scholarly journals Research on Measurement Method of Parachute Scanning Platform Based on MEMS Device

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 402
Author(s):  
Ning Liu ◽  
Tianqi Tian ◽  
Zhong Su ◽  
Wenhao Qi
Keyword(s):  
Physical Simulation ◽  
Inertial Sensors ◽  
Rotational Velocity ◽  
Attitude Measurement ◽  
Matlab Simulation ◽  
Scanning Angle ◽  
Reduce Development Time ◽  
Motion Parameters ◽  
Motion Characteristics ◽  
Scanning Motion

This paper studies the measurement of motion parameters of a parachute scanning platform. The movement of a parachute scanning platform has fast rotational velocity and a complex attitude. Therefore, traditional measurement methods cannot measure the motion parameters accurately, and thus fail to satisfy the requirements for the measurement of parachute scanning platform motion parameters. In order to solve these problems, a method for measuring the motion parameters of a parachute scanning platform based on a combination of magnetic and inertial sensors is proposed in this paper. First, scanning motion characteristics of a parachute-terminal-sensitive projectile are analyzed. Next, a high-precision parachute scanning platform attitude measurement device is designed to obtain the data of magnetic and inertial sensors. Then the extended Kalman filter is used to filter and observe errors. The scanning angle, the scanning angle velocity, the falling velocity, and the 2D scanning attitude are obtained. Finally, the accuracy and feasibility of the algorithm are analyzed and validated by MATLAB simulation, semi-physical simulation, and airdrop experiments. The presented research results can provide helpful references for the design and analysis of parachute scanning platforms, which can reduce development time and cost.

scholarly journals An Enhanced Fusion Strategy for Reliable Attitude Measurement Utilizing Vision and Inertial Sensors

2019 ◽  
Vol 9 (13) ◽  
pp. 2656
Author(s):  
Zhang ◽  
Shen ◽  
Chen ◽  
Cao ◽  
Zhao ◽  
...  
Keyword(s):  
Physical Simulation ◽  
Inertial Sensors ◽  
Training Model ◽  
Activation Function ◽  
Integrated System ◽  
Attitude Measurement ◽  
Fusion Strategy ◽  
Cubature Kalman Filter ◽  
Attitude Measurements ◽  
Hidden Layer

In this paper, we present a radial basis function (RBF) and cubature Kalman filter (CKF) based enhanced fusion strategy for vision and inertial integrated attitude measurement for sampling frequency discrepancy and divergence. First, the multi-frequency problem of the integrated system and the reason for attitude divergence are analyzed. Second, the filter equation and attitude differential equation are constructed to calculate attitudes separately in time series when visual and inertial data are available or when there are only inertial data. Third, attitude errors between inertial and vision are sent to the input layer of RBF for training. After this, through the activation function of the hidden layer, the errors are transferred to the output layer for weighting the sums, and the training model is established. To overcome the problem of divergence inherent in a multi-frequency system, the well-trained RBF, which can output the attitude errors, is utilized to compensate the attitudes calculated by pure inertial data. Finally, semi-physical simulation experiments under different scenarios are performed to validate the effectiveness and superiority of the proposed scheme in accurate attitude measurements and enhanced anti-divergence capability.

On the Motion Characteristics of Tripode Joints. Part 1: General Case

1984 ◽  
Vol 106 (2) ◽  
pp. 228-234 ◽  
Author(s):  
E. Akbil ◽  
T. W. Lee
Keyword(s):  
Constant Velocity ◽  
Analytical Study ◽  
Orbital Motion ◽  
Analytical Investigation ◽  
Rigorous Proof ◽  
Input Output ◽  
Arbitrary Position ◽  
Motion Parameters ◽  
Motion Characteristics ◽  
Output Equation

This paper is concerned with the analytical investigation of the motion characteristics of tripode joints with general proportions and arbitrary position of shafts. It provides a rigorous proof that the tripode joint is not a true constant velocity joint except in ideal cases, and this is due to the inherent orbital motion of the output spider shaft. Algebraic derivations of the input-output equation and explicit relations for motion parameters are presented. From this general analytical study, some insights into the behavior of the tripode joint are observed and interpreted.

