Download or read book Development and Control of a Pediatric Lower Limb Exoskeleton for Gait Guidance written by Anthony Clarence C. Goo and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several genetic, developmental and neurological disorders can cause various levels of gait impairment in the pediatric population. Powered lower limb orthoses, or exoskeletons, have recently been used to address gait impairment and afford therapists alternative solutions and strategies for gait therapy. Most exoskeleton research has focused on the adult population while the pediatric population remains underserved. The limitations of current pediatric exoskeletons make them impractical for use in both community and clinical settings. Furthermore, exoskeleton controllers suitable for these environments should promote human volitional control while guiding the subject towards a dynamically stable healthy gait pattern. This dissertation presents the design of a pediatric lower limb exoskeleton and the application of a virtual constraint-based controller on the device. First, a small and lightweight exoskeleton joint actuator capable of delivering the torque and power requirements needed to assist and guide the hip and knee joints was developed. Testing and in-air gait tracking of a model leg in a provisional orthosis demonstrated that the joint actuators were suitable for use in a pediatric exoskeleton. Second, an adjustable exoskeleton frame was designed and fabricated, and a human factors assessment of the fully assembled pediatric lower limb exoskeleton demonstrated that the device was lightweight, comfortable, easily adjustable and suitable for children. Third, a virtual constraint-based controller was applied on an underactuated adult exoskeleton. This initial investigation demonstrated that virtual constraint-based control guided the subject towards a dynamically stable gait in a time-invariant manner, provided greater volitional control to the subject and promoted active participation in the walking exercise. Finally, this dissertation research concluded with the application of a virtual constraint-based controller on the pediatric lower limb exoskeleton in treadmill walking experiments. The results showed that virtual constraint-based control reduced gait variability and the amount of robotic intervention applied relative to proportional-derivative control. Subject feedback also indicated that the virtual constraint-based controller was easier to use compared to time-based proportional-derivative control. This dissertation research demonstrates that the developed exoskeleton is suitable as an investigative platform for pediatric exoskeleton controllers and that virtual constraint-based controllers have potential for the rehabilitation and guidance of pediatric gait.

Download or read book Development and Assessment of a Control Approach for a Lower limb Exoskeleton for Use in Gait Rehabilitation Post Stroke written by Spencer Ambrose Murray and published by . This book was released on 2016 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Control of a Lower limb Exoskeleton Emulator for Accelerated Development of Gait Exoskeletons written by Kyle B. Heer and published by . This book was released on 2017 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Control Strategies for Robotic Exoskeletons to Assist Post Stroke Hemiparetic Gait written by Julio Salvador Lora Millán and published by Springer Nature. This book was released on with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigations of a Novel Lower limb Exoskeleton Control Strategy written by Nathan Roy Quinn and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A novel controller was developed with a single positional input to determine the torques for each joint of a hip-knee-ankle leg of an exoskeleton during stance, and a regenerative minimum jerk based swing control policy. Simulations were performed in MATLAB, and Simulink environments. These simulations involved using a dynamic model to evaluate if the novel controller could produce natural gait patterns. Additionally, simulations evaluating regenerative minimum jerk methods were performed in Simulink to investigate swing control applicability. The stance control results demonstrated that proper progression through stance sub-phase is generated along with predictable torque outputs, however, the lack of synchronization between legs leads to uncoordinated gait. Swing control simulations demonstrated successful implementation of a regenerative minimum jerk control policy on a three degree-of-freedom leg. Moving forward, a high-level controller could be used to finalize the control framework by ensuring synchronization between the independent legs."--Page ii.

Download or read book Multi objective User Tunable Interface for Assistance Control of a Lower Limb Exoskeleton written by Kurt Stewart and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of assistive lower limb exoskeletons lacks controllers that allow user adjustment according to their needs and desires. This thesis develops and shows simulation evidence for allowing user-intuitive control by providing adjustment of gait based on gait performance measures the user cares about while walking. Using the NSGA-II multiobjective optimization algorithm to generate trajectories for a virtual constraint-based exoskeleton system a lookup table was generated which provides user adjustment of speed, comfort, effort proxy, and natural walking measures. The findings in this thesis demonstrate a variety of gait across these performance measures which can be used to formulate a user-adjustable controller.

