scholarly journals Biomechanical Signals of Varied Modality and Location Contribute Differently to Recognition of Transient Locomotion

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5390
Author(s):  
Mahdieh Kazemimoghadam ◽  
Nicholas P. Fey
Keyword(s):  
Joint Angle ◽  
Poor Performance ◽  
Heel Strike ◽  
Joint Angles ◽  
Intent Recognition ◽  
Stair Ascent ◽  
Straight Line ◽  
Angle Data ◽  
Mechanical Sensing ◽  
Accuracy Rates

Intent recognition in lower-limb assistive devices typically relies on neuromechanical sensing of an affected limb acquired through embedded device sensors. It remains unknown whether signals from more widespread sources such as the contralateral leg and torso positively influence intent recognition, and how specific locomotor tasks that place high demands on the neuromuscular system, such as changes of direction, contribute to intent recognition. In this study, we evaluated the performances of signals from varying mechanical modalities (accelerographic, gyroscopic, and joint angles) and locations (the trailing leg, leading leg and torso) during straight walking, changes of direction (cuts), and cuts to stair ascent with varying task anticipation. Biomechanical information from the torso demonstrated poor performance across all conditions. Unilateral (the trailing or leading leg) joint angle data provided the highest accuracy. Surprisingly, neither the fusion of unilateral and torso data nor the combination of multiple signal modalities improved recognition. For these fused modality data, similar trends but with diminished accuracy rates were reported during unanticipated conditions. Finally, for datasets that achieved a relatively accurate (≥90%) recognition of unanticipated tasks, these levels of recognition were achieved after the mid-swing of the trailing/transitioning leg, prior to a subsequent heel strike. These findings suggest that mechanical sensing of the legs and torso for the recognition of straight-line and transient locomotion can be implemented in a relatively flexible manner (i.e., signal modality, and from the leading or trailing legs) and, importantly, suggest that more widespread sensing is not always optimal.

scholarly journals Genome-Wide Association Studies Based on Equine Joint Angle Measurements Reveal New QTL Affecting the Conformation of Horses

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 370 ◽  
Author(s):  
Annik Imogen Gmel ◽  
Thomas Druml ◽  
Rudolf von Niederhäusern ◽  
Tosso Leeb ◽  
Markus Neuditschko
Keyword(s):  
Joint Angle ◽  
Association Studies ◽  
Genome Wide Association ◽  
Cranial Morphology ◽  
Genome Wide Association Studies ◽  
Joint Angles ◽  
Mineral Density ◽  
Mixed Effect ◽  
Stifle Joint ◽  
Genome Wide

The evaluation of conformation traits is an important part of selection for breeding stallions and mares. Some of these judged conformation traits involve joint angles that are associated with performance, health, and longevity. To improve our understanding of the genetic background of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal, fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the 300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide single nucleotide polymorphisms (SNPs) in a mixed-effect model. We identified two significant quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 × 10−7), 50 kb downstream of the ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 × 10−7), 49 kb downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated with the stifle joint on ECA8 (p = 3.10 × 10−7); the poll on ECA1 (p = 6.83 × 10−7); the fetlock joint of the hind limb on ECA27 (p = 5.42 × 10−7); and the carpal joint angle on ECA3 (p = 6.24 × 10−7), ECA4 (p = 6.07 × 10−7), and ECA7 (p = 8.83 × 10−7). The application of angular measurements in genetic studies may increase our understanding of the underlying genetic effects of important traits in equine breeding.

scholarly journals Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2690
Author(s):  
Bo Pan ◽  
Xuguang Wang ◽  
Zhenyang Xu ◽  
Lianjun Guo ◽  
Xuesong Wang
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Joint Angle ◽  
Simulation Software ◽  
Dissipated Energy ◽  
Energy Structure ◽  
Joint Angles ◽  
Crack Penetration ◽  
Before And After ◽  
The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

