scholarly journals FBG-Based Estimation of External Forces Along Flexible Instrument Bodies

2021 ◽  
Vol 8 ◽  
Author(s):  
Omar Al-Ahmad ◽  
Mouloud Ourak ◽  
Johan Vlekken ◽  
Emmanuel Vander Poorten
Keyword(s):  
Estimation Error ◽  
Diagnostic Procedures ◽  
Point Load ◽  
Applied Force ◽  
Force Estimation ◽  
Rod Theory ◽  
External Point ◽  
External Forces ◽  
Distributed Forces ◽  
Flexible Instruments

A variety of medical treatment and diagnostic procedures rely on flexible instruments such as catheters and endoscopes to navigate through tortuous and soft anatomies like the vasculature. Knowledge of the interaction forces between these flexible instruments and patient anatomy is extremely valuable. This can aid interventionalists in having improved awareness and decision-making abilities, efficient navigation, and increased procedural safety. In many applications, force interactions are inherently distributed. While knowledge of their locations and magnitudes is highly important, retrieving this information from instruments with conventional dimensions is far from trivial. Robust and reliable methods have not yet been found for this purpose. In this work, we present two new approaches to estimate the location, magnitude, and number of external point and distributed forces applied to flexible and elastic instrument bodies. Both methods employ the knowledge of the instrument’s curvature profile. The former is based on piecewise polynomial-based curvature segmentation, whereas the latter on model-based parameter estimation. The proposed methods make use of Cosserat rod theory to model the instrument and provide force estimates at rates over 30 Hz. Experiments on a Nitinol rod embedded with a multi-core fiber, inscribed with fiber Bragg gratings, illustrate the feasibility of the proposed methods with mean force error reaching 7.3% of the maximum applied force, for the point load case. Furthermore, simulations of a rod subjected to two distributed loads with varying magnitudes and locations show a mean force estimation error of 1.6% of the maximum applied force.

scholarly journals The Effects of Moving Load on the Hydroelastic Response of a Very Large Floating Structure

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Le Zhu ◽  
Fei Shao ◽  
Qian Xu ◽  
Yonggang Sun ◽  
Qingna Ma
Keyword(s):  
Moving Load ◽  
Fluid Motion ◽  
Elastic Beam ◽  
Point Load ◽  
Floating Structure ◽  
Very Large Floating Structure ◽  
External Point ◽  
The Fourier Transform ◽  
The Time Domain ◽  
Hydroelastic Response

The hydroelastic response of a very large floating structure in regular waves suffering an external moving point load is considered. The linearized velocity potential theory is adopted to describe the fluid flow. To take into account the coupled effects of the structure deformation and fluid motion, the structure is divided into multiple segments and connected by an elastic beam. Then through adding a stiffness matrix arising from the elastic beam into the multiple bodies coupled motion equations, the hydroelastic response is considered. By applying the Fourier transform to the obtained frequency domain coefficients, the motion equation is transformed into the time domain and the external point load is further considered. The accuracy and effectiveness of the proposed method are verified through the comparison with experimental results. Finally, extensive results are provided, and the effects of the moving point load on the hydroelastic response of the very large floating structure are investigated in detail.

scholarly journals Ground Reaction Force Estimation in Prosthetic Legs With Nonlinear Kalman Filtering Methods

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Seyed Fakoorian ◽  
Vahid Azimi ◽  
Mahmoud Moosavi ◽  
Hanz Richter ◽  
Dan Simon
Keyword(s):  
Kalman Filter ◽  
Continuous Time ◽  
Lyapunov Functions ◽  
Unscented Kalman Filter ◽  
Estimation Error ◽  
Reaction Force ◽  
Force Estimation ◽  
Joint Angles ◽  
Estimation Errors ◽  
Reaction Forces

