Classification of Serial Robot-Manipulators with Nonremovable Singularities

1996 ◽  
Vol 118 (2) ◽  
pp. 202-208 ◽  
Author(s):  
A. Karger
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulators ◽  
Removable Singularity ◽  
Singular Set ◽  
Singular Configurations ◽  
Serial Robot ◽  
Small Change ◽  
6 Degrees Of Freedom ◽  
4 Degrees Of Freedom

In this paper we discuss singular configurations of serial robot-manipulators with respect to their removability. A removable singularity is a singularity which can be removed from a motion of the end-effector by a small change of the motion. The most interesting situation appears for robot-manipulators with 5 degrees of freedom, because the case of 4 degrees of freedom is easy and singular configurations of robot-manipulators with 6 degrees of freedom are nonremovable. In the paper we give the complete list of all 5R robot-manipulators which have nonremovable singularities. The image of the singular set in the parameter space for such manipulators can be a plane, a quadric, a cylinder or an algebraic surface of degree 3 or 7. All of them are explicitly given.

Singularity Analysis of Serial Robot-Manipulators

1996 ◽  
Vol 118 (4) ◽  
pp. 520-525 ◽  
Author(s):  
A. Karger
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
Singularity Analysis ◽  
Singular Set ◽  
Singular Configurations ◽  
Special Cases ◽  
Serial Robot ◽  
Singular Configuration ◽  
Actual Configuration

This paper is devoted to the description of the set of all singular configurations of serial robot-manipulators. For 6 degrees of freedom serial robot-manipulators we have developed a theory which allows to describe higher order singularities. By using Lie algebra properties of the screw space we give an algorithm, which determines the degree of a singularity from the knowledge of the actual configuration of axes of the robot-manipulator only. The local shape of the singular set in a neighbourhood of a singular configuration can be determined as well. We also solve the problem of escapement from a singular configuration. For serial robot-manipulators with the number of degrees of freedom different from six we show that up to certain exceptions singular configurations can be avoided by a small change of the motion of the end-effector. We also give an algorithm which allows to determine equations of the singular set for any serial robot-manipulator. We discuss some special cases and give examples of singular sets including PUMA 560.

scholarly journals Development of a Spherical Positioning Robot and Neuro-Navigation System for Precise and Repetitive Non-Invasive Brain Stimulation

2019 ◽  
Vol 9 (21) ◽  
pp. 4561
Author(s):  
Shin ◽  
Ryu ◽  
Cho ◽  
Yang ◽  
Lee
Keyword(s):  
Brain Stimulation ◽  
Navigation System ◽  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Human Head ◽  
Non Invasive ◽  
Serial Robot ◽  
The Subject ◽  
6 Degrees Of Freedom ◽  
Spherical Mechanism

Although non-invasive brain stimulation techniques do not involve surgical procedures, the challenge remains in correctly locating the stimulator from outside the head. There is a limit to which one can manually and precisely position and orient the stimulator or repeatedly move the stimulator around the same position. Therefore, in this study, we developed a serial robot with 6 degrees-of-freedom to move the stimulator and a neuro-navigation system to determine the stimulus point from looking at the shape of the subject’s brain. The proposed robot applied a spherical mechanism while considering the safety of the subject, and the workspace of the robot was designed considering the shape of the human head. Position-based visual servoing was applied to compensate for unexpected movements during subject stimulation. We also developed a neuro-navigation system that allows us visually to check the focus of the stimulator and the human brain at the same time and command the robot to the desired point. To verify the system performance, we first performed repeatability and motion compensation experiments of the robot and then evaluated the repeated biosignal response experiments through transcranial magnetic stimulation, a representative technique of non-invasive brain stimulation.

scholarly journals Analysis of Multiaxis Vibration Simulators

1995 ◽  
Vol 2 (6) ◽  
pp. 461-470
Author(s):  
Norman Fitz-Coy
Keyword(s):  
Degrees Of Freedom ◽  
Mathematical Procedure ◽  
Singular Configurations ◽  
Corrective Measures ◽  
6 Degrees Of Freedom

A mathematical procedure that quantitatively addresses issues critical to the design and operation of multiaxis vibration simulators is presented. Both kinematic and dynamic issues are considered. The analysis is applied to both 3 and 6 degrees of freedom configurations. The existence of singular configurations is mentioned and appropriate corrective measures are recommended. A methodology for determining the required actuator commands is also presented.

