Reproducing tactile and proprioception based on the human-in-the-closed-loop conceptual approach

Prosthetic limb embodiment remains a significant challenge for many amputees due to traditional designs' lack of sensory feedback. To address this challenge, the effectiveness of non-invasive neuromuscular electrical stimulation (NMES) controlled by a hybrid proportional-differential (PD)-Fuzzy logic system was evaluated for providing real-time proprioception and tactile feedback. The study used a human-in-the-closed-loop approach with ten participants: five upper limb amputees and five non-disabled individuals as the control group. An applied force, the joint angle of a prosthetic hand's finger, and surface electromyography signals generated by the biceps muscle all regulate the intensity of sensory feedback. Additionally, the C6 and C7 myotomes were selected as elicitation sites. The average threshold for detecting action motion and force was around 21° and 1.524N, respectively. The participants successfully reproduced desired joint angles within the range of 0°-110° at five separate intervals. In the weight recognition experiment, the amputee participant's minimum number of false predictions was four. The highest accuracy achieved was 80.66% in detecting object size and stiffness. Additionally, unpaired t-tests were performed for the means of the results of the experiments to determine statistically significant differences between groups. The results suggest that stimulation of myotomes by NMES is an effective non-invasive method for delivering rich multimodal sensation information to individuals with disabilities, including upper limb amputees, without needing visual or auditory cues. These findings contribute to the development of non-invasive sensory substitution in prostheses

The effects of manipulated somatosensory input on simulated falls during walking

Previous research has demonstrated that there is a distinct relationship between aging and instability. The somatosensory system plays a significant role in balance control in conjunction with vision and the vestibular system (Qiu et al., 2012). Evidence has shown that manipulation of the mechanoreceptors on the plantar surface of the foot has a direct effect on balance control. By manipulating these receptors with hypothermic anesthesia and vibration, researchers are capable of simulating the effect of sensory modification on healthy individuals, in order to understand the role that plantar-surface sensation has in adapting to perturbation during gait (Perry et al., 2001; Priplata et al., 2006). This study included 14 healthy young adults (mean age 23.07 (±2.43)). Within this study, participants were asked to walk the length of an 8-meter platform at a comfortable speed. Participants were required to walk with reduced, enhanced and normal levels of somatosensory information of the plantar foot surface. During walking trials the participants travelled along a raised platform that had 4 sections in which removable foam squares were placed to provide either a stable or unstable situation when stepped upon. Located underneath three of these squares were three force plates (OR-6-2000 (AMTI, Waterdown, MA)). In order to prevent learning bias the location of the foam, as well as the direction of the perturbation was randomized. Participants were perturbed in either the anterior or lateral direction based upon the direction in which the removable foam squares within the platform were placed. Moreover, participants experienced three separate conditions (control, vibration, and cooled) on the plantar surface of the foot to manipulate the sensory information received. Electromyography (AMT-8 (Bortec, Calgary, Alberta)) was used to analyze magnitude and onset changes in muscle activity within the Gastrocnemius and Tibialis Anterior of the right lower limb, and the Rectus Femoris, and Biceps Femoris muscles of the left lower limb. Three-dimensional motion analysis was also used to capture observable changes in gait (Optotrak, NDI, Waterloo, Ontario). A main effect of condition was found for the third burst of muscle activity recorded within the Tibialis Anterior (F(2,17)=2.75, p\u3c0.01), with post-hoc analysis between the cooled and vibration conditions. A significant positive correlation was found between Rectus Femoris EMG amplitude and rate of loading (r=0.94,p=0.05). Within the anterior perturbations, a main effect for condition was observed for maximum COM velocity ((F(2,35)=3.71, p=0.05), minimum COP velocity (F(2,35)=4.62, p=0.03), and for the maximum distance between COM and COP (F(2,35)=4.37, p=0.04). A trend was also observed for the maximum distance the COM travelled within the lateral direction in the BOS (F(9,35)=2.61, p=0.06). Within the lateral perturbations, a trending effect for condition was also observed for maximum COM velocity (F(2,55)=3.07, p=0.06), the maximum distance between the COM and COP (F(2,55)=2.98, p=0.06), and a main effect was observed for condition for the rate of loading (F(2,55)=3.86, p=0.03). This study provides evidence of a relationship between the plantar cutaneous mechanoreceptors and gait parameters regarding to balance control as observed by the significant effects on commonly used measurements of balance control (i.e. COP and COM velocity). A relationship between mechanoreceptors and EMG amplitude, as well as foot contact forces and EMG amplitude is also evident. These relationships may be used to further knowledge for balance control during adaptive gait, as well as provide further development of footwear and insoles to improve balance control

