Wearable robots based on soft materials will augment mobility and performance of the host without restricting natural kinematics. Such wearable robots will need soft sensors to monitor the movement ...of the wearer and robot outside the lab. Until now wearable soft sensors have not demonstrated significant mechanical robustness nor been systematically characterized for human motion studies of walking and running. Here, we present the design and systematic characterization of a soft sensing suit for monitoring hip, knee, and ankle sagittal plane joint angles. We used hyper-elastic strain sensors based on microchannels of liquid metal embedded within elastomer, but refined their design with the use of discretized stiffness gradients to improve mechanical durability. We found that these robust sensors could stretch up to 396% of their original lengths, would restrict the wearer by less than 0.17% of any given joint’s torque, had gauge factor sensitivities of greater than 2.2, and exhibited less than 2% change in electromechanical specifications through 1500 cycles of loading–unloading. We also evaluated the accuracy and variability of the soft sensing suit by comparing it with joint angle data obtained through optical motion capture. The sensing suit had root mean square (RMS) errors of less than 5° for a walking speed of 0.89 m/s and reached a maximum RMS error of 15° for a running speed of 2.7 m/s. Despite the deviation of absolute measure, the relative repeatability of the sensing suit’s joint angle measurements were statistically equivalent to that of optical motion capture at all speeds. We anticipate that wearable soft sensing will also have applications beyond wearable robotics, such as in medical diagnostics and in human–computer interaction.
Lower limb amputees experience gait impairments, in part due to limitations of prosthetic limbs and the lack of a functioning biarticular gastrocnemius (GAS) muscle. Energy storing prosthetic feet ...restore the function of the soleus, but not GAS. We propose a transtibial prosthesis that implements a spring mechanism to replicate the GAS. A prototype Biarticular Prosthesis (BP) was tested on seven participants with unilateral transtibial amputation. Participants walked on an instrumented treadmill with motion capture, first using their prescribed prosthesis, then with the BP in four different spring stiffness conditions. A custom OpenSim musculoskeletal model, including the BP, was used to estimate kinematics, joint torques, and muscle forces. Kinematic symmetry was evaluated by comparing the amputated and intact angles of the ankle, knee, and hip. The BP knee and ankle torques were compared to the intact GAS. Finally, work done by the BP spring was calculated at the ankle and knee. There were no significant differences between conditions in kinematic symmetry, indicating that the BP performs similarly to prescribed prostheses. When comparing the BP torques to intact GAS, higher spring stiffness better approximated peak GAS torques, but those peaks occurred earlier in the gait cycle. The BP spring did positive work on the knee joint and negative work on the ankle joint, and this work increased as BP spring stiffness increased. The BP has the potential to improve amputee gait compensations associated with the lack of biarticular GAS function, which may reduce their walking effort and improve quality of life.
Abstract The bony motion of the foot during the stance phase of gait is useful to further our understanding of joint function, disease etiology, injury prevention and surgical intervention. In this ...study, we used a 10-segment in vitro foot model with anatomical coordinate systems and a robotic gait simulator (RGS) to measure the kinematics of the tibia, talus, calcaneus, cuboid, navicular, medial cuneiform, first metatarsal, hallux, third metatarsal, and fifth metatarsal from six cadaveric feet. The RGS accurately reproduced in vivo vertical ground reaction force (5.9% body weight RMS error) and tibia to ground kinematics. The kinematic data from the foot model generally agree with invasive in vivo descriptions of bony motion and provides the most realistic description of bony motion currently available for an in vitro model. These data help to clarify the function of several joints that are difficult to study in vivo ; for example, the combined range of motion of the talonavicular, naviculocuneiform, metatarsocuneiform joints provided more sagittal plane mobility (27.4°) than the talotibial joint alone (23.2°). Additionally, the anatomical coordinate systems made it easier to meaningfully determine bone-to-bone motion, describing uniplanar motion as rotation about a single axis rather than about three. The data provided in this study allow for many kinematic interpretations to be made about dynamic foot bone motion, and the methodology presents a means to explore many invasive foot biomechanics questions under near-physiologic conditions.
