scholarly journals Virtual Grasping: Closed-Loop Force Control Using Electrotactile Feedback

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Nikola Jorgovanovic ◽  
Strahinja Dosen ◽  
Damir J. Djozic ◽  
Goran Krajoski ◽  
Dario Farina
Keyword(s):  
Closed Loop ◽  
Feedforward Control ◽  
Human Subjects ◽  
Real Life ◽  
Sensory Substitution ◽  
Vibrotactile Stimulation ◽  
Loop Control ◽  
Control Robustness ◽  
Grasping Force ◽  
Virtual Grasping

Closing the control loop by providing somatosensory feedback to the user of a prosthesis is a well-known, long standing challenge in the field of prosthetics. Various approaches have been investigated for feedback restoration, ranging from direct neural stimulation to noninvasive sensory substitution methods. Although there are many studies presenting closed-loop systems, only a few of them objectively evaluated the closed-loop performance, mostly using vibrotactile stimulation. Importantly, the conclusions about the utility of the feedback were partly contradictory. The goal of the current study was to systematically investigate the capability of human subjects to control grasping force in closed loop using electrotactile feedback. We have developed a realistic experimental setup for virtual grasping, which operated in real time, included a set of real life objects, as well as a graphical and dynamical model of the prosthesis. We have used the setup to test 10 healthy, able bodied subjects to investigate the role of training, feedback and feedforward control, robustness of the closed loop, and the ability of the human subjects to generalize the control to previously “unseen” objects. Overall, the outcomes of this study are very optimistic with regard to the benefits of feedback and reveal various, practically relevant, aspects of closed-loop control.

Closing the Loops Without Human Subjects: A Survey of Control Approaches in Simulation of Human-Artifact Interaction

2010 ◽  
Author(s):  
Wilhelm “Wilfred” F. van der Vegte ◽  
Imre Horva´th
Keyword(s):  
Closed Loop ◽  
Human Subjects ◽  
Product Model ◽  
Embedded Control ◽  
Loop Control ◽  
Control Loops ◽  
Human Control ◽  
Cognitive Simulation ◽  
Human Models ◽  
Interaction Simulation

To include interactions with human users in simulations of the use of products, the most common approach is to couple human subjects to the behavioral product model in the simulation loop using interfaces based on VR and haptics. Replacing human subjects by human models with simulation capabilities could offer a cost-saving alternative. Currently available human models have not yet been deployed this way. This paper explores the possibilities to achieve mutual closed-loop coupling between human models and artifact models for enabling fully software-based interaction simulations. We have not only investigated human control in simulations, but also solutions to include embedded control in artifacts. The paper critically reviews existing (partial) solutions to simulate or execute control behaviors, and to close the control loops we identified in human-artifact interaction simulation. We concluded that closed-loop control of interaction simulations can be achieved by selectively combining existing partial solutions. Inclusion of decision-making appears to be the biggest challenge. Promising solutions are (i) cognitive simulation and (ii) execution of conjectured interactions specified as logical instructions, typically in the form of scenarios. Based on scenarios, which we expect to be more intuitive for designers, a new approach is now being developed.

scholarly journals Wearable Biofeedback System to Induce Desired Walking Speed in Overground Gait Training

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 4002
Author(s):  
Huanghe Zhang ◽  
Yefei Yin ◽  
Zhuo Chen ◽  
Yufeng Zhang ◽  
Ashwini K. Rao ◽  
...  
Keyword(s):  
Closed Loop ◽  
Walking Speed ◽  
New Technology ◽  
Past Research ◽  
Gait Training ◽  
Open Loop ◽  
Vibrotactile Stimulation ◽  
Loop Control ◽  
Biofeedback System ◽  
Walking Speeds

Biofeedback systems have been extensively used in walking exercises for gait improvement. Past research has focused on modulating the wearer’s cadence, gait variability, or symmetry, but none of the previous works has addressed the problem of inducing a desired walking speed in the wearer. In this paper, we present a new, minimally obtrusive wearable biofeedback system (WBS) that uses closed-loop vibrotactile control to elicit desired changes in the wearer’s walking speed, based on the predicted user response to anticipatory and delayed feedback. The performance of the proposed control was compared to conventional open-loop rhythmic vibrotactile stimulation with N = 10 healthy individuals who were asked to complete a set of walking tasks along an oval path. The closed-loop vibrotactile control consistently demonstrated better performance than the open-loop control in inducing desired changes in the wearer’s walking speed, both with constant and with time-varying target walking speeds. Neither open-loop nor closed-loop stimuli affected natural gait significantly, when the target walking speed was set to the individual’s preferred walking speed. Given the importance of walking speed as a summary indicator of health and physical performance, the closed-loop vibrotactile control can pave the way for new technology-enhanced protocols for gait rehabilitation.

