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With the development of human-like robotic technologies, robots have been advanced to sense and recognize objects, which is one branch of artificial intelligence to mimic human reactions. Although high-performance computer technologies are used, the ability of object recognition by touch is still low due to the lack of proper sensors. Therefore, this research studied the object learning and recognition system through robot touches by developing an artificial sensory system acting as an electronic skin with tactile sensors. The Tactile Sensor is developed in this research, consisting of 15 Tactile Sensor Arrays and the palm’s touchpoints. Furthermore, recognition analysis was developed on Bag of Word (BoW) and Convolution Neural Network (CNN) algorithms. With the BoW technique, using Support Vector Machine (SVM) as a classifier with Moment Analysis Descriptor (MA) provided the highest accuracy, showing more than 80.15% accuracy from five grasping of an object. With the CNN approach, InceptionNetV3 provided the highest accuracy of 98.28% from only one capture of an object.

Parallel pinch is an important grasp method. The end phalanx of the traditional parallel pinch and self-adaptive gripper moves in an arc trajectory, which requires the auxiliary lifting motion of the industrial manipulator, which is inconvenient to use. To solve this problem, a novel robot finger is designed and implemented—Hoecken's finger. In this finger, the Hoecken linkage mechanism is used to realize the straight-line trajectory of the end joint, the differential mechanism set on the surface of the phalanxes is used to realize the shape self-adaptation of the first and second phalanxes, and the parallel four-bar linkage in series is used to realize the attitude keeping, thus comprehensively realizing the underactuated gripper driven by a single motor. After analyzing the grasp force and grasp motion of Hoecken's fingers, the optimized parameters are obtained, and the Hoecken's gripper is developed. The experimental results show that the gripper can realize the self-adaptive grasp function of straight parallel pinch, the grasp is stable, and the grasp range is large. It can be applied to more scenes that need to grasp objects. [ABSTRACT FROM AUTHOR]

The current underactuated robot hands use a single actuator to drive multiple degrees of freedom, enabling them to perform grasping functions. This paper design a multi-mode compound grasping robot finger driven by linkage, called MCG hand. The MCG hand includes a base, two motors, three phalanx, multiple shafts, two motors, two driving wheels, four linkages, three springs, and two limit blocks. This unique design allows the MCG finger to perform various grasping modes, such as parallel, coupling, middle, and distal phalanx self-adaptive, proximal, and distal gesture-changeable modes, as well as their combinations. The device can independently control the rotation of the proximal phalanx and the distal joint and realize the parallel pinching action of the distal phalanx. It can also realize the coupling function of the proximal and distal phalanx. It has automatic adaptability to objects of different shapes and sizes. Furthermore, the MCG finger provides enveloping grasping with multiple contact points, resulting in a more stable grip. The easy switching between modes through simple control, along with its wide application range and low manufacturing and maintenance costs, make the MCG hand a versatile solution for various applications. [ABSTRACT FROM AUTHOR]

Parallel pinching is an important grasping mode of robot hands. However，because the end phalange moves along the arc track，the robot hand needs the manipulator to cooperate with the lifting when pinching objects on the desktop，which increases the difficulty of grasping objects of different sizes. To solve this problem，a linear parallel pinching mode is introduced in which the end phalange is translational in a linear trajectory. Based on this model，a SHKL finger，for linear parallel pinching and adaptive grasping based on springs and Hoeckens linkage is proposed. The SHKL finger uses Hoeckens linkage to realize the linear movement of the end joint，uses double parallel four-bar linkage with the same direction and speed to realize the attitude fixation of the end phalange relative to the palm，and uses elastic joints，springs and limits to realize the self-adaptive grasping. The theoretical analysis and experimental results show that the SHKL hand has the functions of linear parallel pinching and self-adaptive grasping. Its grasping is stable and its control is easy.

