scholarly journals Terrain Feature Estimation Method for a Lower Limb Exoskeleton Using Kinematic Analysis and Center of Pressure

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4418 ◽  
Author(s):  
Myounghoon Shim ◽  
Jong In Han ◽  
Ho Seon Choi ◽  
Seong Min Ha ◽  
Jung-Hoon Kim ◽  
...  
Keyword(s):  
Lower Limb ◽  
Kinematic Analysis ◽  
Center Of Pressure ◽  
Contact Point ◽  
Estimation Method ◽  
Least Square Method ◽  
Least Square ◽  
Estimation Accuracy ◽  
Lower Limb Exoskeleton ◽  
Contact Points

While controlling a lower limb exoskeleton providing walking assistance to wearers, the walking terrain is an important factor that should be considered for meeting performance and safety requirements. Therefore, we developed a method to estimate the slope and elevation using the contact points between the limb exoskeleton and ground. We used the center of pressure as a contact point on the ground and calculated the location of the contact points on the walking terrain based on kinematic analysis of the exoskeleton. Then, a set of contact points collected from each step during walking was modeled as the plane that represents the surface of the walking terrain through the least-square method. Finally, by comparing the normal vectors of the modeled planes for each step, features of the walking terrain were estimated. We analyzed the estimation accuracy of the proposed method through experiments on level ground, stairs, and a ramp. Classification using the estimated features showed recognition accuracy higher than 95% for all experimental motions. The proposed method approximately analyzed the movement of the exoskeleton on various terrains even though no prior information on the walking terrain was provided. The method can enable exoskeleton systems to actively assist walking in various environments.

scholarly journals The Parameter Estimation of Double Exponential Pulse Based on a Least Infinity Norm Fitting Method

2021 ◽  
Vol 2083 (4) ◽  
pp. 042002
Author(s):  
Yuewu Shi ◽  
Wei Wang ◽  
Zhizhen Zhu ◽  
Xin Nie
Keyword(s):  
Estimation Error ◽  
Estimation Method ◽  
Maximum Amplitude ◽  
Least Square Method ◽  
Least Square ◽  
Physical Parameters ◽  
Infinity Norm ◽  
Fitting Method ◽  
Double Exponential ◽  
Exponential Pulse

Abstract This paper presents an estimation method of double exponential pulse (DEP) between the physical parameters rise time (t r), full width at half maximum amplitude (t FWHM) and the mathematical parameters α, β. A newly fitting method based on the least infinity norm criterion is proposed to deal with the estimation problem of DEP. The calculation process and equation of parameters of this method is proposed based on an m-th-order polynomial fitting model. This estimation method is compared with the least square method by the same data and fitting function. The results show that the maximum estimation error of parameters of double exponential pulse obtained by the least infinity norm method is 1.5 %.

Investigation of Human Locomotion With a Powered Lower Limb Exoskeleton

2021 ◽  
pp. 233-254
Author(s):  
Sergey Fedorovich Jatsun ◽  
Andrey Yatsun ◽  
Sergei Savin
Keyword(s):  
Lower Limb ◽  
Pressure Sensors ◽  
Human Locomotion ◽  
Sensor System ◽  
Assistive Device ◽  
Supporting Surface ◽  
Lower Limb Exoskeleton ◽  
Contact Points ◽  
Human Ability

In this chapter, the lower limb exoskeleton is studied. The roles of the exoskeleton both as a measurement device for studying human locomotion and as an assistive device that restores the human ability to walk are discussed. Particular attention is given to the investigation of the role of the pressure sensors and other devices that allow us to measure normal reactions at the contact points with the supporting surface and also detect these contacts. The way the geometry of the supporting surface affects the sensors system of the robot is considered, and new designs for feet sensor system are proposed. These include elastic foot, a foot with actuated sensors, and a foot with spring-damper systems.

scholarly journals Lower Limb Exoskeleton Gait Planning Based on Crutch and Human-Machine Foot Combined Center of Pressure

