Examination of Tactor Configurations for the Design of Vibrotactile Feedback Systems for Use in Lower-Limb Prostheses

2018 ◽  
Author(s):  
Sam Shi ◽  
Matthew J. Leineweber ◽  
Jan Andrysek
Keyword(s):  
Lower Limb ◽  
Negative Relationship ◽  
Feedback System ◽  
Elevated Pressure ◽  
Intensity Level ◽  
Response Accuracy ◽  
Feedback Systems ◽  
Vibrotactile Feedback ◽  
Lower Limb Prosthesis ◽  
Lower Limb Prostheses

Vibrotactile feedback may be able to compensate for the loss of sensory input in lower-limb prosthesis users. Designing an effective vibrotactile feedback system would require that users could perceive and correctly respond to vibrotactile stimuli applied by the tactors. Our study explored three key tactor configuration variables (i.e. vibratory intensity, prosthetic pressure, spacing between adjacent tactors) through two experiments. The vibration propagation experiment investigated the effects of tactor configurations on vibratory amplitude at the prosthesis-limb interface. Results revealed a positive relationship between vibratory amplitude and intensity, and a negative relationship between vibratory amplitude and prosthetic pressure. The vibrotactile perception experiment investigated the effects of tactor configurations on user response accuracy, and found that greater spacing between tactors, and higher prosthetic pressure resulted in more accurate responses from the subjects. These findings inform the design of a vibrotactile feedback system for use in lower-limb prostheses: 1) the tactors may be best placed in areas of slightly elevated pressure at the prosthesis-limb interface; 2) a higher vibratory intensity level should improve performance for vibrotactile feedback systems; and 3) more spacing between adjacent tactors improves user response accuracy.

Exploring the Tactor Configurations of Vibrotactile Feedback Systems for Use in Lower-Limb Prostheses1

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Sam Shi ◽  
Matthew J. Leineweber ◽  
Jan Andrysek
Keyword(s):  
Response Time ◽  
Lower Limb ◽  
Vibration Amplitude ◽  
Feedback System ◽  
User Perception ◽  
Feedback Systems ◽  
Vibrotactile Feedback ◽  
Spatial Error ◽  
Vibration Intensity ◽  
Time Accuracy

Vibrotactile feedback may be able to compensate for the loss of sensory input in lower-limb prosthesis users to improve the mobility function. Designing an effective vibrotactile feedback system requires that users are able to perceive and respond to vibrotactile stimuli correctly and in a timely manner. Our study explored four key tactor configuration variables (i.e., tactors’ prosthetic layer, vibration intensity, prosthetic pressure, and spacing between adjacent tactors) through two experiments. The vibration propagation experiment investigated the effects of tactor configurations on vibration amplitude at the prosthesis–limb interface. Results revealed a positive relationship between vibration amplitude and intensity and a weak relationship between vibration amplitude and prosthetic pressure. Highest vibration amplitudes were observed when the tactor was located on the inner socket layer. The second experiment involving a sample of ten able-bodied and three amputee subjects investigated the effects of tactor configurations on user perception measured by response time, accuracy identifying tactors’ stimulation patterns, and spatial error in locating the tactors. Results showed that placing the tactors on the inner socket layer, greater spacing between adjacent tactors, and higher vibration intensity resulted in better user perception. The above findings can be directly applied to the design of vibrotactile feedback systems to increase the user response accuracy and decrease the response time required for dynamic tasks such as gait. They can also help to inform future clinical trials informing the optimization of tactor configuration variables.

A Haptic Feedback System for Lower-Limb Prostheses

2008 ◽  
Vol 16 (3) ◽  
pp. 270-277 ◽  
Author(s):  
R.E. Fan ◽  
M.O. Culjat ◽  
Chih-Hung King ◽  
M.L. Franco ◽  
R. Boryk ◽  
...  
Keyword(s):  
Lower Limb ◽  
Haptic Feedback ◽  
Feedback System ◽  
Lower Limb Prostheses

scholarly journals A Cost-Effective Inertial Measurement System for Tracking Movement and Triggering Kinesthetic Feedback in Lower-Limb Prosthesis Users

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1844
Author(s):  
McNiel-Inyani Keri ◽  
Ahmed W. Shehata ◽  
Paul D. Marasco ◽  
Jacqueline S. Hebert ◽  
Albert H. Vette
Keyword(s):  
Lower Limb ◽  
Balance Control ◽  
Low Cost ◽  
Feedback System ◽  
Inertial Measurement ◽  
Upper Limb Prosthesis ◽  
Kinesthetic Feedback ◽  
Kinesthetic Illusion ◽  
Limb Prosthesis ◽  
Lower Limb Prostheses

Advances in lower-limb prosthetic technologies have facilitated the restoration of ambulation; however, users of such technologies still experience reduced balance control, also due to the absence of proprioceptive feedback. Recent efforts have demonstrated the ability to restore kinesthetic feedback in upper-limb prosthesis applications; however, technical solutions to trigger the required muscle vibration and provide automated feedback have not been explored for lower-limb prostheses. The study’s first objective was therefore to develop a feedback system capable of tracking lower-limb movement and automatically triggering a muscle vibrator to induce the kinesthetic illusion. The second objective was to investigate the developed system’s ability to provide kinesthetic feedback in a case participant. A low-cost, wireless feedback system, incorporating two inertial measurement units to trigger a muscle vibrator, was developed and tested in an individual with limb loss above the knee. Our system had a maximum communication delay of 50 ms and showed good tracking of Gaussian and sinusoidal movement profiles for velocities below 180 degrees per second (error < 8 degrees), mimicking stepping and walking, respectively. We demonstrated in the case participant that the developed feedback system can successfully elicit the kinesthetic illusion. Our work contributes to the integration of sensory feedback in lower-limb prostheses, to increase their use and functionality.