Gyroscope-Free Link Parameter Measurement Using Accelerometers and Magnetometer

2014 ◽  
Author(s):  
Vishesh Vikas ◽  
Carl D. Crane
Keyword(s):  
Angular Velocity ◽  
Joint Angle ◽  
Inertial Sensors ◽  
Angular Acceleration ◽  
Parameter Measurement ◽  
Joint Angles ◽  
Symmetry Constraint ◽  
Estimation Techniques ◽  
Angular Velocities ◽  
Joint Parameters

Knowledge of joint angles, angular velocities is essential for control of link mechanisms and robots. The estimation of joint angles and angular velocity is performed using combination of inertial sensors (accelerometers and gyroscopes) which are contactless and flexible at point of application. Different estimation techniques are used to fuse data from different inertial sensors. Bio-inspired sensors using symmetrically placed multiple inertial sensors are capable of instantaneously measuring joint parameters (joint angle, angular velocities and angular acceleration) without use of any estimation techniques. Calibration of inertial sensors is easier and more reliable for accelerometers as compared to gyroscopes. The research presents gyroscope-less, multiple accelerometer and magnetometer based sensors capable of measuring (not estimating) joint parameters. The contribution of the improved sensor are four-fold. Firstly, the inertial sensors are devoid of symmetry constraint unlike the previously researched bio-inspired sensors. However, the accelerometer are non-coplanarly placed. Secondly, the accelerometer-magnetometer combination sensor allows for calculation of a unique rotation matrix between two link joined by any kind of joint. Thirdly, the sensors are easier to calibrate as they consist only of accelerometers. Finally, the sensors allow for calculation of angular velocity and angular acceleration without use of gyroscopes.

Investigating the Effect of Real-Time Center of Pressure (CoP) Feedback Training on the Swing Phase of Lower Limb Kinematics in Transfemoral Prostheses with SACH foot

2021 ◽  
Author(s):  
Ashutosh Tiwari ◽  
Abhijeet Kujur ◽  
Jyoti Kumar ◽  
Deepak Joshi
Keyword(s):  
Real Time ◽  
Lower Limb ◽  
Knee Flexion ◽  
Center Of Pressure ◽  
Feedback System ◽  
Swing Phase ◽  
Flexion Angle ◽  
Heel Strike ◽  
Knee Flexion Angle ◽  
Joint Angles

Abstract Transfemoral amputee often encounters reduced toe clearance resulting in trip-related falls. Swing phase joint angles have been shown to influence the toe clearance therefore, training intervention that targets shaping the swing phase joint angles can potentially enhance toe clearance. The focus of this study was to investigate the effect of the shift in the location of the center of pressure (CoP) during heel strike on modulation of the swing phase joint angles in able-bodied participants (n=6) and transfemoral amputees (n=3). We first developed a real-time CoP-based visual feedback system such that participants could shift the CoP during treadmill walking. Next, the kinematic data were collected during two different walking sessions- baseline (without feedback) and feedback (shifting the CoP anteriorly/posteriorly at heel strike to match the target CoP location). Primary swing phase joint angle adaptations were observed with feedback such that during the mid-swing phase, posterior CoP shift feedback significantly increases (p<0.05) the average hip and knee flexion angle by 11.55 degrees and 11.86 degrees respectively in amputees, whereas a significant increase (p<0.05) in ankle dorsiflexion, hip and knee flexion angle by 3.60 degrees, 3.22 degrees, and 1.27 degrees respectively compared to baseline was observed in able-bodied participants. Moreover, an opposite kinematic adaptation was seen during anterior CoP shift feedback. Overall, results confirm a direct correlation between the CoP shift and the modulation in the swing phase lower limb joint angles.

scholarly journals A Workspace Visualization Method for a Multijoint Industrial Robot Based on the 3D-Printing Layering Concept

2020 ◽  
Vol 10 (15) ◽  
pp. 5241
Author(s):  
Guoqiang Fu ◽  
Chun Tao ◽  
Tengda Gu ◽  
Caijiang Lu ◽  
Hongli Gao ◽  
...  
Keyword(s):  
3D Printing ◽  
Joint Angle ◽  
Industrial Robot ◽  
Selection Method ◽  
Forward Kinematics ◽  
Visualization Method ◽  
Joint Angles ◽  
Boundary Extraction ◽  
Simulation And Experiment ◽  
Constraint Information