Product management using a multifunctional shelf, and manipulation using an electromagnet hand and a magnetic marker, are proposed for stock and disposal tasks. The multifunctional shelf manages the type, position, and number of products on the shelf, and plans display and disposal operations. The shelf provides directions to a mobile manipulator for moving products on the shelf according to the display and disposal plan. The proposed multifunctional shelf has a camera on each level that helps the mobile manipulator recognize the product. By optimizing the movement of products, the display and disposal work can be performed much more efficiently. To quickly grasp the product, a new manipulation strategy using a magnetic marker and an electromagnet hand is proposed. The electromagnet hand has two electromagnets and can quickly grasp and release the magnet marker by changing the S/N pole pair. Experiments using the proposed multifunctional shelf and electromagnet hand were conducted to demonstrate the effectiveness of the proposed system. [ABSTRACT FROM AUTHOR]

Modern industrial applications of robotics such as small-series production and automated warehousing require versatile grippers, i.e., grippers that can pick up the widest possible variety of objects. These objects must often be grasped or placed inside a container, which limits the size of the gripper. In this article, we propose to combine the two most popular gripper technologies in order to maximise versatility: finger grippers and suction-cup (vacuum) grippers. Many researchers and a few companies have followed this same idea in the past, but their gripper designs are often overly complex or too bulky to pick up objects inside containers. Here, we develop a gripper where the suction cup is lodged inside the palm of a two-finger robotic hand. The suction cup is mounted on a retractile rod that can extend to pick up objects inside containers without interference from the two fingers. A single actuator drives both the finger and sliding-rod motions so as to minimise the gripper complexity. The opening and closing sequence of the gripper is achieved by using a planetary gear train as transmission between the actuator, the fingers and the suction cup sliding mechanism. Special attention is paid to minimise the overall gripper size; its diameter being kept to 75 mm, which is that of the end link of the common UR5 robot. A prototype of the gripper is built and its versatility is demonstrated in a short accompanying video.

Featured Application: The ESMGM robot hand has a universal grasping function. With its continuous improvement, it could be widely used in industrial production, medical rehabilitation, and other services in the future. Giving robot hands more powerful functions has always been one of the goals pursued by scholars in this field. In this paper, an electromagnetic switching multiple grasping modes robot hand (ESMGM hand) is proposed, which integrates three typical grasping modes and therefore has versatile usage and improved performance. The switchable CPS mechanism developed in this paper integrated the parallel grasping and coupled grasping modes, which are incompatible with each other, through ingenious design. The partial effective transmission mechanism guarantees the fusion and connection to self-adaptive grasping mode from both parallel grasping mode and coupled grasping mode. Based on the above two essential mechanisms, the specific structure of the ESMGM robot hand is designed. Theoretical analyses for the kinematic and grasping forces are performed, and the results show that the ESMGM hand not only has multiple grasping functions but also has the characteristics of equitable grasping motions, adequate grasping forces, and stable grasping effects. To further verify the performance of the ESMGM hand, the prototype of the ESMGM hand is manufactured, and grasping experiments are performed. The grasping forces distribution results are consistent with the theoretical analysis results. The general grasping experiments also illustrate that the ESMGM hand has the features of fast electromagnetic switching speed, good adaptability, high stability, fast response, and broad application prospects. [ABSTRACT FROM AUTHOR]

Parallel pinch is an important grasp method. The end phalanx of the traditional parallel pinch and self-adaptive gripper moves in an arc trajectory, which requires the auxiliary lifting motion of the industrial manipulator, which is inconvenient to use. To solve this problem, a novel robot finger is designed and implemented—Hoecken’s finger. In this finger, the Hoecken linkage mechanism is used to realize the straight-line trajectory of the end joint, the differential mechanism set on the surface of the phalanxes is used to realize the shape self-adaptation of the first and second phalanxes, and the parallel four-bar linkage in series is used to realize the attitude keeping, thus comprehensively realizing the underactuated gripper driven by a single motor. After analyzing the grasp force and grasp motion of Hoecken’s fingers, the optimized parameters are obtained, and the Hoecken’s gripper is developed. The experimental results show that the gripper can realize the self-adaptive grasp function of straight parallel pinch, the grasp is stable, and the grasp range is large. It can be applied to more scenes that need to grasp objects.