A method to estimate ground reaction forces (GRFs) in a robot/prosthesis system is presented. The system includes a robot that emulates human hip and thigh motion, along with a powered (active) transfemoral prosthetic leg. We design a continuous-time extended Kalman filter (EKF) and a continuous-time unscented Kalman filter (UKF) to estimate not only the states of the robot/prosthesis system but also the GRFs that act on the foot. It is proven using stochastic Lyapunov functions that the estimation error of the EKF is exponentially bounded if the initial estimation errors and the disturbances are sufficiently small. The performance of the estimators in normal walk, fast walk, and slow walk is studied, when we use four sensors (hip displacement, thigh, knee, and ankle angles), three sensors (thigh, knee, and ankle angles), and two sensors (knee and ankle angles). Simulation results show that when using four sensors, the average root-mean-square (RMS) estimation error of the EKF is 0.0020 rad for the joint angles and 11.85 N for the GRFs. The respective numbers for the UKF are 0.0016 rad and 7.98 N, which are 20% and 33% lower than those of the EKF.

scholarly journals The Role of Buckling in the Estimation of Compressive Strength of Corrugated Cardboard Boxes

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4578 ◽  
Author(s):  
Tomasz Garbowski ◽  
Tomasz Gajewski ◽  
Jakub Krzysztof Grabski
Keyword(s):  
Compressive Strength ◽  
Analytical Approach ◽  
Estimation Error ◽  
Full Range ◽  
Shear Stiffness ◽  
Width Ratio ◽  
Force Estimation ◽  
Corrugated Cardboard ◽  
Precise Prediction

This paper presents analytical methods for estimating the static top-to-bottom compressive strength of simple corrugated packaging, in which the torsional and shear stiffness of corrugated cardboard as well as the panel depth-to-width ratio are included. The methods are compared herein with a basic and more detailed buckling description with the successful McKee formula, which is over fifty years old but still widely used among packaging designers and quality control departments. Additionally, the assumptions and applied simplifications used in the literature are analyzed, and the limits of applicability of different versions of the selected methods are checked. Finally, all approaches are verified with the experiment results of various packaging designs made of corrugated cardboard. The results show that, for certain proportions of dimensions of simple flap boxes, simplified methods give an even two times larger estimation error than the analytical approach proposed in the paper. Furthermore, it is evidenced that including all flexural, torsional and shear stiffnesses in the buckling force estimation gives a very precise prediction of the box compressive strength for the full range of package dimensions.

Development of a Pneumatic Surgical Manipulator IBIS IV

2010 ◽  
Vol 22 (2) ◽  
pp. 179-188 ◽  
Author(s):  
Kotaro Tadano ◽  
◽  
Kenji Kawashima ◽  
Kazuyuki Kojima ◽  
Naofumi Tanaka ◽  
...  
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Force Measurement ◽  
Use Of Force ◽  
Robotic Manipulators ◽  
Force Estimation ◽  
Improved Model ◽  
External Forces ◽  
Surgical Manipulator

In teleoperated, minimally invasive surgery systems, the measurement and conveyance of a sense of force to the operator is problematic. In order to carry out safer and more precise operations using robotic manipulators, force measurement and operator feedback are very important factors. We previously proposed a pneumatic surgical manipulator that is capable of estimating external force without the use of force sensors. However, the force estimation had a sensitivity of only 3 N because of inertia and friction effects. In this paper, we develop a new and improved model of the pneumatic surgical manipulator, IBIS IV. We evaluate its performance in terms of force estimation. The experimental results indicate that IBIS IV estimates external forces with a sensitivity of 1.0 N. We also conduct an in-vivo experiment and confirm the effectiveness and improvement of the manipulator.

Load Reduction Control on Tool-Insertion Port for Laparoscopic Surgical Robot Using Semi-Active Joints

2020 ◽  
Vol 32 (5) ◽  
pp. 1000-1009
Author(s):  
Koki Aizawa ◽  
Daisuke Haraguchi ◽  
Kotaro Tadano ◽  
◽  
◽  
...  
Keyword(s):  
Robotic Surgery ◽  
External Force ◽  
Control Method ◽  
Torque Control ◽  
Robotic Arm ◽  
Force Estimation ◽  
External Forces ◽  
Six Degree Of Freedom ◽  
Surgical Manipulations ◽  
Active Joints

