scholarly journals METHODOLOGY FOR A TASK-SPECIFIC AND PERSONALISED DEVELOPMENT OF AN INITIAL EXOSKELETON DESIGN

2021 ◽  
Vol 1 ◽  
pp. 2077-2086
Author(s):  
Tobias Drees ◽  
Steffen Kunnen ◽  
Robin Pluhnau ◽  
Arun Nagarajah
Keyword(s):  
Degrees Of Freedom ◽  
Development Process ◽  
Methodological Approach ◽  
Use Case ◽  
Six Degrees Of Freedom ◽  
Development Methodology ◽  
Technical Functions ◽  
Exoskeleton Design ◽  
The Relationship

AbstractThe use of exoskeletons promises improved ergonomics, empowerment of users and prevention of musculoskeletal disorders. However, the development process is complex and a generic development methodology that will guide and assist designers through it is missing. The goal of this paper is to describe a methodological approach that will assist the conceptual design of exoskeletons. Based on derived methodological requirements, activities 1, 2, and 3 of the VDI 2221 (Methodology for the development of technical products) are specified to adapt the generic guideline to the development process of exoskeletons. These activities include the analysis and determination of the relationship between the use case, product requirements and motions, technical functions, and design solutions. For generating a list of product requirements designers must focus on the workers’ motions and needs for a for a task-specific and personalised development. Use case specific movements are generalised by using rotational and translational basic movements that result in six degrees of freedom and from which a function structure is derived. The method is critically reviewed based on the established methodological requirements.

Development of a 6-DOF Testing Platform for Multirotor Flying Vehicles with Suspended Loads

Aerospace ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 355
Author(s):  
Saad M. S. Mukras ◽  
Hanafy M. Omar
Keyword(s):  
Degrees Of Freedom ◽  
Center Of Mass ◽  
Performance Testing ◽  
Flight Performance ◽  
Testing Platform ◽  
Six Degrees Of Freedom ◽  
Mass Properties ◽  
Test Platform ◽  
Suspended Loads

The development of multirotor vehicles can often be a dangerous and costly undertaking due to the possibility of crashes resulting from faulty controllers. The matter of safety in such activities has primarily been addressed through the use of testbeds. However, testbeds for testing multirotor vehicles with suspended loads have previously not been reported. In this study, a simple yet novel testing platform was designed and built to aid in testing and evaluating the performances of multirotor flying vehicles, including vehicles with suspended loads. The platform allows the flying vehicle to move with all six degrees of freedom (DOF). Single or three-DOF motions can also be performed. Moreover, the platform was designed to enable the determination of the mass properties (center of mass and moments of inertia) of small multirotor vehicles (which are usually required in the development of new control systems). The applicability of the test platform for the in-flight performance testing of a multirotor vehicle was successfully demonstrated using a Holybro X500 quadcopter with a suspended load. The test platform was also successfully used to determine the mass properties of the vehicle.

scholarly journals In-situ measurement technologies for flow behaviour and contact status of fibre-reinforced thermoplastics during forming with a six degree of freedom press

2018 ◽  
Vol 190 ◽  
pp. 07004
Author(s):  
Birk Wonnenberg ◽  
Franz Dietrich ◽  
Klaus Dröder
Keyword(s):  
Degrees Of Freedom ◽  
Optical Measurements ◽  
Image Processing Algorithm ◽  
Forming Process ◽  
Contact State ◽  
Six Degrees Of Freedom ◽  
Reinforced Plastics ◽  
Reinforced Thermoplastics ◽  
Six Degree Of Freedom

The paper presents investigations on a forming process, which is implemented in a forming press based on a Stewart platform. In contrast to common forming techniques, this buildup offers not only one but six degrees of freedom. This is of particular interest when it comes to the forming of materials that show significant anisotropic behaviour such as fibre-reinforced plastics. Therefore, an experimental setup is presented to record characteristic variables during the forming process of fibre-reinforced thermoplastics. The contact state is of particular interest for this kind of forming process because it changes continuously in shape and position as the forming process progresses. For this purpose, temperatures at different places in the tool are recorded to provide information about the flow velocity of the material and the contact state between tool and workpiece. This allows the determination of the exact time and position of the contact between material and forming tool as well as the duration of this contact. The results are compared with optical measurements analysed by image processing algorithm and process forces measured by load cells.