Multifingered robot hand robot operates using teleoperation

The purpose of research on anthropomorphic dextrous manipulation is to develop anthropomorphic dextrous robot hand which approximates the versatility and sensitivity of the human hand by teleoperation methods that will communicate in master– slave manners. Glove operates as master part and multi-fingered hand as slave. The communication medium between operator and multi-fingered hand is via KC-21 Bluetooth wireless modules. Multi-fingered hand developed using 5 volt, 298:1 gear ratio micro metal dc motors which controlled using L293D motor drivers and actuator controlled the movement of robot hand combined with dextrous human ability by PIC18F4520 microcontroller. The slave components of 5 fingers designed with 15 Degree of Freedom (DOF) by 3 DOF for each finger. Fingers design, by modified IGUS 07-16-038-0 enclosed zipper lead E-Chain® Cable Carrier System, used in order to shape mimic as human size. FLEX sensor, bend sensing resistance used for both master and slave part and attached as feedback to the system, in order to control position configuration. Finally, the intelligence, learning and experience aspects of the human can be combined with the strength, endurance and speed of the robot in order to generate proper output of this project

The effect of maximal isometric training on doublet-induced force enhancement and its relationship with changes in voluntary rate of force development

Motor unit double discharges (i.e. doublets), which are excitatory potentials that occur at shorter-than-normal intervals (e.g. 5-10 ms) during normal muscle activation, are known to cause muscle force to exceed that predicted from a standard, linear summation of twitch forces. However, although a marked increase in the occurrence of motor unit doublets at the onset of a contraction has been observed after explosive-type exercise training, and has been correlated with changes in RFD (Van Cutsem et al., 1998), little is known about the influence of strength training on the physiological and biomechanical benefits derived from the phenomenon. The present research examined the effects of 4 weeks of ‘explosive’ isometric knee extensor strength training on voluntary and electrically-evoked contractile RFD (calculated as the time derivative of the moment-time curve) in 8 untrained male participants. Electrical stimulation (NMES) trains were delivered to the muscle at 20 Hz and 40 Hz and incorporated short (5 and 10 ms) inter-pulse intervals (IPIs) at the onset of stimulation (i.e. variable-frequency trains; VFT). The influence of the short inter-pulse interval was assessed by comparison to a constant frequency train (i.e. the VFT:CFT ratio). Following the training, substantial improvements in maximum isometric knee extensor strength (MVC) (24.3 ± 13.3%, p = 0.002) and RFD measured to time intervals of 50 (55.5 ± 50.3%, p = 0.011), 100 (34.0 ± 47.2%, p = 0.01) and 150 ms (31.9 ± 38.2%, p = 0.02) were observed. RFD normalised to MVC (RFDnorm), measured to time intervals of 50 and 100 ms from the onset of contraction, improved by 44.9 ± 38.8% (p = 0.04) and 13.8 ± 12.2% (p = 0.01), respectively. There was a significant reduction in the VFT:CFT ratio after training when a 10-ms IPI preceded a 20-Hz train when measured to 30 (-13.7 ± 11.3%, p = 0.03), 50 (-13.9 ± 8.4%, p = 0.007), 100 (-8.6 ± 10.2%, p = 0.04), and 200 ms (-8.1 ± 5.3%, p = 0.009) as well as in the interval 100-200 ms (-7.4 ± 6.6%, p = 0.02). However, no significant changes were observed for other stimulation frequency-IPI combinations. Moderate-to-very strong positive correlations were observed between changes in RFDnorm and changes in VFT:CFT when measured within some time periods, particularly in the early phase of the contraction (r = 0.02 – 0.91). In conclusion, the effect of a high-frequency double discharge at stimulation onset remained unchanged or, under some conditions, was reduced after 4 weeks of explosive-type knee extensor training. Additionally, training-dependent improvements in the ability to rapidly reach a specified torque level relative to peak MVC torque (i.e. RFDnorm) were greater for those participants whose VFT:CFT ratio either did not decline or declined the least. These data provide evidence that explosive training may reduce the effect of a high frequency discharge at the onset of a contraction, and that greater increases in RFD may occur in those who most retain this ability

Investigation of the feasibility of using focal vibratory stimulation with robotic aided therapy for spasticity rehabilitation in spinal cord injury