Download or read book Energy Recycling and Management for Lower Limb Exoskeleton written by Hao Lee and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lower Limb Exoskeleton, a wearable robot that is designed to provide lower limb assistance to users, has been rapidly developed in the previous decade. The goal of these robots is to replace human labor with robots while still having humans involved. However, while these robot suits provide sufficient assistance to the users, the efficiency of the robot is often overseen. Thus, restrict the exoskeleton's operating time or required it to connect to an external power supply. However, there is plenty of energy wasted in human motions. In this study, we target "loaded bipedal walking" as the primary motion to assist. In chapter 2, we applied trajectory optimization on different mechanical designs for lower-limb exoskeletons. It is commonly known that humans tend to use more energy to walk compared to other limb-based locomotion animals. This higher energy usage is due to "heel strikes" and "negative work" during human gait. Passive walkers elevate this phenomenon by utilizing elastic joints that absorb/reuse some of the negative work. The objective of this study is to absorb energy at one phase of the gait cycle, store it, and then release it at a later phase through the use of a lower limb exoskeleton. Knee geometry is one important factor in energy efficiency during gait. Animals with reversed knees compared to humans (backward knee), such as ostriches, exhibit improved energy efficiency. As part of this study, new energy optimization strategies were developed utilizing collision-based ground reaction forces and a discrete lagrangian. The minimal cost of transport (CoT) gait patterns were calculated with both forward-knee and backward-knee human-exoskeleton models. Simulation results show that wearing a backward-knee exoskeleton can reduce the CoT by 15% of while carrying external loads ranging from 20 to 60 kg. In addition, when the exoskeleton utilized energy recycling, the CoT was shown to be further reduced to 35%. These simulation results suggested that the optimal design for an exoskeleton aimed at utilizing energy recycling principles should incorporate backward-knee configurations much like those found in energy-efficient biped/quadruped animals. In fact, since the potential energy sources (heel strikes, negative work) and the main energy consumer (ankle push-off) occurs in the opposite legs, the ideal actuators for the exoskeleton need to be able to recycle, store, and transfer energy between different legs. To satisfy the actuator's requirements from chapter 2, in chapter 3 we choose pneumatic actuators as the actuator for our exoskeleton. Pneumatic actuators are a popular choice for wearable robotics due to their high force-to-weight ratio and natural compliance, which allows them to absorb and reuse wasted energy during movement. However, traditional pneumatic control is energy inefficient and difficult to precisely control due to nonlinear dynamics, latency, and the challenge of quantifying mechanical properties. To address these issues, In chapter 3, we developed a wearable pneumatic actuator with energy recycling capabilities and applied the sparse identification of nonlinear dynamics (SINDy) algorithm to generate a nonlinear delayed differential model from simple pressure measurements. Using only basic knowledge of thermal dynamics, SINDy was able to train models of solenoid valve-based pneumatic systems with a training accuracy of 90.58% and a test accuracy of 86.44%. The generated model, when integrated with model predictive control (MPC), resulted in a 5% error in pressure control. By using MPC for human assistive impedance control, the actuator was able to output the desired force profile and recycle around 88% of the energy used in negative work. These results demonstrate an energy-efficient and easily calibrated actuation scheme for designing assistive devices such as exoskeletons and orthoses. In chapter 4, we presented Pneumatic Exoskeleton with Reversible Knee (PERK). It utilizes the pneumatic actuators we developed in chapter 3 and the control strategies we concluded in chapter 2. Three clinical trials were done on three different test subjects. The results showed despite different walking patterns across different test subjects, there is less potential energy change during the swing phase of walking, potentially reducing the energy loss during the heel strike. In addition, during the double support phase, there is less energy consumption in the pneumatic system while configuring it as backward-knee, indicating it is easier or more intuitive for the user to have the exoskeleton recycling the dissipated energy with the backward-knee mechanism.