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7216
Author(s):  
Wei Yang ◽  
Jiyu Zhang ◽  
Sheng Zhang ◽  
Canjun Yang
Keyword(s):  
Lower Limb ◽  
Stride Length ◽  
Center Of Pressure ◽  
Balance Control ◽  
Effective Means ◽  
Stability Control ◽  
Planning Method ◽  
Gait Planning ◽  
Lower Limb Exoskeleton ◽  
Cord Injury

With the help of wearable robotics, the lower limb exoskeleton becomes a promising solution for spinal cord injury (SCI) patients to recover lower body locomotion ability. However, fewer exoskeleton gait planning methods can meet the needs of patient in real time, e.g., stride length or step width, etc., which may lead to human-machine incoordination, limit comfort, and increase the risk of falling. This work presents a human-exoskeleton-crutch system with the center of pressure (CoP)-based gait planning method to enable the balance control during the exoskeleton-assisted walking with crutches. The CoP generated by crutches and human-machine feet makes it possible to obtain the overall stability conditions of the system in the process of exoskeleton-assisted quasi-static walking, and therefore, to determine the next stride length and ensure the balance of the next step. Thus, the exoskeleton gait is planned with the guidance of stride length. It is worth emphasizing that the nominal reference gait is adopted as a reference to ensure that the trajectory of the swing ankle mimics the reference one well. This gait planning method enables the patient to adaptively interact with the exoskeleton gait. The online gait planning walking tests with five healthy volunteers proved the method’s feasibility. Experimental results indicate that the algorithm can deal with the sensed signals and plan the landing point of the swing leg to ensure balanced and smooth walking. The results suggest that the method is an effective means to improve human–machine interaction. Additionally, it is meaningful for the further training of independent walking stability control in exoskeletons for SCI patients with less assistance of crutches.

scholarly journals A New Distribution for Modeling Lifetime Data with Different Methods of Estimation and Censored Regression Modeling

2020 ◽  
Vol 8 (2) ◽  
pp. 610-630 ◽  
Author(s):  
Mohamed Ibrahim ◽  
Emrah Altun EA ◽  
Haitham M. Yousof
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Method ◽  
Estimation Method ◽  
Least Square Method ◽  
Least Square ◽  
Likelihood Method ◽  
Survival Times ◽  
New Model ◽  
Von Mises ◽  
Bootstrapping Method

In this paper and after introducing a new model along with its properties, we estimate the unknown parameter of the new model using the Maximum likelihood method, Cram er-Von-Mises method, bootstrapping method, least square method and weighted least square method. We assess the performance of all estimation method employing simulations. All methods perform well but bootstrapping method is the best in modeling relief times whereas the maximum likelihood method is the best in modeling survival times. Censored data modeling with covariates is addressed along with the index plot of the modified deviance residuals and its Q-Q plot.

Investigation of Human Locomotion With a Powered Lower Limb Exoskeleton

2018 ◽  
pp. 26-47 ◽  
Author(s):  
Sergey Fedorovich Jatsun ◽  
Andrey Yatsun ◽  
Sergei Savin
Keyword(s):  
Lower Limb ◽  
Pressure Sensors ◽  
Human Locomotion ◽  
Sensor System ◽  
Assistive Device ◽  
Supporting Surface ◽  
Lower Limb Exoskeleton ◽  
Contact Points ◽  
Human Ability

In this chapter, the lower limb exoskeleton is studied. The roles of the exoskeleton both as a measurement device for studying human locomotion and as an assistive device that restores the human ability to walk are discussed. Particular attention is given to the investigation of the role of the pressure sensors and other devices that allow us to measure normal reactions at the contact points with the supporting surface and also detect these contacts. The way the geometry of the supporting surface affects the sensors system of the robot is considered, and new designs for feet sensor system are proposed. These include elastic foot, a foot with actuated sensors, and a foot with spring-damper systems.

scholarly journals Comparison of M Estimation, S Estimation, with MM Estimation to Get the Best Estimation of Robust Regression in Criminal Cases in Indonesia

