medical students were compared using the dV-trainer®. Each subject completed three virtual endo-wrist modules (“Pick and Place,” “Peg Board,“ and “Match Board”). Performance was recorded using a built-in scoring algorithm.RESULTS:In the Peg Board module, the performance of surgical fellows was better in terms of the number of instrument collisions and number of drops (P < 0.05). However, no significant differences were found in the percentage scores of the three endo-wrist modules between the groups.CONCLUSION:Robotic dexterity was not significantly affected by laparoscopic experience in this study. Laparoscopic experience is not an important factor for learning robotic skills.

Dexterous and Lightweight Robotic Hand-held Forceps for Laparoscopy Surgery

Dexterous and Lightweight Robotic Hand-held Forceps for Laparoscopy Surgery

A Study of Calculation Method for Finger Joint Angular Displacement Based on the Finger Inverse Kinematics

A simple method for measuring and calculating the finger joint angular displacement was proposed to serve as the basis for designing dexterous hand and rehabilitation robot hand. The direct kinematics model and the inverse kinematics equation of the finger were established at the beginning of this paper. Then, the trajectory of the fingertip, from which the coordinates of the fingertip were extracted by using AutoCAD, was captured by camera. Finally, the trajectory coordinates of the fingertip were substituted into the inverse kinematics equations to solve the angular displacements of the proximal interphalangeal (PIP), distal interphalangeal (DIP) and metacarpophalangeal (MCP) joints. The calculating precision testing of the finger joint angular displacement needs to substitute the angular displacements calculated before into the direct kinematics equations of the finger to calculate the trajectory of the fingertip. Then, the average Euclidean distance between the calculated trajectory and the real trajectory was computed to test the calculating precision of the finger joint angular displacement. The average Euclidean distance of each fingers is less than 0.05mm, which proves the high calculating precision of the finger joint angular displacement and the efficiency of the method presented in this paper.

Gait analysis of a radial symmetrical hexapod robot based on parallel mechanisms

Most gait studies of multi-legged robots in past neglected the dexterity of robot body and the relationship between stride length and body height. This paper investigates the performance of a radial symmetrical hexapod robot based on the dexterity of parallel mechanism. Assuming the constraints between the supporting feet and the ground with hinges, the supporting legs and the hexapod body are taken as a parallel mechanism, and each swing leg is regarded as a serial manipulator. The hexapod robot can be considered as a series of hybrid serial-parallel mechanisms while walking on the ground. Locomotion performance can be got by analyzing these equivalent mechanisms. The kinematics of the whole robotic system is established, and the influence of foothold position on the workspace of robot body is analyzed. A new method to calculate the stride length of multi-legged robots is proposed by analyzing the relationship between the workspaces of two adjacent equivalent parallel mechanisms in one gait cycle. Referring to service region and service sphere, weight service sphere and weight service region are put forward to evaluate the dexterity of robot body. The dexterity of single point in workspace and the dexterity distribution in vertical and horizontal projection plane are demonstrated. Simulation shows when the foothold offset goes up to 174 mm, the dexterity of robot body achieves its maximum value 0.1644 in mixed gait. The proposed methods based on parallel mechanisms can be used to calculate the stride length and the dexterity of multi-legged robot, and provide new approach to determine the stride length, body height, footholds in gait planning of multi-legged robot.

Path Planning for Dexterous Mobility

In order to overcome a large variety of run-time constraints, robots are being designed to be more resourceful by incorporating more sensory and motor options for any given task. The added flexibility provides a basis for dexterous problem solving, but challenges planners by increasing the complexity of search. Moreover, the cost of functionally equivalent options can vary dramatically. In the worst case, naive approaches to planning avoid expensive actions until inexpensive options are explored exhaustively leading to poor overall search performance. We present a dexterous robot that introduces multiple types of locomotor actions with significant differences in cost and situational value and apply standard search techniques to demonstrate the additional challenges that arise in the context of dexterous mobility. Results highlight incentives, opportunities, and impact for overcoming these challenges. Additionally, we present a prototype for a path planner that uses environmental features to define an efficient set of subgoals for dexterous motion planning.

