Evaluation of Power-Assist System by Computer Simulation

2016 ◽  
Vol 20 (3) ◽  
pp. 477-483 ◽  
Author(s):  
Yoshiaki Taniai ◽  
◽  
Tomohide Naniwa ◽  
Yasutake Takahashi ◽  
Masayuki Kawai
Keyword(s):  
Computer Simulation ◽  
Evaluation Framework ◽  
Metabolic Energy ◽  
Evaluation Index ◽  
Optimality Principle ◽  
Upper Arm ◽  
Reaching Movement ◽  
Effective Power ◽  
Arm Reaching ◽  
Motor Paralysis

Powered exoskeletons have been proposed and developed in various works with the aim of compensating for motor paralysis or reducing weight, workload, or metabolic energy consumption. However, development of the power-assist system depends on the development and evaluation of real powered exoskeletons, and few studies have evaluated the performance of the power-assist system by means of computer simulation. In this paper, we propose an evaluation framework based on computer simulation for the development of an effective power-assist system and demonstrate an analysis of a power-assisted upper-arm reaching movement. We employed the optimality principle to obtain the adapted movements of humans for power-assist systems and compared the performances of power- and non-power-assisted movements in terms of the evaluation index of the power-assist system.

Optimality of Upper-Arm Reaching Trajectories Based on the Expected Value of the Metabolic Energy Cost

2015 ◽  
Vol 27 (8) ◽  
pp. 1721-1737 ◽  
Author(s):  
Yoshiaki Taniai ◽  
Jun Nishii
Keyword(s):  
Energy Cost ◽  
Cost Model ◽  
Expected Value ◽  
Metabolic Energy ◽  
Stride Frequency ◽  
Movement Trajectory ◽  
Potential Candidate ◽  
Upper Arm ◽  
Reaching Task ◽  
Arm Reaching

When we move our body to perform a movement task, our central nervous system selects a movement trajectory from an infinite number of possible trajectories under constraints that have been acquired through evolution and learning. Minimization of the energy cost has been suggested as a potential candidate for a constraint determining locomotor parameters, such as stride frequency and stride length; however, other constraints have been proposed for a human upper-arm reaching task. In this study, we examined whether the minimum metabolic energy cost model can also explain the characteristics of the upper-arm reaching trajectories. Our results show that the optimal trajectory that minimizes the expected value of energy cost under the effect of signal-dependent noise on motor commands expresses not only the characteristics of reaching movements of typical speed but also those of slower movements. These results suggest that minimization of the energy cost would be a basic constraint not only in locomotion but also in upper-arm reaching.

Kinematics patterns of upper arm reaching movement in robot-mediated therapy

2011 ◽  
Author(s):  
Mario Cesarelli ◽  
Maria Romano ◽  
Gianni D'Addio ◽  
Alessandro Marco De Nunzio ◽  
Nicola Pappone
Keyword(s):  
Upper Arm ◽  
Reaching Movement ◽  
Arm Reaching

Nonlinear Reference Shaping with Endpoint Position Feedback for Large Acceleration Avoidance in Reaching Movement

2010 ◽  
Vol 22 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Fumi Seto ◽  
◽  
Tomomichi Sugihara ◽  
Keyword(s):  
Computer Simulation ◽  
External Force ◽  
Reaching Movement ◽  
Reference Position ◽  
Position Feedback ◽  
Original Target ◽  
Flexible Behavior ◽  
Initial Acceleration ◽  
Living Environments

The nonlinear reference shaping for manipulators used in ordinary living environments is proposed. It generates an intermediate reference position, and it is combined with control based on the virtual springdamper hypothesis. Initial acceleration is moderated by the reference position inserted between the original target and current endpoint position and by a secondorder lag filter. The endpoint position is fed back to prevent from excessive trailing force and large acceleration, resulting in smooth reaching movement and flexible behavior against external force. The feasibility of the concept of the proposed controller is confirmed through computer simulation on a planar 4-DOF manipulator.

scholarly journals The duration of reaching movement is longer than predicted by minimum variance

2016 ◽  
Vol 116 (5) ◽  
pp. 2342-2345 ◽  
Author(s):  
Chunji Wang ◽  
Yupeng Xiao ◽  
Etienne Burdet ◽  
James Gordon ◽  
Nicolas Schweighofer
Keyword(s):  
Minimum Variance ◽  
Reaching Movements ◽  
Movement Duration ◽  
Slow Movement ◽  
Reaching Movement ◽  
End Point ◽  
Parsimonious Explanation ◽  
Arm Reaching ◽  
The Central Nervous System ◽  
Duration Condition

Whether the central nervous system minimizes variability or effort in planning arm movements can be tested by measuring the preferred movement duration and end-point variability. Here we conducted an experiment in which subjects performed arm reaching movements without visual feedback in fast-, medium-, slow-, and preferred-duration conditions. Results show that 1) total end-point variance was smallest in the medium-duration condition and 2) subjects preferred to carry out movements that were slower than this medium-duration condition. A parsimonious explanation for the overall pattern of end-point errors across fast, medium, preferred, and slow movement durations is that movements are planned to minimize effort as well as end-point error due to both signal-dependent and constant noise.

Online gain update for manual following response accompanied by gaze shift during arm reaching

2015 ◽  
Vol 113 (4) ◽  
pp. 1206-1216 ◽  
Author(s):  
Naotoshi Abekawa ◽  
Hiroaki Gomi
Keyword(s):  
Continuous Monitoring ◽  
Visual Motion ◽  
Target Location ◽  
Body Movement ◽  
Gaze Shift ◽  
Reaching Movement ◽  
The Gaze ◽  
Arm Reaching ◽  
Online Corrections ◽  
The Brain

To capture objects by hand, online motor corrections are required to compensate for self-body movements. Recent studies have shown that background visual motion, usually caused by body movement, plays a significant role in such online corrections. Visual motion applied during a reaching movement induces a rapid and automatic manual following response (MFR) in the direction of the visual motion. Importantly, the MFR amplitude is modulated by the gaze direction relative to the reach target location (i.e., foveal or peripheral reaching). That is, the brain specifies the adequate visuomotor gain for an online controller based on gaze-reach coordination. However, the time or state point at which the brain specifies this visuomotor gain remains unclear. More specifically, does the gain change occur even during the execution of reaching? In the present study, we measured MFR amplitudes during a task in which the participant performed a saccadic eye movement that altered the gaze-reach coordination during reaching. The results indicate that the MFR amplitude immediately after the saccade termination changed according to the new gaze-reach coordination, suggesting a flexible online updating of the MFR gain during reaching. An additional experiment showed that this gain updating mostly started before the saccade terminated. Therefore, the MFR gain updating process would be triggered by an ocular command related to saccade planning or execution based on forthcoming changes in the gaze-reach coordination. Our findings suggest that the brain flexibly updates the visuomotor gain for an online controller even during reaching movements based on continuous monitoring of the gaze-reach coordination.

Sign in / Sign up

Export Citation Format

Share Document