The workspace of a robot provides the necessary constraint information for path planning and reliable control of the robot. In this paper, a workspace visualization method for a multijoint industrial robot is proposed to obtain a detailed workspace by introducing the 3D-printing layering concept. Firstly, all possible joint-angle groups of one pose in the joints’ ranges are calculated in detail according to the POE (product of exponential) theory-based forward-kinematics expressions of the multijoint industrial robot. Secondly, a multisolution selection method based on the key degree of the joint is proposed to select the appropriate joint-angle groups. The key degrees of all joints and their key order are obtained according to the sensitivity expressions of all joint angles, calculated from the Jacobian matrix of the robot. One principle based on the smallest differences of the nominal angle is established to select the possible solutions for one joint from the possible solutions for the joint with the smaller key order. The possible solutions for the joint with the highest key order are the appropriate joint-angle group. Thirdly, a workspace visualization method based on the layering concept of 3D printing is presented to obtain a detailed workspace for a multijoint industrial robot. The boundary formula of each layer is derived by forward kinematics, which is expressed as a circle or a ring. The maximum and minimum values of the radius are obtained according to the travel range of the joint angles. The height limitations of all layers are obtained with forward kinematics. A workspace boundary-extraction method is presented to obtain the array of path points of the boundary at each layer. The proposed postprocessing method is used to generate the joint-angle code of each layer for direct 3D printing. Finally, the effectiveness of the multisolution selection method and the workspace visualization method were verified by simulation and experiment.

scholarly journals Estimation of Continuous Joint Angles of Upper Limb Based on sEMG by Using GA-Elman Neural Network

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Junhong Wang ◽  
Qiqi Hao ◽  
Xugang Xi ◽  
Jiuwen Cao ◽  
Anke Xue ◽  
...  
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Elbow Joint ◽  
Joint Angle ◽  
Wavelet Packet ◽  
Upper Limbs ◽  
Joint Angles ◽  
Semg Signal ◽  
Elman Neural Network ◽  
Shoulder Movement

The estimation of continuous and simultaneous multijoint angle based on surface electromyography (sEMG) signal is of considerable significance in rehabilitation practice. However, there are few studies on the continuous joint angle of multiple joints at present. In this paper, the wavelet packet energy entropy (WPEE) of the special subspace was investigated as a feature of the sEMG signal. An Elman neural network optimized by genetic algorithm (GA) was established to estimate the joint angle of shoulder and elbow. First, the accuracy of the method is verified by estimating the angle of the shoulder joint. Then, this method was used to simultaneously and continuously estimate the shoulder and elbow joint angle. Six subjects flexed and extended the upper limbs according to the intended movements of the experiment. The results show that this method can obtain a decent performance with a RMSE of 3.4717 and R2 of 0.8283 in shoulder movement and with a RMSE of 4.1582 and R2 of 0.8114 in continuous synchronous movement of the shoulder and elbow.

scholarly journals Kinematic-based locomotion mode recognition for power augmentation exoskeleton

2017 ◽  
Vol 14 (5) ◽  
pp. 172988141773032 ◽  
Author(s):  
Hongchul Kim ◽  
Young June Shin ◽  
Jung Kim
Keyword(s):  
Joint Angle ◽  
Identification Accuracy ◽  
Sensor Data ◽  
Knee Joint Angle ◽  
Stair Ascent ◽  
Mode Recognition ◽  
Different Types ◽  
Locomotion Mode ◽  
The Difference ◽  
Foot Position

