scholarly journals On the Structural Synthesis of Multi-Fingered Hands

2000 ◽  
Author(s):  
Jyh-Jone Lee ◽  
Chun-Po Chen
Keyword(s):  
Contact Geometry ◽  
Human Hand ◽  
Robot Arm ◽  
Structural Synthesis ◽  
End Effector ◽  
New Approach ◽  
Mechanical Hand ◽  
Autonomous Manipulation ◽  
Force Closure ◽  
Human Hands

Abstract Compared to the serial type of six-freedom robot arm attached with an end-effector, the multi-fingered hand system can provide more dexterity and versatility in the field of autonomous manipulation tasks. Designs of multi-fingered hands can be found in the literature, to name a few, Mechanical Hand by Skinner [13], Multi-jointed Finger System by Okada [6], Stanford/JPL Hand (or Salisbury Hand) [11], Utah-MIT Hand [3], and NTU-1 Hand [5]. Generally, these mechanical hand systems have been designed to simulate a subset function of human hands. The structures of these systems basically resemble the skeleton of human hand and are constructed by designers’ intuition. Not much literature addressed about the structural synthesis of multi-fingered hands. This paper presents a new approach for the structural synthesis of multi-fingered hands. It takes into account both the total mobility and the force closure criterion of the system. Based upon the Grübler’s mobility equation, relations regarding the numbers of fingers, contact geometry, and object freedoms are established. Subsequently, by applying the force closure criterion, the total number of possible multi-fingered hands with given mobility are synthesized.

scholarly journals Structural Synthesis of Multi-Fingered Hands

2002 ◽  
Vol 124 (2) ◽  
pp. 272-276 ◽  
Author(s):  
Jyh-Jone Lee ◽  
Lung-Wen Tsai
Keyword(s):  
Degrees Of Freedom ◽  
Structural Characteristics ◽  
Human Hand ◽  
Functional Requirements ◽  
Structural Synthesis ◽  
Constraint Equations ◽  
Mechanical Hand ◽  
Force Closure ◽  
Systematic Enumeration ◽  
Mechanical Hands

The kinematic structure of a mechanical hand typically resembles the skeleton of a human hand and it is usually designed to emulate a subset of the functions of a human hand. This paper analyzes the structural characteristics associated with the functional requirements of a mechanical hand. Using the mobility criterion and force closure concept, constraint equations for structural synthesis of multi-fingered mechanical hands are derived. A procedure for systematic enumeration of the kinematic structures of mechanical hands is established. An atlas of feasible kinematic structures of multi-fingered hands having a mobility number ranging from 3 to 6 and contact degrees of freedom ranging from 1 to 5 is developed. Further, two theorems concerning the structural characteristics of mechanical hands are presented.

The Dynamic Analysis and Design of a High-Speed Insertion Hand Using the Generalized Centroid and Virtual Mass

1990 ◽  
Vol 112 (4) ◽  
pp. 646-652 ◽  
Author(s):  
H. Asada ◽  
Y. Kakumoto
Keyword(s):  
Dynamic Process ◽  
High Speed ◽  
Virtual Mass ◽  
End Effector ◽  
New Approach ◽  
Analysis And Design ◽  
Mechanical Hand ◽  
Approach Speed ◽  
Mass Property ◽  
Mass Properties

A new approach to the design of an assembly end effector for the high-speed insertion of a peg into a chamfered hole is presented. The peg is supported by a special mechanical hand that allows it to be guided along the chamfer surface without bouncing on it, even when bumping against the chamfer at a high speed. The dynamic process of the peg insertion is analyzed, and mass properties of the hand mechanism for successful insertion are derived by using the theory of generalized centroid and virtual mass. Namely, for successful high-speed insertion, the generalized centroid must be put near the tip of the peg, and the virtual mass in the horizontal direction must be minimized. Following this, a hand that meets the mass property conditions is designed, built and tested. It is demonstrated that this hand accomplishes a high approach-speed of over 2 m/s.

