A Multimodal Sensory Apparatus for Robotic Prosthetic Feet Combining Optoelectronic Pressure Transducers and IMU

Timely and reliable identification of control phases is functional to the control of a powered robotic lower-limb prosthesis. This study presents a commercial energy-store-and-release foot prosthesis instrumented with a multimodal sensory system comprising optoelectronic pressure sensors (PS) and IMU. The performance was verified with eight healthy participants, comparing signals processed by two different algorithms, based on PS and IMU, respectively, for real-time detection of heel strike (HS) and toe-off (TO) events and an estimate of relevant biomechanical variables such as vertical ground reaction force (vGRF) and center of pressure along the sagittal axis (CoPy). The performance of both algorithms was benchmarked against a force platform and a marker-based stereophotogrammetric motion capture system. HS and TO were estimated with a time error lower than 0.100 s for both the algorithms, sufficient for the control of a lower-limb robotic prosthesis. Finally, the CoPy computed from the PS showed a Pearson correlation coefficient of 0.97 (0.02) with the same variable computed through the force platform

Computational Tools and Experimental Methods for the Development of Passive Prosthetic Feet

Modern prosthetic foot designs are incredibly diverse in comparison to what was o↵ered to amputees at the turn of the millennium. Powered ankles can supply natural levels of joint torque, whilst passive feet continue to optimise for kinematic goals. However, most passive feet still do not solve the issue of unhealthy loads, and an argument can be made that optimisation methods have neglected the less active and elderly amputee. This thesis creates a framework for a novel approach to prosthetic foot optimisation by focusing on the transitionary motor tasks of gait initiation and termination.An advanced FEA model has been created in ANSYS® using boundary con-ditions derived from an ISO testing standard that replicates stance phase loading. This model can output standard results found in the literature and goes beyond by parameterising the roll-over shape within the software using custom APDL code. Extensive contact exploration and an experimental study have ensured the robustness of the model. Subject force and kinematic data can be used for specific boundary conditions, which would allow for easy adaptation to the transitionary motor tasks.This FEA model has been used in the development of prosthetic experiment tool, which can exchange helical springs to assess e↵ects of small changes in sti↵-ness on gait metrics. A rigorous design methodology was employed for all compo-nents, including parametric design studies, response surface optimisation, and ISO level calculations. The design has been manufactured into a working prototype and is ready for clinical trials to determine its efficacy.The conclusion of this framework is in the development of an experimental method to collect subject data for use in the models. A pilot study uncovered reliable protocols, which were then verified with ANOVA statistics. Proportional ratios were defined as additions to metric peak analyses already found in the liter-ature. These tools are ready for deployment in full clinical trials with amputees, so that a new prosthetic optimisation pathway can be discovered for the benefit of less active or elderly amputees

Enhancing Biomechanical Function through Development and Testing of Assistive Devices for Shoulder Impairment and Total Limb Amputation

Assistive devices serve as a potential for restoring sensorimotor function to impaired individuals. My research focuses on two assistive devices: a passive shoulder exoskeleton and a muscle-driven endoprosthesis (MDE). Previous passive shoulder exoskeletons have focused on testing during static loading conditions in the shoulder. However, activities of daily living are based on dynamic tasks. My research for passive shoulder exoskeletons analyzes the effect that a continuous passive assistance has on shoulder biomechanics. In my research I showed that passive assistance decreases the muscular activation in muscles responsible for positive shoulder exoskeleton. An MDE has the potential to have accurate and precise control of movement as well as restore a sense of proprioception to the user. Such a transformative and invasive device has never previously been tested. Therefore, my research focused on analyzing fundamental principles of the MDE in an in-vivo rabbit model. The two concepts I tested in my research were the feasibility of implanting an orthopedic device underneath the skin at the distal end of a limb following amputation and the locomotor restorative capabilities of an artificial tendon used for muscle-device connection. In my work I proved the feasibility of implanting fully-footed rigid endoprostheses underneath the skin and isolated the primary factors for a successful surgery and recovery. In addition, my research showed that although artificial tendons have the potential to restore locomotor function, proper in-situ tendon lengths must be achieved for optimal movement. This research informed the design and testing of a fully jointed muscle-driven endoprosthesis prototype

Peak Trailing Limb Angle and Propulsion Symmetry in Individuals with Below Knee Amputation