This article presents a kinematic-based method for locomotion mode recognition, for use in the control of an exoskeleton for power augmentation, to implement natural and smooth locomotion transition. The difference in vertical foot position between a foot already in contact with ground and a foot newly in contact with the ground was calculated via kinematics for the entire exoskeleton and used to identify the locomotion mode with other sensor data including data on the knee joint angle and inclination of the thigh, shank, and foot. Locomotion on five different types of terrain—level-ground walking, stair ascent, stair descent, ramp ascent, and ramp descent—were identified using two-layer decision tree classes. An updating process is proposed to improve identification of the transition and accuracy using the foot inclination at the mid-stance. An average identification accuracy of more than 99% was achieved in experiments with eight subjects for single terrains (no terrain transitions) and hybrid terrains. The experimental results show that the proposed method can achieve high accuracy without significant misrecognition and minimize the delay in locomotion mode recognition of the exoskeleton.

Analysis of the mero-carpopodite joint of the American lobster and snow crab. II. Kinematics, morphometrics and moment arms

2003 ◽  
Vol 83 (6) ◽  
pp. 1249-1259 ◽  
Author(s):  
S.C. Mitchell ◽  
M.E. DeMont
Keyword(s):  
Joint Angle ◽  
Snow Crab ◽  
Moment Arm ◽  
Scaling Effects ◽  
Joint Angles ◽  
Positive Allometry ◽  
Moment Arms ◽  
Arm Reaching ◽  
Flexion Extension ◽  
The Moment

This research reports on the kinematics of lobster and snow crab walking, documents changes in the moment arms of the mero-carpopodite joint during rotation, and examines scaling effects of morphological and mechanical variables in these crustacean species. Forward walking lobsters and lateral walking crabs were recorded and images analysed to describe the kinematics of these animals, and subsequently morphometric and moment arm measurements made. During forward walking the lobster maintains fixed mero-carpopodite joint angles during both the power and recovery strokes, though each of the walking legs maintains different joint angles. Legs 3 and 5 are maintained at angles which appear to equalize the flexor and extensor moment arms, and leg 4 joint angle appears to maximize the extensor moment arm. The snow crab has a joint excursion angle of between approximately 50° to 150° and, during flat bed walking, the leading and trailing legs move through similar excursion angles. The length of the meropodite for both species are longer for the anterior two leg pairs relative to the posterior two pairs and the rate of growth of the meropodite is largely isometric for the lobster while consistently increases with positive allometry in the crab. The flexor and extensor moment arms generated as the joint undergoes flexion/extension show two distinct patterns with the extensor moment arm being maximized at relatively low joint angles (55°–115°) and the flexor moment arm reaching a plateau at joint extension with angles between 95° and 155°. The flexor apodeme possesses the largest moment arms in all legs for both species, suggesting the flexors are able to generate greater torques. It appears that, mechanically, these laterally moving animals may be ‘pulling’ with the leading legs to a greater extent than ‘pushing’ with the trailing legs.

Information signaled by sensory fibers in medial articular nerve

1975 ◽  
Vol 38 (6) ◽  
pp. 1464-1472 ◽  
Author(s):  
F. J. Clark
Keyword(s):  
Knee Joint ◽  
Entire Range ◽  
Joint Angle ◽  
Nerve Fibers ◽  
Pacinian Corpuscle ◽  
Joint Angles ◽  
Discharge Characteristics ◽  
Gentle Pressure ◽  
Sensory Fibers ◽  
Deep Pressure

Responses of 331 individual medial articular nerve fibers innervating the cat knee joint were tested to bending the joint over its entire range and to pressing on the tissues of the joint. The 331 fibers were classified into five groups on the basis of their discharge characteristics: slowly adapting (64), phasic (103), Pacinian corpuscle-like (12), weakly activated (39), and nonactivated (113). Five of the slowly adapting and all twelve of the Pacinian corpuscle-like receptors responded at intermediate joint angles. The remainder responded, if at all, only near the extremes of joint bending or twisting. Many of these same receptors could be activated by pressing about the knee. Sometimes gentle pressure on the focus sufficed to produce a vigorous discharge. The properties of these receptors are considered to be consistent with the hypothesis that articular mechanoreceptors do not signal joint angle but are involved in deep-pressure sensations.

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