Vibrotactile grasping force and hand aperture feedback for myoelectric forearm prosthesis users

2014 ◽  
Vol 39 (3) ◽  
pp. 204-212 ◽  
Author(s):  
Heidi JB Witteveen ◽  
Hans S Rietman ◽  
Peter H Veltink
Keyword(s):  
Upper Limb ◽  
Force Feedback ◽  
Feedback Condition ◽  
Limb Loss ◽  
Vibrotactile Stimulation ◽  
Vibrotactile Feedback ◽  
Task Durations ◽  
Grasping Force ◽  
Additional Value ◽  
Virtual Grasping

Background: User feedback about grasping force and hand aperture is very important in object handling with myoelectric forearm prostheses but is lacking in current prostheses. Vibrotactile feedback increases the performance of healthy subjects in virtual grasping tasks, but no extensive validation on potential users has been performed. Objectives: Investigate the performance of upper-limb loss subjects in grasping tasks with vibrotactile stimulation, providing hand aperture, and grasping force feedback. Study design: Cross-over trial. Methods: A total of 10 subjects with upper-limb loss performed virtual grasping tasks while perceiving vibrotactile feedback. Hand aperture feedback was provided through an array of coin motors and grasping force feedback through a single miniature stimulator or an array of coin motors. Objects with varying sizes and weights had to be grasped by a virtual hand. Results: Percentages correctly applied hand apertures and correct grasping force levels were all higher for the vibrotactile feedback condition compared to the no-feedback condition. With visual feedback, the results were always better compared to the vibrotactile feedback condition. Task durations were comparable for all feedback conditions. Conclusion: Vibrotactile grasping force and hand aperture feedback improves grasping performance of subjects with upper-limb loss. However, it should be investigated whether this is of additional value in daily-life tasks. Clinical relevance This study is a first step toward the implementation of sensory vibrotactile feedback for users of myoelectric forearm prostheses. Grasping force feedback is crucial for optimal object handling, and hand aperture feedback is essential for reduction of required visual attention. Grasping performance with feedback is evaluated for the potential users.

Pre-Scheduled PID Control of a Solar Thermal Power Plant

1995 ◽  
Vol 17 (3) ◽  
pp. 132-142 ◽  
Author(s):  
A. Meaburn ◽  
F. M. Hughes
Keyword(s):  
Closed Loop ◽  
Feedforward Control ◽  
Thermal Power ◽  
Low Frequency ◽  
Outlet Temperature ◽  
Experimental Frequency ◽  
Efficient Operation ◽  
Loop Control ◽  
Tuning Method ◽  
Control Scheme

Efficient operation of a distributed solar collector field requires effective regulation of the outlet temperature. Control schemes utilising PI-based controllers, whether adaptive or fixed parameter, have been shown to be unsuitable for this application with a stable well-damped response only obtained at the expense of an unacceptably low speed of response. The reason for this is that collector fields possess low-frequency resonance dynamics which tend to restrict the bandwidth of such controllers. This paper examines the suitability and capability of PID controllers in this application area. Using experimental frequency response data, the Ziegler-Nichols tuning method for PID design is demonstrated to yield an unstable closed-loop system. However, by adopting a strategy which specifically aims to counter the adverse phase characteristics of the plant at resonance, good effective closed-loop control can be achieved. This is implemented as a pre-scheduled control scheme on the Acurex collector field at the Plataforma Solar de Almeria and tested in conjunction with a feedforward control scheme.

scholarly journals Luminophonics experiment: A user study on visual sensory substitution device

2015 ◽  
Author(s):  
Shern Shiou Tan ◽  
Tomas Maul ◽  
Neil Mennie
Keyword(s):  
Visually Impaired ◽  
User Study ◽  
Human Subjects ◽  
Sensory System ◽  
Real Life ◽  
Sensory Substitution ◽  
Depth Information ◽  
Daily Lives ◽  
Information Preservation ◽  
Care Givers