In robotic surgery, the load exerted on the insertion port in the patient’s abdominal wall due to misalignment of the robot’s remote center of motion and the insertion port or external forces acting on the tip of the forceps during surgery, can not only stress the patient’s body but also increase the friction between the robotic forceps and the trocar, and adversely affect fine surgical manipulations or the accuracy of force estimation. To reduce such loads on the insertion port in robotic surgery, this study proposes a control method for a surgical assist robotic arm with semi-active joints. The control method was implemented on a six-degree-of-freedom pneumatically driven vertical multi-joint robotic arm with a two-axis gimbal joint (two semi-active joints) that only executes torque control, which was previously developed by the authors, and verified through an experiment. The load on the insertion port is reduced by applying torque control on the semi-active joints to compensate for the external forces on the forceps. We constructed a control system that includes a disturbance compensator and conducted a velocity-control experiment by subjecting the forceps constrained by the insertion port to an external force. The results showed that when the torque was compensated for by the semi-active joints, the load on the insertion port was reduced by 65% and 52% when the external force on the tip of the forceps was 0 N and 3 N, respectively.

Amphibious Urbanization as a Sustainable Flood Mitigation Strategy in South-East Asia

2012 ◽  
Vol 622-623 ◽  
pp. 1696-1700 ◽  
Author(s):  
Mohamad Ibrahim Mohamad ◽  
Mohammad Ali Nekooie ◽  
Zulhilmi Bin Ismail ◽  
Roohollah Taherkhani
Keyword(s):  
East Asia ◽  
Point Load ◽  
Mitigation Strategy ◽  
Load Test ◽  
Flood Mitigation ◽  
South East Asia ◽  
Force Estimation ◽  
Environmental Aspects ◽  
Floodplain Area ◽  
New Strategies

Appling amphibious urbanization is a new smart and sustainable flood mitigation strategy for floodplain area in South-East Asia. The objective of this study is to evaluate the technological and environmental aspects of the amphibious house as a sustainable flood mitigation strategy in South-East Asia. The technological and environmental aspects are investigated under sustainability. The point load test and drag force estimation and interviews are conducted. Amphibious urbanization is completely aligned with the technological aspects of a safe living conditions during flood rush. This system identified as one of the green and most sustainable new strategies in South-East Asia.

VIV Force Identification Using Classical Optimal Control Algorithm

2009 ◽  
Author(s):  
Jie Wu ◽  
Philippe Mainc¸on ◽  
Carl M. Larsen ◽  
Halvor Lie
Keyword(s):  
Dynamic Equilibrium ◽  
Mass Matrix ◽  
Measurement Data ◽  
Cross Flow ◽  
Force Estimation ◽  
Euler Beam ◽  
Force Coefficient ◽  
Contour Plots ◽  
Flow Vortex ◽  
External Forces

Due to the difficulty of direct force measurements in vortex induced vibration (VIV) experiments with long elastic cylinders, accelerometer and bending strain measurement are available. Still, obtaining information on the force is of great interest to researchers. The work presented in this paper follows the same principle as Mainc¸on (2004), who estimated external forces acting on a riser subjected to VIV from measured response by using a classical optimal tracking algorithm. The objective of this study is to first present a method for extracting VIV forces from measured data with long elastic riser models subjected to current. The second objective is to extract first order (primary) cross-flow force coefficients by a combined use of modal filtering. The algorithm minimizes the sum of the squares of the discrepancies between measured and predicted response plus a constant times the sum of squares of the external forces, while satisfying the system’s dynamic equilibrium equation. FEM discretization of the riser with Euler beam elements leads to a stiffness and mass matrix. The dimension of these matrixes is reduced by eliminating the rotation degree of freedom using master-slave condensation, which greatly facilitates the matrix iteration. Displacement is used in this study as input to the algorithm to identify forces. The method is verified against synthetic measurement data. The results showed the algorithm’s capability to accurately estimate the input forces from noisy measurement data. The method is applied to the data from a rotating rig test to identify hydrodynamic forces in primary cross-flow vortex shedding frequency range. The emphasis is on extracting force coefficient database. One important finding is that the high mode component of the force contributed little to the response, while it resulted in complication of the coefficient data base. Therefore, they are neglected by filtering the measurement with modal analysis before the use of inverse force estimation. The excitation and added mass coefficients are calculated and their contour plots are generated. Comparisons with existing data are investigated.

