The Multi-Variable Torque-Displacement Relation at the Ankle

2009 ◽  
Author(s):  
Hyunglae Lee ◽  
Patrick Ho ◽  
Hermano Igo Krebs ◽  
Neville Hogan
Keyword(s):  
Vector Field ◽  
Thin Plate ◽  
Degrees Of Freedom ◽  
Cross Validation ◽  
Experimental Results ◽  
Two Degrees Of Freedom ◽  
Ankle Impedance ◽  
Passive Behavior ◽  
Mechanical Spring ◽  
Neural Feedback

In this paper, we report measurements of the multi-variable torque-displacement relation at the ankle. The passive behavior of the ankle in two degrees of freedom (inversion-eversion and dorsiflexion-plantarflexion) was quantified using the Anklebot. The measured torque-displacement relationship was represented as a vector field using thin-plate spline smoothing with generalized cross validation. Analysis of the experimental results showed that, when maximally relaxed, the ankle behaved like a mechanical spring. However, if muscles were active, the torque-displacement relation was not spring-like. Implications for the contribution of neural feedback to ankle impedance are discussed.

Development of a Human Symbiotic Assist Arm “PAS-Arm” (Experimental System and Creation of Virtual Guiding Surfaces)

2013 ◽  
Vol 25 (2) ◽  
pp. 285-293 ◽  
Author(s):  
Mineo Higuchi ◽  
◽  
Tsukasa Ogasawara ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Experimental System ◽  
Major Axis ◽  
Experimental Results ◽  
Physical Interaction ◽  
Assist Device ◽  
Two Degrees Of Freedom ◽  
Direct Physical Interaction ◽  
Continuously Variable Transmissions

We describe a new robotic assist device: the passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator. PASArms are physically passive. The force to manipulate the arm end must be provided by the operator. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces that constrain and guide the motion of the operator. PAS-Arms have three joints and a three dimensional workspace, but possess only two degrees of freedom due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. In this paper, we first discuss the manipulability ellipsoid for the PAS-Arm. The major axis of the ellipsoid is the direction in which the arm end may be easily manipulated, and vice versa. We have developed an experimental system for the PAS-Arm. The CVTs of the experimental system may not adjust the transmission ratio to zero. Second, we describe an algorithm to address that problem. Finally, we present initial experiments that verify the PAS-Arm mechanism. The experimental results successfully produced virtual guiding surfaces.1 1. This paper is the full translation from the transactions of JSME, Series C, Vol.76, No.763, pp. 611-618, 2010.

scholarly journals Quantitative Characterization of Steady-State Ankle Impedance With Muscle Activation

2010 ◽  
Author(s):  
Hyunglae Lee ◽  
Patrick Ho ◽  
Mohammad A. Rastgaar ◽  
Hermano Igo Krebs ◽  
Neville Hogan
Keyword(s):  
Steady State ◽  
Vector Field ◽  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Human Subjects ◽  
Mechanical Impedance ◽  
Field Analysis ◽  
Lower Extremity Function ◽  
Ankle Impedance

Characterization of multi-variable ankle mechanical impedance is crucial to understanding how the ankle supports lower-extremity function during interaction with the environment. This paper reports quantification of steady-state ankle impedance when muscles were active. Vector field approximation of repetitive measurements of the torque-angle relation in two degrees of freedom (inversion/eversion and dorsiflexion/plantarflexion) enabled assessment of spring-like and non-spring-like components. Experimental results of eight human subjects showed direction-dependent ankle impedance with greater magnitude than when muscles were relaxed. In addition, vector field analysis demonstrated a non-spring-like behavior when muscles were active, although this phenomenon was subtle in the unimpaired young subjects we studied.

scholarly journals Interface Based on Electrooculography for Velocity Control of a Robot Arm

2010 ◽  
Vol 7 (3) ◽  
pp. 199-207 ◽  
Author(s):  
Eduardo Iáñez ◽  
José M. Azorín ◽  
Eduardo Fernández ◽  
Andrés Úbeda
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Results ◽  
Processing Algorithm ◽  
Robot Arm ◽  
Velocity Control ◽  
Two Degrees Of Freedom ◽  
Real Robot ◽  
The Difference

This paper describes a technique based on electrooculography to control a robot arm. This technique detects the movement of the eyes, measuring the difference of potential between the cornea and the retina by placing electrodes around the ocular area. The processing algorithm developed to obtain the position of the eye at the blink of the user is explained. The output of the processing algorithm offers, apart from the direction, four different values (zero to three) to control the velocity of the robot arm according to how much the user is looking in one direction. This allows controlling two degrees of freedom of a robot arm with the eyes movement. The blink has been used to mark some targets in tests. In this paper, the experimental results obtained with a real robot arm are shown.

