Evolution of a Novel Finger Mechanism for Robust Industrial End Effectors

2008 ◽  
Author(s):  
Venketesh N. Dubey ◽  
Richard M. Crowder
Keyword(s):  
Industrial Application ◽  
Degrees Of Freedom ◽  
Industrial Applications ◽  
Stringent Requirement ◽  
End Effector ◽  
Safety Requirements ◽  
Safety And Reliability ◽  
Different Shapes ◽  
End Effectors ◽  
And Control

This paper presents design for a finger mechanism that has evolved from the stringent requirement of ruggedness and reliability in an industrial application. The paper initially describes the need for a special purpose end effector to operate in a constrained environment and then takes through the various stages of design modifications that were required to ensure safety and reliability. This resulted into a rigid link finger design, which is adaptive to different shapes and operated by a single actuator providing up to 3 degrees of freedom to the finger. A number of such finger mechanisms can be assembled together in different configurations to design special purpose end effectors. This paper covers two such designs and briefly discusses the grasping and control issues associated with the limited number of actuators built into the end effector, and evaluates their suitability in industrial environments. The design overcomes limitations of majority of existing tendon based end effectors requiring a large number of actuators to be controlled thus meeting the space and safety requirements for constrained industrial applications.

scholarly journals Grasping and Control Issues in Adaptive End Effectors

2004 ◽  
Author(s):  
Venketesh N. Dubey ◽  
Richard M. Crowder
Keyword(s):  
Industrial Applications ◽  
End Effector ◽  
Industrial Environment ◽  
Laboratory Environment ◽  
Safety Requirements ◽  
Grasping And Manipulation ◽  
Minimum Number ◽  
End Effectors ◽  
Adaptive Nature ◽  
And Control

Research into robotic grasping and manipulation has led to the development of a large number of tendon based end effectors. Many are, however, developed as a research tool, which are limited in application to the laboratory environment. The main reason being that the designs requiring a large number of actuators to be controlled. Due to the space and safety requirements, very few have been developed and commissioned for industrial applications. This paper presents design of a rigid link finger operated by a minimum number of actuators, which may be suitable for a number of adaptive end effectors. The adaptive nature built into the end effector (due to limited number of actuators) presents considerable problems in grasping and control. The paper discusses the issues associated with such designs. The research can be applicable to any adaptive end effectors that are controlled by limited number of actuators and evaluates their suitability in industrial environment.

Development of a Reconfigurable End-Effector Prototype

2017 ◽  
Author(s):  
Frank Khelfa ◽  
Lukas Zimmer ◽  
Paul Motzki ◽  
Stefan Seelecke
Keyword(s):  
Degrees Of Freedom ◽  
Material Handling ◽  
Exchange Process ◽  
End Effector ◽  
Locking Mechanism ◽  
Different Shapes ◽  
End Effectors ◽  
Future Work ◽  
Crucial Part

Material handling is a crucial part of manufacturing and assembly in industry. In state-of-the-art handling systems, robots use various end-effectors to grip and transport different shapes of workpieces. The exchange process of fitted end-effectors to appropriate workpieces, often requires to interrupt the manufacturing process. From the prospective of economic efficiency, there is an inherent benefit creating a reconfigurable end-effector that is able to adjust automatically to different workpiece geometries. In this work a novel end-effector prototype based on shape memory alloys (SMA’s) is developed and experimentally validated. The end-effector prototype has four arms with two SMA driven reconfigurable degrees of freedom (DOF’s) to allow gripping of different workpiece shapes and geometries. Each arm is rotatable by 90 degrees (1. DOF) and uses a counterweight to relieve the SMA wire. The tip of the arm is driven by a separate SMA in a 20 degree range and it has a special locking mechanism to hold different positions without any flowing current. The designs of the actuator constructions are presented and a prototype is produced via rapid-prototyping. Future work will include the characterization of the second DOF and controlling the positions of both DOF’s by using a PID controller based on the SMA self-sensing ability.

Design of an Underactuated Robotic End-Effector With a Focus on Power Tool Manipulation

2014 ◽  
Author(s):  
Michael Rouleau ◽  
Dennis Hong
Keyword(s):  
Disaster Response ◽  
Degrees Of Freedom ◽  
Humanoid Robot ◽  
Servo Motor ◽  
End Effector ◽  
Design Considerations ◽  
Wide Range ◽  
End Effectors ◽  
Four Bar Linkage ◽  
Careful Design

End-effectors require careful design considerations to be able to successfully hold and use power tools while maintaining the ability to also grasp a wide range of other objects. This paper describes the design of an end effector for a humanoid robot built for disaster response scenarios. The end effector is comprised of two independently actuated fingers with two opposing stationary rigid hollow pylons built to allow the pinching of objects and to provide protection for the opposing fingers when retracted and not in use. Each finger has two degrees of freedom (DOF) and is actuated with one servo motor through the use of an underactuated four bar linkage. Using only two fingers and two actuators the end-effector has the ability to hold a power tool while also being able to simultaneously actuate the trigger of the tool independently. The combination of compliant fingers and rigid pylons along with the careful design of the palm structure creates a strong robust dexterous end-effort that is simple to control.