Abstract Robotic grippers that gently handle objects of various shapes are required for various applications these days. Conventional finger-shaped grippers are multifunctional and can grip various objects; however, grasping an item without slippage requires planning the positioning of the fingers at appropriate locations on the item. Hence, a ring-shaped soft gripper that coils itself around objects like a rubber band is suggested in this paper. The proposed gripper comprises a soft tube containing laminated sponges interleaved with plastic sheets. Evacuation of the air within the sponges shrinks them and decreases the diameter of the ring, thereby allowing the gripper to firmly hold objects. The gripper is therefore flexible enough to coil around objects of various shapes without gaps. Furthermore, the rigidity of the compressed sponges inside the gripper prevents wobbling of the gripped objects. The air within the gripper can be used to adjust the gripping force. The minimum diameter of the gripper after evacuating the air within the sponges is approximately one-fourth of the original diameter. Thus, the proposed gripper is expected to be used in various applications as it automatically conforms to the different shapes while simply gripping objects gently and securely.

The current underactuated robot hands use a single actuator to drive multiple degrees of freedom, enabling them to perform grasping functions. This paper design a multi-mode compound grasping robot finger driven by linkage, called MCG hand. The MCG hand includes a base, two motors, three phalanx, multiple shafts, two motors, two driving wheels, four linkages, three springs, and two limit blocks. This unique design allows the MCG finger to perform various grasping modes, such as parallel, coupling, middle, and distal phalanx self-adaptive, proximal, and distal gesture-changeable modes, as well as their combinations. The device can independently control the rotation of the proximal phalanx and the distal joint and realize the parallel pinching action of the distal phalanx. It can also realize the coupling function of the proximal and distal phalanx. It has automatic adaptability to objects of different shapes and sizes. Furthermore, the MCG finger provides enveloping grasping with multiple contact points, resulting in a more stable grip. The easy switching between modes through simple control, along with its wide application range and low manufacturing and maintenance costs, make the MCG hand a versatile solution for various applications.

In various experimental settings, electromyography (EMG) signals have been used to control robots. EMG-based robot control requires intrinsic parameters for control, which makes it difficult for users to understand the input protocol. When a proper input is not provided, the response time of the system varies; as such, the user's subjective delay should be investigated regardless of the actual delay. In this study, we investigated the influence of the subjective perception of delay on brain activation. Brain recordings were taken while subjects used EMG signals to control a robot hand, which requires a basic processing delay. We used muscle synergy for the grip command of the robot hand. After controlling the robot by grasping their hand, one of four additional delay durations (0 ms, 50 ms, 125 ms, and 250 ms) was applied in every trial, and subjects were instructed to answer whether the delay was natural, additional, or whether they were not sure. We compared brain activity based on responses ("sure" and "not sure"). Our results revealed a significant power difference in the theta band of the parietal lobe, and this time range included the interval in which the subjects could not feel the delay. Our study provides important insights that should be considered when constructing an adaptive system and evaluating its usability. [ABSTRACT FROM AUTHOR]

In contrast to their more rigid counterparts, soft robots have the ability to gently grip and maneuver objects with open-loop kinematic control. Guided by several recent designs and implementations of soft robot hands, the present paper analyzes a rod-based model for the fingers in the hand of a soft robot. We show precisely how gripping is achieved and how the performance can be affected by varying the system's parameters. The designs we are interested in feature pneumatic control of the soft robot and we model this actuation as a varying intrinsic curvature profile of the rod. Our work provides a framework for the theoretical analysis of the soft robot and the resulting analysis can also be used to develop some design guidelines.

