The goal of this study was to validate a series elastic actuator (SEA)-based robotic arm that can mimic three abnormal muscle behaviors, namely lead-pipe rigidity, cogwheel rigidity, and spasticity ...for medical education training purposes. Key characteristics of each muscle behavior were first modeled mathematically based on clinically-observed data across severity levels. A controller that incorporated feedback, feedforward, and disturbance observer schemes was implemented to deliver haptic target muscle resistive torques to the trainee during passive stretch assessments of the robotic arm. A series of benchtop tests across all behaviors and severity levels were conducted to validate the torque estimation accuracy of the custom SEA (RMSE: ~ 0.16 Nm) and the torque tracking performance of the controller (torque error percentage: < 2.8 %). A clinical validation study was performed with seven experienced clinicians to collect feedback on the task trainer's simulation realism via a Classification Test and a Disclosed Test. In the Classification Test, subjects were able to classify different muscle behaviors with a mean accuracy > 87 % and could further distinguish severity level within each behavior satisfactorily. In the Disclosed Test, subjects generally agreed with the simulation realism and provided suggestions on haptic behaviors for future iterations. Overall, subjects scored 4.9 out of 5 for the potential usefulness of this device as a medical education tool for students to learn spasticity and rigidity assessment.
Pressure ulcers (PUs) are prevalent among immobile bed or wheelchair-reliant individuals who experience prolonged sedentary positions. Pressure relief and frequent repositioning of body posture help ...to mitigate complications associated with PUs. Adherence with regular repositioning is difficult to maintain due to nursing labour shortages or constraints of in-home caregivers. Manual repositioning, transferring, and lifting of immobile patients are physically demanding tasks for caregivers. This review aimed to explore and categorize these devices, discuss the significant technical challenges that need addressing, and identify potential design opportunities.
In this review, a literature search was conducted using PubMED, Science Direct, Google Scholar and IEEE Xplore databases including studies from 1995 until Feb 2023 with keywords such as pressure ulcer, assistive device, pressure relief, repositioning, transfer, etc. Both commercial and research-level devices were included in the search.
142 devices or technologies were identified and classified into four main categories that were further subcategorized. Within each category, the devices were investigated in terms of their mechanical design, actuation methods, control strategies, sensing technologies, and level of autonomy. Limitations of current technologies are design complexity, lack of patient comfort, and a lack of autonomy requiring caregivers frequent intervention.
Several devices have been developed to help with prevention and mitigation of PUs. There remain challenges that hinder the widespread accessibility and use of current technologies. Advancements in assistive technologies for pressure ulcer mitigation could lie at the intersection of robotics, sensors, perception, user-centered design, and autonomous systems.
IMPLICATIONS FOR REHABILITATION
Future advancements in assistive technologies for pressure ulcer mitigation could lie at the intersection of robotics, sensors, perception, user-centered design, and autonomous systems.
Most existing technologies for prevention of pressure ulcers are focused on the mechanical advantage rather than user's needs and preferences. Future designers, engineers, and product developers must be educated to conduct user needs studies concurrently with the development of technology to design the devices based on the user's needs to ensure a balanced design outcome.
To fulfill the need for reliable and consistent medical training of the neurological examination technique to assess ankle clonus, a series elastic actuator (SEA) based haptic training simulator was ...proposed and developed. The simulator's mechanism (a hybrid of belt and linkage drive) and controller (impedance control) were designed to render a realistic and safe training environment. Benchtop tests demonstrated that the prototype simulator was able to accurately estimate the interaction torque from the trainee (average RMSE of 0.2 Nm) and closely track a chirp torque command up to 10 Hz (average RMSE of <0.22 Nm). The high-level impedance controller could switch between different clinically encountered states (i.e., no clonus, unsustained clonus, and sustained clonus) based on trainee's assessment technique. The simulator was evaluated by a group of 17 experienced physicians and physical therapists. Subjects were instructed to induce sustained clonus using their normal technique. The simulator was assessed in two common clinical positions (seated and supine). Subjects scored simulation realism on a variety of control features. To expedite controller design iteration, feedback from Day 1 was used to modify simulation parameters prior to testing on Day 2 with a new subject group. On average, all subjects could successfully trigger a sustained clonus response within 4-5 attempts in the first position and 2-3 in the second. Feedback on the fidelity of simulation realism improved between Day 1 and Day 2. Results suggest that this SEA-based simulator could be a viable training tool for healthcare trainees learning to assess ankle clonus.
ABSTRACT
Introduction: X‐linked myopathy with excessive autophagy (XMEA) is characterized by autophagic vacuoles with sarcolemmal features. Mutations in VMA21 result in insufficient lysosome ...acidification, causing progressive proximal weakness with onset before age 20 years and loss of ambulation by middle age. Methods: We describe a patient with onset of slowly progressive proximal weakness of the lower limbs after age 50, who maintains ambulation with the assistance of a cane at age 71. Results: Muscle biopsy at age 66 showed complex muscle fiber splitting, internalized capillaries, and vacuolar changes characteristic of autophagic vacuolar myopathy. Vacuoles stained positive for sarcolemmal proteins, LAMP2, and complement C5b‐9. Ultrastructural evaluation further revealed basal lamina reduplication and extensive autophagosome extrusion. Sanger sequencing identified a known pathologic splice site mutation in VMA21 (c.164–7T>G). Conclusions: This case expands the clinical phenotype of XMEA and suggests VMA21 sequencing be considered in evaluating men with LAMP2‐positive autophagic vacuolar myopathy. Muscle Nerve 50: 138–144, 2014
This paper describes the development of a 1-DOF kinesthetic force display device in the form of an arm training simulator that replicates the haptic feeling of lead-pipe rigidity in the elbow joint. ...Patients with lead-pipe rigidity have uniformly elevated muscle tone throughout the range of motion, which is an important clinical sign for diagnosing Parkinson's disease during a neurological examination. The simulator could provide training opportunities for healthcare trainees to learn and practice the assessment technique for lead-pipe rigidity. The simulator was driven by a series elastic actuator in order to have more accurate joint torque control in a safe and cost-effective manner for rendering abnormal muscle resistance. A mathematical model of lead-pipe rigidity based on hyperbolic tangent was proposed to recreate the elevated muscle resistance at different Unified Parkinson's Disease Rating Scale (UPDRS) 0-3. Performance of the simulator was evaluated through benchtop tests and rigidity simulation tests. Preliminary results suggested the simulator had good torque control accuracy (an average RMSE < 0.27 Nm) and good fidelity in mimicking clinically-measured lead-pipe rigidity at UPDRS 0-3.
PDF