General Characteristics of the Motion of Multiple-Pode Joints

1984 ◽  
Vol 51 (1) ◽  
pp. 171-178 ◽  
Author(s):  
T. W. Lee ◽  
E. Akbil
Keyword(s):  
Functional Analysis ◽  
Analytical Method ◽  
Input Output ◽  
Displacement Analysis ◽  
General Displacement ◽  
Motion Parameters ◽  
The Creation ◽  
Motion Characteristics ◽  
And Behavior ◽  
Output Equation

This paper presents an analytical method on the investigation of the motion characteristics of a class of spatial mechanical components involving the ball-and-trunnion type of joint, namely, the multiple-pode joint. Algebraic derivations of the input-output equation and explicit relations for motion parameters are presented for these joints as well as their shaft couplings. From this general displacement analysis, some insights into the basic nature and behavior of the multiple-pode joint are observed and interpreted. The creation of shaft couplings using these joints and their functional analysis are also illustrated in several cases.

scholarly journals Classifier Module of Types of Movements Based on Signal Processing and Deep Learning Techniques

2021 ◽  
Vol 10 (1) ◽  
pp. 14
Author(s):  
Manuel Gil-Martín ◽  
Javier López-Iniesta ◽  
Rubén San-Segundo
Keyword(s):  
Signal Processing ◽  
Deep Learning ◽  
Frequency Domain ◽  
Inertial Sensors ◽  
Wearable Sensors ◽  
Window Size ◽  
Learning Techniques ◽  
Repetitive Movements ◽  
Unique Approach ◽  
Motion Characteristics

Human Activity Recognition (HAR) has been widely addressed by deep learning techniques. However, most prior research applied a general unique approach (signal processing and deep learning) to deal with different human activities including postures and gestures. These types of activity typically have highly diverse motion characteristics, which could be captured with wearable sensors placed on the user’s body. Repetitive movements such as running or cycling have repetitive patterns over time and generate harmonics in the frequency domain, while postures such as sitting or lying are characterized by a fixed position, with some positional changes and gestures or non-repetitive movements being based on an isolated movement usually performed by a limb. This work proposes a classifier module to perform an initial classification among these different types of movements, which would allow for applying afterwards the most appropriate approach in terms of signal processing and deep learning techniques for each type of movement. This classifier has been evaluated using the PAMAP2 and OPPORTUNITY datasets using a subject-wise cross-validation methodology. These datasets contain recordings from inertial sensors on hands, arms, chest, hip, and ankles, collected in a non-intrusive way. In the case of PAMAP2, the baseline approach for classifying the 12 activities using 5-s windows in the frequency domain obtained an accuracy of 85.26 ± 0.25%. However, an initial classifier module could distinguish between repetitive movements and postures using 5-s windows reaching higher performances. Afterward, specific window size, signal format, and deep learning architecture were used for each type of movement module, obtaining a final accuracy of 90.09 ± 0.35% (an absolute improvement of 4.83%).

A Kirigami-Inspired 8R Linkage and Its Evolved Overconstrained 6R Linkages With the Rotational Symmetry of Order Two

2014 ◽  
Vol 6 (2) ◽  
Author(s):  
Ketao Zhang ◽  
Jian S. Dai
Keyword(s):  
Screw Theory ◽  
Rotational Symmetry ◽  
Structural Evolution ◽  
Joint Space ◽  
Geometric Characteristics ◽  
Constraint Analysis ◽  
Motion Parameters ◽  
Motion Characteristics ◽  
The Relationship

This paper presents a novel metamorphic 8R linkage extracted from a kirigami-fold with pregrooved creases and two overconstrained 6R linkages evolved from the 8R linkage by taking the concept of metamorphosis in the sense of structural evolution. The geometric characteristics and the parametric constraints of the evolved 6R linkages are identified following the structural evolution of the 8R linkage. The paper reveals that the evolved 6R linkages are special line-symmetric Bricard 6R loops characterized by the rotational symmetry of order two. The joint space of the overconstrained 6R linkages is analyzed and the relationship between motion parameters of the evolved 6R linkages and reconfiguration parameters of the metamorphic 8R linkage are derived. The motion characteristics of the overconstrained 6R linkages are further verified in terms of screw theory. The bifurcation and trifurcation associated with various transitory positions of the evolved 6R linkages having distinct parametric constraints are consequently identified based on constraint analysis.

