AssistOn-Finger: An under-actuated finger exoskeleton for robot-assisted tendon therapy

SUMMARYWe present AssistOn-Finger, a novel under-actuated active exoskeleton for robot-assisted tendon therapy of human fingers. The primary use for the exoskeleton is to assist flexion/extension motions of a finger within its full range, while decreasing voluntary muscle contractions helping to keep the tendon tension levels to stay within acceptable limits, avoiding gap formation or rupture of the suture. The device can also be employed to administer range of motion (RoM)/strengthening exercises. AssistOn-Fingeris designed to be passively back-driveable, can cover the whole RoM of patients, and can do so in a natural and coordinated manner. In particular, the device employs human finger as an integral part of its kinematics and when coupled to a human operator, the parallel kinematic structure of exoskeleton supports three independent degrees of freedom, dictated by the kinematics of the human finger. Automatically aligning its joint axes to match finger joint axes, AssistOn-Fingercan guarantee ergonomy and comfort throughout the therapy. The self-aligning feature also significantly shortens the setup time required to attach the patient to the exoskeleton. We present the kinematic type selection for the exoskeleton to satisfy the design requirements for tendon therapy applications, detail optimal dimensional synthesis of the device considering trade-offs between multiple design criteria and discuss implementation details of the exoskeleton. We also present feasibility studies conducted on healthy volunteers and provide statistical evidence on the efficacy of exoskeleton driven exercises in keeping the average muscle recruitment and the maximum tendon tension levels as low as human guided therapies.

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Design of a Two-DOFs Driving Mechanism for a Motion-Assisted Finger Exoskeleton

Applied Sciences ◽

10.3390/app10072619 ◽

2020 ◽

Vol 10 (7) ◽

pp. 2619 ◽

Cited By ~ 2

Author(s):

Giuseppe Carbone ◽

Eike Christian Gerding ◽

Burkard Corves ◽

Daniele Cafolla ◽

Matteo Russo ◽

...

Keyword(s):

Degrees Of Freedom ◽

Experimental Tests ◽

Design Solution ◽

Driving Mechanism ◽

Dimensional Synthesis ◽

Linkage Mechanism ◽

Healthy Human ◽

Wide Range ◽

Finger Motion ◽

Human Finger

This paper presents a novel exoskeleton mechanism for finger motion assistance. The exoskeleton is designed as a serial 2-degrees-of-freedom wearable mechanism that is able to guide human finger motion. The design process starts by analyzing the motion of healthy human fingers by video motion tracking. The experimental data are used to obtain the kinematics of a human finger. Then, a graphic/geometric synthesis procedure is implemented for achieving the dimensional synthesis of the proposed novel 2 degrees of freedom linkage mechanism for the finger exoskeleton. The proposed linkage mechanism can drive the three finger phalanxes by using two independent actuators that are both installed on the back of the hand palm. A prototype is designed based on the proposed design by using additive manufacturing. Results of numerical simulations and experimental tests are reported and discussed to prove the feasibility and the operational effectiveness of the proposed design solution that can assist a wide range of finger motions with proper adaptability to a variety of human fingers.

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Hybrid Seven-bar Press Mechanism

Tehnički glasnik ◽

10.31803/tg-20180203202102 ◽

2018 ◽

Vol 12 (3) ◽

pp. 181-187

Author(s):

M. Erkan Kütük ◽

L. Canan Dülger

Keyword(s):

Genetic Algorithm ◽

Objective Function ◽

Design Optimization ◽

Hybrid System ◽

Degrees Of Freedom ◽

Dimensional Synthesis ◽

Design Variables ◽

Optimization Study ◽

Metal Stamping

An optimization study with kinetostatic analysis is performed on hybrid seven-bar press mechanism. This study is based on previous studies performed on planar hybrid seven-bar linkage. Dimensional synthesis is performed, and optimum link lengths for the mechanism are found. Optimization study is performed by using genetic algorithm (GA). Genetic Algorithm Toolbox is used with Optimization Toolbox in MATLAB®. The design variables and the constraints are used during design optimization. The objective function is determined and eight precision points are used. A seven-bar linkage system with two degrees of freedom is chosen as an example. Metal stamping operation with a dwell is taken as the case study. Having completed optimization, the kinetostatic analysis is performed. All forces on the links and the crank torques are calculated on the hybrid system with the optimized link lengths

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Measurements of Tendon Movement Within the Bicipital Groove After Suprapectoral Intra-articular Biceps Tenodesis in a Cadaveric Model

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120977538 ◽

2021 ◽

Vol 9 (1) ◽

pp. 232596712097753

Author(s):

Brian J. Kelly ◽

Alan W. Reynolds ◽

Patrick J. Schimoler ◽

Alexander Kharlamov ◽

Mark Carl Miller ◽

...

