scholarly journals Self-Localization of Tethered Drones without a Cable Force Sensor in GPS-Denied Environments

Drones ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 135
Author(s):  
Amer Al-Radaideh ◽  
Liang Sun
Keyword(s):  
Original Problem ◽  
Pulse Width Modulation ◽  
Thrust Force ◽  
Three Dimensional ◽  
Force Sensor ◽  
Tension Force ◽  
Cable Tension ◽  
Inertial Measurement ◽  
Cable Force ◽  
Measurement Units

This paper considers the self-localization of a tethered drone without using a cable-tension force sensor in GPS-denied environments. The original problem is converted to a state-estimation problem, where the cable-tension force and the three-dimensional position of the drone with respect to a ground platform are estimated using an extended Kalman filter (EKF). The proposed approach uses the data reported by the onboard electric motors (i.e., the pulse width modulation (PWM) signals), accelerometers, gyroscopes, and altimeter, embedded in the commercial-of-the-shelf (COTS) inertial measurement units (IMU). A system-identification experiment was conducted to determine the model that computes the drone thrust force using the PWM signals. The proposed approach was compared with an existing work that assumes known cable-tension force. Simulation results show that the proposed approach produces estimates with less than 0.3-m errors when the actual cable-tension force is greater than 1 N.

Benchmarking the Accuracy of Inertial Measurement Units for Estimating Joint Reactions

2013 ◽  
Author(s):  
Ryan S. McGinnis ◽  
Jessandra Hough ◽  
N. C. Perkins
Keyword(s):  
Three Dimensional ◽  
Correlation Coefficients ◽  
Human Motion ◽  
Load Cell ◽  
Great Promise ◽  
Human Motion Analysis ◽  
Double Pendulum ◽  
Inertial Measurement Units ◽  
Inertial Measurement ◽  
Measurement Units

Newly developed miniature wireless inertial measurement units (IMUs) hold great promise for measuring and analyzing multibody system dynamics. This relatively inexpensive technology enables non-invasive motion tracking in broad applications, including human motion analysis. The second part of this two-part paper advances the use of an array of IMUs to estimate the joint reactions (forces and moments) in multibody systems via inverse dynamic modeling. In particular, this paper reports a benchmark experiment on a double-pendulum that reveals the accuracy of IMU-informed estimates of joint reactions. The estimated reactions are compared to those measured by high precision miniature (6 dof) load cells. Results from ten trials demonstrate that IMU-informed estimates of the three dimensional reaction forces remain within 5.0% RMS of the load cell measurements and with correlation coefficients greater than 0.95 on average. Similarly, the IMU-informed estimates of the three dimensional reaction moments remain within 5.9% RMS of the load cell measurements and with correlation coefficients greater than 0.88 on average. The sensitivity of these estimates to mass center location is discussed. Looking ahead, this benchmarking study supports the promising and broad use of this technology for estimating joint reactions in human motion applications.

Drilling CFRP Laminates by Dual-Axis Grinding Wheel System With Copper/Diamond Functionally Graded Grinding Wheel

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Takahiro Kunimine ◽  
Hideaki Tsuge ◽  
Daisuke Ogawa ◽  
Motoko Yamada ◽  
Hisashi Sato ◽  
...  
Keyword(s):  
Thrust Force ◽  
Three Dimensional ◽  
Chip Morphology ◽  
Force Sensor ◽  
Functionally Graded ◽  
Grinding Wheel ◽  
Drilling Process ◽  
Low Thrust ◽  
Hole Quality ◽  
Cfrp Laminates

This study aims to investigate the drilling performance of a copper/diamond functionally graded grinding wheel (FGGW) fabricated by centrifugal sintered-casting for carbon fiber-reinforced plastic (CFRP) laminates by originally designed dual-axis grinding wheel (DAGW) system. The copper/diamond FGGW was also originally designed and fabricated by the centrifugal sintered-casting to suppress abrasive-grain wear and reduce the consumption of abrasive grains in our previous study. Drilling tests were carried out over 50 holes in dry machining. Thrust force was evaluated with force sensor during drilling test. Hole diameter, roundness, and roughness were measured to assess hole quality. Drill chips were observed by scanning electron microscope (SEM) to investigate chip morphology. Precision drilling without burring and delamination was achieved in CFRP laminates. Good hole-quality was still obtained over 50 holes due to the low thrust force during drilling. Specific three-dimensional (3D) drilling process of the DAGW system enabled stable and precision drilling with low thrust force in CFRP laminates continuously.