State Estimation of an Advanced Rowing Machine Using Optimized Kalman Filtering

2017 ◽  
Author(s):  
Hanieh Mohammadi ◽  
Gholamreza Khademi ◽  
Dan Simon ◽  
Hanz Richter
Keyword(s):  
Standard Deviation ◽  
State Estimation ◽  
Estimation Error ◽  
Simultaneous Estimation ◽  
Force Estimation ◽  
Estimation Errors ◽  
Input Force ◽  
Load Cells ◽  
Friction Models ◽  
Active Impedance

This research addresses the problem of state estimation of an advanced rowing machine with energy regeneration. It is assumed that the states of the system, which are position, velocity, and capacitor charge, are measurable. The user force input to the system can be measured by load cells. It is shown that the need for load cells can be eliminated by estimating the force with an unknown-input Kalman filter. The estimated states and the unknown user force input are passed to the controller of the system, which is either an inversion-based controller or a semi-active impedance controller. Two friction models are considered for this system: Coulomb friction, and LuGre friction. The Kalman gains are tuned using an evolutionary algorithm to minimize the standard deviation of the estimation error. The results verify the effectiveness of the proposed approach for simultaneous estimation of the states and the input force. The standard deviation of the state estimation errors are only 10% of their measurement noise. The standard deviation of the input force estimation error is 0.1 N when using an optimized Kalman gain, which is only 25% of the value obtained when using manually tuned gains.

Transparency Improvement by External Force Estimation in a Time-Delayed Nonlinear Bilateral Teleoperation System

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
H. Amini ◽  
S. M. Rezaei ◽  
Ahmed A. D. Sarhan ◽  
J. Akbari ◽  
N. A. Mardi
Keyword(s):  
Control Algorithm ◽  
Force Measurement ◽  
Bilateral Teleoperation ◽  
Force Estimation ◽  
Teleoperation System ◽  
Control Scheme ◽  
Environmental Force ◽  
The Stability ◽  
External Forces ◽  
Teleoperation Systems

Teleoperation systems have been developed in order to manipulate objects in environments where the presence of humans is impossible, dangerous or less effective. One of the most attractive applications is micro telemanipulation with micropositioning actuators. Due to the sensitivity of this operation, task performance should be accurately considered. The presence of force signals in the control scheme could effectively improve transparency. However, the main restriction is force measurement in micromanipulation scales. A new modified strategy for estimating the external forces acting on the master and slave robots is the major contribution of this paper. The main advantage of this strategy is that the necessity for force sensors is eliminated, leading to lower cost and further applicability. A novel control algorithm with estimated force signals is proposed for a general nonlinear macro–micro bilateral teleoperation system with time delay. The stability condition in the macro–micro teleoperation system with the new control algorithm is verified by means of Lyapunov stability analysis. The designed control algorithm guarantees stability of the macro–micro teleoperation system in the presence of an estimated operator and environmental force. Experimental results confirm the efficiency of the novel control algorithm in position tracking and force reflection.

Pressure Pipe Damage: Numerical Estimation of Point Load Effect II

2013 ◽  
Vol 577-578 ◽  
pp. 533-536 ◽  
Author(s):  
Zdeněk Majer ◽  
Michal Zouhar ◽  
Martin Ševčík ◽  
Luboš Náhlík ◽  
Pavel Hutař
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Hoop Stress ◽  
Simple Relation ◽  
Point Load ◽  
Numerical Estimation ◽  
Load Effect ◽  
Pressure Pipe ◽  
External Point

It has been shown that the service lifetime of buried pipes can be reduced especially in relation to stress concentration caused by external point loads. If the pipe is loaded locally the stress is concentrated there and a crack can initiate at this position or the existing crack can be affected by corresponding stress redistribution. In the paper, the effect of a hard indenter, material properties, and the hoop stress level on the stress intensity factor of the axial inner crack are evaluated. A simple relation for estimation of the stress intensity factor value without FEM simulations is proposed.

Sign in / Sign up

Export Citation Format

Share Document