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.

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.

Analysis and control of redundant manipulator dynamics based on an extended operational space

Robotica ◽  
2001 ◽  
Vol 19 (6) ◽  
pp. 649-662 ◽  
Author(s):  
Ki Cheol Park ◽  
Pyung-Hun Chang ◽  
Sukhan Lee
Keyword(s):  
Null Space ◽  
Performance Measure ◽  
The Self ◽  
Real Time Control ◽  
End Effector ◽  
Time Control ◽  
Operational Space ◽  
Minimum Number ◽  
And Control ◽  
Self Motion

In this paper a new concept, named the Extended Operational Space (EXOS), has been proposed for the effective analysis and the real-time control of the robot manipulators with kinematic redundancy. The EXOS consists of the operational space (OS) and the optimal null space (NS): the operational space is used to describe manipulator end-effector motion; whereas the optimal null space, described by the minimum number of NS vectors, is used to express the self motion.Based upon the EXOS formulation, the kinematics, statics, and dynamics of redundant manipulators have been analyzed, and control laws based on the dynamics have been proposed. The inclusion of only the minimum number of NS vectors has changed the resulting dynamic equations into a very compact form, yet comprehensive enough to describe: not only the dynamic behavior or the end effector, but also that of the self motion; and at the same time the interaction of these two motions. The comprehensiveness is highlighted by the demonstration of the dynamic couplings between OS dynamics and NS dynamics, which are quite elusive in other approaches.Using the proposed dynamic controls, one can optimize a performance measure while tracking a desired end-effector trajectory with a better computational efficiency than the conventional methods. The effectiveness of the proposed method has been demonstrated by simulations and experiments.

A Practical Robotic End-Effector for Grasping Postal Sacks

2004 ◽  
Vol 126 (1) ◽  
pp. 154-161 ◽  
Author(s):  
H. Kazerooni
Keyword(s):  
Material Handling ◽  
Deformable Objects ◽  
Postal Service ◽  
End Effector ◽  
New Class ◽  
End Effectors ◽  
And Control ◽  
The U.S

This article describes a new class of end-effectors that can be used with robotic and material handling devices for grabbing and holding deformable objects with undefined shapes such as sacks and bags. These end-effectors can grab and hold filled sacks from any point on the sack and regardless of the sack orientation and position. The first prototype end-effector, designed for the U.S. Postal Service, has two rollers. The rollers are pushed toward each other by the force of a spring. When the rollers are powered to spin, the inward spinning of the rollers causes the sack material to be dragged in between the rollers due to the friction between the surfaces of the rollers and the sack material. The spring pushes the rollers toward each other with sufficient force to hold the sack material in place between the rollers. The end-effector described here has been evaluated and proven to be exceedingly effective in grabbing and holding postal sacks. This article describes the underlying principles of the design, grasp conditions and control of the end-effector.

GOVERNMENT/BUSINESS SYNERGY: EARLY AMERICAN INNOVATIONS IN BUDGETING AND COST ACCOUNTING

1992 ◽  
Vol 19 (2) ◽  
pp. 123-145 ◽  
Author(s):  
R. Penny Marquette ◽  
Richard K. Fleischman
Keyword(s):  
Twentieth Century ◽  
Progressive Era ◽  
Cost Accounting ◽  
American Government ◽  
Significant Cost ◽  
Industrial Environment ◽  
Early American ◽  
Planning And Control ◽  
And Control ◽  
Governmental Budgeting

This paper examines certain interactions between American government and business which resulted in important innovations in the areas of budgeting and cost accounting early in the twentieth century. The evidence suggests that budgeting methods were initially developed by municipal reformers of the Progressive era and were subsequently adapted by business for planning and control purposes. In like fashion, standard costing and variance analysis were significant cost accounting techniques born to an industrial environment which came to contribute markedly to a continuing improvement of governmental budgeting procedures.

scholarly journals Force-Free Control for Direct Teaching of a Surgical Assistant Robot End Effector with Wire-Driven Bidirectional Telescopic Mechanism

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3498
Author(s):  
Youqiang Zhang ◽  
Cheol-Su Jeong ◽  
Minhyo Kim ◽  
Sangrok Jin
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Friction Model ◽  
Surgical Instruments ◽  
Control Input ◽  
End Effector ◽  
Motor Current ◽  
Direct Teaching ◽  
End Effectors ◽  
Teaching Operation