Experimental results for the flexible joint cable-suspended manipulator of ICaSbot

Robotica ◽  
2013 ◽  
Vol 31 (6) ◽  
pp. 887-904 ◽  
Author(s):  
M. H. Korayem ◽  
M. Bamdad ◽  
H. Tourajizadeh ◽  
A. H. Korayem ◽  
R. M. Zehtab ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Parallel Robot ◽  
Joint Space ◽  
End Effector ◽  
Flexible Joint ◽  
Cable Robot ◽  
Six Dof ◽  
And Control ◽  
Computed Torque

SUMMARYIn this paper, design, dynamic, and control of the motors of a spatial cable robot are presented considering flexibility of the joints. End-effector control in order to control all six spatial degrees of freedom (DOFs) of the system and motor control in order to control the joints flexibility are proposed here. Corresponding programing of its operation is done by formulating the kinematics and dynamics and also control of the robot. Considering the existence of gearboxes, flexibility of the joints is modeled in the feed-forward term of its controller to achieve better accuracy. A two sequential closed-loop strategy consisting of proportional derivative (PD) for linear actuators in joint space and computed torque method for nonlinear end-effector in Cartesian space is presented for further accuracy. Flexibility is estimated using modeling and simulation by MATLAB and SimDesigner. A prototype has been built and experimental tests have been done to verify the efficiency of the proposed modeling and controller as well as the effect of flexibility of the joints. The ICaSbot (IUST Cable-Suspended robot) is an under-constrained six-DOF parallel robot actuated by the aid of six suspended cables. An experimental test is conducted for the manufactured flexible joint cable robot of ICaSbot and the outputs of sensors are compared with simulation. The efficiency of the proposed schemes is demonstrated.

Kinematics of the Translational 3-URC Mechanism1

2004 ◽  
Vol 126 (6) ◽  
pp. 1113-1117 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Explicit Form ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Industrial Applications ◽  
Parallel Architectures ◽  
Six Degrees Of Freedom ◽  
Spatial Mechanisms ◽  
Six Dof ◽  
And Control ◽  
Spherical Motion

The use of less than six degrees of freedom (dof) mechanisms instead of six-dof ones is always recommended when the application makes it possible, since their architectures and control are simpler to manufacture and implement respectively. Three-dof mechanisms constitute an important subset of less-than-six-dof mechanisms, since either translational or spherical motion can be obtained through three-dof spatial mechanisms and many industrial applications require the only translational or spherical motion. This paper presents a new translational parallel mechanism (TPM), named translational 3-URC. The new mechanism belongs to the parallel architectures with 3-URC topology, which contain another architecture that is a spherical parallel wrist. The proposed TPM is not overconstrained and has three equal legs whose kinematic pairs are three revolute pairs and one passive cylindrical pair per leg. Its actuated pairs are three revolute pair located on the frame. The position and velocity analyses of the translational 3-URC will be addressed and solved. Its singularity conditions will be written in explicit form and geometrically interpreted.

Design, testing and evaluation of an end-effector for self-relocation

Robotica ◽  
2015 ◽  
Vol 34 (12) ◽  
pp. 2689-2728 ◽  
Author(s):  
Feng Han ◽  
Kui Sun ◽  
Yu Liu ◽  
Hong Liu
Keyword(s):  
Degrees Of Freedom ◽  
Physical Simulation ◽  
Industrial Robot ◽  
Space Environment ◽  
Air Bearing ◽  
End Effector ◽  
Six Degrees Of Freedom ◽  
Soft Capture ◽  
End Effectors ◽  
Prototype Design

SUMMARYTwo identical end-effectors are indispensable for self-relocation of a space manipulator, which is an effective way of extending its servicing capability. The prototype design is intimately linked to the requirements. The significant features and functionality of the end-effector and its grapple fixture are described, including the key analysis efforts. The characteristics of the end-effector and their suitability for self-relocation and payload handling were confirmed by testing, which used two prototype end-effectors, a semi-physical simulation testbed system with two, six degrees of freedom (DOF) industrial robot arms, and an air-bearing testbed system with a seven DOF manipulator. The results demonstrate that the end-effector satisfies the requirements and it can work well in a simulated space environment. With the compliance motion of the manipulator, the end-effector can perform soft capture and the manipulator can securely self-relocate and handle the payload.

scholarly journals Soft Robotics: Biological Inspiration, State of the Art, and Future Research

2008 ◽  
Vol 5 (3) ◽  
pp. 99-117 ◽  
Author(s):  
Deepak Trivedi ◽  
Christopher D. Rahn ◽  
William M. Kier ◽  
Ian D. Walker
Keyword(s):  
Degrees Of Freedom ◽  
State Of The Art ◽  
Future Research ◽  
Robot Design ◽  
The Novel ◽  
Soft Robots ◽  
Biological Inspiration ◽  
End Effectors ◽  
And Control ◽  
Complex Movement

