Design of Wearable Lower Leg Orthotic Based on Six-Bar Linkage

2017 ◽  
Author(s):  
Shramana Ghosh ◽  
Nina Robson ◽  
J. M. McCarthy
Keyword(s):  
Lower Leg ◽  
Wearable Device ◽  
Skeletal Structure ◽  
Dimensional Synthesis ◽  
Leg Injuries ◽  
Orthotic Device ◽  
Serial Chain ◽  
Compact Size ◽  
Optical Motion ◽  
Optical Motion Capture

The paper presents the design of a lower leg orthotic device based on dimensional synthesis of multi-loop six-bar linkages. The wearable device is comprised of a 2R serial chain, termed the backbone, sized according to the wearer’s limb anthropometric dimensions. The paper is a result of our current efforts in proposing a systematic process for the development of 3D printed customized assistive devices for patients with reduced limb mobility, based on anthropometric data and physiological task. To design the wearable device, the physiological task of the limb is obtained using an optical motion capture system and its dimensions are set such that it matched the lower leg kinematics as closely as possible. As a next step a six-bar linkage is synthesized and ensured that its motion is as close as possible to the physiological task. Next, the 2R backbone is replaced by the wearer’s limb to provide the skeletal structure for the multi-loop wearable device. During the final stage of the process the 2R backbone is relocated to parallel the human’s limb on one side, providing support and stability. The designed device can be secured to the thigh of the user to guide the lower leg without causing any discomfort and to ensure a natural physiological gait trajectory. This results in orthotic device for assisting people with lower leg injuries with compact size and better wearability.

Rigid Body Guidance of Human Gait as Constrained TRS Serial Chain

2014 ◽  
Author(s):  
Gim Song Soh
Keyword(s):  
Degrees Of Freedom ◽  
Point Of View ◽  
Human Gait ◽  
Synthesis Process ◽  
Dimensional Synthesis ◽  
Two Degrees Of Freedom ◽  
Serial Chain ◽  
Optical Motion ◽  
Musculoskeletal Function ◽  
Optical Motion Capture

The motion of gait is a cyclical activity that requires the coordination between locomotion mechanism, motor control and musculoskeletal function. The basic assumption is that one stride is the same as the next. From a simplified kinematics point of view, the human gait can be considered as a TRS serial chain with six degrees-of-freedom driven by the pelvis rotational and tilting motion during walking. This paper presents a dimensional synthesis procedure for the design of two degrees-of-freedom of spatial eight-bar linkages by mechanically constraining a TRS serial chain. The goal is to develop a methodology for the design of under-actuated lower limb walking devices or passively driven exoskeleton systems. The dimensional synthesis process starts with the specification of the links of a TRS chain according to the gait anthropometric data. We show the various ways how four TS constraints can be used to constrain the links of the this chain to obtain a two degrees-of-freedom spatial eight-bar linkage. We formulate and solve the design equations as well as analyze the resulting eight-bar linkage from the data we obtained from an optical motion capture system. An example demonstrates our results.

Creating Robust Passive Multi-Loop Wearable Hand Devices

2019 ◽  
Author(s):  
Nina Robson ◽  
Bin Yun Chen ◽  
Jong-Seob Won ◽  
Gim Song Soh
Keyword(s):  
Cost Effective ◽  
Preliminary Test ◽  
Skeletal Structure ◽  
Prototype Model ◽  
Dimensional Synthesis ◽  
Natural Manner ◽  
Backbone Chain ◽  
Optical Motion ◽  
Human Finger ◽  
Precision Grasping