Custom insoles are commonly prescribed to patients with diabetes to redistribute plantar pressure and decrease the risk of ulceration. Advances in 3D printing have enabled the creation of 3D-printed ...personalized metamaterials whose properties are derived not only from the base material but also the lattice microstructures within the metamaterial. Insoles manufactured using personalized metamaterials have both patient-specific geometry and stiffnesses. However, the safety and biomechanical effect of the novel insoles have not yet been tested clinically.
Individuals without ulcer, neuropathy, or deformity were recruited for this study. In-shoe walking plantar pressure at baseline visit was taken and sensels with pressure over 200 kPa was used to define offloading region(s). Three pairs of custom insoles (two 3D printed insoles with personalized metamaterials (Hybrid and Full) designed based on foot shape and plantar pressure mapping and one standard-of-care diabetic insole as a comparator). In-shoe plantar pressure measurements during walking were recorded in a standardized research shoe and the three insoles and compared across all four conditions.
Twelve individuals were included in the final analysis. No adverse events occurred during testing. Maximum peak plantar pressure and the pressure time integral were reduced in the offloading regions in the Hybrid and Full but not in the standard-of-care compared to the research shoe.
This feasibility study confirms our ability to manufacture the 3D printed personalized metamaterials insoles and demonstrates their ability to reduce plantar pressure. We have demonstrated the ability to modify the 3D printed design to offload certain parts of the foot using plantar pressure data and a patient-specific metamaterials in the 3D printed insole design. The advance in 3D printed technology has shown its potential to improve current care.
This paper describes the development, properties, and evaluation of a musculoskeletal model that reflects the anatomical and prosthetic properties of a transtibial amputee using OpenSim. Average ...passive prosthesis properties were used to develop CAD models of a socket, pylon, and foot to replace the lower leg. Additional degrees of freedom (DOF) were included in each joint of the prosthesis for potential use in a range of research areas, such as socket torque and socket pistoning. The ankle has three DOFs to provide further generality to the model. Seven transtibial amputee subjects were recruited for this study. 3 D motion capture, ground reaction force, and electromyographic (EMG) data were collected while participants wore their prescribed prosthesis, and then a passive prototype prosthesis instrumented with a 6-DOF load cell in series with the pylon. The model's estimates of the ankle, knee, and hip kinematics comparable to previous studies. The load cell provided an independent experimental measure of ankle joint torque, which was compared to inverse dynamics results from the model and showed a 7.7% mean absolute error. EMG data and muscle outputs from OpenSim's Static Optimization tool were qualitatively compared and showed reasonable agreement. Further improvements to the muscle characteristics or prosthesis-specific foot models may be necessary to better characterize individual amputee gait. The model is open-source and available at (
https://simtk.org/projects/biartprosthesis
) for other researchers to use to advance our understanding and amputee gait and assist with the development of new lower limb prostheses.
•A metamaterial design allows patient-specific insole stiffness.•A novel workflow to fabricate custom 3D printed elastomeric insoles was presented.•3D printed insoles matched or improved durability ...and a reduced shear stiffness.•3D printed insoles reduced regional plantar pressure compared to standard insoles.
Patients with diabetes mellitus are at elevated risk for secondary complications that result in lower extremity amputations. Standard of care to prevent these complications involves prescribing custom accommodative insoles that use inefficient and outdated fabrication processes including milling and hand carving. A new thrust of custom 3D printed insoles has shown promise in producing corrective insoles but has not explored accommodative diabetic insoles. Our novel contribution is a metamaterial design application that allows the insole stiffness to vary regionally following patient-specific plantar pressure measurements. We presented a novel workflow to fabricate custom 3D printed elastomeric insoles, a testing method to evaluate the durability, shear stiffness, and compressive stiffness of insole material samples, and a case study to demonstrate how the novel 3D printed insoles performed clinically. Our 3D printed insoles results showed a matched or improved durability, a reduced shear stiffness, and a reduction in plantar pressure in clinical case study compared to standard of care insoles.