Loss of vision is a severe impairment to the dominant sensory system. It often has a catastrophic effect upon the sufferer, with knock-on effects to their standard of living, their ability to support themselves, and their care-givers lives. Research into visual impairments is multi-faceted, focusing on the causes of these debilitating conditions as well as attempting to alleviate the daily lives of affected individuals. One of the methods is through the usage of sensory substitution device. Our proposed system, Luminophonics, focuses on visual to auditory cross modalities information conversions. A visual to audio sensory substitution device a type of system that obtains a continual stream visual inputs which it converts into corresponding auditory soundscape. Ultimately, this device allows the visually impaired to visualize the surrounding environment by only listening to the generated soundscape. Even though there is a huge potential for this kind of devices, public usage is still minimal (Loomis, 2010). In order to promote the adoption from the visually impaired, the overall performance of these devices need to be improved in terms of soundscape interpretability, information preservation and listening comfort amongst other factors. Luminophonics has developed 3 type of prototypes, which we have used to explore different ideas pertaining to visual to audio sensory substitution. In addition to these, one of the prototypes has been converted to include depth information using time of flight camera. Previously, an automated measurement method is used to evaluate the performance of the 3 prototypes (Tan, 2013). The results of the measurement cover the effectiveness in terms of interpretability and information preservation. The main purpose of the experiment reported herein, was to test the prototypes on human subjects in order to gain greater insight on how they perform in real-life situations.

scholarly journals Multichannel Electrotactile Feedback With Spatial and Mixed Coding for Closed-Loop Control of Grasping Force in Hand Prostheses

2017 ◽  
Vol 25 (3) ◽  
pp. 183-195 ◽  
Author(s):  
Strahinja Dosen ◽  
Marko Markovic ◽  
Matija Strbac ◽  
Minja Belic ◽  
Vladimir Kojic ◽  
...  
Keyword(s):  
Closed Loop ◽  
Closed Loop Control ◽  
Loop Control ◽  
Grasping Force ◽  
Mixed Coding

scholarly journals Electrotactile feedback improves performance and facilitates learning in the routine grasping task

2016 ◽  
Vol 26 (3) ◽  
Author(s):  
Milica Isaković ◽  
Minja Belić ◽  
Matija Štrbac ◽  
Igor Popović ◽  
Strahinja Došen ◽  
...  
Keyword(s):  
Force Control ◽  
Closed Loop ◽  
Feedforward Control ◽  
Open Loop ◽  
Spatial Coding ◽  
Accuracy And Precision ◽  
Array Electrode ◽  
Grasping Force ◽  
Four Levels ◽  
And Training

Aim of this study was to investigate the feasibility of electrotactile feedback in closed loop training of force control during the routine grasping task. The feedback was provided using an array electrode and a simple six-level spatial coding, and the experiment was conducted in three amputee subjects. The psychometric tests confirmed that the subjects could perceive and interpret the electrotactile feedback with a high success rate. The subjects performed the routine grasping task comprising 4 blocks of 60 grasping trials. In each trial, the subjects employed feedforward control to close the hand and produce the desired grasping force (four levels). First (baseline) and the last (validation) session were performed in open loop, while the second and the third session (training) included electrotactile feedback. The obtained results confirmed that using the feedback improved the accuracy and precision of the force control. In addition, the subjects performed significantly better in the validation vs. baseline session, therefore suggesting that electrotactile feedback can be used for learning and training of myoelectric control.

Design and Modelling of a 90-Degree Ball Valve with a Linear Pressure Drop

2020 ◽  
Author(s):  
Daniel A. Gutierrez ◽  
Jose M. Garcia-Bravo ◽  
Aaron L. Reid ◽  
Brittany A. Newell ◽  
Paul McPherson ◽  
...  
Keyword(s):  
Closed Loop ◽  
Flow Characteristic ◽  
Linear Trend ◽  
Low Cost ◽  
Real Life ◽  
Ball Valve ◽  
Vast Number ◽  
Loop Control ◽  
Control Fluid ◽  
Or Gate

Globe valves also known as ball or gate valves are used to control fluid flow in a vast number of applications. Most of the existing applications use them because of their simplicity and very low cost. However, these valves are known for their poor precision for controlling the flow and the lack of electromechanical means for their actuation. Moreover, because of their low linearity their use in closed loop control applications make them nearly unusable. The goal of this research project was to investigate means for redesigning the metering area of a ball valve in such a manner that the pressure vs. flow characteristic would be close to a linear trend. Two different profiles where designed and tested experimentally and modelled using CFD techniques for the estimation of their valve flow coefficients. The model was able to accurately predict the behaviour of the valve with less than a 10% error when fully open. The model can be used for scaling the size of the ball for larger applications and for tuning controlling strategies for flow dispensation in real life applications. 

Sign in / Sign up

Export Citation Format

Share Document