Automation is currently delayed in garment factory. In order to automate the work in a garment factory, a method of single sheet separation from piled fabric is required. In this study, we developed a method of single sheet separation from piled fabrics by a roller hand mechanism with a rotating mechanism added to the tip of a robot hand. We designed a rigid body dynamics model for separating a sheet of fabric by this mechanism, and conducted experiments on the separation of a sheet of fabric. As a result, we succeeded in separating only single sheet of fabrics with a high probability. It is necessary to eliminate failures for practical use. However, it is difficult to eliminate failure completely due to the characteristics of fabrics. First, in order to improve the reliability of the separation process, we devised a method to determine the success of separation by the thickness of fabrics, created a mechanism and actually verified. We have succeeded in improving the reliability of single sheet separation process from piled fabrics. However, there was a failure pattern that cannot be addressed by this method. Therefore, we devised a method to determine the success of separation by the weight of fabrics, created a mechanism and actually verified. As a result, the reliability was further improved.

Traditional robot fingers with parallel and self-adaptive hybrid grasping mode have double-chain transmission mechanisms， which have disadvantages of complexity in mechanisms. A novel design of a parallel and indirectly self-adaptive underactuated robot finger with a single chain transmission mechanism， called PISA hand is presented. The method uses three gears， two racks， a slider， a block， a limit and a spring to achieve using a single motor to drive two phalanges. The PISA finger can realized the pinching grasp with the distal phalanx and enveloping grasp with the proximal phalanx with a slider and the distal phalanx. The composition and movement process of the PISA finger are introduced in detail. Theoretical analysis of the range and grasping force are given. Simulation and experimental results show that the PISA finger can automatically switch the grasping modes according to the different positions and shapes of the object so as to achieve stable grasping. The PISA hand has high transmission efficiency， compact structure.

We have developed a pneumatic artificial rubber muscle having a bending direction that can be changed using two shape-memory polymer (SMP) sheets, the stiffness of which depends on the temperature. In the present study, we attached two SMP sheets with embedded electrical heating wires to both sides of a pneumatic artificial rubber muscle in order to realize multidirectional actuation and evaluated the basic characteristics of the artificial muscle. The actuator is based on the design of a conventional curved-type artificial rubber muscle. Since only a heated SMP sheet becomes soft, the rigid SMP sheet inhibits the extension of the side of the actuator. Therefore, bending motion can be induced when air is supplied to the internal bladder. By controlling the temperature of the SMP sheets, the bending direction of the prototype actuator could be changed. Namely, three kinds of motions, such as two-directional bending and axial extension, became possible. Moreover, we improved the manufacturing method and the structure of the artificial muscle, such as the stitching method and the SMP sheet thickness, and evaluated the characteristics of the two-directional bending and the axial extension motions of the prototype actuator. We also calculated the theoretical values and compared these values with the experimental results. Furthermore, we examined the application of the actuators to a robot hand. Using the two-directional motion of the actuator, the proposed robot hand can grasp either small or large objects. The experimental results conducted using this prototype confirm the feasibility of the newly proposed actuator. [ABSTRACT FROM AUTHOR]

There has been an explosion of ideas in soft robotics over the past decade, resulting in unprecedented opportunities for end effector design. Soft robot hands offer benefits of low-cost, compliance, and customized design, with the promise of dexterity and robustness. The space of opportunities is vast and exciting. However, new tools are needed to understand the capabilities of such manipulators and to facilitate manipulation planning with soft manipulators that exhibit free-form deformations. To address this challenge, we introduce a sampling based approach to discover and model continuous families of manipulations for soft robot hands. We give an overview of the soft foam robots in production in our lab and describe novel algorithms developed to characterize manipulation families for such robots. Our approach consists of sampling a space of manipulation actions, constructing Gaussian Mixture Model representations covering successful regions, and refining the results to create continuous successful regions representing the manipulation family. The space of manipulation actions is very high dimensional; we consider models with and without dimensionality reduction and provide a rigorous approach to compare models across different dimensions by comparing coverage of an unbiased test dataset in the full dimensional parameter space. Results show that some dimensionality reduction is typically useful in populating the models, but without our technique, the amount of dimensionality reduction to use is difficult to predict ahead of time and can depend on the hand and task. The models we produce can be used to plan and carry out successful, robust manipulation actions and to compare competing robot hand designs.