Three-Degree-of-Freedom Parallel Robot Arm

2006 ◽  
Author(s):  
Martin Hosek ◽  
Michael Valasek ◽  
Jairo Moura
Keyword(s):  
Parallel Robot ◽  
Degree Of Freedom ◽  
Motion Path ◽  
Angular Orientation ◽  
Robot Arm ◽  
Flat Panel Display ◽  
End Effector ◽  
Cluster Tools ◽  
Manufacturing Applications ◽  
Three Degree Of Freedom

This paper presents single- and dual-end-effector configurations of a planar three-degree of freedom parallel robot arm designed for automated pick-place operations in vacuum cluster tools for semiconductor and flat-panel-display manufacturing applications. The basic single end-effector configuration of the arm consists of a pivoting base platform, two elbow platforms and a wrist platform, which are connected through two symmetric pairs of parallelogram mechanisms. The wrist platform carries an end-effector, the position and angular orientation of which can be controlled independently by three motors located at the base of the robot. The joints and links of the mechanism are arranged in a unique geometric configuration which provides a sufficient range of motion for typical vacuum cluster tools. The geometric properties of the mechanism are further optimized for a given motion path of the robot. In addition to the basic symmetric single end-effector configuration, an asymmetric costeffective version of the mechanism is derived, and two dual-end-effector alternatives for improved throughput performance are described. In contrast to prior attempts to control angular orientation of the end-effector(s) of the conventional arms employed currently in vacuum cluster tools, all of the motors that drive the arm can be located at the stationary base of the robot with no need for joint actuators carried by the arm or complicated belt arrangements running through the arm. As a result, the motors do not contribute to the mass and inertia properties of the moving parts of the arm, no power and signal wires through the arm are necessary, the reliability and maintenance aspects of operation are improved, and the level of undesirable particle generation is reduced. This is particularly beneficial for high-throughput applications in vacuum and particlesensitive environments.

Cooperation and Null-Space Control of Networked Omni-Directional Mobile Manipulators

2020 ◽  
Author(s):  
Michael John Chua ◽  
Yen-Chen Liu
Keyword(s):  
Degrees Of Freedom ◽  
Null Space ◽  
Kinematic Model ◽  
Mobile Manipulator ◽  
Main Task ◽  
Mobile Manipulators ◽  
Robot Arm ◽  
Task Space ◽  
End Effector ◽  
Mobile Base

Abstract This paper presents cooperation and null-space control for networked mobile manipulators with high degrees of freedom (DOFs). First, kinematic model and Euler-Lagrange dynamic model of the mobile manipulator, which has an articulated robot arm mounted on a mobile base with omni-directional wheels, have been presented. Then, the dynamic decoupling has been considered so that the task-space and the null-space can be controlled separately to accomplish different missions. The motion of the end-effector is controlled in the task-space, and the force control is implemented to make sure the cooperation of the mobile manipulators, as well as the transportation tasks. Also, the null-space control for the manipulator has been combined into the decoupling control. For the mobile base, it is controlled in the null-space to track the velocity of the end-effector, avoid other agents, avoid the obstacles, and move in a defined range based on the length of the manipulator without affecting the main task. Numerical simulations have been addressed to demonstrate the proposed methods.

scholarly journals Detachable Robotic Grippers for Human-Robot Collaboration

2021 ◽  
Vol 8 ◽  
Author(s):  
Zubair Iqbal ◽  
Maria Pozzi ◽  
Domenico Prattichizzo ◽  
Gionata Salvietti
Keyword(s):  
Degrees Of Freedom ◽  
Tactile Feedback ◽  
Industrial Robots ◽  
Physical Interaction ◽  
Robot Arm ◽  
Robotic Hands ◽  
End Effector ◽  
External Power ◽  
Self Powered ◽  
Automatic Tool

Collaborative robots promise to add flexibility to production cells thanks to the fact that they can work not only close to humans but also with humans. The possibility of a direct physical interaction between humans and robots allows to perform operations that were inconceivable with industrial robots. Collaborative soft grippers have been recently introduced to extend this possibility beyond the robot end-effector, making humans able to directly act on robotic hands. In this work, we propose to exploit collaborative grippers in a novel paradigm in which these devices can be easily attached and detached from the robot arm and used also independently from it. This is possible only with self-powered hands, that are still quite uncommon in the market. In the presented paradigm not only hands can be attached/detached to/from the robot end-effector as if they were simple tools, but they can also remain active and fully functional after detachment. This ensures all the advantages brought in by tool changers, that allow for quick and possibly automatic tool exchange at the robot end-effector, but also gives the possibility of using the hand capabilities and degrees of freedom without the need of an arm or of external power supplies. In this paper, the concept of detachable robotic grippers is introduced and demonstrated through two illustrative tasks conducted with a new tool changer designed for collaborative grippers. The novel tool changer embeds electromagnets that are used to add safety during attach/detach operations. The activation of the electromagnets is controlled through a wearable interface capable of providing tactile feedback. The usability of the system is confirmed by the evaluations of 12 users.

scholarly journals A New Approach to the Solution of Robot Kinematics Based on Relative Transformation Matrices