Background: Individuals with lower extremity amputation often present with kinematic and kinetic gait asymmetries and often have difficulty achieving symmetrical walking using their prescribed prosthesis. To understand the impact of limb loss on gait measures, studies often compare individuals with lower limb amputation to healthy control participants or compare the amputated limb to the uninvolved limb while completing a specified task like steady state walking. Commonly implemented treatments for individuals with lower limb amputation are based upon the assumption that equal use of both legs (symmetry) while completing bipedal tasks (e.g., walking) would be beneficial, matching the behavior seen in healthy control individuals. Underlying kinematic or kinetic symmetry, as well as a potential relationship of the two biomechanical gait variables in individuals with below knee amputation have not been thoroughly evaluated during steady state treadmill walking. Methods: We explored potential underlying (a)symmetries in peak trailing limb angle (kinematic) and peak anterior ground reaction force (kinetic) in individuals with below knee amputation walking at self-selected walking speed on a treadmill without upper extremity support. We then implemented real-time visual feedback to alter symmetry and examine the potential relationship between peak trailing limb angle and peak anterior ground reaction force. Later, we recruited and tested healthy control individuals with and without a solid ankle foot orthosis (SAFO) walking at their self-selected walking speed on a treadmill and exposed them to a similar visual feedback program to alter their baseline (a)symmetry. Population: We enrolled eleven of the planned twenty-four individuals with unilateral below knee amputation and fourteen healthy control participants without any lower extremity pathology or gait abnormality. Results: We found that individuals with below knee amputation do have peak trailing limb and anterior ground reaction force asymmetries and unencumbered healthy control individuals demonstrate symmetry of the same outcome measures while walking on a treadmill at self-selected walking speed. The use of real time visual feedback yielded statistically significant differences in peak trailing limb angle in healthy control participants without a solid ankle foot orthosis (p=0.04), peak and impulse anterior ground reaction forces when wearing a solid ankle foot orthosis (p=0.04). Statistically significant correlation between peak trailing limb angle and peak anterior ground reaction force were found in individuals with below knee amputation at baseline (p=0.0004), with real time visual feedback for peak trailing limb angle (p\u3c0.0001), and peak anterior ground reaction force (p=0.0002). Conclusions: Real time visual feedback is one intervention used to alter walking symmetry. Our results do not demonstrate an overwhelming response to real time visual feedback by individuals with below knee amputation or their healthy control counterparts and should be interpreted with caution. This work does provide meaningful information for further studies and interventions to alter symmetry during steady state walking and begins to explore the potential relationship between peak trailing limb angel and peak anterior ground reaction force production during self-selected treadmill walking in individuals with below knee amputation as well as otherwise healthy control individuals

The Influence of Asymmetry on the Metabolic Cost of Locomotion

In this dissertation, the measurement and impact of asymmetrical locomotion were investigated. In the first study, ten able-bodied individuals were asked to run on a treadmill from which interlimb symmetries of joint level kinematics and kinetics were measured. To obtain a stable measure of interlimb symmetry, an average of 15 strides were needed. However, no differences were found between averages from bins of consecutive and inconsecutive strides. Further, no differences were noted between the average interlimb symmetry and interlimb symmetries calculated from the first, middle, or last, strides. Although there were differences between symmetry calculations, neither measure required a greater number of strides to become a stable measure of interlimb symmetry. In study two, ten able-bodied individuals were asked to walk on a treadmill from which interlimb symmetries of joint level kinematics and spatiotemporal parameters were calculated. The interlimb symmetries became stable with an average of 8 strides. No systematic differences between subsets of three, five, or eight strides were noted. Further, no differences were noted between subsets when utilizing consecutive or inconsecutive strides. Finally, although it required eight strides to achieve a stable mean symmetry index, no differences were noted between the average interlimb symmetry index of the first three, five, and eight strides for all measures. In study three, the metabolic cost of walking asymmetrically was explored for ten able-bodied individuals. Walking with a unilaterally added 2kg mass at the ankle resulted in an increased metabolic cost of walking compared with normal walking. The asymmetrical swing times were calculated and replicated without the mass via an audible metronome that when matched to initial foot strikes resulted in asymmetrical swing times. This temporally asymmetrical swing time also resulted in an increased metabolic cost of walking compared with normal walking. Additionally, walking to a symmetrical metronome with the added mass increased the metabolic cost of walking. Forcing temporal symmetry when walking with a unilaterally added mass and forcing temporal asymmetry when walking without a unilaterally added mass were found to result in metabolic penalty compared with unmanipulated walking with and without a unilaterally added mass. The findings of this dissertation indicate that 15 and 8 strides should be collected when studying interlimb symmetries during running and walking, respectively. However, whether the strides are collected consecutively or whether these strides are collected early or late within a trial does not appear to effect results. Further, there does not appear to be a statistical difference between the strides required to achieve a stable mean and fewer strides in able-bodied locomotion. Lastly, forcing an unnatural temporal gait pattern will result in a metabolic penalty during walking. Without interlimb mass differences, an asymmetrical gait pattern results in a greater metabolic cost of walking than a symmetrical gait pattern. More importantly for persons with a unilateral amputation; when interlimb mass differences are present, a symmetrical gait pattern results in a greater metabolic cost of walking than an asymmetrical gait pattern

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development