Giving robot hands more powerful functions has always been one of the goals pursued by scholars in this field. In this paper, an electromagnetic switching multiple grasping modes robot hand (ESMGM hand) is proposed, which integrates three typical grasping modes and therefore has versatile usage and improved performance. The switchable CPS mechanism developed in this paper integrated the parallel grasping and coupled grasping modes, which are incompatible with each other, through ingenious design. The partial effective transmission mechanism guarantees the fusion and connection to self-adaptive grasping mode from both parallel grasping mode and coupled grasping mode. Based on the above two essential mechanisms, the specific structure of the ESMGM robot hand is designed. Theoretical analyses for the kinematic and grasping forces are performed, and the results show that the ESMGM hand not only has multiple grasping functions but also has the characteristics of equitable grasping motions, adequate grasping forces, and stable grasping effects. To further verify the performance of the ESMGM hand, the prototype of the ESMGM hand is manufactured, and grasping experiments are performed. The grasping forces distribution results are consistent with the theoretical analysis results. The general grasping experiments also illustrate that the ESMGM hand has the features of fast electromagnetic switching speed, good adaptability, high stability, fast response, and broad application prospects.

Robotic grippers that gently handle objects of various shapes are required for various applications these days. Conventional finger-shaped grippers are multifunctional and can grip various objects; however, grasping an item without slippage requires planning the positioning of the fingers at appropriate locations on the item. Hence, a ring-shaped soft gripper that coils itself around objects like a rubber band is suggested in this paper. The proposed gripper comprises a soft tube containing laminated sponges interleaved with plastic sheets. Evacuation of the air within the sponges shrinks them and decreases the diameter of the ring, thereby allowing the gripper to firmly hold objects. The gripper is therefore flexible enough to coil around objects of various shapes without gaps. Furthermore, the rigidity of the compressed sponges inside the gripper prevents wobbling of the gripped objects. The air within the gripper can be used to adjust the gripping force. The minimum diameter of the gripper after evacuating the air within the sponges is approximately one-fourth of the original diameter. Thus, the proposed gripper is expected to be used in various applications as it automatically conforms to the different shapes while simply gripping objects gently and securely. [ABSTRACT FROM AUTHOR]

In the grasping and manipulation of 3D deformable objects by robotic hands, the physical contact constraints between the fingers and the object have to be considered in order to validate the robustness of the task. Nevertheless, previous works rarely establish contact interaction models based on these constraints that enable the precise control of forces and deformations during the grasping process. This paper considers all steps of the grasping process of deformable objects in order to implement a complete grasp planning pipeline by computing the initial contact points (pregrasp strategy), and later, the contact forces and local deformations of the contact regions while the fingers close over the grasped object (grasp strategy). The deformable object behavior is modeled using a nonlinear isotropic mass-spring system, which is able to produce potential deformation. By combining both models (the contact interaction and the object deformation) in a simulation process, a new grasp planning method is proposed in order to guarantee the stability of the 3D grasped deformable object. Experimental grasping experiments of several 3D deformable objects with a Barrett hand (3-fingered) and a 6-DOF industrial robotic arm are executed. Not only will the final stable grasp configuration of the hand + object system be obtained, but an arm + hand approaching strategy (pregrasp) will also be computed. [ABSTRACT FROM AUTHOR]