Keyword(s):

Biceps Tendon ◽

Full Range ◽

Elbow Flexion ◽

Biceps Tenodesis ◽

Bicipital Groove ◽

Biceps Tenotomy ◽

Flexion Extension ◽

Before And After ◽

Long Head ◽

Scapular Motion

Background: Lesions of the long head of the biceps can be successfully treated with biceps tenotomy or tenodesis when surgical management is elected. The advantage of a tenodesis is that it prevents the potential development of a cosmetic deformity or cramping muscle pain. Proponents of a subpectoral tenodesis believe that “groove pain” may remain a problem after suprapectoral tenodesis as a result of persistent motion of the tendon within the bicipital groove. Purpose/Hypothesis: To evaluate the motion of the biceps tendon within the bicipital groove before and after a suprapectoral intra-articular tenodesis. The hypothesis was that there would be minimal to no motion of the biceps tendon within the bicipital groove after tenodesis. Study Design: Controlled laboratory study. Methods: Six fresh-frozen cadaveric arms were dissected to expose the long head of the biceps tendon as well as the bicipital groove. Inclinometers and fiducials (optical markers) were used to measure the motions of the scapula, forearm, and biceps tendon through a full range of shoulder and elbow motions. A suprapectoral biceps tenodesis was then performed, and the motions were repeated. The motion of the biceps tendon was quantified as a function of scapular or forearm motion in each plane, both before and after the tenodesis. Results: There was minimal motion of the native biceps tendon during elbow flexion and extension but significant motion during all planes of scapular motion before tenodesis, with the most motion occurring during shoulder flexion-extension (20.73 ± 8.21 mm). The motion of the biceps tendon after tenodesis was significantly reduced during every plane of scapular motion compared with the native state ( P < .01 in all planes of motion), with a maximum motion of only 1.57 mm. Conclusion: There was a statistically significant reduction in motion of the biceps tendon in all planes of scapular motion after the intra-articular biceps tenodesis. The motion of the biceps tendon within the bicipital groove was essentially eliminated after the suprapectoral biceps tenodesis. Clinical Relevance: This arthroscopic suprapectoral tenodesis technique can significantly reduce motion of the biceps tendon within the groove in this cadaveric study, possibly reducing the likelihood of groove pain in the clinical setting.

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Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

Global Spine Journal ◽

10.1177/21925682211006061 ◽

2021 ◽

pp. 219256822110060

Author(s):

Jun-Xin Chen ◽

Yun-He Li ◽

Jian Wen ◽

Zhen Li ◽

Bin-Sheng Yu ◽

...

Keyword(s):

Intervertebral Disc ◽

Degrees Of Freedom ◽

Mechanical Stability ◽

Biomechanical Testing ◽

Bending Stiffness ◽

Biomechanical Study ◽

Torsional Stiffness ◽

P Value ◽

Lateral Bending ◽

Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

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Workspace, dexterity and dimensional optimization of microhexapod

Assembly Automation ◽

10.1108/aa-03-2015-020 ◽

2015 ◽

Vol 35 (4) ◽

pp. 341-347 ◽

Cited By ~ 1

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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Optimal Time-Space Trade-Offs for Sorting

BRICS Report Series ◽

10.7146/brics.v5i10.19282 ◽

1998 ◽

Vol 5 (10) ◽

Cited By ~ 6

Author(s):

Jakob Pagter ◽

Theis Rauhe

Keyword(s):

Lower Bound ◽

Upper Bound ◽

Fundamental Problem ◽

Full Range ◽

Optimal Time ◽

Sorting Algorithm ◽

Logarithmic Factor ◽

Time Space ◽

Trade Offs ◽

Space Product

We study the fundamental problem of sorting in a sequential model of computation and in particular consider the time-space trade-off (product of time and space) for this problem.<br />Beame has shown a lower bound of Omega(n^2) for this product leaving a gap of a logarithmic factor up to the previously best known upper bound of O(n^2 log n) due to Frederickson. Since then, no progress has been made towards tightening this gap.<br />The main contribution of this paper is a comparison based sorting algorithm which closes this gap by meeting the lower bound of Beame. The time-space product O(n^2) upper bound holds for the full range of space bounds between log n and n/log n. Hence in this range our algorithm is optimal for comparison based models as well as for the very powerful general models considered by Beame.

