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Background
Functional neuromuscular stimulation, lower limb orthosis, powered lower limb exoskeleton, and hybrid neuroprosthesis (HNP) technologies can restore stepping in individuals with paraplegia due to spinal cord injury (SCI). However, a self-contained muscle-driven controllable exoskeleton approach based on an implanted neural stimulator to...
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Assistive technology (AT) is any device, software, or equipment designed for and used by individuals with disabilities to engage in everyday activities and achieve independence. However, the usefulness of those technology-based or supported treatments is a complex issue that has led to the development of various conceptual models for assistive tech...
Wearable exoskeletons have showed improvements in levels of disability and quality of life in people with neurological disorders. However, it is important to understand users’ perspectives. The aim of this study was to explore the patients’ and physiotherapists’ satisfaction from gait training with the EKSO GT® exoskeleton in people with multiple s...
Background
Spinal cord injury (SCI) is a serious clinical condition that impacts a patient's physical, psychological, and socio-economic status. The aim of this pilot study was to evaluate the effects of training with a newly developed powered wearable exoskeleton (Hyundai Medical Exoskeleton [H-MEX]) on functional mobility, physiological health, a...
Abstract Background The Hand Extension Robot Orthosis (HERO) Grip Glove was iteratively designed to meet requests from therapists and persons after a stroke who have severe hand impairment to create a device that extends all five fingers, enhances grip strength and is portable, lightweight, easy to put on, comfortable and affordable. Methods Eleven...
Citations
... Although joint torque and motion can be precisely controlled with actuators equipped in an exoskeletal system, the heavy weight of the system makes it difficult for patients to wear and operate it for a long time. Researchers have investigated various control methods for hybrid systems of FES and exoskeletons to track the desired joint movements (Durfee, 2006;Quintero et al., 2010;Farris et al., 2011;Sharma et al., 2013;Ha et al., 2015;Chang et al., 2017). Ha et al. (2015) proposed to control the profile for muscle stimulation based on the difference between motor torque and muscle torque estimation to minimize the contribution of motor in joint trajectory tracking. ...
... Ha et al. (2015) proposed to control the profile for muscle stimulation based on the difference between motor torque and muscle torque estimation to minimize the contribution of motor in joint trajectory tracking. Chang et al. (2017) developed a hybrid system for paraplegic patients utilizing a sensor-driven finite state machine to determine gait phases for stepping. Sharma et al. (2013) developed a gait simulation model of a hybrid system of FES and knee-ankle foot orthosis (KAFO), and by using the simulation model they proposed control parameters to optimize the gait rehabilitation system. ...
... In this study, EMG data from healthy human participants was used to produce a natural simulation profile of FES. Based on the gait phase-based FSM algorithms (Quintero et al., 2010;Chang et al., 2017), continuous FES profiles can be provided for every step of the gait cycle. Also, the amplitude and duration of the FES profile are adaptively adjusted depending on the gait speed ranging from 1 to 5 km/h. ...
This study proposes a novel gait rehabilitation method that uses a hybrid system comprising a powered ankle–foot orthosis (PAFO) and FES, and presents its coordination control. The developed system provides assistance to the ankle joint in accordance with the degree of volitional participation of patients with post-stroke hemiplegia. The PAFO adopts the desired joint angle and impedance profile obtained from biomechanical simulation. The FES patterns of the tibialis anterior and soleus muscles are derived from predetermined electromyogram patterns of healthy individuals during gait and personalized stimulation parameters. The CNN-based estimation model predicts the volitional joint torque from the electromyogram of the patient, which is used to coordinate the contributions of the PAFO and FES. The effectiveness of the developed hybrid system was tested on healthy individuals during treadmill walking with and without considering the volitional muscle activity of the individual. The results showed that consideration of the volitional muscle activity significantly lowers the energy consumption by the PAFO and FES while providing adaptively assisted ankle motion depending on the volitional muscle activities of the individual. The proposed system has potential use as an assist-as-needed rehabilitation system, where it can improve the outcome of gait rehabilitation by inducing active patient participation depending on the stage of rehabilitation.
... ADP actuation can be added to achieve high maneuverability and improved balance ability. Active actuation at LEE hip joint capable of power generation and power release in different joint location would better replicate the biomechanics characteristics of the corresponding healthy joints [53,[61][62][63]67]. Even though the previous declaration is accepted by most readers, it still deserves to be discussed in depth regarding how power provided in different joints could significantly improve locomotion ability and what approaches are essential to implement power propulsion for LEEs. ...