Traditional robots have rigid underlying structures that limit their ability to interact with their environment. For example, conventional robot manipulators have rigid links and can manipulate objects using only their specialised end effectors. These robots often encounter difficulties operating in unstructured and highly congested environments. A variety of animals and plants exhibit complex movement with soft structures devoid of rigid components. Muscular hydrostats (e.g. octopus arms and elephant trunks) are almost entirely composed of muscle and connective tissue and plant cells can change shape when pressurised by osmosis. Researchers have been inspired by biology to design and build soft robots. With a soft structure and redundant degrees of freedom, these robots can be used for delicate tasks in cluttered and/or unstructured environments. This paper discusses the novel capabilities of soft robots, describes examples from nature that provide biological inspiration, surveys the state of the art and outlines existing challenges in soft robot design, modelling, fabrication and control.

The QuadroG Robot, a Parallel Robot With a Configurable Platform for Haptic Applications

2015 ◽  
Author(s):  
Salua Hamaza ◽  
Patrice Lambert ◽  
Marco Carricato ◽  
Just Herder
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Parallel Robot ◽  
Parallel Robots ◽  
End Effector ◽  
Contact Points ◽  
Loop Chain ◽  
End Effectors ◽  
4 Degrees Of Freedom

This paper explores the fundamentals of parallel robots with configurable platforms (PRCP), as well as the design and the kinematic analysis of those. The concept behind PRCP is that the rigid (non-configurable) end-effector is replaced by a closed-loop chain, the configurable platform. The use of a closed-loop chain allows the robot to interact with the environment from multiple contact points on the platform, which reflects the presence of multiple end-effectors. This results in a robot that successfully combines motion and grasping capabilities into a structure that provides an inherent high stiffness. This paper aims to introduce the QuadroG robot, a 4 degrees of freedom PRCP which finely merges planar motion together with grasping capabilities.

scholarly journals On Differential Mechanisms for Underactuated, Lightweight, Adaptive Prosthetic Hands

2021 ◽  
Vol 15 ◽  
Author(s):  
Geng Gao ◽  
Mojtaba Shahmohammadi ◽  
Lucas Gerez ◽  
George Kontoudis ◽  
Minas Liarokapis
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Minimal Set ◽  
Prosthetic Devices ◽  
Multiple Degrees Of Freedom ◽  
Prosthetic Hands ◽  
Promising Application ◽  
End Effectors ◽  
Critical Components ◽  
And Control

Over the last decade underactuated, adaptive robot grippers and hands have received an increased interest from the robotics research community. This class of robotic end-effectors can be used in many different fields and scenarios with a very promising application being the development of prosthetic devices. Their suitability for the development of such devices is attributed to the utilization of underactuation that provides increased functionality and dexterity with reduced weight, cost, and control complexity. The most critical components of underactuated, adaptive hands that allow them to perform a broad set of grasp poses are appropriate differential mechanisms that facilitate the actuation of multiple degrees of freedom using a single motor. In this work, we focus on the design, analysis, and experimental validation of a four output geared differential, a series elastic differential, and a whiffletree differential that can incorporate a series of manual and automated locking mechanisms. The locking mechanisms have been developed so as to enhance the control of the differential outputs, allowing for efficient grasp selection with a minimal set of actuators. The differential mechanisms are applied to prosthetic hands, comparing them and describing the benefits and the disadvantages of each.

scholarly journals Modeling and Control of a Cable-Suspended Sling-Like Parallel Robot for Throwing Operations

2020 ◽  
Vol 10 (24) ◽  
pp. 9067
Author(s):  
Deng Lin ◽  
Giovanni Mottola ◽  
Marco Carricato ◽  
Xiaoling Jiang
Keyword(s):  
Mathematical Models ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Target Point ◽  
Inertial Effects ◽  
End Effector ◽  
Modeling And Control ◽  
And Control ◽  
Three Degrees Of Freedom

Cable-driven parallel robots can provide interesting advantages over conventional robots with rigid links; in particular, robots with a cable-suspended architecture can have very large workspaces. Recent research has shown that dynamic trajectories allow the robot to further increase its workspace by taking advantage of inertial effects. In our work, we consider a three-degrees-of-freedom parallel robot suspended by three cables, with a point-mass end-effector. This model was considered in previous works to analyze the conditions for dynamical feasibility of a trajectory. Here, we enhance the robot’s capabilities by using it as a sling, that is, by throwing a mass at a suitable time. The mass is carried at the end-effector by a gripper, which releases the mass so that it can reach a given target point. Mathematical models are presented that provide guidelines for planning the trajectory. Moreover, results are shown from simulations that include the effect of cable elasticity. Finally, suggestions are offered regarding how such a trajectory can be optimized.

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