Download or read book Development of a Lightweight and High Strength Underactuated Lower Limb Robot Exoskeleton for Gait Rehabilitation written by Fahad Hussain and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of robot-assisted physical rehabilitation and robotics technology for providing support to the elderly population is rapidly evolving. Lower limb robot aided rehabilitation and assistive technology have been a focus for the engineering community over the last three decades as several robotic lower limb exoskeletons have been proposed in the literature as well as some being commercially available. One of the most important aspects of developing exoskeletons is the selection of the appropriate material. Strength to weight ratio is the most important factor to be considered before selection of a manufacturing material. The material selection strongly influences the overall weight and performance of the exoskeleton robot. In addition to material selection the type of mechanism and the actuation strongly effect the overall weight of the lower limb robotic exoskeleton. Most of the lower limb exoskeleton provided in the literature use a parallel mechanism, are properly actuated and either use aluminium or steel as their manufacturing materials. All these factors significantly increase the weight of the lower limb robot exoskeleton and make the device heavy, bulky, and uncomfortable for the wearer. Furthermore, an increase in weight contributes to a decrease of energy efficiency, reduces the energy efficiency of the final product, and increase the running cost of the designed robot devices. This thesis explores the wide-ranging potential of lower limb robot exoskeletons in the context of physical rehabilitation. Implementation and testing of a lightweight and high strength material without effecting the reliability was the main research objective of the present work. In this research, a linkage based under-actuated mechanism was used for the development of a lightweight design. Structural and mechanical load analysis of the mechanism was performed by using an advanced approach of finite element analysis. Three materials, namely structural steel, aluminium, and carbon reinforced fibre were compared as the manufacturing materials of the modelled mechanism. After that, a weight estimation was carried out for all three materials and the material which exhibits the best response under mechanical load analysis was selected. From the weight comparison, the carbon reinforced fibre provided the least weight for the digital twin of a lower limb exoskeleton. After material selection, the next step was the topology optimisation to further decrease the mass of the designed prototype without effecting the mechanical performance. The optimisation was carried out by using a multi-mode single objective genetic algorithm (GA) and a reduction of 30 % in the weight of the designed prototype was obtained. The selected material, which is carbon fibre, is a type of polymer material that is highly anisotropic, meaning it shows different material behaviour in different orientations of applied force. The next stage of the research work was the material characterization of the manufacturing material, which was carried out both analytically and experimentally. For defining the optimal criteria for fiber orientation, Hashin's Failure Criteria is considered, and experimental work is performed to determine the most suitable fibre orientation. The material monotonic tensile properties were experimentally determined by experimental work and used to select a suitable orientation to manufacture a physical prototype model of the lower limb robot exoskeleton. After that the manufacturing process was carried out which is divided into three main steps. The first step was the use of the suitable lightweight and high strength material, which was selected by weight comparison in the design stage. The second step was the use of a single actuator to actuate the whole mechanical system and the final step was the use fabrication method to get a strong and reliable structure. Shaping of the different exoskeleton parts was carried out by CNC milling and parts were assembled to build a robotic prototype. A DC motor was used to actuate the complete prototype, which includes hip, knee, and ankle joints. In the end, a reliability analysis was carried out by using a machine learning based approach. A machine learning framework was developed for time-dependent reliability analysis of the developed robot. A neural network algorithm was designed to estimate the time-dependent reliability of the joint displacement and the positions of the end-effector first. From the above methodology, a lightweight and high strength lower limb robot exoskeleton was just not only conceptualized but a significant work was done to get a physical model starting from the material selection and concluding with the fabrication of a physical prototype. The reliability analysis gives an overview of the mechanism safety as a function of joint displacement. The designed prototype of carbon reinforced fibre was four times lighter in weight as compared to steel and three times lighter than aluminium, which is expected to give the wearer a comfortable wearing experience and improves the overall physical rehabilitation experience for the patients.