An arc-shaped polyvinylidene fluoride/ionic polymer metal composite dynamic curvature sensor with contact detection and scanning ability

This paper presents a novel flexible dynamic curvature sensor with contact sensing functionality. The sensor is fabricated from a piezoelectric polyvinylidene fluoride (PVDF) film and integrated into an actuator fabricated from an ionic polymer metal composite (IPMC), which allows the curvature/contact-detection of various curved targets in direct contact with the device, and the curvature-sensing mechanism can also perform a scanning motion by using the electrically controlled IPMC actuator. This polymer-based sensor can detect large curvature changes and can dynamically sense any variations in curvature as a function of time. Moreover, the embedded contact function of the curvature sensor can monitor whether the target contacts a specific point of the sensor. This text details the device design, working principle, fabrication process, and testing procedure. The results show that more than 200% curvature change can be detected based on the fabricated device with a curvature radius of 6mm. The contact function is verified by a 20% voltage amplitude increase, and the sensing mechanism scans a range of 2.7mm with the 5mm long handle portion of the IPMC actuator driven by a voltage of 8V. The developed device could be applied to a dexterous robot for monitoring the changes in shape of a substance, or to a catheter for medical applications.

In silico investigation of a surgical interface for remote control of modular miniature robots in minimally invasive surgery.

Aim. Modular mini-robots can be used in novel minimally invasive surgery techniques like natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single site (LESS) surgery. The control of these miniature assistants is complicated. The aim of this study is the in silico investigation of a remote controlling interface for modular miniature robots which can be used in minimally invasive surgery. Methods. The conceptual controlling system was developed, programmed, and simulated using professional robotics simulation software. Three different modes of control were programmed. The remote controlling surgical interface was virtually designed as a high scale representation of the respective modular mini-robot, therefore a modular controlling system itself. Results. With the proposed modular controlling system the user could easily identify the conformation of the modular mini-robot and adequately modify it as needed. The arrangement of each module was always known. The in silico investigation gave useful information regarding the controlling mode, the adequate speed of rearrangements, and the number of modules needed for efficient working tasks. Conclusions. The proposed conceptual model may promote the research and development of more sophisticated modular controlling systems. Modular surgical interfaces may improve the handling and the dexterity of modular miniature robots during minimally invasive procedures.

EXPERIMENTAL ANALYSIS ON SPATIAL AND CARTESIAN IMPEDANCE CONTROL FOR THE DEXTEROUS DLR/HIT II HAND

This paper presents an experimental study on impedance control in both Cartesian and object level with adaptive friction compensation for dexterous robot hand based on joint torque feedback. To adaptively decrease the effects of high friction caused by complex transmission systems and joint coupling, a friction observer is proposed based on the extended Kalman filter (EKF) in this paper. A Cartesian impedance controller is implemented on a multi-fingered dexterous robot hand with identical fingers, based on the modelling of each modular finger. In addition, a flexible n-fingered object frame is proposed in this paper, applicable to any finger configuration with three or more fingers (n ≥ 3). This enables the design of a 6-DoF spatial impedance controller. Stability of the closedloop system with friction observer is analysed. A position error of less than 0.16 ◦ is achieved using joint impedance control with adaptive friction compensation, which shows significant improvement in performance, as compared to 1.5 ◦ without compensation, and 0.5 ◦ with fixed-parameters friction compensation. Experimental results confirm the improvement in performance for the robot hand with Cartesian impedance control and adaptive joint friction compensation, demonstrating the effectiveness of spatial impedance controller with the proposed object frame and estimation strategy.

人間の直接教示動作の統計的性質からのロボットへの作業スキル移植

Although the demand to build a dexterous robot like a human, i.e., a robot that can execute a given task robustly against the variation of the environment, is increasing, it is difficult to implement an explicit sensory feedback law to adapt the variation of the environment. To solve the above problem, transferring human skills to robots has attracted attention in the robotics community and direct teaching is known as one of the powerful methods to transfer human skills to robots. We have already proposed a method to extract human skill automatically by using direct teaching. In this method, human skill is extracted in two aspects, i.e., appropriate nominal trajectories and sensory feedback laws. However, the proposed method didn't consider the direction of correlation between the force and the velocity and is limited to a specific DOF system with a specific number of sensory inputs. In this paper we extend the proposed method so that considered the direction of correlation between the force and the velocity by using canonical correlations and it can be applied to arbitrary DOF systems with arbitrary number of sensory inputs.