scholarly journals Motion Characteristics of Subclinical Tremors in Parkinson’s Disease and Healthy Subjects

2021 ◽  
Author(s):  
PING YI CHAN ◽  
ZAIDI MOHD RIPIN ◽  
Sanihah Abdul Halim ◽  
Wan Nor Arifin ◽  
Ahmad Shukri Yahya ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Inertial Sensors ◽  
Frequency Dispersion ◽  
Normal Subjects ◽  
Peak Frequency ◽  
Distal Segment ◽  
Full Spectrum ◽  
Flexion Extension ◽  
Motion Characteristics

Abstract The Parkinson’s disease tremor characteristics reported previously are not applicable to the full spectrum of severity. The characteristics of high- and low-amplitude tremors differ in signal regularity and frequency dispersion, which indicates that characterization should be studied in separate severity. The subclinical tremor of Parkinson’s disease is close to physiological tremor, yet their distinctive features are still undetermined. This study aims to determine joint motion characteristics that are unique to subclinical Parkinson’s disease tremors. The tremors were characterized by four hand–arm motions based on displacement and peak frequencies. The rest and postural tremors of 63 patients and 62 normal subjects were measured with inertial sensors. The baseline was established from normal tremors, and the joint motions were compared within and between the two subject groups. Displacement analysis shows that pronation–supination and wrist abduction–adduction are the most and least predominant tremor motions respectively, for both Parkinson’s disease and normal tremors. However, the subclinical Parkinson’s disease has significant greater in amplitude and peak frequency in specific predominant motions as compared to normal tremor. The flexion-extension of normal postural tremor increases in frequency from proximal to distal segment, which is explainable by mechanical oscillation. This characteristic is also observed in patients but with amplification in wrist and elbow joints. The contributed distinctive characteristics of subclinical tremors provide clues on the physiological manifestation that is a result of the neuromuscular mechanism of Parkinson’s disease.

scholarly journals Effect of semen extenders on sperm motion of in vitro stored muscovy drake spermatozoa

2011 ◽  
Vol 27 (3) ◽  
pp. 733-740
Author(s):  
V. Gerzilov ◽  
P. Rashev ◽  
A. Bochukov ◽  
P. Bonchev
Keyword(s):  
Motion Analysis ◽  
Computer Assisted ◽  
Sperm Velocity ◽  
In Vitro Storage ◽  
Motion Parameters ◽  
Motion Characteristics ◽  
Sperm Motion

A study for the influence of semen extenders IMV-buffer, HIA- 1 and AU on sperm motion characteristics of Muscovy drake spermatozoa was carried out. The semen from each male (n=6) was divided into three equal parts and diluted in ratio 1:3 (semen:extender) with the IMV-buffer, HIA-1 and AU respectively, and then was stored at temperature 0-4C? for 6 hours. Sperm motion parameters - velocity of spermatozoa (rapid, medium, slow and statistic), VCL, VSL, VAP, LIN, STR, WOB were measured using a Sperm Class Analizer (Micropticum, Spain). Computer-assisted sperm motion analysis indicated that Muscovy spermatozoa preserved a rapid and medium sperm velocity after 6 hours in vitro storage in three examination extenders. The total VCL, VSL and VAP of spermatozoa in the semen diluted with AU extender were 110.47?7.44 ?m/s, 29.42?2.02 ?m/s and 57.39?3.73 ?m/s, in the semen diluted with IMV-buffer were 94.93?11.10 ?m/s, 27.57?2.45 ?m/s and 51.35?4.98 ?m/s, and in the semen diluted with HIA-1 were 68.48?12.74 ?m/s, 20.08?4.18 ?m/s and 37.75?7.65 ?m/s, as the differences were significant between AU and HIA-1 - (P<0.05). About LIN, STR, WOB there were no significant differences for the influence of the extenders.