A Lower Limb Prosthesis Haptic Feedback System for Stair Descent

2017 ◽  
Author(s):  
Astrini Sie ◽  
Jonathan Realmuto ◽  
Eric Rombokas
Keyword(s):  
Lower Limb ◽  
Haptic Feedback ◽  
The Body ◽  
Lower Limbs ◽  
Prosthetic Limbs ◽  
Stair Descent ◽  
Lower Limb Prosthesis ◽  
Limb Prosthesis ◽  
Flat Ground ◽  
Lower Limb Prostheses

Though there are a variety of prosthetic limbs that address the motor deficits associated with amputation, there has been relatively little progress in restoring sensation. Prosthetic limbs provide little direct sensory feedback of the forces they encounter in the environment, but “closing the loop” between sensation and action can make a great difference in performance [1]. For users of lower limb prostheses, stair descent is a difficult and dangerous task. The difficulty in stair descent can be attributed to three different factors: 1) Absence of tactile and haptic sensations at the bottom of the foot. Although force on the prosthetic socket provides some haptic feedback of the terrain being stepped on, this feedback does not provide information on the location of the staircase edge. 2) Insufficient ankle flexion of lower limb prostheses. Dorsiflexion of the physiological ankle during stair descent is about 27°. Even prostheses that provide active dorsiflexion provide less than this number, and regular prostheses provide almost no ankle dorsiflexion. The first two factors are analogous to the sensation of stair descent for someone without amputation wearing ski boots. 3) Prosthetic feet are optimized for flat-ground walking, offering undesirable energy storage at ankle flexion and energy return at toe-off. This can result in unwanted extra energy at the end of stance phase, propelling the user forward down the stairs. Most lower limb prosthesis designs focus on flat ground walking, but there has been less progress in addressing the challenges of stair descent. One technique that users of prosthetic lower limbs can use for addressing these challenges is to employ an “overhanging toe” foot placement strategy. Under this strategy, the edge of the staircase is used as a pivot point for the foot to roll over the stair. This reduces the need for ankle flexion by allowing the knee and hip to compensate, and avoids storing energy in the prosthetic spring. This strategy is dynamic, and requires the user to know the amount of toe overhang to adjust the movement of the rest of the body. Most haptic devices built to assist individuals wearing prostheses focus on upper extremity tasks [2–4] or standing and walking [5,6]. Whereas previous lower limb sensory replacement systems have targeted standing measures, here we focus on stair descent. The system provides cues of the stair edge location via vibrotactile stimulations on the thigh.

Effect of observation on lower limb prosthesis gait biomechanics: Preliminary results

2016 ◽  
Vol 40 (6) ◽  
pp. 739-743 ◽  
Author(s):  
Connor Malchow ◽  
Goeran Fiedler
Keyword(s):  
Outcome Measures ◽  
Lower Limb ◽  
Gait Pattern ◽  
Upper Body ◽  
Secondary Outcome ◽  
Double Support ◽  
Lateral Tilt ◽  
Gait Parameters ◽  
Lower Limb Prosthesis ◽  
Lower Limb Prostheses

Background: The Hawthorne effect, a subcategory of reactivity, causes human behavior to change when under observation. Such an effect may apply to gait variation of persons with prosthetics or orthotics devices. Objectives: This study investigated whether the presence of observers directly affects the gait pattern of users of lower limb prostheses. Study design: Within-subject intervention study. Methods: Primary outcome measures were gait parameters of initial double support time and upper body lateral tilt angle, which were collected with a mobile sensor attached to the subjects’ back. To make subjects feel unwatched, a certain amount of deception was necessary, and two different conditions were created and statistically compared against each other: one in which the subjects were initially unaware of the attention of observers and another one in which the same subjects were aware of a group of observers. Results: Data from two subjects using trans-femoral prosthesis are reported. Findings included a change in step initial double support percentage by up to 14.2% ( p = 0.019). Considerable changes were also noted in secondary outcome measures including speed, stride length, and stride symmetry. Conclusions: A reactivity effect of observation exists in prosthetics gait analysis. More comprehensive studies may be motivated by these preliminary findings. Clinical relevance Results of this study suggest that users of lower limb prostheses walk differently when their gait is being assessed (e.g. in the prosthetist’s office) than in situations without observers. This may in part explain the clinical experience that modifications of prosthetic fit or alignment provide only short-term betterment.

Optimal Model Reference Control Scheme Design for Nonlinear Strict-Feedback Systems

2020 ◽  
Vol 38 (9A) ◽  
pp. 1342-1351
Author(s):  
Musadaq A. Hadi ◽  
Hazem I. Ali
Keyword(s):  
Reference Model ◽  
Feedback System ◽  
Optimization Method ◽  
Feedback Systems ◽  
Model Reference ◽  
Scheme Design ◽  
Model Reference Control ◽  
Control Scheme ◽  
Lyapunov Stability Analysis ◽  
Strict Feedback

In this paper, a new design of the model reference control scheme is proposed in a class of nonlinear strict-feedback system. First, the system is analyzed using Lyapunov stability analysis. Next, a model reference is used to improve system performance. Then, the Integral Square Error (ISE) is considered as a cost function to drive the error between the reference model and the system to zero. After that, a powerful metaheuristic optimization method is used to optimize the parameters of the proposed controller. Finally, the results show that the proposed controller can effectively compensate for the strictly-feedback nonlinear system with more desirable performance.

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