Multibody Analysis and Control of a Full-Wrist Exoskeleton for Tremor Alleviation

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jiamin Wang ◽  
Oumar R. Barry
Keyword(s):  
Degrees Of Freedom ◽  
Controller Design ◽  
Wrist Joint ◽  
Three Dimensional ◽  
Design Parameters ◽  
Light Power ◽  
Multibody Modeling ◽  
Flexion Extension ◽  
Reliable Performance ◽  
Rotational Joint

Abstract Uncontrollable shaking in the human wrist, caused by pathological tremor, can significantly undermine the power and accuracy in object manipulation. In this paper, the design of a tremor alleviating wrist exoskeleton (TAWE) is introduced. Unlike the works in the literature that only consider the flexion/extension (FE) motion, in this paper, we model the wrist joint as a constrained three-dimensional (3D) rotational joint accounting for the coupled FE and radial/ulnar deviation (RUD) motions. Hence TAWE, which features a six degrees-of-freedom (DOF) rigid linkage structure, aims to accurately monitor, suppress tremors, and provide light-power augmentation in both FE and RUD wrist motions. The presented study focuses on providing a fundamental understanding of the feasibility of TAWE through theoretical analyses. The analytical multibody modeling of the forearm–TAWE assembly provides insight into the necessary conditions for control, which indicates that reliable control conditions in the desired workspace can be acquired by tuning the design parameters. Nonlinear regressions are then implemented to identify the information that is crucial to the controller design from the unknown wrist kinematics. The proposed analytical model is validated numerically with V-REP and the result shows good agreement. Simulations also demonstrate the reliable performance of TAWE under controllers designed for tremor suppression and movement assistance.

Design of Spatial Non-Anthropomorphic Articulated Systems Based on Arm Joint Constraint Kinematic Data for Human Interactive Robotics Applications

2015 ◽  
Author(s):  
Hyosang Moon ◽  
Nina P. Robson
Keyword(s):  
Degrees Of Freedom ◽  
Wrist Joint ◽  
Design Parameters ◽  
Human Hand ◽  
Link Length ◽  
Hand Motion ◽  
Motion Constraints ◽  
Hand Kinematics ◽  
Minimum Jerk ◽  
Articulated Systems

The design of human interactive robotic systems requires additional considerations compared to conventional robotic designs to take into account human factors. In this paper, a recently developed linkage kinematic synthesis incorporating higher order motion constraints is utilized to the synthesis of a five degree of freedom serial TS linkage for human interactive applications. The T represents a universal two degrees-of-freedom shoulder, while the S defines a spherical three degrees-of-freedom wrist joint. The desired hand kinematics and its time derivatives can be obtained by a motion capture system as well as from the hand-object/environment contact geometries at two task locations. In order to determine the design parameters (i.e., locations of the base/shoulder and moving/wrist pivots, as well as the link length connecting these joints), position, velocity and acceleration constraint equations of the TS linkage are solved in the vicinity of the initial and the final reaching locations. The entire robotic joint trajectories are formulated via minimum jerk theory to closely approximate human natural hand profile with an elbow joint constraint. In this manner, the TS linkage system can be designed to guarantee to reproduce the natural human hand kinematics with the minimum amount of information about the desired hand kinematic specifications. The applicability of the proposed technique was verified by designing a TS linkage system from a captured human data, and then comparing the generated end-effector trajectory with the human hand motion trajectory, which show promising results.

Helical Axis Data Visualization and Analysis of the Knee Joint Articulation

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Ricardo Manuel Millán Vaquero ◽  
Alexander Vais ◽  
Sean Dean Lynch ◽  
Jan Rzepecki ◽  
Karl-Ingo Friese ◽  
...  
Keyword(s):  
Knee Joint ◽  
Lie Algebra ◽  
Degrees Of Freedom ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Patient Specific ◽  
Helical Axis ◽  
Accurate Analysis ◽  
Related Data ◽  
Flexion Extension