Directional Variation of Active and Passive Ankle Static Impedance

2009 ◽  
Author(s):  
Patrick Ho ◽  
Hyunglae Lee ◽  
Hermano Igo Krebs ◽  
Neville Hogan
Keyword(s):  
Muscle Contraction ◽  
Degrees Of Freedom ◽  
Mechanical Impedance ◽  
Active Muscle ◽  
Two Degrees Of Freedom ◽  
Static Component ◽  
Ankle Impedance ◽  
Directional Variation

Though ankle mechanical impedance plays an important role in posture and locomotion, it has been inadequately characterized. Unlike previous studies, which confined themselves to measurements along the primary axes of the ankle in an isolated fashion, the study reported here characterized the static component of ankle impedance in two degrees of freedom. In addition, the effect of active muscle contraction on ankle static impedance was measured. We found that ankle static impedance varied significantly with direction under passive conditions. We further observed that, while muscle contraction increased the magnitude of ankle static impedance, its directional variation was essentially unchanged.

Development of a Marine Self-Balancing Table with Two-Axis Motion Control System

2014 ◽  
Vol 577 ◽  
pp. 342-345
Author(s):  
Minh Phu Huynh ◽  
Shyh Chour Huang
Keyword(s):  
Fuzzy Logic ◽  
Control System ◽  
Motion Control ◽  
Fuzzy Logic Control ◽  
Degrees Of Freedom ◽  
Experimental Results ◽  
Motion Control System ◽  
Two Degrees Of Freedom ◽  
Logic Control

The purpose of this research is to design and construct a marine self-balancing table with two-axis motion control system. This table has two degrees of freedom, is fixed in an ocean-going ship and can be self-balanced when the ship is moving in the sea. Control of the table is based on fuzzy logic control. A prototype of the marine self-balancing table is also manufactured in this research. Experimental results show that this table can be self-balanced with a tolerance of 10.

ON HOMOCLINIC CHAOS AND A CONTROL CHAOS STRATEGY APPLIED TO A FREE-JOINT NONHOLONOMIC MANIPULATOR

2007 ◽  
Vol 17 (06) ◽  
pp. 2009-2020
Author(s):  
JEFFERSON CASSIANO ◽  
JOSÉ MANOEL BALTHAZAR
Keyword(s):  
Control Strategy ◽  
Horizontal Plane ◽  
Degrees Of Freedom ◽  
Robotic System ◽  
Experimental Results ◽  
Two Degrees Of Freedom ◽  
Homoclinic Chaos

In this work, the occurrence of chaos (homoclinic scene) is verified in a robotic system with two degrees of freedom by using Poincaré–Mel'nikov method. The studied problem was based on experimental results of a two-joint planar manipulator — first joint actuated and the second joint free — that resides in a horizontal plane. This is the simplest model of nonholonomic free-joint manipulators. The purpose of the present study is to verify analytically those results and to suggest a control strategy.

The scientific bases of autocontrol with vibration phase for a resonance beating-vibration system with two degrees of freedom driven by debalances

1996 ◽  
Vol 18 (2) ◽  
pp. 43-48
Author(s):  
Tran Van Tuan ◽  
Do Sanh ◽  
Luu Duc Thach
Keyword(s):  
Degrees Of Freedom ◽  
Regulation System ◽  
Vibration System ◽  
Two Degrees Of Freedom ◽  
System Operating

In the paper it is introduced a method for studying dynamics of beating-vibrators by means of digital calculation with the help of the machine in accordance with the needs by the helps of an available auto regulation system operating with high reability.

scholarly journals Optimization of LLC Resonant Converter with Two Degrees of Freedom Based on Operation Stage Trajectory Analysis

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Ziheng Xiao ◽  
Zhixing He ◽  
Yong Ning ◽  
Hongliang Wang ◽  
An Luo ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Trajectory Analysis ◽  
Resonant Converter ◽  
Two Degrees Of Freedom ◽  
Operation Stage ◽  
Llc Resonant Converter
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