... The recruited subjects should range from AIS A to AIS D. Severe SCI patients can be recruited to investigate the exoskeleton efficacy on both motor function recovery and sensory function recovery [55,79,88]. Partly impaired patients with spared sensory or motor function can be used to verify the single efficacy of exoskeletons on motor or sensory recovery [51,67,73]. In general, the period with severe SCI injury may be longer than in partial injury patients, sensory functions are harder to recover than motor functions. ...
Locomotion disorder caused by Spinal Cord Injury (SCI) leads to a considerably decreased quality of people's life. Although there are no known cure methods for SCI, a lower-extremity exoskeleton (LEE) has a perspective to restore the locomotion ability of SCI patients. Statistics show that the number of published articles on LEEs has exponentially increased in the past 20 years; however, no reviews have been conducted to summarize these studies comprehensively. To fill up this open gap, a comprehensive review from engineering to clinical standpoint is carried out, which is based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methods, including their structural designs, drive forms, control methods, and clinical assessments. A systematic discussion among them is performed while considering the main scientific and technical aspects. The analysis indicates that the actuator configuration, motor selection, state transition, trajectory tracking, transparency implementation, and clinical factor design in exoskeleton development are full of challenges, which should be investigated in more technical efforts in the future.
... At the same time, it can also collect sEMG and EEG and recognize the movement intention of lower limbs through multisource signals. This improves the accuracy of motion intention recognition and can also use these sensors to do more work, such as rehabilitation assessment, fatigue monitoring, etc. (Ferrarello et al., 2013;Chang et al., 2017). Hua et al. (2019) have developed an innovative Weight-Bearing Lower Limb Exoskeleton. ...
Stroke is a significant cause of disability worldwide, and stroke survivors often experience severe motor impairments. Lower limb rehabilitation exoskeleton robots provide support and balance for stroke survivors and assist them in performing rehabilitation training tasks, which can effectively improve their quality of life during the later stages of stroke recovery. Lower limb rehabilitation exoskeleton robots have become a hot topic in rehabilitation therapy research. This review introduces traditional rehabilitation assessment methods, explores the possibility of lower limb exoskeleton robots combining sensors and electrophysiological signals to assess stroke survivors' rehabilitation objectively, summarizes standard human-robot coupling models of lower limb rehabilitation exoskeleton robots in recent years, and critically introduces adaptive control models based on motion intent recognition for lower limb exoskeleton robots. This provides new design ideas for the future combination of lower limb rehabilitation exoskeleton robots with rehabilitation assessment, motion assistance, rehabilitation treatment, and adaptive control, making the rehabilitation assessment process more objective and addressing the shortage of rehabilitation therapists to some extent. Finally, the article discusses the current limitations of adaptive control of lower limb rehabilitation exoskeleton robots for stroke survivors and proposes new research directions.
... Benefits of exoskeletal-assisted rehabilitation include restoring and improving gait function, reducing the energetic costs of walking, and improving endurance [2]. Exoskeleton devices are equipped with actuators to provide limb assistance such as electrical motors [3]- [5], hydraulic [6] and pneumatic [7], [8] actuators. The selection of actuators is important since they increase the inertia of the exoskeleton potentially increasing the metabolic costs and inducing misalignment, which may lead to discomfort, pain, and even injury [9]. ...
... After substituting for (5), (6), and (18), ...
Lower-limb exoskeletons can aid restoring mobility in people with movement disorders. Cable-driven exoskeletons can offload their actuators away from the human body to reduce the weight imposed on the user and enable precise control of joints. However, ensuring limb coordination through bidirectional motion control of joints using cables raise the technical challenge of preventing the occurrence of undesired cable slackness or counteracting forces between cables. Thus, motivation exists to develop a control design framework that integrates both a joint control loop to ensure suitable limb tracking and a cable control loop to maintain cable tension properly. In this paper, a two-layer control structure consisting of high and low-level controllers are developed to ensure a knee-joint exoskeleton system follows the desired joint trajectories and adjusts the cable tension, respectively. A repetitive learning controller is designed for the high-level knee joint tracking objective motivated by the periodic nature of the desired leg swings (i.e., to achieve knee flexion and extension). Low-level robust controllers are developed for a pair of cables, each actuated by an electric motor, to track target motor trajectories composed of motor kinematics and offset angles to mitigate cable slackness. The offset angles are computed using admittance models that exploit measurements of the cable tensions as inputs. Each electric motor switches its role between tracking the knee joint trajectory (i.e., the motor acts as the leader motor to achieve flexion or extension) and implementing the low-level controller (i.e., the motor acts as the follower motor to reduce slackness). Hence, at any time, one motor is the leader and the other is the follower. A Lyapunov-based stability analysis is developed for the high-level joint controller to ensure global asymptotic tracking and the low-level follower controller to guarantee global exponential tracking. The designed controllers are implemented during leg swing experiments in six able-bodied individuals while wearing the knee joint cable-driven exoskeleton. A comparison of the results obtained in two trials with and without using the admittance model (i.e., exploiting cable tension measurements) is presented. The experimental results indicate improved knee joint tracking performance, smaller control input magnitudes, and reduced cable slackness in the trial that leveraged cable tension feedback compared to the trial that did not exploit tension feedback.
