Identification of Mechanical Impedance Parameters of Human Upper Limbs Using Mechanical Perturbation Method

2021 ◽  
pp. 141-147
Author(s):  
Huaiwu Zou ◽  
Haoran Tao ◽  
Zhou Zhou ◽  
Bingshan Hu
Keyword(s):  
Perturbation Method ◽  
Mechanical Impedance ◽  
Upper Limbs ◽  
Mechanical Perturbation ◽  
Impedance Parameters

Identification of Time-Varying Stiffness, Damping, and Equilibrium Position in Human Forearm Movements

Motor Control ◽  
1999 ◽  
Vol 3 (4) ◽  
pp. 394-413 ◽  
Author(s):  
Jürgen Konczak ◽  
Kai Brommann ◽  
Karl Theodor Kalveram
Keyword(s):  
Equilibrium Position ◽  
A Priori ◽  
Joint Stiffness ◽  
Mechanical Impedance ◽  
Forward Model ◽  
Positional Error ◽  
Directed Movement ◽  
External Bias ◽  
Human Forearm ◽  
Impedance Parameters

Knowledge of how stiffness, damping, and the equilibrium position of specific limbs change during voluntary motion is important for understanding basic strategies of neuromotor control. Presented here is an algorithm for identifying time-dependent changes in joint stiffness, damping, and equilibrium position of the human forearm. The procedure requires data from only a single trial. The method relies neither on an analysis of the resonant frequency of the arm nor on the presence of an external bias force. Its validity was tested with a simulated forward model of the human forearm. Using the parameter estimations as forward model input, the angular kinematics (model output) were reconstructed and compared to the empirically measured data. Identification of mechanical impedance is based on a least-squares solution of the model equation. As a regularization technique and to improve the temporal resolution of the identification process, a moving temporal window with a variable width was imposed. The method's performance was tested by (a) identifying a priori known hypothetical time-series of stiffness, damping, and equilibrium position, and (b) determining impedance parameters from recorded single-joint forearm movements during a hold and a goal-directed movement task. The method reliably reconstructed the original angular kinematics of the artificial and human data with an average positional error of less than 0.05 rad for movement amplitudes of up to 0.9 rad, and did not yield hypermetric trajectories like previous procedures not accounting for damping.

A Log-linearized Viscoelastic Model for Measuring Changes in Vascular Impedance

2011 ◽  
pp. 326-334
Author(s):  
Abdugheni Kutluk ◽  
Ryuji Nakamura ◽  
Toshio Tsuji ◽  
Teiji Ukawa ◽  
Noboru Saeki ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Linear Model ◽  
Viscoelastic Model ◽  
Vertical Direction ◽  
Mechanical Impedance ◽  
Arterial Walls ◽  
Arm Position ◽  
Vascular Impedance ◽  
Nonlinear Viscoelastic ◽  
Impedance Parameters

This chapter proposes a new nonlinear model, called a log-linearized viscoelastic model, to estimate the dynamic characteristics of human arterial walls. The model employs mechanical impedance factors, including stiffness and viscosity, in beat-to-beat measured from biological signals such as arterial blood pressure and photoplethysmograms. The validity of the proposed method is determined by demonstrating how arterial wall impedance properties change during arm position testing in the vertical direction. The estimated stiffness indices are compared with those of the conventional linear model. Estimated impedance parameters with contribution ratios exceeding 0.97 were used for comparison. The results indicated that stiffness and viscosity decrease when the arm is raised and increase when it is lowered, in the same pattern as mean blood pressure. However, the changes seen in the proposed nonlinear viscoelastic parameter are smaller (P < 0.05) than those of the linear model. This result suggests that the proposed nonlinear arterial viscoelastic model is less affected by changes in mean intravascular pressure during arm position changes.

Development of Mechanical-Impedance-Varying Mechanism in Admittance Control

2018 ◽  
Vol 30 (6) ◽  
pp. 863-872
Author(s):  
Toru Tsumugiwa ◽  
◽  
Miho Yura ◽  
Atsushi Kamiyoshi ◽  
Ryuichi Yokogawa
Keyword(s):  
Motion Control ◽  
Control Strategy ◽  
Impedance Control ◽  
Mechanical Impedance ◽  
Force Sensor ◽  
Robot Motion ◽  
Admittance Control ◽  
Input Force ◽  
Mechanical Variable ◽  
Impedance Parameters

There have been numerous studies on the physical human-robot cooperative task system with impedance/admittance control in robot motion control. However, the problem of stability persists, wherein the control system becomes unstable when the robot comes into contact with a highly stiff environment. A variable impedance control strategy was proposed to circumvent this stability problem. However, a number of studies on variable impedance control are based on the variation of a parameter in the robot motion control software, and a mechanical variable impedance control has not been proposed. The purpose of this research is to propose a mechanical variable impedance control strategy using a mechanical device based on the lever principle. The proposed mechanism can adjust the magnitude of the input force to the force sensor by changing the position of application of the operating force on the beam. Adjusting the magnitude of the input force to the force sensor is equivalent to varying the impedance parameters of the robot; therefore, it is feasible to achieve mechanical variable impedance control using the proposed mechanism. In this study, the gain adjustment characteristics of the proposed mechanism were evaluated. The experimental results demonstrated that the operator can vary the impedance parameters of the robot by mechanically adjusting the input force to the force sensor and operating the robot using the proposed mechanism.

scholarly journals Emotional evaluation on the mechanical impedance parameters of the robot

1995 ◽  
Vol 31 (Supplement) ◽  
pp. 538-539
Author(s):  
Satoru Shibata ◽  
Kanya Tanaka ◽  
Akira Shimizu
Keyword(s):  
Mechanical Impedance ◽  
Emotional Evaluation ◽  
Impedance Parameters

IMPACT AND FORCE CONTROL WITH SWITCHING BETWEEN MECHANICAL IMPEDANCE PARAMETERS

2005 ◽  
Vol 38 (1) ◽  
pp. 169-174
Author(s):  
Zotovic Ranko ◽  
Ángel Valera Fernández ◽  
Pedro J. García Gil
Keyword(s):  
Force Control ◽  
Mechanical Impedance ◽  
Impedance Parameters

Virtual Driving Simulator for Measuring Dynamic Properties of Human Arm Movements

2006 ◽  
Vol 18 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Yoshiyuki Tanaka ◽  
◽  
Ryoma Kanda ◽  
Naoki Yamada ◽  
Hitoshi Fukuba ◽  
...  
Keyword(s):  
Driving Simulator ◽  
Impedance Control ◽  
Dynamic Properties ◽  
Mechanical Impedance ◽  
Rotational Axis ◽  
Human Movements ◽  
Human Arm ◽  
Robotic Devices ◽  
Impedance Parameters ◽  
Machine Systems

This paper presents a virtual driving simulator using robotic devices as an example of human-machine systems to investigate dynamic properties of human movements in the operation of drive interfaces, such as steering wheels and transmission shifters. The simulator has virtual steering and transmission systems under variable impedance control, providing the operators with realistic operational response. Mechanical impedance parameters around the steering rotational axis were measured to demonstrate the effectiveness of the developed simulator.

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