Effects of Architecture Design on Safety Level of Airborne Electronic Systems

2012 ◽  
Vol 236-237 ◽  
pp. 862-868
Author(s):  
Fang Yan
Keyword(s):  
Development Process ◽  
Electronic System ◽  
Electronic Systems ◽  
System Safety ◽  
Safety Level ◽  
Common Error ◽  
Safety Effect ◽  
Assurance Process ◽  
The Relationship

Safety level is the key input to the development process and assurance process of airborne electronic system, and is influenced by both the safety effect and the architecture used. The paper focuses on the determination of principle how the architectures influence the level assignment. The relationship between system safety objectives and assurance process was discussed; six architectures were studied in aspects of capability of common error limitation, and the concept of independence was introduced to characterize the architectures. The method to assign levels considering architectures influence was proposed using architecture independence concept, and a yaw damper system was studied for assurance level assignment to verify the principal.

A Six-Degree-of-Freedom Test System for the Study of Joint Mechanics and Ligament Forces

1995 ◽  
Vol 117 (4) ◽  
pp. 383-389 ◽  
Author(s):  
J. M. Hollis
Keyword(s):  
Degrees Of Freedom ◽  
Test System ◽  
Testing System ◽  
Joint Mechanics ◽  
Six Degrees Of Freedom ◽  
Position Feedback ◽  
Six Degree Of Freedom ◽  
Good Agreement

A joint testing system was designed to transmit a specified motion or force to a joint in all six degrees of freedom (d.o.f.) using a spatial linkage system for position feedback. The precise reproducibility of position provided by this method of position feedback allows determination of in situ ligament forces for external joint loadings. Load on the structure of interest is calculated from six d.o.f. load cell output after the loaded position is reproduced with all other structures removed. In a test of this system, measured loads showed good agreement with applied loads.

scholarly journals A Gyro-Free System for Measuring the Parameters of Moving Objects

2014 ◽  
Vol 14 (5) ◽  
pp. 263-269 ◽  
Author(s):  
Dimitar Dichev ◽  
Hristofor Koev ◽  
Totka Bakalova ◽  
Petr Louda
Keyword(s):  
Degrees Of Freedom ◽  
Moving Objects ◽  
Measuring System ◽  
Measurement Channel ◽  
Measuring Instruments ◽  
Additional Measurement ◽  
Free System ◽  
Six Degrees Of Freedom ◽  
Measurement Concept

Abstract The present paper considers a new measurement concept of modeling measuring instruments for gyro-free determination of the parameters of moving objects. The proposed approach eliminates the disadvantages of the existing measuring instruments since it is based, on one hand, on a considerably simplified mechanical module, and on the other hand, on the advanced achievements in the area of nanotechnologies, microprocessor and computer equipment. A specific measuring system intended for measuring the trim, heel, roll, and pitch of a ship has been developed in compliance with the basic principles of this concept. The high dynamic accuracy of this measuring system is ensured by an additional measurement channel operating in parallel with the main channel. The operating principle of the additional measurement channel is based on an appropriate correction algorithm using signals from linear MEMS accelerometers. The presented results from the tests carried out by means of stand equipment in the form of a hexapod of six degrees of freedom prove the effectiveness of the proposed measurement concept

Determination of Hydrodynamic Parameters for Remotely Operated Vehicles

2016 ◽  
Author(s):  
Ole A. Eidsvik ◽  
Ingrid Schjølberg
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Analytical Data ◽  
Relative Difference ◽  
Accurate Estimate ◽  
Six Degrees Of Freedom ◽  
Hydrodynamic Parameters ◽  
Planar Motion Mechanism ◽  
Rotational Degrees Of Freedom

In this paper the hydrodynamic parameters that characterize the behavior of a typical unmanned underwater vehicle are evaluated. A complete method for identifying these parameters is described. The method is developed to give a brief and accurate estimate of these parameters in all six degrees of freedom using basic properties of the vehicle such as dimensions, mass and shape. The method is based on both empirical and analytical results for typical reference geometries (ellipsoids, cubes, etc.). The method is developed to be applicable for a wide variety of UUV designs as these typically varies substantially. The method is then applied to a small observation class ROV. The results are first verified using an experimental method in which the full scale ROV is towed using a planar motion mechanism. An additional verification is performed with numerical simulations using Computational Fluid Dynamics and a radiation/diffraction program. The method shows promising results for both damping and added mass for the tested case. The translational degrees of freedom are more accurate than the rotational degrees of freedom which are expected as most empirical and analytical data are for translational degrees of freedom. The case study also reveals that the relative difference between the numerical simulations and the experimental results are similar to the relative difference between the proposed method and the experiment.