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Design of Workspace of Human Fingers and Computer Keyboard Operation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.484-485.1118 ◽

2014 ◽

Vol 484-485 ◽

pp. 1118-1125

Author(s):

Rao Shun

Keyword(s):

Degrees Of Freedom ◽

Index Finger ◽

Operation Mode ◽

Penalty Function Method ◽

Three Dimension ◽

Mechanism Model ◽

Reachable Workspace ◽

Human Arm ◽

Dimension Space ◽

Human Finger

There are more and more complex tools and machinery that need be operated by human fingers in our modem industrial environment. Such as computer keyboards, screwdriver, handle wrench, button and switch. All of those should be designed to work effectively and safely with the operators for whom they were designed. At first, ergonomic consideration in design is reachable; this means the operators fingertip must be able to reach the operating component. This is generally no question because human arm has much more degrees of freedom required to position his arms, hands and fingers in the three-dimension space. However, some times we need the finger operate with a fixed wrist. For example in the case in the typing, the reachable workspace of the finger must take into account in such situation.Finger contacting is the most familiar operation mode of the man-machine system, and the index finger takes on the primary operation tasks. From viewpoint of ergonomic engineering, the operation component should be placed within the workspace of the fingertip to reduced or eliminate the movement of palm and arm should to the greatest extent during finger manipulation. Therefore the research of the workspace of ginger is significant to the ergonomic design of the operation device. In this paper, the reachable workspace and workspace under direction restrain of contacting for the index finger are determined using serial mechanism model and the Penalty Function Method based on geometric measurement of human body. The optimal operating position and orientation of human finger is analyzed.

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Finite Element Model of the Human Knee Joint to Study Tibio-Femoral Contact Mechanics

10.1115/imece2000-2562 ◽

2000 ◽

Author(s):

Tammy Haut Donahue ◽

Maury L. Hull ◽

Mark M. Rashid ◽

Christopher R. Jacobs

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Degrees Of Freedom ◽

Soft Tissues ◽

Element Model ◽

Human Knee ◽

Human Knee Joint ◽

Solid Models ◽

Flexion Extension ◽

A New Technique

Abstract A finite element model of the tibio-femoral joint in the human knee was created using a new technique for developing accurate solid models of soft tissues (i.e. cartilage and menisci). The model was used to demonstrate that constraining rotational degrees of freedom other than flexion/extension when the joint is loaded in compression markedly affects the load distribution between the medial and lateral sides of the joint. The model also was used to validate the assumption that the bones can be treated as rigid.

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Displacement Analysis and Design of a (2–RRU)–URR Parallel Mechanism Performing 2R1T Output Motion for Thumb Rehabilitation

Robotics ◽

10.3390/robotics9030067 ◽

2020 ◽

Vol 9 (3) ◽

pp. 67

Author(s):

Woo-hyeok Choi ◽

Yukio Takeda

Keyword(s):

Parallel Mechanism ◽

Degrees Of Freedom ◽

Human Hand ◽

Displacement Analysis ◽

Analysis And Design ◽

Reachable Workspace ◽

Flexion Extension ◽

Basic Characteristics ◽

Narrow Space ◽

Input Torque

The thumb assists other fingers, and any damage in its functionality prevents the human hand from performing dexterous functions. In this paper, the kinematic design of the (2–RRU)–URR parallel mechanism as the application of the thumb rehabilitation device is proposed. This mechanism is an over-constrained mechanism capable of achieving the required mobility with fewer joints. Three degrees of freedom exist—two rotational and one translational mobility—that are related to each thumb movement: adduction–abduction and flexion–extension. Considering the narrow space of the hand, actuators are designed to divide its placement into the surface of the palm. To avoid the collisions between the device and the hand, an offset was adopted. The displacement analysis problem is solved by dividing it into two parts: the planar motion generator (PMG) and orientation generator (OG), according to each functional motion, and the corresponding equations and procedures are presented. To clarify the basic characteristics of this mechanism, the reachable workspace of the PMG and rotational ability and sensitivity of the OG is demonstrated numerically. Because a large input torque difference is dangerous in the rehabilitation mechanism, the effective workspace is determined according to the magnitude of the input torque differences and compared with the measured thumb movements.

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