Industrial robots equipped with various grippers have been introduced in production sites and most of them are electrically driven. Because of the electric actuator's characteristics, they have no back drivability, making it difficult for them to grasp flexible objects. In this study, therefore, we propose a pneumatically driven robot hand capable of grasping flexible objects by effectively employing the compressibility and back drivability of air. [ABSTRACT FROM AUTHOR]

The traditional coupled and self-adaptive fingers realize firstly coupling and secondly self-adaptive hybrid grasping mode with three springs and two sets of independently transmission mechanisms,which have disadvantages of complexity in mechanisms,huge consuming in power,and difficulty in spring selection.Aiming at the problem,a novel coupled and self-adaptive underactuated finger mechanism,called COSA-LET finger is designed. The COSA-LET finer includes multiple racks,two toggle blocks,two limiting blocks,and two springs,which has two joints driven by one motor and a serial transmission mechanism. The coupling function of COSA-LET finger is realized by two opposite-direction racks,and a gear with a spring and a limiting block,the de-coupling problem of the finger in the self-adaptive stage is solved by dividing torque of the motor into two joint shafts with a spring and the delay-ticking transmission effect of two toggle blocks in linear empty-trip racks. Grasping force analysis and experimental results show that the COSA-LET robotic hand with three COSA-LET fingers has the coupled and self-adaptive hybrid grasping function,enable to adapt objects of different shapes and sizes,autonomously switch between the coupled mode and the self-adaptive mode.

This paper proposes a structure and a measurement method of a very small range image sensor for short distance measurement using a multi-slit laser projector. In recent years, industrial robots used in production lines have become widespread, and development of humanoid robots that operate in the same environment as humans is also proceeding. Many of these robots have an arm mechanism for gripping an object. In order to grasp an object, it is necessary to measure the distance and the object, so these robots are equipped with range image sensors. However, if the position of the range image sensor is away from the arm end, occlusion occurs by the arm during the gripping operation, and the object to be gripped cannot be measured. Therefore, a very small range image sensor that can be attached to a robot hand is required. The sensor used in this research projects multi-slit laser and measures the distance by the disparity of the detected laser light. For measurement, it is necessary to identify the number of each slit laser. Therefore, for the discrimination, the intensity information of the laser light image is used. The effectiveness of the proposed sensor is verified through short-range object measurement experiments.

In this article, a flexible tactile sensor that made of conductive silicone rubber for dexterous robot hand is designed. The tactile sensor is made up of four microsensors. The maximum gripping force is simulated when the degree of a robot finger joint is 138. Meanwhile, a control system to analyze the creep and hysteresis characteristics and a processing system of the tactile sensor is designed. We also demonstrated an experiment for the application of robot grasp object, showing the finger's flexibility and sensitivity. Then the feedback data is sent to control system to provide precise grasp action changes for the robot hand. [ABSTRACT FROM AUTHOR]

Robot hand is the device used for robots to interact with the environments, it has many potential applications. Traditional robot hands cannot translate their finger end along a straight line, which makes them not suitable for grasping thin objects on a flat surface. In order to overcome the bottleneck of traditional hands and enlarge the application possibility of robot hands, this paper develops a novel hybrid grasping modes hand with the variable geometrical structure (called VGS hand). The hand consists of 4-DOF (degree of freedom), two actuators and two fingers. It can perform both linear-parallel and self-adaptive grasping modes. Kinematics, dynamics, and contact forces analysis are conducted to provide a theoretical reference for the design. A prototype was manufactured for grasping experiments; the results of the experiments indicate that the hand has a good grasping performance and can meet different application requirements. [ABSTRACT FROM AUTHOR]