2022 ◽  
Vol 18 (2) ◽  
pp. 251-260
Author(s):  
Malecita Nur Atala Singgih ◽  
Achmad Fauzan
Keyword(s):  
Regression Analysis ◽  
Robust Regression ◽  
Estimation Method ◽  
Least Square Method ◽  
Influential Factors ◽  
Least Square ◽  
Method Of Moment ◽  
Best Estimate ◽  
M Estimation ◽  
Mm Estimation

Crime incidents that occurred in Indonesia in 2019 based on Survey Based Data on criminal data sourced from the National Socio-Economic Survey and Village Potential Data Collection produced by the Central Statistics Agency recorded 269,324 cases. The high crime rate is caused by several factors, including poverty and population density. Determination of the most influential factors in criminal acts in Indonesia can be done with Regression Analysis. One method of Regression Analysis that is very commonly used is the Least Square Method. However, Regression Analysis can be used if the assumption test is met. If outliers are found, then the assumption test is not completed. The outlier problem can be overcome by using a robust estimation method. This study aims to determine the best estimation method between Maximum Likelihood Type (M) estimation, Scale (S) estimation, and Method of Moment (MM) estimation on Robust Regression. The best estimate of Robust Regression is the smallest Residual Standard Error (RSE) value and the largest Adjusted R-square. The analysis of case studies of criminal acts in Indonesia in 2019 showed that the best estimate was the S estimate with an RSE value of 4226 and an Adjusted R-square of 0.98  

scholarly journals Vision-based kinematic analysis of the Delta robot for object catching

Robotica ◽  
2021 ◽  
pp. 1-21
Author(s):  
Sachin Kansal ◽  
Sudipto Mukherjee
Keyword(s):  
Kinematic Analysis ◽  
Inverse Kinematics ◽  
Least Square Method ◽  
Least Square ◽  
Kinematic Parameters ◽  
Implicit Model ◽  
Implicit Equations ◽  
Sensor Module ◽  
Fixed Base ◽  
Projection Error

SUMMARY This paper proposes a vision-based kinematic analysis and kinematic parameters identification of the proposed architecture, designed to perform the object catching in the real-time scenario. For performing the inverse kinematics, precise estimation of the link lengths and other parameters needs to be present. Kinematic identification of Delta based upon Model10 implicit model with ten parameters using the iterative least square method is implemented. The loop closure implicit equations have been modelled. In this paper, a vision-based kinematic analysis of the Delta robots to do the catching is discussed. A predefined library of ArUco is used to get a unique solution of the kinematics of the moving platform with respect to the fixed base. The re-projection error while doing the calibration in the vision sensor module is 0.10 pixels. Proposed architecture interfaced with the hardware using the PID controller. Encoders are quadrature and have a resolution of 0.15 degrees embedded in the experimental setup to make the system closed-loop (acting as feedback unit).

scholarly journals Path generation for flying robots in mountainous regions

2016 ◽  
Vol 9 (1) ◽  
pp. 44-60 ◽  
Author(s):  
Amirreza Kosari ◽  
Hossein Maghsoudi ◽  
Abolfazl Lavaei
Keyword(s):  
Numerical Technique ◽  
Estimation Method ◽  
Least Square Method ◽  
Least Square ◽  
Performance Criteria ◽  
Mission Design ◽  
Vertical Acceleration ◽  
Mountainous Regions ◽  
Terrain Following ◽  
Flying Robots

In this paper, a new path planning method is proposed to resolve the problem of two-dimensional terrain following flight of flying robots in mountainous regions. The performance criteria considered for this mission design could include either the minimum vertical acceleration or the minimum flying time. To impose the terrain following/terrain avoidance constraints, various approaches such as least square method, Fourier series method, Gaussian estimation method, and Chebyshev orthogonal polynomial are explored. The resulting optimal control problem is discretized by employing a numerical technique namely direct collocation and then transformed into a nonlinear programming problem. The efficacy of the proposed method is demonstrated by extensive simulations, and particularly, it has been verified that this method is able to produce a solution that satisfies all hard constraints of the underlying problem.

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