This paper shows the design and modeling of an end effector with a bidirectional telescopic mechanism to allow a surgical assistant robot to hold and handle surgical instruments. It also presents a force-free control algorithm for the direct teaching of end effectors. The bidirectional telescopic mechanism can actively transmit force both upwards and downwards by staggering the wires on both sides. In order to estimate and control torque via motor current without a force/torque sensor, the gravity model and friction model of the device are derived through repeated experiments. The LuGre model is applied to the friction model, and the static and dynamic parameters are obtained using a curve fitting function and a genetic algorithm. Direct teaching control is designed using a force-free control algorithm that compensates for the estimated torque from the motor current for gravity and friction, and then converts it into a position control input. Direct teaching operation sensitivity is verified through hand-guiding experiments.

scholarly journals Magnetic Driven Two-Finger Micro-Hand with Soft Magnetic End-Effector for Force-Controlled Stable Manipulation in Microscale

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 410
Author(s):  
Dan Liu ◽  
Xiaoming Liu ◽  
Pengyun Li ◽  
Xiaoqing Tang ◽  
Masaru Kojima ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Force Feedback ◽  
Soft Magnetic ◽  
End Effector ◽  
Force Microscopy ◽  
System A ◽  
Atomic Force ◽  
Afm Probe ◽  
End Effectors ◽  
Fixed End

In recent years, micromanipulators have provided the ability to interact with micro-objects in industrial and biomedical fields. However, traditional manipulators still encounter challenges in gaining the force feedback at the micro-scale. In this paper, we present a micronewton force-controlled two-finger microhand with a soft magnetic end-effector for stable grasping. In this system, a homemade electromagnet was used as the driving device to execute micro-objects manipulation. There were two soft end-effectors with diameters of 300 μm. One was a fixed end-effector that was only made of hydrogel, and the other one was a magnetic end-effector that contained a uniform mixture of polydimethylsiloxane (PDMS) and paramagnetic particles. The magnetic force on the soft magnetic end-effector was calibrated using an atomic force microscopy (AFM) probe. The performance tests demonstrated that the magnetically driven soft microhand had a grasping range of 0–260 μm, which allowed a clamping force with a resolution of 0.48 μN. The stable grasping capability of the magnetically driven soft microhand was validated by grasping different sized microbeads, transport under different velocities, and assembly of microbeads. The proposed system enables force-controlled manipulation, and we believe it has great potential in biological and industrial micromanipulation.

scholarly journals Deviation Tolerance Performance Evaluation and Experiment of Picking End Effector for Famous Tea

Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 128
Author(s):  
Yingpeng Zhu ◽  
Chuanyu Wu ◽  
Junhua Tong ◽  
Jianneng Chen ◽  
Leiying He ◽  
...  
Keyword(s):  
Success Rate ◽  
Negative Pressure ◽  
Evaluation Method ◽  
Orthogonal Experiment ◽  
Spatial Position ◽  
End Effector ◽  
Significance Level ◽  
Growth Environment ◽  
End Effectors ◽  
Average Success Rate

Accurately obtaining the posture and spatial position of tea buds through machine vision and other technologies is difficult due to the small size, different shapes, and complex growth environment of tea buds. Therefore, end effectors are prone to problems, such as picking omission and picking error. This study designs a picking end effector based on negative pressure guidance for famous tea. This end effector uses negative pressure to guide tea buds in a top-down manner, thereby correcting their posture and spatial position. Therefore, the designed end effector has deviation tolerance performance that can improve the picking success rate. The pre-experiment is designed, the tip of apical bud is referred to as the descent position, and the negative pressure range is determined to be 0.6 to 0.9 kPa. A deviation tolerance orthogonal experiment is designed. Experimental results show that various experimental factors are ranked in terms of the significance level of the effect on the average success rate, and the significance ranking is as follows: negative pressure (P) > pipe diameter (D) > descent speed (V). An evaluation method of deviation tolerance performance is presented, and the optimal experiment factor-level combination is determined as: P = 0.9 kPa, D = 34 mm, V = 20 mm/s. Within the deviation range of a 10 mm radius, the average success rate of the negative pressure guidance of the end effector is 97.36%. The designed end effector can be applied to the intelligent picking of famous tea. This study can provide a reference for the design of similar picking end effectors for famous tea.

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