The occurrence of a traumatic spinal cord injury is in hundreds of thousands of people every year. Survivors are left with loss of many bodily functions, loss of sensation below the point of injury and many more painful and uncomfortable repercussions which interfere with activities of daily living. Over 70% of people with SCI develop spasticity: abnormally increased muscle tone and connected joint stiffness that interfere with residual volitional control of the limbs. Treatments for spasticity include many pharmacological and non-pharmacological techniques, however many of them have severe sideeffects. Evidence suggest the use of vibratory stimulation to relieve repercussions of spasticity, despite not agreeing on the most advantageous protocol. This thesis evaluated effects that focal vibratory stimulation have on the muscle performance. Within two studies, focal muscle vibration is compared against different application conditions such as timing and location. The results suggests that if focal vibrations are applied to the relaxed muscle, the increase in muscle's force is observed. Analysis of the cortical waves indicates minimal cortical involvement in vibratory stimulation modulation. On the other hand, FV applied of the connected tendon/bone imposed to a contraction seems to have a potential to increase muscle's activation. There is evidence that motor cortex is responding to this stimulation to stabilise the muscle in order to perform the contraction. Within clinical trial, focal muscle vibratory stimulation is employed in total of 6 interventional sessions while a joint's spastic exor and extensor muscles were relaxed. Spasticity appears to be reduced as a consequence of the stimulation. Moreover, engaging the joint into robotic-aided therapy increase volitional control of the wrist, according to the analysis of the active range of motion, joint stiffness and kinematic parameters associated to the movement. The measurement and movement facilitation device used in the clinical trial was designed and developed in accordance to the spasticity and spinal cord injury repercussions consideration. The studies conducted for this thesis demonstrated feasibility and potential for the use of focal muscle vibratory stimulation to enhance muscle power in healthy muscles but also relieve consequences of spasticity. Vibrations combined with movement robotic-aided therapy have a prospects to enhance motor control

Doctor of Philosophy

dissertationUpper limb amputees desire an artificial arm that allows for multiple degrees of freedom of control over the movements of the prosthesis, coupled with direct sensory feedback. The goal of this work was to assess if it is feasible to interface artificial limbs to severed nerves of human upper limb amputees. Longitudinal intrafascicular electrodes were interfaced to severed nerve stumps of long-term human amputees. Initial studies conducted for two days following electrode implantation showed that it is possible to provide discrete, unitary, painless, graded sensations of touch, joint movement and position referred to the missing limb. Amputees were able to generate and control motor nerve activity uniquely associated with the missing limb movements. Longer term studies conducted for a period of up to 4 weeks showed recorded motor nerve activity and elicited sensations remained stable and there was no significant change in the stimulation parameters. Finally, amputees were able to control a modified Utah Artificial Arm. Results of our studies show that it is possible to interface an artificial limb to the severed nerves of upper limb amputees. Further work is required to refine the hardware which can be eventually incorporated into the artificial arm, allowing the amputees to wear the prosthesis and more precisely execute movements related to real life activities of daily living

Effect of a neuromuscular electrical stimulation muscle strength training intervention on muscle force and mass, physical health and quality of life in people with spinal cord injury

Spinal cord injury (SCI) leads to significant deficits in muscle strength and mass, impacting negatively on physical health and quality of life (QoL). Physical rehabilitation techniques for people with SCI rely on constant updates and the accumulation of evidence regarding the efficacy of available and/or new physical interventions. Neuromuscular electrical stimulation (NMES) is already commonly used to activate skeletal muscles and subsequently reverse muscle atrophy, however NMES as a high-intensity “strength training” intervention appears to be a particularly promising technique for increasing muscle strength and mass and to subsequently improve physical health and quality of life (QoL) in people with SCI. Nonetheless, there are many factors limiting the use of standard NMES protocols, and further evidence pertaining to the use of high-intensity NMES strength training in clinical populations is warranted. The primary aim of the research described in this thesis was to examine the effects of NMES as a high-intensity muscle strength training intervention, specifically using wide-pulse width (1000 μs), low-to-moderate frequency (30 Hz) NMES combined with tendon vibration, on muscle strength and mass, physical health, symptoms of spasticity and QoL in people with SCI. This thesis includes two cross-sectional studies examining the effects of patellar tendon vibration (55 Hz, 7 mm amplitude) superimposed onto wide-pulse width (1000 μs) NMES (e.g. 30 Hz over 2 s) on the peak muscular (knee extensor) force and total impulse elicited by, and rate of recovery from, the intervention in healthy subjects (Study 1) and in people with chronic SCI (Study 2). The results of Study 1 revealed that superimposing tendon vibration onto wide-pulse width NMES leads to an increase in the muscle work performed before fatigue in only some individuals (i.e. positive responders, 50% of individuals in the current study), but decreases it in others (i.e. negative responders). However, it tends to reduce the voluntary force loss that was consistently experienced after a training session using high-intensity NMES, and may thus allow for additional exercise or rehabilitation work to be performed without ongoing voluntary muscle fatigue in healthy people. The results of Study 2 also identified positive and negative responders to tendon vibration in people with SCI, however the responses were less clear and a defined effect of tendon vibration superimposed onto NMES was not discerned. In Study 3, a 12-week (twice-weekly) high-intensity NMES strength training intervention was implemented in people with chronic SCI; based on results of Study 2, high-force contractions were evoked by NMES without superimposed tendon vibration. A significant increase in muscle mass (45%) and strength (tetanic evoked force; 31.8%), amelioration of spasticity symptoms, and improvement in some aspects of physical health and QoL were observed. Therefore, the use of high-intensity NMES strength training appears to be an effective rehabilitation tool to increase muscle force and mass, ameliorate symptoms of spasticity and improve physical and mental health outcomes in people with SCI