Design of a Parallel Architecture Robotic Spine Exoskeleton With Series Elastic Actuators

2017 ◽  
Author(s):  
Chawin Ophaswongse ◽  
Rosemarie C. Murray ◽  
Sunil K. Agrawal
Keyword(s):  
Degrees Of Freedom ◽  
Human Subjects ◽  
Parallel Architecture ◽  
Six Degrees Of Freedom ◽  
In Series ◽  
Machine Interface ◽  
Position And Orientation ◽  
Human Usage ◽  
Series Elastic Actuators ◽  
Series Elastic

This paper proposes a novel methodology for the design of series elastic actuators in parallel-actuated platforms which have full six degrees-of-freedom in position and orientation. Series elastic actuators can potentially contribute to lower power consumption and provide a better human-machine interface for the user. This is an important consideration in the use of a robotic spine exoskeleton for human subjects, which motivates this work. In the study of parallel-actuated systems with full six degrees-of-freedom, the effect of compliance in series with actuators has not been adequately studied from the perspective of kinematics and wrench capabilities. These analyses are performed in this paper with the goal to improve the design of the robotic spine exoskeleton (ROSE) and its human usage.

scholarly journals Wrench Capability of a Stewart Platform With Series Elastic Actuators

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Chawin Ophaswongse ◽  
Rosemarie C. Murray ◽  
Sunil K. Agrawal
Keyword(s):  
Degrees Of Freedom ◽  
Stewart Platform ◽  
Six Degrees Of Freedom ◽  
In Series ◽  
Novel Method ◽  
Machine Interface ◽  
Position And Orientation ◽  
Human Usage ◽  
Series Elastic Actuators ◽  
Series Elastic

This paper proposes a novel method for analyzing linear series elastic actuators (SEAs) in a parallel-actuated Stewart platform, which has full six degrees-of-freedom (DOF) in position and orientation. SEAs can potentially provide a better human–machine interface for the user. However, in the study of parallel-actuated systems with full 6DOF, the effect of compliance in series with actuators has not been adequately studied from the perspective of wrench capabilities. We found that some parameters of the springs and the stroke lengths of the linear actuators play a major role in the actuation limits of the system. This is an important consideration when adding SEAs into a Stewart platform or other parallel-actuated robots to improve their human usage.

Alternative Inverse Kinematic Equations for General RRP and RRR Regional Structures of Manipulators

1996 ◽  
Author(s):  
Peregrine E. J. Riley
Keyword(s):  
Degrees Of Freedom ◽  
Joint Angle ◽  
Inverse Kinematic ◽  
Intersection Point ◽  
Degree Polynomial ◽  
Six Degrees Of Freedom ◽  
Common Intersection ◽  
Position And Orientation ◽  
Spatial Positioning ◽  
Orientational Structure

Abstract Many manipulators with six degrees of freedom are constructed with two distinct sections, a regional structure for spatial positioning, and an orientational structure having a common intersection point for the joint axes. With this arrangement, inverse kinematic solutions for position and orientation may be found separately. While solutions for general three link manipulators have been available since the work of Pieper in 1969, this paper presents new forms of the inverse kinematic equations for general RRP and RRR regional structures. Cartesian coordinates of the F-surface (generated by movement of the outer two joints) together with the outer joint angle are used as the equation variables. In addition, a second degree polynomial approxiamation of the equation may be used for quick iteration to a solution. It is hoped that these new equations will be useful by themselves and in workspace regions where solutions using equations in terms of the joint variables are numerically inaccurate or impossible.

Validation of a Novel 3D-Printed Instrumented Spatial Linkage That Measures Changes in the Rotational Axes of the Tibiofemoral Joint

2013 ◽  
Author(s):  
Daniel P. Bonny ◽  
S. M. Howell ◽  
M. L. Hull
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Anatomic Landmarks ◽  
Tibiofemoral Joint ◽  
Six Degrees Of Freedom ◽  
Revolute Joints ◽  
Flexion Extension ◽  
3D Printed ◽  
Total Knee ◽  
Position And Orientation