Download or read book Design and Development of a Powered Pediatric Lower limb Orthosis written by Curt A. Laubscher and published by . This book was released on 2020 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gait impairments from disorders such as cerebral palsy are important to address early in life. A powered lower-limb orthosis can offer therapists a rehabilitation option using robot-assisted gait training. Although there are many devices already available for the adult population, there are few powered orthoses for the pediatric population. The aim of this dissertation is to embark on the first stages of development of a powered lower-limb orthosis for gait rehabilitation and assistance of children ages 6 to 11 years with walking impairments from cerebral palsy.This dissertation presents the design requirements of the orthosis, the design and fabrication of the joint actuators, and the design and manufacturing of a provisional version of the pediatric orthosis. Preliminary results demonstrate the capabilities of the joint actuators, confirm gait tracking capabilities of the actuators in the provisional orthosis, and evaluate a standing balance control strategy on the under-actuated provisional orthosis in simulation and experiment. In addition, this dissertation presents the design methodology for an anthropometrically parametrized orthosis, the fabrication of the prototype powered orthosis using this design methodology, and experimental application of orthosis hardware in providing walking assistance with a healthy adult. The presented results suggest the developed orthosis hardware is satisfactorily capable of operation and functional with a human subject. The first stages of development in this dissertation show encouraging results and will act as a foundation for further development of the device for rehabilitation and assistance of children with walking impairments.

Download or read book DESIGN AND DEVELOPMENT OF LOWER LIMB EXOSKELETON FOR REHABILITATION written by YUGAN A/L VELUSAMY (TP016733) and published by . This book was released on 2013 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 2020 International Conference on Computational Performance Evaluation ComPE written by IEEE Staff and published by . This book was released on 2020-07-02 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Performance Evaluation of Emerging Computing, Electrical, Electronics, Management, and Health Technologies

Download or read book Development of Effective Hip knee ankle Exoskeleton Assistance for Different Walking Conditions written by Gwendolyn Bryan and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lower-limb exoskeletons could assist people in a variety of locomotor activities such as walking, running, jumping, and carrying loads. These devices could be beneficial to first responders, military personnel, laborers, and in the future, may be able to assist patient populations and older adults. Recent successful strategies for able-bodied individuals have reduced the metabolic cost of walking by up to 24% when assisting the hips, ankles or both joints. However, there has been limited exploration into simultaneous assistance at the hips, knees, and ankles which may lead to the greatest metabolic reductions of any joint configuration. It is currently unclear how to effectively assist the whole leg as well as how that effective assistance should vary with gait condition. In my doctoral research, I developed a bilateral lower-limb exoskeleton emulator and used it to optimize hip-knee-ankle exoskeleton assistance in a variety of gait conditions. This device is a flexible research testbed that can quickly apply a wide variety of assistance strategies by simply updating the device controller. We used the bilateral lower-limb exoskeleton emulator to optimize hip-knee-ankle exoskeleton assistance through human-in-the-loop optimization, a strategy that adjusts exoskeleton assistance in real time using online user performance measurements. In the first optimization study, we optimized exoskeleton assistance to minimize metabolic cost at slow (1.0 m/s), medium (1.25 m/s) and fast (1.5 m/s) walking speeds. Exoskeleton assistance reduced the metabolic cost of walking relative to walking in the device without assistance by 26% for slow walking, 47% for medium-speed walking, and 50% for fast walking. In the second study, we optimized exoskeleton assistance to minimize the metabolic cost of walking with no load, a light load (15% of user body weight), and a heavy load (30% of user body weight). The weight was applied through a weight vest. Exoskeleton assistance reduced the metabolic cost of walking by 48% with no load, 36% with the light load, and 43% with the heavy load. The results of these studies show that hip-knee-ankle exoskeleton assistance can substantially decrease the metabolic cost of walking at a variety of speeds and with different worn loads. The results from these studies could inform the design of future exoskeleton products and influence future exoskeleton experiments. Exoskeleton products could use the optimized torque profiles found here to dictate needed device capabilities, and the metabolic reductions from these studies provide a benchmark for expected performance. Future exoskeleton experiments could use the optimized torque profiles as a starting point to investigate useful exoskeleton assistance in novel gait conditions, during non-steady state walking, and with patient populations or older adults. While optimizing exoskeleton assistance to reduce metabolic cost was effective for able-bodied adults, it may be beneficial to investigate alternative performance metrics for patient populations like increasing self-selected walking speed or enhancing balance. The results of these studies could inform effective exoskeleton assistance for future products and studies for years to come.