Study on Cable Forces in Cable-Stayed Bridges Based on Forward Simulation Method

2014 ◽  
Vol 1020 ◽  
pp. 130-136
Author(s):  
Chuan Tian ◽  
Jun Dong ◽  
Tian Liang
Keyword(s):  
Finite Element ◽  
Calculation Method ◽  
Element Model ◽  
Simulation Method ◽  
Tension Force ◽  
Frequency Method ◽  
Cable Tension ◽  
Finite Element Software ◽  
Cable Force ◽  
Forward Calculation

According to cable tension calculation of cable-stayed bridge on construction, and combining with the example of Xinzao Pearl River Grand Bridge, this work proposes forward-calculation method to analyze cable tension force on construction and establishes geometric calculation simulation model to compare measured cable tension with theoretical cable tension. This paper introduces some kinds of methods calculating cable tension force on construction. It importantly discusses the principle and method of forward-calculation and the practical application in the actual project. Spacial finite element model is established for analysis based on finite element software MIDAS and the application of forward-analysis iterative method is considered to analyze the cable tension on construction , then the method of determining cable force on construction is explored. Finally the result shows that the cable tension based on forward-calculation method is usually accurate, the measured value is approximately equal to the theoretical value and the error is in the extent permitted. The correctness and reliability of the frequency method is effectively confirmed and the cable tension calculation of the similar bridge on construction is compatibly applied.

Quantifying jump-specific loads in beach volleyball by an inertial measurement device

2020 ◽  
pp. 174795412097310
Author(s):  
Marcus Schmidt ◽  
Eike Meyer ◽  
Thomas Jaitner
Keyword(s):  
Performance Indicator ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Limited Resources ◽  
Height Measurement ◽  
Measurement Device ◽  
Match Play ◽  
Inertial Measurement ◽  
Play Analysis ◽  
Measurement Units

The ability to complete a large volume of high intensity jumps represents an important performance indicator in beach volleyball. Inertial measurement units are suitable tools to monitor those jump-specific loads but the applicability in beach volleyball lacks research. This study evaluates the accuracy of a commercially available inertial measurement device in beach volleyball for (i) jump count during match-play and (ii) jump height measurement under laboratory conditions. Jump count measures were compared to retrospective video analysis to determine precision and recall. Jump heights were referenced to three-dimensional motion analysis to determine typical errors of estimate, correlations and Bland-Altman statistics. Match-play analysis results in excellent precision (0.975) for a total of 439 jumps and recall values between 0.836–1.000 depending on jump type. Jump heights revealed good to excellent correlations for block (r = 0.81) and spike jumps (r = 0.90), with a mean bias of 2.61 and 7.69 cm, respectively. The device demonstrates good validity for measuring jump count as well as vertical displacement. Due to its potential for nearly real time feedback with constraints of limited resources, we assume that this device will have considerable benefits for quantifying jump-specific load in beach volleyball.

scholarly journals Fusing Accelerometry with Videography to Monitor the Effect of Fatigue on Punching Performance in Elite Boxers

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5749
Author(s):  
Nicos Haralabidis ◽  
David John Saxby ◽  
Claudio Pizzolato ◽  
Laurie Needham ◽  
Dario Cazzola ◽  
...  
Keyword(s):  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Statistical Parametric Mapping ◽  
Shoulder Abduction ◽  
Inertial Measurement Units ◽  
Inertial Measurement ◽  
Fatigue Protocol ◽  
Custom Made ◽  
Measurement Units