The two kinematic axes of the tibiofemoral joint, the flexion-extension (F-E) and longitudinal rotation (LR) axes [1], are unrelated to the anatomic landmarks often used to align prostheses during total knee arthroplasty (TKA) [1, 2]. As a result, conventional TKA changes the position and orientation of the joint line, thus changing the position and orientation of the F-E and LR axes and consequently the kinematics of the knee. However, the extent to which TKA changes these axes is unknown. An instrument that can measure the locations of and any changes to these axes is an instrumented spatial linkage (ISL), a series of six instrumented revolute joints that can measure the six degrees of freedom of motion (DOF) between two rigid bodies without constraining motion. Previously, we computationally determined how best to design and use an ISL such that rotational and translational errors in locating the F-E and LR axes were minimized [3]. However, this ISL was not constructed and therefore its ability to measure changes in the axes has not been validated. Therefore the objective was to construct the ISL and quantify the errors in measuring changes in position and orientation of the F-E axis.

scholarly journals Testing of a MEMS Dynamic Inclinometer Using the Stewart Platform

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4233 ◽  
Author(s):  
Zhihua Liu ◽  
Chenguang Cai ◽  
Ming Yang ◽  
Ying Zhang
Keyword(s):  
Mechanical System ◽  
Real Time ◽  
Degrees Of Freedom ◽  
Cross Coupling ◽  
Micro Electro Mechanical System ◽  
Stewart Platform ◽  
Forward Kinematics ◽  
Six Degrees Of Freedom ◽  
Position And Orientation ◽  
The Cross

The micro-electro-mechanical system (MEMS) dynamic inclinometer integrates a tri-axis gyroscope and a tri-axis accelerometer for real-time tilt measurement. The Stewart platform has the ability to generate six degrees of freedom of spatial orbits. The method of applying spatial orbits to the testing of MEMS inclinometers is investigated. Inverse and forward kinematics are analyzed for controlling and measuring the position and orientation of the Stewart platform. The Stewart platform is controlled to generate a conical motion, based on which the sensitivities of the gyroscope, accelerometer, and tilt sensing are determined. Spatial positional orbits are also generated in order to obtain the tilt angles caused by the cross-coupling influence. The experiment is conducted to show that the tested amplitude frequency deviations of the gyroscope and tilt sensing sensitivities between the Stewart platform and the traditional rotator are less than 0.2 dB and 0.1 dB, respectively.

Use of 1DOF Haptic Device for Remote-Controlled 6DOF Assembly

2014 ◽  
Vol 8 (3) ◽  
pp. 452-459 ◽  
Author(s):  
Ryoya Kamata ◽  
◽  
Ryosuke Tamura ◽  
Satoshi Niitsu ◽  
Hiroshi Kawaharada ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Force Feedback ◽  
Haptic Device ◽  
Prototype System ◽  
Assembly Operation ◽  
Six Degrees Of Freedom ◽  
Controlled Assembly ◽  
Sense Of Reality ◽  
Position And Orientation ◽  
Assembly Operations

This paper describes a remote controlled assembly using a haptic device. Most haptic devices have six Degrees Of Freedom (DOFs) for a higher sense of reality. However, for assembly operation, the simultaneous motion of parts with only one or two DOFs is required, and force feedback to operators is used only to maintain contact and detect collisions among parts. This leads to the possibility of assembly operations using a haptic device with a small number of DOFs. In this paper, we propose virtual planes to perform remote control of a 6DOF assembly by way of 1DOF user operations. Virtual planes separate the DOFs for user operation and for automatically generated motions that complement the user operation DOF in each assembly operation. A prototype system was developed with a 6DOF manipulator and camera. The system allows an operator to place virtual planes in any position and orientation using a camera image of the workspace. The experiment results showed the effectiveness of the method for remote controlled assembly without geometry information on the parts.

Modeling and Control of Four-bar Mechanism with Series Elastic Actuators

2020 ◽  
Author(s):  
Felipe R. Lopes ◽  
Marco A. Meggiolaro
Keyword(s):  
Human Interaction ◽  
Robotic Manipulation ◽  
Modeling And Control ◽  
Lqr Control ◽  
In Series ◽  
Flexible Behavior ◽  
Series Elastic Actuators ◽  
New Generation ◽  
And Control ◽  
Series Elastic