Knee osteoarthritis is a leading cause of ambulatory disability in adults. The most prescribed mobility aid, the walking cane, is often underloaded and therefore fails to reduce knee joint loading ...and provide symptomatic relief. For this study, a novel walking cane with haptic biofeedback was designed to improve cane loading and reduce the knee adduction moment (KAM).
To determine; 1) the short-term efficacy of a novel walking cane using haptic biofeedback to encourage proper cane loading and 2) the effects of the novel cane on KAM.
Cane loading and KAM, peak knee adduction moment (PKAM), and knee adduction angular impulse (KAAI)) while walking were calculated under five conditions: 1) naïve, 2A) after scale training (apply 20%BW to cane while standing, using a beam scale), 2B) scale recall (attempt to load the cane to 20%BW), 3A) after haptic training (vibrotactile biofeedback delivered when target cane load achieved), and 3B) haptic recall (attempt to load the cane to 20%BW with vibrotactile biofeedback delivered). Compared to the naïve condition all interventions significantly increased cane loading and reduced PKAM and KAAI. No differences between haptic recall and scale recall condition were observed.
The haptic biofeedback cane was shown to be an effective and simple way to increase cane loading and reduced knee loading. Haptic biofeedback and scale training were equally effective at producing immediate short-term improvements in cane loading and knee loading. Future studies should examine the long-term effects of scale training and canes with haptic biofeedback on knee joint health, pain, and osteoarthritis disease progression.
ObjectivesDecision aids (DAs) for clients in home and community care can support shared decision-making (SDM) with patients, healthcare teams and informal caregivers. We aimed to identify DAs ...developed for home and community care, verify their adherence to international DA criteria and explore the involvement of interprofessional teams in their development and use.DesignSystematic review reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.Data sourcesSix electronic bibliographic databases (MEDLINE, Embase, CINAHL Plus, Web of Science, PsycINFO and the Cochrane Library) from inception to November 2019, social media and grey literature websites up to January 2021.Eligibility criteriaDAs designed for home and community care settings or including home care or community services as options.Data extraction and synthesisTwo reviewers independently reviewed citations. Analysis consisted of a narrative synthesis of outcomes and a thematic analysis. DAs were appraised using the International Patient Decision Aid Standards (IPDAS). We collected information on the involvement of interprofessional teams, including nurses, in their development and use.ResultsAfter reviewing 10 337 database citations and 924 grey literature citations, we extracted characteristics of 33 included DAs. DAs addressed a variety of decision points. Nearly half (42%) were relevant to older adults. Several DAs did not meet IPDAS criteria. Involvement of nurses and interprofessional teams in the development and use of DAs was minimal (33.3% of DAs).ConclusionDAs concerned a variety of decisions, especially those related to older people. This reflects the complexity of decisions and need for better support in this sector. There is little evidence about the involvement of interprofessional teams in the development and use of DAs in home and community care settings. An interprofessional approach to designing DAs for home care could facilitate SDM with people being cared for by teams.PROSPERO registration numberCRD42020169450.
Lower limb dynamic cadaveric gait simulators are useful to investigate the biomechanics of the foot and ankle, but many systems have several common limitations, which include simplified tendon ...forces, nonphysiologic tibial kinematics, greatly reduced velocities, scaled body weight (BW), and, most importantly, trial-and-error vertical ground reaction force (vGRF) control. This paper presents the design, development, and validation of the robotic gait simulator (RGS), which addresses these limitations. A 6-degrees-of-freedom (6-DOF) parallel robot was utilized as part of the RGS to recreate the relative tibia to ground motion. A custom-designed nine-axis proportional-integral-derivative (PID) force-control tendon actuation system provided force to the extrinsic tendons of the cadaveric lower limb. A fuzzy logic vGRF controller was developed, which altered tendon forces in real time and iteratively adjusted the robotic trajectory in order to track a target vGRF. The RGS was able to accurately reproduce 6-DOF tibial kinematics, tendon forces, and vGRF with a cadaveric lower limb. The fuzzy logic vGRF controller was able to track the target in vivo vGRF with an average root-mean-square error of only 5.6% BW during a biomechanically realistic 3/4 BW, 2.7-s stance phase simulation.
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