For warehouse automation, stocking items in storage shelves (stowing stage) and picking them off the shelves (picking stage) should be automated. To achieve this, we propose a Suction Pinching Hand, an unstable-to-stable transformation (UST) strategy, and an entrance passing (EP) strategy. The Suction Pinching Hand has two underactuated fingers and one extendable and foldable suction finger whose fingertip has a suction cup. The suction finger is useful during the picking stage to enter and manipulate various objects in a cluttered narrow space, with such spaces being typical in efficient warehouses. As this manipulation is sometimes unstable, the underactuated fingers are used simultaneously to stabilize the grasp after the suction finger moves the object to a relatively open space. The UST strategy realizes the transition from unstable object manipulation in a narrow space to stabilization in a relatively open space. In the stowing stage, proximity sensors in the underactuated fingers are used to sense when the object is touched, for securing a direct pinching motion executable in the stowing stage. Finally, the EP strategy ensures that the picked object is able to pass through the entrance of the shelf bin and be successfully stowed. Experiments demonstrate both the ability of our robot hand to grasp various objects stably and safely, and the effectiveness of the UST and EP strategies during the picking and stowing stages. [ABSTRACT FROM AUTHOR]

In the grasping and manipulation of 3D deformable objects by robotic hands, the physical contact constraints between the fingers and the object have to be considered in order to validate the robustness of the task. Nevertheless, previous works rarely establish contact interaction models based on these constraints that enable the precise control of forces and deformations during the grasping process. This paper considers all steps of the grasping process of deformable objects in order to implement a complete grasp planning pipeline by computing the initial contact points (pregrasp strategy), and later, the contact forces and local deformations of the contact regions while the fingers close over the grasped object (grasp strategy). The deformable object behavior is modeled using a nonlinear isotropic mass-spring system, which is able to produce potential deformation. By combining both models (the contact interaction and the object deformation) in a simulation process, a new grasp planning method is proposed in order to guarantee the stability of the 3D grasped deformable object. Experimental grasping experiments of several 3D deformable objects with a Barrett hand (3-fingered) and a 6-DOF industrial robotic arm are executed. Not only will the final stable grasp configuration of the hand + object system be obtained, but an arm + hand approaching strategy (pregrasp) will also be computed.

In recent years, force control has become more important due to the physical interaction of robots with humans and applications of robots to complex environments. Impedance control is widely used in force control; however, it cannot reproduce the behavior of plastic deformation because it returns to the initial position when the force is removed, similar to elastic deformation. On the other hand, Senoo et al. have proposed plastic deformation control based on the Maxwell model. However, because plastic deformation control is model-based, it is subject to the modeling and parameter errors of the controlled system. A robot hand is relatively small and lightweight; because it uses a gearbox with a high reduction ratio for its joints, it is significantly affected by friction and tends to deviate strongly from the desired motion. Therefore, in this study, a method that is robust against modeling and parameter errors is proposed by feeding back the error from the desired trajectory with the inner position loop. Then, the effectiveness of the proposed method is shown through simulations and experiments using an actual robotic system.

This paper presents the mechanical design of a new three-fingered robot hand for a robot designed to handle tableware. The finger mechanism has three joints and consists of a pair of fourbar linkage mechanisms, one small gas spring, and one feed screw mechanism. As the feed screw moves, the finger mechanism performs flexion and extension operations with its joints interlocked. The gas spring generates gripping force, which is adjusted at the position of the moving part moved by the feed screw. Therefore, the three-fingered robot hand can open and close synchronously, powered by a single motor in the base of the hand. The hand grips with mechanical flexibility. In addition, it canmaintain its grip with no power supply. Tests show that the hand can successfully perform the movements required to grasp various kinds of tableware. [ABSTRACT FROM AUTHOR]

Humanoid robot hands are expected to replace human hands in the dexterous manipulation of objects. This paper presents a review of humanoid robot hand research and development. Humanoid hands are also applied to multifingered haptic interfaces, hand rehabilitation support systems, sEMG prosthetic hands, telepalpation systems, etc. The developed application systems in our group are briefly introduced. [ABSTRACT FROM AUTHOR]