We present processing methods and visualization techniques for accurately characterizing and interpreting kinematical data of flexion–extension motion of the knee joint based on helical axes. We make use of the Lie group of rigid body motions and particularly its Lie algebra for a natural representation of motion sequences. This allows to analyze and compute the finite helical axis (FHA) and instantaneous helical axis (IHA) in a unified way without redundant degrees of freedom or singularities. A polynomial fitting based on Legendre polynomials within the Lie algebra is applied to provide a smooth description of a given discrete knee motion sequence which is essential for obtaining stable instantaneous helical axes for further analysis. Moreover, this allows for an efficient overall similarity comparison across several motion sequences in order to differentiate among several cases. Our approach combines a specifically designed patient-specific three-dimensional visualization basing on the processed helical axes information and incorporating computed tomography (CT) scans for an intuitive interpretation of the axes and their geometrical relation with respect to the knee joint anatomy. In addition, in the context of the study of diseases affecting the musculoskeletal articulation, we propose to integrate the above tools into a multiscale framework for exploring related data sets distributed across multiple spatial scales. We demonstrate the utility of our methods, exemplarily processing a collection of motion sequences acquired from experimental data involving several surgery techniques. Our approach enables an accurate analysis, visualization and comparison of knee joint articulation, contributing to the evaluation and diagnosis in medical applications.

Tilting Pad Bearing Pivot Friction and Design Effects on Thermal Bow-Induced Rotor Vibration

2021 ◽  
Vol 143 (12) ◽  
Author(s):  
Dongil Shin ◽  
Alan B. Palazzolo
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Design Parameters ◽  
Flexible Beam ◽  
Thermally Induced ◽  
Tilting Pad ◽  
Speed Range ◽  
Transient Simulations ◽  
Nonlinear Transient ◽  
Tilting Pad Journal Bearing

Abstract The Morton effect (ME) is a thermally induced vibration problem observed in a rotor supported by hydrodynamic bearings. The journal’s synchronous orbiting induces nonuniform viscous heating on its circumference, and the ensuing thermal bow often causes unacceptable vibration levels in the rotor. This paper investigates the influence of the tilting pad journal bearing (TPJB)’s pivot design on the severity and instability speed range of ME vibration. Simulations are conducted with two different types of pivots: cylindrical (CYL) and spherical (SPH), which produce different pad degrees-of-freedom and nonlinear pivot stiffness due to their geometries. The friction between pad and pivot, which only exists with the spherical pivot, is modeled, and its impact on the ME is evaluated. The example rotor model, as obtained from the literature, is single overhung, with experimentally measured excessive vibration and large journal temperature differentials, near 8000 rpm. The bearing and journal are modeled with three-dimensional (3D) finite elements, and the shaft with flexible beam elements for ME simulation. Nonlinear transient simulations are carried out for a wide operating speed range with varying pivot design parameters. Simulation results indicate that the predicted ME instability is sensitive to the pivot shape, pivot flexibility, and pad-pivot friction.

Three-dimensional model predictive controller design for approach to landing with microburst encounter

2017 ◽  
Vol 232 (11) ◽  
pp. 2034-2047 ◽  
Author(s):  
A Hassanpour ◽  
Seid H Pourtakdoust
Keyword(s):  
Degrees Of Freedom ◽  
Controller Design ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Model Predictive Controller ◽  
Predictive Controller ◽  
Lateral Displacements ◽  
Alternative Routes

Microburst is considered an extreme powerful hazard for aircrafts, especially during takeoff, approach and landing phases of flight. Current airborne piloting practices involve taking alternative routes, if early detection of microburst wind shear (MBW) for its effective avoidance is possible. In this respect, design and analysis of precision automatic flight path control systems for microburst penetration are of outmost importance whose success can significantly reduce crash risks and thus enhance the flight safety. The current study is focused on the design and analysis of a three-dimensional model predictive controller for a wide body transport type aircraft encountering MBW in approach to landing phase of flight. This task is performed utilizing the full nonlinear six degrees of freedom aircraft equations of motion and the most complete 3D model of the MBW and its gradients. The results are promising for online applications as the proposed model predictive controller-based controller has effectively guided and kept the aircraft on the approach glide path with negligible deviations against aircraft initial lateral displacements, sharp edge gust disturbance as well as the MBW.