Instantaneous Center of Rotation and Singularities of Planar Parallel Manipulators

2005 ◽  
Vol 33 (3) ◽  
pp. 251-259 ◽  
Author(s):  
H. R. Mohammadi Daniali
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Classification Scheme ◽  
Parallel Manipulators ◽  
Singular Configurations ◽  
Classification Of Singularities ◽  
Instantaneous Center ◽  
Three Degrees Of Freedom ◽  
Planar Parallel Manipulators

With regard to planar parallel manipulators, a general classification of singularities into three groups is given. The classification scheme relies on the properties of instantaneous centers of rotation. This method is very fast and can easily be applied to the manipulators under study. The method is applied to a planar three-degrees-of-freedom parallel manipulator and all its singular configurations are found.

scholarly journals Development and assessment of a telesonography system for musculoskeletal imaging

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Mohammed Obaid ◽  
Qianwei Zhang ◽  
Scott J. Adams ◽  
Reza Fotouhi ◽  
Haron Obaid
Keyword(s):  
Degrees Of Freedom ◽  
Ultrasound Images ◽  
Ultrasound Probe ◽  
Rural And Remote ◽  
Significant Delay ◽  
Remote Communities ◽  
Internet Connection ◽  
Good For ◽  
4 Degrees Of Freedom

Abstract Background Telesonography systems have been developed to overcome barriers to accessing diagnostic ultrasound for patients in rural and remote communities. However, most previous telesonography systems have been designed for performing only abdominal and obstetrical exams. In this paper, we describe the development and assessment of a musculoskeletal (MSK) telesonography system. Methods We developed a 4-degrees-of-freedom (DOF) robot to manipulate an ultrasound probe. The robot was remotely controlled by a radiologist operating a joystick at the master site. The telesonography system was used to scan participants’ forearms, and all participants were conventionally scanned for comparison. Participants and radiologists were surveyed regarding their experience. Images from both scanning methods were independently assessed by an MSK radiologist. Results All ten ultrasound exams were successfully performed using our developed MSK telesonography system, with no significant delay in movement. The duration (mean ± standard deviation) of telerobotic and conventional exams was 4.6 ± 0.9 and 1.4 ± 0.5 min, respectively (p = 0.039). An MSK radiologist rated quality of real-time ultrasound images transmitted over an internet connection as “very good” for all telesonography exams, and participants rated communication with the radiologist as “very good” or “good” for all exams. Visualisation of anatomic structures was similar between telerobotic and conventional methods, with no statistically significant differences. Conclusions The MSK telesonography system developed in this study is feasible for performing soft tissue ultrasound exams. The advancement of this system may allow MSK ultrasound exams to be performed over long distances, increasing access to ultrasound for patients in rural and remote communities.

scholarly journals Human Hand Anatomy-Based Prosthetic Hand

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 137
Author(s):  
Larisa Dunai ◽  
Martin Novak ◽  
Carmen García Espert
Keyword(s):  
3D Printing ◽  
Degrees Of Freedom ◽  
Use Of Force ◽  
Hand Movements ◽  
Human Hand ◽  
Prosthetic Hand ◽  
Object Surface ◽  
Hand Phalanges ◽  
High Level

The present paper describes the development of a prosthetic hand based on human hand anatomy. The hand phalanges are printed with 3D printing with Polylactic Acid material. One of the main contributions is the investigation on the prosthetic hand joins; the proposed design enables one to create personalized joins that provide the prosthetic hand a high level of movement by increasing the degrees of freedom of the fingers. Moreover, the driven wire tendons show a progressive grasping movement, being the friction of the tendons with the phalanges very low. Another important point is the use of force sensitive resistors (FSR) for simulating the hand touch pressure. These are used for the grasping stop simulating touch pressure of the fingers. Surface Electromyogram (EMG) sensors allow the user to control the prosthetic hand-grasping start. Their use may provide the prosthetic hand the possibility of the classification of the hand movements. The practical results included in the paper prove the importance of the soft joins for the object manipulation and to get adapted to the object surface. Finally, the force sensitive sensors allow the prosthesis to actuate more naturally by adding conditions and classifications to the Electromyogram sensor.

4D in in vivo 2-photon laser scanning fluorescence microscopy with sample motion in 6 degrees of freedom

2011 ◽  
Vol 200 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Sabine Scheibe ◽  
Mario M. Dorostkar ◽  
Christian Seebacher ◽  
Rainer Uhl ◽  
Frank Lison ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Laser Scanning ◽  
Degrees Of Freedom ◽  
Sample Motion ◽  
6 Degrees Of Freedom

Workspace, dexterity and dimensional optimization of microhexapod

2015 ◽  
Vol 35 (4) ◽  
pp. 341-347 ◽  
Author(s):  
E. Rouhani ◽  
M. J. Nategh
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Screw Theory ◽  
Design Parameters ◽  
Dimensional Synthesis ◽  
Content Type ◽  
Workspace Analysis ◽  
The Difference ◽  
Flexure Joints ◽  
6 Degrees Of Freedom

Purpose – The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Design/methodology/approach – Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Findings – It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease. Originality/value – The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator.

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