Recent Contributions Under the Bureau of Ships Fundamental Hydromechanics Research Program

1959 ◽  
Vol 3 (02) ◽  
pp. 47-64
Author(s):  
M. St. Denis ◽  
J.P. Craven
Keyword(s):  
Research Program ◽  
Degrees Of Freedom ◽  
Bending Moment ◽  
Elastic Response ◽  
Inertial System ◽  
Ship Motions ◽  
Six Degrees Of Freedom ◽  
The Third ◽  
Ship Performance

The third main nautical objective, Seakeeping, refers to that aspect of ship performance in which the seaway enters in a dominant manner and affects fundamentally the character of the problem. In the section on Control [3],1 a pattern was introduced according to which seakeeping was related to the uncontrolled as well as the controlled oscillations which take place with reference to a ship's inertial system. But, more broadly speaking, seakeeping includes all of the following subjects:Description of the seaway.Determination of the forces imposed by the seaway on the vessel—the excitation (hydrodynamic loadings, wave bending moment, slamming forces, and so on).Determination of the response of the ship in her six degrees of freedom (ship motions).Prediction of the perils to which a ship may be exposed (capsizing, foundering, safety at sea).Prediction of the loss in speed she will sustain in heavy weather.Evaluation of the amount of stabilization necessary to prevent unacceptable or undesirable displacements and accelerations. The elastic response and strength of a vessel's structure, though not included under seakeeping, depend, nevertheless, in an essential manner thereon.

scholarly journals A Force/Position Hybrid Controller for Rehabilitation Robot

2019 ◽  
Vol 14 (5) ◽  
pp. 615
Author(s):  
Jin Hua ◽  
Lile He ◽  
Zhiqiang Kang ◽  
Keding Yan
Keyword(s):  
Degrees Of Freedom ◽  
Ageing Population ◽  
Rehabilitation Robot ◽  
Simulation Environment ◽  
Rehabilitation Care ◽  
Robot Operating System ◽  
Six Degrees Of Freedom ◽  
Motion System ◽  
Hybrid Controller ◽  
The Relationship

The growing ageing population in China poses a huge demand for rehabilitation care, which can be satisfied by the latest robot technology. Focusing on the motion system of a six degrees-of-freedom (DOF) robot, this paper explores the relationship between the force, torque, velocity and the postures of the end effector and joint. Drawing on robot control theories, the existing manipulator force/position hybrid controllers were reviewed, and a force/position hybrid controller was designed for path planning of rehabilitation robot. Then, the robot was modelled on the Robot Operating System (ROS), using the Unified Robot Description Format (URDF) file and the MoveIt! Setup Assistant. Finally, our controller was tested in the ROS virtual simulation environment. The results show that our controller can facilitate and optimize the design of the path of rehabilitation robot.

Modeling and prototype experiment of a six-DOF parallel micro-manipulator with nano-scale accuracy

2014 ◽  
Vol 229 (14) ◽  
pp. 2611-2625
Author(s):  
Yi Dong ◽  
Feng Gao ◽  
Yi Yue
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Result ◽  
Element Analysis ◽  
Six Degrees Of Freedom ◽  
Compliant Structure ◽  
Nano Scale ◽  
Stiffness Model ◽  
Micro Manipulator ◽  
Six Dof ◽  
The Relationship

This paper presents a high-accurate micro-manipulator featured with monolithic compliant structure, orthogonally arranged parallel mechanism and piezoelectric (PZT) actuation. 6-SPS mechanism is employed to provide six degrees of freedom (DOF), including three linear translations and three rotations. The kinematics and stiffness of the micro-manipulator is studied first in this paper. Then, the relationship between PZT nominal displacement and the end pose is derived. Aiming at achieving trajectories with nano-scale accuracy, a two-step strategy is proposed. Finite element analysis (FEA) is conducted to verify the kinematics and stiffness model. Finally, in order to demonstrate the performance of the micro-manipulator, experiments of typical trajectories are carried out. The experimental result shows that the proposed micro-manipulator is capable of achieving trajectories with nano-scale accuracy.

A new methodology for the determination of the workspace of six-DOF redundant parallel structures actuated by nine wires

Robotica ◽  
2006 ◽  
Vol 25 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Carlo Ferraresi ◽  
Marco Paoloni ◽  
Francesco Pescarmona
Keyword(s):  
Degrees Of Freedom ◽  
New Method ◽  
Parallel Structure ◽  
Graphical Form ◽  
Six Degrees Of Freedom ◽  
Parallel Structures ◽  
Six Dof ◽  
Force Reflection ◽  
Master Device

The WiRo-6.3 is a six-degrees of freedom (six-DOF) robotic parallel structure actuated by nine wires, whose characteristics have been thoroughly analyzed in previous papers in reference. It is thought to be a master device for teleoperation; thus, it is moved by an operator through a handle and can convey a force reflection on the operator's hand. A completely new method for studying the workspace of this device, and of virtually any nine-wire parallel structure actuated by wire is presented and discussed, and its results are given in a graphical form.

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