Wearable sensors and motion capture technology are accepted instruments to measure spatiotemporal variables during punching performance and to study the externally observable effects of fatigue. This study aimed to develop a computational framework enabling three-dimensional inverse dynamics analysis through the tracking of punching kinematics obtained from inertial measurement units and uniplanar videography. The framework was applied to six elite male boxers performing a boxing-specific punch fatigue protocol. OpenPose was used to label left side upper-limb landmarks from which sagittal plane kinematics were computed. Custom-made inertial measurement units were embedded into the boxing gloves, and three-dimensional punch accelerations were analyzed using statistical parametric mapping to evaluate the effects of both fatigue and laterality. Tracking simulations of a sub-set of left-handed punches were formulated as optimal control problems and converted to nonlinear programming problems for solution with a trapezoid collocation method. The laterality analysis revealed the dominant side fatigued more than the non-dominant, while tracking simulations revealed shoulder abduction and elevation moments increased across the fatigue protocol. In future, such advanced simulation and analysis could be performed in ecologically valid contexts, whereby multiple inertial measurement units and video cameras might be used to model a more complete set of dynamics.

scholarly journals Embedded inertial sensor for tracking projectile impact on granular media

2021 ◽  
Vol 249 ◽  
pp. 15007
Author(s):  
Stefan Köstler ◽  
Jinchen Zhao ◽  
Chen Lyu ◽  
Simeon Völkel ◽  
Kai Huang
Keyword(s):  
Particle Tracking ◽  
Granular Medium ◽  
Granular Media ◽  
Inertial Sensor ◽  
Three Dimensional ◽  
Velocity Data ◽  
Inertial Measurement ◽  
Granular Dynamics ◽  
Axial Acceleration ◽  
Measurement Units

Due to the opacity of most granular materials, it is often desirable to have three dimensional (3D) particle tracking techniques beyond optical imaging to explore granular dynamics. Using inertial measurement units (IMU) embedded in a projectile, we obtain the trajectory of projectile impacting on a granular medium under microgravity using tri-axial acceleration and angular velocity data. In addition to the standard algorithm for reconstruction, we emphasize solutions to various sources of error to determine projectile trajectory accurately.

scholarly journals Effect of IMU Design on IMU-Derived Stride Metrics for Running

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2601 ◽  
Author(s):  
Michael V Potter ◽  
Lauro V Ojeda ◽  
Noel C Perkins ◽  
Stephen M Cain
Keyword(s):  
Angular Velocity ◽  
Stride Length ◽  
Three Dimensional ◽  
Sampling Frequency ◽  
Inertial Measurement Units ◽  
Running Speed ◽  
Inertial Measurement ◽  
Gait Parameters ◽  
Measurement Units ◽  
Human Running

Researchers employ foot-mounted inertial measurement units (IMUs) to estimate the three-dimensional trajectory of the feet as well as a rich array of gait parameters. However, the accuracy of those estimates depends critically on the limitations of the accelerometers and angular velocity gyros embedded in the IMU design. In this study, we reveal the effects of accelerometer range, gyro range, and sampling frequency on gait parameters (e.g., distance traveled, stride length, and stride angle) estimated using the zero-velocity update (ZUPT) method. The novelty and contribution of this work are that it: (1) quantifies these effects at mean speeds commensurate with competitive distance running (up to 6.4 m/s); (2) identifies the root causes of inaccurate foot trajectory estimates obtained from the ZUPT method; and (3) offers important engineering recommendations for selecting accurate IMUs for studying human running. The results demonstrate that the accuracy of the estimated gait parameters generally degrades with increased mean running speed and with decreased accelerometer range, gyro range, and sampling frequency. In particular, the saturation of the accelerometer and/or gyro induced during running for some IMU designs may render those designs highly inaccurate for estimating gait parameters.

Sign in / Sign up

Export Citation Format

Share Document