Dexterity Analysis of a Surgical Assistant 6-UPS Parallel Robot

A 6-UPS parallel is adopted to complete mating surfaces grinding of the cervical implant prosthesis instead of the manual surgical instruments in robot-assisted surgery cervical disc replacement system. Therefore, the surgical assistant parallel robot end-effector has better flexibility in some continuous space and best movement and force transmission performance on the moving trajectory beyond reasonable structures and enough degrees of freedom of the grinding movement. In this paper, the dexterity of the surgical assistant 6-UPS parallel robot is analyzed. Firstly, the vector construction method is used to solve Jacobian matrix of the surgical assistant 6-UPS parallel robot, and then the linear velocity and angular velocity dexterity indicators are used to analyze the dexterity of the surgical assistant parallel robot. From the results, the parallel robot movement and force transmission performance degrades away from the surgical space and the cervical vertebra grinding parallel robot has best grinding performance near the center surgical workspace of the moving platform.

A survey of bio-inspired robotics hands implementation: New directions in dexterous manipulation

Recently, significant advances have been made in ROBOTICS, ARTIFICIAL INTELLIGENCE and other COGNITIVE related fields, allowing to make much sophisticated biomimetic robotics systems. In addition, enormous number of robots have been designed and assembled, explicitly realize biological oriented behaviors. Towards much skill behaviors and adequate grasping abilities (i.e. ARTICULATION and DEXTEROUS MANIPULATION), a new phase of dexterous hands have been developed recently with biomimetically oriented and bio-inspired functionalities. In this respect, this manuscript brings a detailed survey of biomimetic based dexterous robotics multi-fingered hands. The aim of this survey, is to find out the state of the art on dexterous robotics end-effectors, known in literature as (ROBOTIC HANDS) or (DEXTEROUS MULTI-FINGERED) robot hands. Hence, this review finds such biomimetic approaches using a framework that permits for a common description of biological and technical based hand manipulation behavior. In particular, the manuscript focuses on a number of developments that have been taking place over the past two decades, and some recent developments related to this biomimetic field of research. In conclusions, the study found that, there are rich research efforts in terms of KINEMATICS, DYNAMICS, MODELING and CONTROL methodologies. The survey is also indicating that, the topic of biomimetic inspired robotics systems make significant contributions to robotics hand design, in four main directions for future research. First, they provide a genuine world test of models of biologically inspired hand designs and dexterous manipulation behaviors. Second, they provide novel manipulation articulations and mechanisms available for industrial and domestic uses, most notably in the field of human like hand design and real world applications. Third, this survey has also indicated that, there are quite large number of attempts to acquire biologically inspired hands. These attempts were almost successful, where they exposed more novel ideas for further developments. Such inspirations were directed towards a number of topics related (HAND MECHANICS AND DESIGN), (HAND TACTILE SENSING), (HAND FORCE SENSING), (HAND SOFT ACTUATION) and (HAND CONFIGURATION AND TOPOLOGY). FOURTH, in terms of employing AI related sciences and cognitive thinking, it was also found that, rare and exceptional research attempts were directed towards the employment of biologically inspired thinking, i.e. (AI, BRAIN AND COGNITIVE SCIENCES) for hand upper control and towards much sophisticated dexterous movements. Throughout the study, it has been found there are number of efforts in terms of mechanics and hand designs, tactical sensing, however, for hand soft actuation, it seems this area of research is still far away from having a realistic muscular type fingers and hand movements.

Качение тел с регулярной поверхностью: теория управляемости и приложения

Pairs of bodies with regular rigid surfaces rolling onto each other in space form a nonholonomic system of a rather general type, posing several interesting control problems of which not much is known. The nonholonomy of such systems can be exploited in practical devices, which is very useful in robotic applications. In order to achieve all potential benefits, a deeper understanding of these types of systems and more practical algorithms for planning and controlling their motions are necessary. In this paper, we study the controllability aspect of this problem, giving a complete description of the reachable manifold for general pairs of bodies, and a constructive controllability algorithm for planning rolling motions for dexterous robot hands.