Spinning projectile’s attitude measurement using intersection ratio of magnetic sensors

2016 ◽  
Vol 231 (5) ◽  
pp. 866-876 ◽  
Author(s):  
Jing Yu ◽  
Xiongzhu Bu ◽  
Chao Xiang ◽  
Bo Yang
Keyword(s):  
Measurement Method ◽  
Inertial Sensors ◽  
Detection System ◽  
Low Cost ◽  
Magnetic Sensor ◽  
Magnetic Sensors ◽  
Attitude Measurement ◽  
Characteristic Ratio ◽  
Zero Crossing ◽  
Attitude Angle

Concerning on the problem of low measuring precision of the current micro-inertial sensors, a novel attitude measurement method is proposed to dismiss the drift for remarkable attitude error. According to the output of the onboard three-axis magnetic sensor in the process of projectile flight, a low-cost attitude detection system is designed by using the intersection ratio of the sensor. First, the output model of the onboard three-axis magnetic sensor is established. The mathematical relationship between the characteristic ratio of magnetic sensor output and the pitch angle is then derived. Then, the solution and correction algorithm of the attitude angles are studied. Finally, the effectiveness of the attitude measurement method has been validated by carrying out the semi-physical experiments. The experimental results indicate that the error of attitude angles is within ±1° and the attitude angle error of the combined magnetic sensors is not cumulative. Meanwhile, the geomagnetic field strength is dispensable during the whole calculation process. Compared with the “Zero Crossing Method”, the proposed method has shown a nearly two-times higher accuracy and has no limitation of “MAGSONDE window”. What is more, this method proves to be more simple and has a doubled update rate in attitude angle calculation.

Dynamic Simulation of a Passive Walking Robot with Friction and Impact

2013 ◽  
Vol 753-755 ◽  
pp. 2025-2028
Author(s):  
Yong Xu ◽  
Shan Ping Zhang ◽  
Xin Yao Song
Keyword(s):  
Time History ◽  
Passive Movement ◽  
Dynamic Parameters ◽  
Walking Robot ◽  
Cyclical Variation ◽  
History Of ◽  
Motion Parameters ◽  
Motion Characteristics ◽  
Stable Passive ◽  
Smooth Dynamics

This paper design an unpowered wadding duck robot based on the non-smooth dynamics as well as friction and impact effects. The duck robot can swing-roll-slip stably and periodically along the slope down without any external drives and controls. The motion characteristics of the robot are investigated and the motion parameters simulations of the passive movement gait are subsequently implemented. The time history of the dynamic parameters showed an obvious cyclical variation, which indicates the robot is able to achieve cyclical, stable passive movement.

scholarly journals Head motion in children with ADHD during resting-state brain imaging

2014 ◽  
Author(s):  
Xiang-zhen Kong
Keyword(s):  
Resting State ◽  
Cross Validation ◽  
Head Motion ◽  
Adhd Group ◽  
Typically Developing ◽  
Clinical Factors ◽  
Children With Adhd ◽  
Technical Artifacts ◽  
Motion Parameters ◽  
Scanning Motion

Although head motion during scanning has been largely considered to reflect simply technical artifacts, there is growing evidence showing that the variable of head motion reflects valuable information regarding individual’s psychological and/or clinical factors. Detailed studies would not only help to deal with the head motion biases, but they also help researchers in understanding the mental disorders. In this study, children with ADHD and demographically-matched typically developing control (TDC) participants underwent rs-fMRI examination without any specific task, and six mean single head motion parameters (three translational and three rotational) and a summary motion index for each participant were obtained. We found that patients with ADHD showed specific patterns of head motion during scanning: motion was significantly increased in the ADHD group, which was mainly contributed by the motion around and along the superior-to-inferior direction. Furthermore, the cross-validation classification analyses showed that the head motion could accurately distinguish children with ADHD from the healthy controls. These results suggest that head motion during scanning reflects useful information about the participants and accounting for head motion from MRI data may be helpful for ADHD diagnosing and treatment with neuroimaging.

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