Download or read book Novel Control for a Post Stroke Gait Rehabilitation Exoskeleton written by Robert Trott and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stroke is the second highest cause of death worldwide and the third leading cause of adult disability across all age brackets. Recovering gait following stroke is a major goal of patients, and hence rehabilitation, as it is central to many activities of daily living. Of the different treatment modalities, robotic assisted gait training is growing in popularity, but is still considered complementary to, and not substitute for conventional therapies comprising physiotherapy, overground walking and body weight supported treadmill training. The potential advantages that lower limb robotics bring to neurorehabilitation over conventional therapies include, higher dosage, specificity, improved consistency, and duration, though these benefits have been slow to manifest. Exoskeletons are well placed to provide these benefits, as well as environmental variation and task salience if they can be used away from outpatient settings. Control strategies that may be enhancing of recovery are often confined to stationary exoskeletons, and the control of mobile exoskeletons is only loosely related to gait, if at all, which limits rehabilitation outcomes. -- The primary aim of this PhD thesis was to develop an adaptive, user-initiated gait Controller that aims to target a novel neural recovery pathway. The Controller would use a robotic exoskeleton, with the intention of developing novel neuroplasticity that is beneficial for gait and would be permissive of simultaneous control of hip and knee posture. A theoretical framework based on the principles of neuroplasticity was proposed that seeks to bring higher engagement, task variance, and volition to gait rehabilitation. This framework considers stroke and rehabilitation timelines and the interaction of the proposal with existing theory, how beneficial neuroplasticity may manifest, and how the proposal may be detrimental. A comprehensive survey of candidate lower limb devices followed (164 devices), to understand exactly what features are compatible, complementary, or contradictory to the proposed control method, and to understand the implications the various specifications have. Specifically, it was found that ambulating exoskeletons that can move around the environment were preferred for their ability to be used in the community and the home, and that extended joint range of motion will be permissive of activities that are supportive of gait such as sit-to-stand and stair ascent/descent. Of the various control systems that have been implemented with exoskeleton devices, trajectory control, where motion is enforced on the limb by the exoskeleton, is preferred. -- The method of control was assessed for suitability as a gait controller through a participant study (n = 21). Participants were asked to reproduce the motion required for the controller, and with minor modification to participant motion it was shown that reliable control signals can be obtained. The remainder of the thesis applies the learnings of the previous stages in the development of the Controller and an accompanying Sensor. The custom Sensor was designed with a small form factor to be applied on the Controller. The thesis concludes with an implementation of the Controller and a successful demonstration of the proposed concept, where the control signals are reproduced on a scale lower limb exoskeleton. The full technical detail and specification of the Controller, and the custom position Sensor developed specific for this application, are presented as part of this work. -- This work has added a new theoretical framework for gait control following stroke and has added technological capability to implement the proposal. It is the primary recommendation of this PhD that the novel control method be tested further with participant studies and that the component hardware be developed further. Therapies targeting novel recovery mechanisms breathe fresh air into rehabilitation and may inspire other new treatments, and future funded work originating from this PhD will see the concept tested with a chronic stroke population, using an ambulating exoskeleton and the Controller.