2016 ◽  
Vol 5 (3) ◽  
pp. 213
Author(s):  
Mohammad Reza Elhami ◽  
Iman Dashti
Keyword(s):  
Robot Manipulator ◽  
Robot Kinematics ◽  
Coordinate Frame ◽  
End Effector ◽  
New Approach ◽  
Transformation Matrices ◽  
The World ◽  
Convenient Approach ◽  
Position And Orientation ◽  
Relative Transformation

In analyzing robot manipulator kinematics, we need to describe relative movement of adjacent linkages or joints in order to obtain the pose of end effector (both position and orientation) in reference coordinate frame. Denavit-Hartenberg established a method based on a 4×4 homogenous matrix so called “A” matrix. This method used by most of the authors for kinematics and dynamic analysis of the robot manipulators. Although it has many advantages, however, finding the elements of this matrix and link/joint’s parameters is sometimes complicated and confusing. By considering these difficulties, the authors proposed a new approach called ‘convenient approach’ that is developed based on “Relative Transformations Principle”. It provides a very simple and convenient way for the solution of robot kinematics compared to the conventional D-H representation. In order to clarify this point, the kinematics of the world known Stanford manipulator has been solved through D-H representation as well as convenient approach and the results are compared.

scholarly journals Gesture Controlled Robot using Arduino

2021 ◽  
Vol 9 (VI) ◽  
pp. 2758-2765
Author(s):  
Biyyala Srijith
Keyword(s):  
Remote Control ◽  
Steering Wheel ◽  
Human Hand ◽  
Robot Arm ◽  
Radio Waves ◽  
Robotic Control ◽  
Accelerometer Sensor ◽  
Left And Right ◽  
Human Touch ◽  
The Right

A Gesture Controlled Car is a robot that can be controlled with a simple human touch. The user only needs to wear a touch device where the sensor is installed. The sensor will record the movement of the hand in a certain direction that will lead to the movement of the robot in the right places. The robot and the touch device are connected wirelessly with radio waves. The user can communicate with the robot in a very friendly way due to wireless communication. We can control the car using accelerometer sensors that are connected to our hand glove. Sensors are designed to replace the remote control commonly used to drive a car. It will allow the user to control the forward, backward, left and right, while using the same accelerometer sensor to control the car's steering wheel. The movement of the car is controlled by the separation method. The machine involves rotating both front and rear wheels on the left or right side to move the non-clockwise side and another pair around the clock causing the car to rotate with its axis without going forward or backward. The main advantage of this machine is that the car with this method can take sharp turns without difficulty. The design and use of a robotic control arm using a flex sensor is suggested. The robot arm is designed to consist of four moving fingers, each with three connectors, an opposing thumb, a round wrist, and an elbow. The robot arm is designed to mimic the movements of a human hand using a hand glove.

scholarly journals Modal Kinematic Analysis of a Parallel Kinematic Robot with Low-Stiffness Transmissions

Robotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 132
Author(s):  
Paolo Righettini ◽  
Roberto Strada ◽  
Filippo Cortinovis
Keyword(s):  
High Speed ◽  
Parallel Robots ◽  
Maximum Speed ◽  
Kinematic Structure ◽  
End Effector ◽  
New Approach ◽  
Working Space ◽  
Modes Of Vibration ◽  
Parallel Kinematic ◽  
Actuated Joints

Several industrial robotic applications that require high speed or high stiffness-to-inertia ratios use parallel kinematic robots. In the cases where the critical point of the application is the speed, the compliance of the main mechanical transmissions placed between the actuators and the parallel kinematic structure can be significantly higher than that of the parallel kinematic structure itself. This paper deals with this kind of system, where the overall performance depends on the maximum speed and on the dynamic behavior. Our research proposes a new approach for the investigation of the modes of vibration of the end-effector placed on the robot structure for a system where the transmission’s compliance is not negligible in relation to the flexibility of the parallel kinematic structure. The approach considers the kinematic and dynamic coupling due to the parallel kinematic structure, the system’s mass distribution and the transmission’s stiffness. In the literature, several papers deal with the dynamic vibration analysis of parallel robots. Some of these also consider the transmissions between the motors and the actuated joints. However, these works mainly deal with the modal analysis of the robot’s mechanical structure or the displacement analysis of the transmission’s effects on the positioning error of the end-effector. The discussion of the proposed approach takes into consideration a linear delta robot. The results show that the system’s natural frequencies and the directions of the end-effector’s modal displacements strongly depend on its position in the working space.

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