Abstract This paper describes a process for assessing multi-loop wearable devices that use a common slider to passively drive the exo-fingers for the physical training of people with limited hand mobility. Each finger design, except for the thumb, is based on an RRR serial chain, termed backbone, constrained into a multi-loop eight-bar slider mechanism using two RR constraints. The thumb utilizes a planar RR backbone chain constrained into a parallel four bar slider. During the physical task acquisition experiments, the subject’s tip finger trajectories are captured using an optical motion capture and its dimensions are set such that they match each of the fingers kinematics as closely as possible. The dimensional synthesis procedure can yield a variety of design candidates that fulfill the desired fingertip precision grasping trajectory. Once it is ensured that the synthesized fingertip motion is close to the physiological fingertip grasping trajectories, performance assessment criteria related to user-device interference and natural joint angle movement are taken into account. After the most preferred design for each finger is chosen, minor modifications related to substituting the backbone chain with the wearer’s limb to provide the skeletal structure of the customized passive device are made. To illustrate the proposed technique, the development of a 3D prototype model of a passively actuated Closed Loop Articulated Wearable (CLAW) hand is presented. The CLAW hand performance with respect to wear-ability and robustness was assessed. Preliminary test results with healthy subjects show that the CLAW hand is easy to operate and able to guide the user’s fingers without causing any discomfort, ensuring both, precision and power grasping in a natural manner. The lack of electrical actuators and sensors simplifies the control, resulting in a lightweight and cost-effective solution for grasping of a variety of objects with different sizes. This work establishes the importance of incorporating novel design candidate assessment techniques, based on human finger kinematic models, within the conceptual design level that can assist in finding robust design candidates with naturalistic joint motion.

scholarly journals Geometric Design of a Passive Mechanical Knee for Lower Extremity Wearable Devices Based on Anthropomorphic Foot Task Geometry Scaling

2015 ◽  
Author(s):  
Shramana Ghosh ◽  
Nina Robson ◽  
J. M. McCarthy
Keyword(s):  
Wearable Devices ◽  
Heel Strike ◽  
Kinematic Synthesis ◽  
Leg Injuries ◽  
Recovery Treatment ◽  
Optical Motion ◽  
Efficient Alternative ◽  
Foot Clearance ◽  
Optical Motion Capture ◽  
Four Bar Linkage

The standard recovery treatment for ankle and lower leg injuries consists of using underarm crutches. Hands-free crutches have recently emerged as a more comfortable, natural and energy efficient alternative. However in the currently available devices such as the iWalk-Free (iWALKFree, Inc., USA) the lack of a knee joint results in abnormal motion pattern at the hip and pelvic joints to ensure foot clearance during the swing phase of the gait. To address this shortcoming, the paper describes the kinematic synthesis of a planar passive four-bar linkage that can be used as a mechanical knee in lower limb exoskeletons and other wearable devices. The knee design is based on anthropomorphic foot walking trajectory obtained from optical motion capture system. The task geometry at the foot, related to the contact and curvature constraints between the foot and the ground at two critical positions ‘heel strike’ and ‘toe off’ is scaled to the knee level. Velocity and acceleration specifications compatible with the contact and curvature constraints assist in defining the synthesis equations for the knee design. A working prototype of a passive wearable crutch substitute that incorporates the mechanical knee shows the applicability of the proposed technique.

scholarly journals Accuracy of a Low-Cost 3D-Printed Wearable Goniometer for Measuring Wrist Motion

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4799
Author(s):  
Calvin Young ◽  
Sarah DeDecker ◽  
Drew Anderson ◽  
Michele L. Oliver ◽  
Karen D. Gordon
Keyword(s):  
Motion Capture ◽  
Low Cost ◽  
Wearable Device ◽  
Matching Task ◽  
Motion Capture System ◽  
Wrist Motion ◽  
Flexion Extension ◽  
Optical Motion ◽  
3D Printed ◽  
Optical Motion Capture

Wrist motion provides an important metric for disease monitoring and occupational risk assessment. The collection of wrist kinematics in occupational or other real-world environments could augment traditional observational or video-analysis based assessment. We have developed a low-cost 3D printed wearable device, capable of being produced on consumer grade desktop 3D printers. Here we present a preliminary validation of the device against a gold standard optical motion capture system. Data were collected from 10 participants performing a static angle matching task while seated at a desk. The wearable device output was significantly correlated with the optical motion capture system yielding a coefficient of determination (R2) of 0.991 and 0.972 for flexion/extension (FE) and radial/ulnar deviation (RUD) respectively (p < 0.0001). Error was similarly low with a root mean squared error of 4.9° (FE) and 3.9° (RUD). Agreement between the two systems was quantified using Bland–Altman analysis, with bias and 95% limits of agreement of 3.1° ± 7.4° and −0.16° ± 7.7° for FE and RUD, respectively. These results compare favourably with current methods for occupational assessment, suggesting strong potential for field implementation.