Measuring the interfacial stress between robots and objects is a prerequisite for robots to finish complicated works. In general, the interfacial stress is the 3-D interfacial stress which not only couple with the vertical normal interfacial stress but also the parallel shear interfacial stress. It is very important to develop a method to decouple the 3-D interfacial stress. This paper presents a measurement method that was able to decouple the measurement of the 3-D interfacial stress components. To implement the method, a 3-D interfacial stress sensor was fabricated based on graphene foams and superelastic materials. A high-resolution multichannel resistance measurement circuit was developed, and experiments were carried out with 3-D stress simulation equipment. The results showed that the sensor was capable of measuring z-direction normal stress at a range of 0–21 kPa with a sensitivity of 0.029 kPa−1 and x- and y-direction shear stresses at a range of 0–12.5 kPa with sensitivities of 0.020, 0.019, 0.018, and 0.019 kPa−1, and the measurement circuit was capable of measuring a range of $100\,\,\Omega -100\,\,\textsf {M}\Omega $ with a resolution of 1%. This method can be utilized in robots to decouple the measurement of the 3-D interfacial stress components. [ABSTRACT FROM AUTHOR]

This paper introduces a novel underactuated hand, the PASA-GB hand, which has a hybrid grasping mode. The hybrid grasping mode is a combination of parallel pinching (PA) grasp and self-adaptive enveloping (SA) grasp. In order to estimate the performance of grasping objects, the potential energy method is used to analyze the grasping poses and stabilities of the PASA-GB hand. The calculation of force distribution shows the influence of the size and position of objects and provides a method to optimize the force distribution. The switch condition between pinching and enveloping grasp is analyzed in detail. Experimental results verify wide adaptability and high practicability of the PASA-GB hand. [ABSTRACT FROM AUTHOR]

This paper introduces a new human-machine interface for individuals with tetraplegia. We investigated the feasibility of piloting an assistive device by processing supra-lesional muscle responses online. The ability to voluntarily contract a set of selected muscles was assessed in five spinal cord-injured subjects through electromyographic (EMG) analysis. Two subjects were also asked to use the EMG interface to control palmar and lateral grasping of a robot hand. The use of different muscles and control modalities was also assessed. These preliminary results open the way to new interface solutions for high-level spinal cord-injured patients. [ABSTRACT FROM PUBLISHER]

Robot hand is the device used for robots to interact with the environments, it has many potential applications. Traditional robot hands cannot translate their finger end along a straight line, which makes them not suitable for grasping thin objects on a flat surface. In order to overcome the bottleneck of traditional hands and enlarge the application possibility of robot hands, this paper develops a novel hybrid grasping modes hand with the variable geometrical structure (called VGS hand). The hand consists of 4-DOF (degree of freedom), two actuators and two fingers. It can perform both linear-parallel and self-adaptive grasping modes. Kinematics, dynamics, and contact forces analysis are conducted to provide a theoretical reference for the design. A prototype was manufactured for grasping experiments; the results of the experiments indicate that the hand has a good grasping performance and can meet different application requirements.

This paper proposes a novel cluster-tube self-adaptive robot hand (CTSA Hand). The CTSA Hand consists of a base, a motor, a transmission mechanism, multiple elastic tendons, and a group of sliding-tube assemblies. Each sliding-tube assembly is composed of a sliding tube, a guide rod, two springs and a hinge. When the hand grasping an object, the object pushes some sliding tubes to different positions according to the surface shape of the object, the motor pulls the tendons tight to cluster tubes. The CTSA Hand can realize self-adaptive grasping of objects of different sizes and shapes. The CTSA Hand can grasp multiple objects simultaneously because the grasping of the hand acts as many grippers in different directions and heights. The grasping forces of the hand are adjusted by a closed-loop control system with potentiometer. Experimental results show that the CTSA Hand has the features of highly self-adaption and large grasping forces when grasping various objects. [ABSTRACT FROM AUTHOR]