Optimal Combination of Minimum Degrees of Freedom to be Actuated in the Lower Limbs to Facilitate Arm-Free Paraplegic Standing

2007 ◽  
Vol 129 (6) ◽  
pp. 838-847 ◽  
Author(s):  
Joon-young Kim ◽  
James K. Mills ◽  
Albert H. Vette ◽  
Milos R. Popovic
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Optimal Combination ◽  
Lower Limbs ◽  
Free Standing ◽  
Joint Torques ◽  
Flexion Extension ◽  
Hip Abduction ◽  
The Individual

Arm-free paraplegic standing via functional electrical stimulation (FES) has drawn much attention in the biomechanical field as it might allow a paraplegic to stand and simultaneously use both arms to perform daily activities. However, current FES systems for standing require that the individual actively regulates balance using one or both arms, thus limiting the practical use of these systems. The purpose of the present study was to show that actuating only six out of 12 degrees of freedom (12-DOFs) in the lower limbs to allow paraplegics to stand freely is theoretically feasible with respect to multibody stability and physiological torque limitations of the lower limb DOF. Specifically, the goal was to determine the optimal combination of the minimum DOF that can be realistically actuated using FES while ensuring stability and able-bodied kinematics during perturbed arm-free standing. The human body was represented by a three-dimensional dynamics model with 12-DOFs in the lower limbs. Nakamura’s method (Nakamura, Y., and Ghodoussi, U., 1989, “Dynamics Computation of Closed-Link Robot Mechanisms With Nonredundant and Redundant Actuators,” IEEE Trans. Rob. Autom., 5(3), pp. 294–302) was applied to estimate the joint torques of the system using experimental motion data from four healthy subjects. The torques were estimated by applying our previous finding that only 6 (6-DOFs) out of 12-DOFs in the lower limbs need to be actuated to facilitate stable standing. Furthermore, it was shown that six cases of 6-DOFs exist, which facilitate stable standing. In order to characterize each of these cases in terms of the torque generation patterns and to identify a potential optimal 6-DOF combination, the joint torques during perturbations in eight different directions were estimated for all six cases of 6-DOFs. The results suggest that the actuation of both ankle flexion∕extension, both knee flexion∕extension, one hip flexion∕extension, and one hip abduction∕adduction DOF will result in the minimum torque requirements to regulate balance during perturbed standing. To facilitate unsupported FES-assisted standing, it is sufficient to actuate only 6-DOFs. An optimal combination of 6-DOFs exists, for which this system can generate able-bodied kinematics while requiring lower limb joint torques that are producible using contemporary FES technology. These findings suggest that FES-assisted arm-free standing of paraplegics is theoretically feasible, even when limited by the fact that muscles actuating specific DOFs are often denervated or difficult to access.

Shoulder Proprioception Device (S.P.D.): A Novel Design for Measuring Shoulder Joint Proprioception

2019 ◽  
Author(s):  
Jeremy R. Schnipke ◽  
Thomas G. Rounds ◽  
Jacob P. Sroka ◽  
Zachary B. Lowe ◽  
Gregory M. Freisinger ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Cost Effective ◽  
Feedback Mechanism ◽  
Shoulder Injuries ◽  
Data Logger ◽  
Effective Manner ◽  
Flexion Extension ◽  
Procedural Time ◽  
The Military