Dimensional Synthesis of a Passive Eight-Bar Slider Exo-Limb for Grasping Tasks

2016 ◽  
Author(s):  
Guan Rong Tan ◽  
Nina Robson ◽  
Gim Song Soh
Keyword(s):  
Motion Capture ◽  
Index Finger ◽  
Synthesis Method ◽  
Wearable Devices ◽  
Least Square ◽  
Dimensional Synthesis ◽  
Infra Red ◽  
Optical Motion ◽  
3D Printed ◽  
Optical Motion Capture

This paper describes a dimensional synthesis method used in the design of a passively actuated finger exoskeleton that takes into account the user limb anthropometric dimensions and contact requirements for grasping objects. The paper is the first step in our current efforts on design of wearable devices that use a common slider at the hand to passively actuate each exo-finger. The finger exoskeleton is comprised of a 3R serial limb and is constrained to an eight-bar slider mechanism. To design the exo-limb, the pose of the index finger was captured using an optical motion capture and its dimensions were determined using a constrained least square optimization of its center of rotation. To facilitate the data capture, a 3D printed wearable Infra-red (IR) marker system was designed and placed on the finger’s phalanx. To illustrate the approach, an example of the design of an index exo-finger is described.

scholarly journals Motion Generation of Passive Slider Multiloop Wearable Hand Devices

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Guan Rong Tan ◽  
Nina Patarinsky Robson ◽  
Gim Song Soh
Keyword(s):  
Human Skin ◽  
Motion Capture ◽  
Synthesis Method ◽  
Middle Finger ◽  
Wearable Devices ◽  
Least Square ◽  
Dimensional Synthesis ◽  
Motion Generation ◽  
Optical Motion ◽  
Optical Motion Capture

This paper describes a dimensional synthesis method used in the design of a passive finger exoskeleton that takes into account the user limb anthropometric dimensions and contact requirements for grasping objects. The paper is the first step in our current efforts on the design of wearable devices that use a common slider at the hand to passively drive each exofinger. The finger exoskeleton is comprised of a 3R serial limb and is constrained to multiloop eight-bar slider mechanism using two RR constraints. To design the exolimb, the pose of the limb was captured using an optical motion capture and its dimensions were determined using a constrained least square optimization, which takes into account human skin movement. To illustrate the generality of our approach, an example of the design of an index and middle finger exolimb is described.

scholarly journals An Intelligent In-Shoe System for Gait Monitoring and Analysis with Optimized Sampling and Real-Time Visualization Capabilities

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2869
Author(s):  
Jiaen Wu ◽  
Kiran Kuruvithadam ◽  
Alessandro Schaer ◽  
Richie Stoneham ◽  
George Chatzipirpiridis ◽  
...  
Keyword(s):  
Real Time ◽  
Inertial Sensor ◽  
Neurological Diseases ◽  
Principal Component ◽  
Sampling Frequency ◽  
Powerful Analytical Tool ◽  
Optical Motion ◽  
Analysis System ◽  
Optical Motion Capture ◽  
Gait Monitoring

The deterioration of gait can be used as a biomarker for ageing and neurological diseases. Continuous gait monitoring and analysis are essential for early deficit detection and personalized rehabilitation. The use of mobile and wearable inertial sensor systems for gait monitoring and analysis have been well explored with promising results in the literature. However, most of these studies focus on technologies for the assessment of gait characteristics, few of them have considered the data acquisition bandwidth of the sensing system. Inadequate sampling frequency will sacrifice signal fidelity, thus leading to an inaccurate estimation especially for spatial gait parameters. In this work, we developed an inertial sensor based in-shoe gait analysis system for real-time gait monitoring and investigated the optimal sampling frequency to capture all the information on walking patterns. An exploratory validation study was performed using an optical motion capture system on four healthy adult subjects, where each person underwent five walking sessions, giving a total of 20 sessions. Percentage mean absolute errors (MAE%) obtained in stride time, stride length, stride velocity, and cadence while walking were 1.19%, 1.68%, 2.08%, and 1.23%, respectively. In addition, an eigenanalysis based graphical descriptor from raw gait cycle signals was proposed as a new gait metric that can be quantified by principal component analysis to differentiate gait patterns, which has great potential to be used as a powerful analytical tool for gait disorder diagnostics.

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