Download or read book Design of a Powered Lower limb Exoskeleton and Control for Gait Assistance in Paraplegics written by Ryan James Farris and published by . This book was released on 2012 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Motion Control of a Lower Limb Robotic Exoskeleton written by Ümit Önen and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter presents the results of research work on design, actuator selection and motion control of a lower extremity exoskeleton developed to provide legged mobility to spinal cord injured (SCI) individuals. The exoskeleton has two degrees of freedom per leg. Hip and knee joints are actuated in the sagittal plane by using DC servomotors. Additional effort supplied by user's arms through crutches is defined as user support rate (USR). Experimentally determined USR values are considered in actuator torque computations for achieving a realistic actuator selection. A custom-embedded system is used to control exoskeleton. Reference joint trajectories are determined by using clinical gait analysis (CGA). Three-loop cascade controllers with current, velocity and position feedback are designed for controlling the joint motions of the exoskeleton. A non-linear ARX model is used to determine controller parameters. Overall performance and an assistive effect of WSE-2 are experimentally investigated by conducting tests with a paraplegic patient with T10 complete injury.

Download or read book Autonomous Assistance as needed Control of a Lower Limb Exoskeleton with Guaranteed Stability written by Samuel Campbell and published by . This book was released on 2020 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lower-limb stroke rehabilitation is physically demanding on therapists and requires the concerted effort of multiple staff members. Researchers have accordingly begun investigating the use of lower-limb exoskeletons for rehabilitation. Unfortunately, if the exoskeleton ensures the correct trajectory regardless of whether or not the user contributes effort, rehabilitation can be ineffective as the patient can begin to slack. Recent research suggests using assistance-as-needed control to facilitate functional motor recovery by only applying torques if the patient deviates too far from the desired trajectory. Assistance-as-needed control has been difficult to employ in lower-limb exoskeletons, however, due to the need to ensure stability. This work demonstrates how virtual constraint control—a method used in prostheses and assistive exoskeleton control with robust stability properties—can be combined with a velocity-modulated deadzone to ensure stability. The simulations suggest the method can accommodate a large deadzone while remaining stable across a range of gait pathologies.

Download or read book Energy Shaping Control of Powered Lower limb Exoskeletons for Assistance of Human Locomotion written by Ge Lv and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The majority of powered lower-limb exoskeletons nowadays are designed to rigidly track time-based kinematic patterns, which forces users to follow specific joint positions. This kinematic control approach is limited to replicating the normative joint kinematics associated with one specific task and user at a time. These pre-defined trajectories cannot adjust to continuously varying activities or changes in user behavior associated with learning during gait rehabilitation. Time-based kinematic control approach must also recognize the user’s intent to transition from one task-specific controller to another, which is susceptible to errors in intent recognition and does not allow for a continuous range of activities. Moreover, fixed joint patterns also do not facilitate active learning during gait rehabilitation. People with partial or full volitional control of their lower extremities should be allowed to adjust their joint kinematics during the learning process based on corrections from the therapist. To address this issue, we propose that instead of tracking reference kinematic patterns, kinetic goals (for example, energy or force) can be enforced to provide a flexible learning environment and allow the user to choose their own kinematic patterns for different locomotor tasks. In this dissertation, we focus on an energetic control approach that shapes the Lagrangian of the human body and exoskeleton in closed loop. This energetic control approach, known as energy shaping, controls the system energy to a specific analytical function of the system state in order to induce different dynamics via the Euler-Lagrange equations. By explicitly modeling holonomic contact constraints in the dynamics, we transform the conventional Lagrangian dynamics into the equivalent constrained dynamics that have fewer (or possibly zero) unactuated coordinates. Based on these constrained dynamics, the matching conditions, which determine what energetic properties of the human body can be shaped, become easier to satisfy. By satisfying matching conditions for human-robot systems with arbitrary system dimension and degrees of actuation, we are therefore able to present a complete theoretical framework for underactuated energy shaping that incorporates both environmental and human interaction. Simulation results on a human-like biped model and experimental results with able-bodied subjects across a variety of locomotor tasks have demonstrated the potential clinical benefits of the proposed control approach.