Abstract Shoulder injuries are a serious and costly issue, particularly in physically intensive professions like athletics and the military. Previous data indicates a dangerous feedback mechanism between reduced shoulder proprioception due to previous injury and higher probability of re-injury due to reduced proprioception. It is therefore important for organizations to possess a device that can accurately and efficiently evaluate and track an individual’s shoulder proprioception, especially following injury. Existing technologies that fill this role are generally impractical or do not quantify proprioception to the necessary levels of accuracy. The Shoulder Proprioception Device (SPD) therefore strives to measure and quantify three-dimensional shoulder proprioception in a highly accurate, user-friendly, and cost-effective manner. This device employs two Inertial Measurement Units (IMUs) with nine degrees-of-freedom attached to the lateral and frontal sides of the upper arm. These sensors are connected to a microcontroller board with a touch screen and datalogger. The screen displays the shoulder angles in real-time and allows the user to store discrete angle positions for further analysis through the data-logger. The system is compact (390 cubic centimeter volume), light (0.34 kilograms), and cost effective ($179 per unit). This device is capable of measuring, in a total procedural time of seven minutes, shoulder proprioception within two degrees of accuracy along the three anatomical planes of motion: sagittal flexion/extension, frontal abduction/adduction, and transverse abduction/adduction. This device is able to both aid upper extremity research and provide data to those making return to duty decisions following injury.

THE THREE-DIMENSIONAL MOVEMENT CORRELATIONS BETWEEN ELBOW AND WRIST JOINT AND ANTHROPOMETRIC DETERMINANTS

2018 ◽  
Vol 18 (02) ◽  
pp. 1850013 ◽  
Author(s):  
WEI WANG ◽  
DONGMEI WANG ◽  
CHENGHUI LAI
Keyword(s):  
Multiple Regression ◽  
Wrist Joint ◽  
Three Dimensional ◽  
Elbow Flexion ◽  
Wrist Flexion ◽  
Factors Affecting ◽  
Bivariate Correlation ◽  
Flexion Extension ◽  
Joint Motions ◽  
The Relationship

This study aimed to investigate three-dimensional (3D) kinematic characteristics of elbow and wrist motions, the relationship between them, and the anthropometric factors affecting them. Using motion capture system, this study measured and calculated the 3D angles of elbow flexion/extension, elbow pronation/supination, wrist flexion/extension, and wrist adduction/abduction of 40 healthy young adults. The study measured nine anthropometric variables and used unpaired [Formula: see text]-tests to assess gender difference. Also, bivariate correlation tests and step-wise multiple regression analyses were performed between joint ranges and anthropometric variables, as well as different joint motions. Results showed two opposite patterns occurred during elbow flexion/extension. The study found a correlation between the range of elbow flexion/extension and the range of elbow pronation/supination that occurred during elbow flexion/extension. Additionally, the study tested joint correlations between the four joint motions. Finally, the study established bivariate and multiple regression relationships between range of elbow motions and anthropometric factors. This research presented an unrecognized pattern of 3D elbow flexion/extension, and associations between various anthropometric factors and different joint motions. These findings can contribute to the design of orthosis of upper extremities and the rehabilitation of joint mobility.

scholarly journals An Approach to Robotic Testing of the Wrist Using Three-Dimensional Imaging and a Hybrid Testing Methodology

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Rohit Badida ◽  
Edgar Garcia-Lopez ◽  
Claire Sise ◽  
Douglas C. Moore ◽  
Joseph J. Crisco
Keyword(s):  
Degrees Of Freedom ◽  
Soft Tissues ◽  
Wrist Joint ◽  
Ct Imaging ◽  
Coordinate Systems ◽  
Standard Material ◽  
Wrist Motion ◽  
Flexion Extension ◽  
Robotic Testing

Abstract Robotic technology is increasingly used for sophisticated in vitro testing designed to understand the subtleties of joint biomechanics. Typically, the joint coordinate systems in these studies are established via palpation and digitization of anatomic landmarks. We are interested in wrist mechanics in which overlying soft tissues and indistinct bony features can introduce considerable variation in landmark localization, leading to descriptions of kinematics and kinetics that may not appropriately align with the bony anatomy. In the wrist, testing is often performed using either load or displacement control with standard material testers. However, these control modes either do not consider all six degrees-of-freedom (DOF) or reflect the nonlinear mechanical properties of the wrist joint. The development of an appropriate protocol to investigate complexities of wrist mechanics would potentially advance our understanding of normal, pathological, and artificial wrist function. In this study, we report a novel methodology for using CT imaging to generate anatomically aligned coordinate systems and a new methodology for robotic testing of wrist. The methodology is demonstrated with the testing of 9 intact cadaver specimens in 24 unique directions of wrist motion to a resultant torque of 2.0 N·m. The mean orientation of the major principal axis of range of motion (ROM) envelope was oriented 12.1 ± 2.7 deg toward ulnar flexion, which was significantly different (p < 0.001) from the anatomical flexion/extension axis. The largest wrist ROM was 98 ± 9.3 deg in the direction of ulnar flexion, 15 deg ulnar from pure flexion, consistent with previous studies [1,2]. Interestingly, the radial and ulnar components of the resultant torque were the most dominant across all directions of wrist motion. The results of this study showed that we can efficiently register anatomical coordinate systems from CT imaging space to robotic test space adaptable to any cadaveric joint experiments and demonstrated a combined load-position strategy for robotic testing of wrist.