A new generation of robots that work in cooperation with humans (called collaborative robots) needs some flexibility to adapt to the environment and activities with people. That is why the Series Elastic Actuator (SEA) has been a breakthrough in actuator technologies. The idea of inserting an elastic element in series with a motor allows a lower output impedance, consequently a flexible behavior in the manipulator, in addition to providing torque feedback to better compensate disturbances caused e.g. by friction losses. This article presents a four-bar mechanism with SEA for the purpose of robotic manipulation. Its kinematics and dynamicsare studied, as well as its regulation and trajectory control. The behavior of the decoupled four-bar mechanism and the characteristics of the SEA are also analyzed. Then the regulation control of the complete system is carried out using LQR control. Finally, a circular trajectory is controlled in a simulation to validate the proposed control strategy. The simulation results show the effectiveness of the proposed controller for the mechanism in the presence of SEAs estimating torque and providing the desired compliance for human interaction.

Six degrees of freedom parallel robots with C5 links

Robotica ◽  
1992 ◽  
Vol 10 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Y. Amirat ◽  
F. Artigue ◽  
J. Pontnau
Keyword(s):  
Automotive Industry ◽  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Parallel Architecture ◽  
Parallel Robot ◽  
Parallel Architectures ◽  
Parallel Robots ◽  
Left Hand ◽  
Six Degrees Of Freedom ◽  
Assembly Tasks

SummaryThis paper presents at first a static and kinematic analysis of closed chains mechanisms which permits to deduce different possible fully parallel architectures. Then we focus on a particular parallel architecture with C5 links designed to perform precise assembly tasks. A general modeling of this C5 parallel robot is presented. Two typical assembly tasks in the automotive industry are also proposed; the first one uses the C5 links parallel robot as a left-hand device, while the second one uses it as the terminal tool of a sequential manipulator.

Effect of compliance location in series elastic actuators

Robotica ◽  
2013 ◽  
Vol 31 (8) ◽  
pp. 1313-1318 ◽  
Author(s):  
Jonathon W. Sensinger ◽  
Lawrence E. Burkart ◽  
Gill A. Pratt ◽  
Richard F. ff. Weir
Keyword(s):  
Gear Ratio ◽  
Large Gear ◽  
Class 1 ◽  
In Series ◽  
Ratio Dependent ◽  
Series Elastic Actuators ◽  
Series Elastic ◽  
Instrumentation Design

SUMMARYSeries elastic actuators have beneficial properties for some robot applications. Several recent implementations contain alternative placements of the compliant element to improve instrumentation design. We use a class 1 versus class 2 lever model and energy-port methods to demonstrate in this paper that these alternative placements should still be classified as series elastic actuators. We also note that the compliance of proximal series elastic actuators is reflected by an augmented gear ratio dependent on the nominal gear ratio, which is significant for small gear ratios and approaches unity for large gear ratios. This reflected compliance is shown to differ depending on the sign of the gear ratio. We demonstrate that although the reflected compliance is only marginally influenced by the magnitude of the gear ratio, there are several notable differences, particularly for small gear ratios.

scholarly journals Design and analysis of a six degrees of freedom serial–parallel robotic mechanism with multi-degree of freedom legs

2018 ◽  
Vol 15 (6) ◽  
pp. 172988141881264
Author(s):  
Ziwei Zhang ◽  
Guoying Meng
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Simple Structure ◽  
Parallel Mechanisms ◽  
Universal Joint ◽  
Six Degrees Of Freedom ◽  
In Series ◽  
Peristaltic Movement ◽  
High Flexibility ◽  
Analytic Models

A novel mobile serial–parallel mechanism with legs for in-pipe use is proposed. The mobile robotic mechanism is composed of two identical three-universal joint–prismatic joint–universal joint parallel mechanisms connected in series and two gripping modules. The proposed parallel mechanism has two rotational freedoms and one translational freedom. In addition, the parallel mechanism can achieve continuous and equivalent rotation. The singularities of the parallel mechanism are analyzed. The overall serial–parallel mechanism has six degrees of freedom, and each gripping module has four degrees of freedom. Each parallel mechanism in the waist module is driven by three servo-electric cylinders and each leg mechanism in the gripping modules is controlled by a linear actuator. The robotic mechanism can perform peristaltic movement and turning in space. The robotic mechanism possesses a simple structure and high flexibility, along with the merits of serial–parallel mechanism. In this article, analytic models for the kinematics and dynamics of the robotic mechanism are derived. Additionally, numerical examples are given, and their solutions are validated based on results obtained by SimMechanics and Adams.

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