Modeling Analysis of the Wrist Dynamics via an Ellipsoidal Joint

2020 ◽  
Author(s):  
Jiamin Wang ◽  
Sunit K. Gupta ◽  
Oumar Barry
Keyword(s):  
Wrist Joint ◽  
Translational Motion ◽  
Dynamical Behavior ◽  
State Space Model ◽  
Regression Function ◽  
Multibody Modeling ◽  
3 Dimensional ◽  
Motion Constraints ◽  
Flexion Extension ◽  
The Stability

Abstract An accurate wrist model is crucial to the understanding of human wrist mechanics and the development of forearm rehabilitation devices. This paper studied the nonlinear dynamics of the wrist through an ellipsoidal joint model. Compared to many studies where a universal joint is used to model the wrist, the proposed ellipsoidal model intends to better approximate the human wrist biomechanics with the use of kinematic constraints. The constraint on the original 3-dimensional rotation of the wrist is realized based on a quaternion formulation, reducing the wrist kinematics to the coupled 2-degree-of-freedom motions of flexion-extension and radial-ulnar deviation. The ellipsoidal joint also introduces additional coupling from the translational motion constraints. The multibody modeling of the wrist model is then established. The stability and control of the model are analyzed based on a constrained state-space model. Numerical simulations validate the analytical results and demonstrate the coupled dynamical behavior of the wrist. The simulations also show that the proposed model constraint is an ideal base regression function for wrist joint parameter identification. Finally, with the involvement of nonlinear stiffness and damping, chaotic-like behaviors and limit cycles are observed. The approach in this study is also generally applicable to a family of ellipsoidal joint systems.

scholarly journals Robust Identification of Three-Dimensional Thumb and Index Finger Kinematics With a Minimal Set of Markers

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Raviraj Nataraj ◽  
Zong-Ming Li
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
Index Finger ◽  
Three Dimensional ◽  
Axial Rotation ◽  
Solution Model ◽  
Convergence Criteria ◽  
Minimal Set ◽  
Motion Error ◽  
Flexion Extension

This study presents a methodology to determine thumb and index finger kinematics while utilizing a minimal set of markers. The motion capture of skin-surface markers presents inherent challenges for the accurate and comprehensive measurement of digit kinematics. As such, it is desirable to utilize robust methods for assessing digit kinematics with fewer markers. The approach presented in this study involved coordinate system alignment, locating joint centers of rotation, and a solution model to estimate three-dimensional (3-D) digit kinematics. The solution model for each digit was based on assumptions of rigid-body interactions, specific degrees of freedom (DOFs) at each located joint, and the aligned coordinate system definitions. Techniques of inverse kinematics and optimization were applied to calculate the 3-D position and orientation of digit segments during pinching between the thumb and index finger. The 3-D joint center locations were reliably fitted with mean coefficients of variation below 5%. A parameterized form of the solution model yielded feasible solutions that met specified tolerance and convergence criteria for over 85% of the test points. The solution results were intuitive to the pinching function. The thumb was measured to be rotated about the CMC joint to bring it into opposition to the index finger and larger rotational excursions (>10 deg) were observed in flexion/extension compared to abduction/adduction and axial rotation for all joints. While the solution model produced results similar to those computed from a full marker set, the model facilitated the usage of fewer markers, which inherently lessened the effects of passive motion error and reduced the post-experimental effort required for marker processing.

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