... Electrical stimulation has been proven to increase muscle force, promote neuroplasticity, and enhance rehabilitation outcomes and is regarded as an effective rehabilitation treatment for gait disorders (Shin et al., 2022). However, most FES systems employ an open-loop control strategy with a constant stimulation mode in the market (Krishnamoorthy et al., 2008;Bulea et al., 2013;Chang et al., 2017). The open-loop control method has a simple computation and quick response advantage, but the constant stimulation mode cannot be adjusted for patients' assistance requirements in real-time. ...
... Due to the disturbances from internal timevarying muscle characteristics with electrical stimulation and external environmental uncertainties, most current FES systems used pre-set stimulation patterns and parameters and mainly focused on the drop foot correction. Patients may not achieve satisfactory gait performances due to the low adaptability of FES control strategies (Krishnamoorthy et al., 2008;Bulea et al., 2013;Chang et al., 2017). Therefore, accurate gait phase detection and adaptive control strategy are the critical parts of high adaptability to provide efficient walking assistance and rehabilitation. ...
Functional electrical stimulation (FES) neuroprostheses have been regarded as an effective approach for gait rehabilitation and assisting patients with stroke or spinal cord injuries. A multiple-channel FES system was developed to improve the assistance and restoration of lower limbs. However, most neuroprostheses need to be manually adjusted and cannot adapt to individual needs. This study aimed to integrate the purely reflexive FES controller with an iterative learning algorithm while a multiple-channel FES walking assistance system based on an adaptive reflexive control strategy has been established. A real-time gait phase detection system was developed for accurate gait phase detection and stimulation feedback. The reflexive controller generated stimulation sequences induced by the gait events. These stimulation sequences were updated for the next gait cycle through the difference between the current and previous five gait cycles. Ten healthy young adults were enrolled to validate the multiple-channel FES system by comparing participants' gait performance to those with no FES controller and purely reflexive controller. The results showed that the proposed adaptive FES controller enabled the adaption to generate fitted stimulation sequences for each participant during various treadmill walking speeds. The maximum, minimum, and range of motion (ROM) of the hip, knee, and ankle joints were furtherly improved for most participants, especially for the hip and knee flexion and ankle dorsiflexion compared with the purely reflexive FES control strategy. The presented system has the potential to enhance motor relearning and promote neural plasticity.
... Further, functional electrical stimulation (FES) is a therapeutic approach that evokes artificial muscle contractions by applying electrical stimuli across skeletal muscles, which can provide improvements in muscle strength, blood flow, bone mineral density, and range of motion Doucet et al. (2012); Reed (1997); Peckham and Knutson (2005). FES has been combined with electrical motors to develop hybrid rehabilitation machines that can mitigate muscle fatigue and prolong the benefits of muscle stimulation by exploiting the electric motor's torque reliability for locomotion Ho et al. (2014); Chang et al. (2017); Nataraj et al. (2017); Alibeji et al. (2017); Chang et al. (2022), upper-limb rehabilitation McCabe et al. (2015); Rouse et al. (2018), and FES-cycling Bellman et al. (2017); Duenas et al. (2019); Ghanbari et al. (2019); Chang and Duenas (2019); Chang et al. (2020). Motorized FES-cycling has been recommended for lower-limb rehabilitation in individuals with limited function who otherwise would not be able to engage in physical activity, since stationary cycling reduces the risks of falling (e.g., compared to assisted walking). ...
Functional electrical stimulation (FES)-induced cycling is a rehabilitation strategy that activates lower-limb muscles to achieve coordinated pedaling in individuals with movement disorders. An electric motor is included in-the-loop assisting the rider as needed to prolong exercise duration and mitigate muscle fatigue. Power tracking objectives have been prescribed for motorized FES-cycling, where muscles and the electric motor are assigned to track desired cadence (speed) and torque trajectories. However, predetermined desired trajectories can yield poor cycling performance since the functional capacity of each individual is unknown. In particular, when muscles are tasked to track a desired torque, a dynamic approach is well-motivated to adjust the torque demand for the rider in real-time (e.g., a constant torque demand may be unfeasible throughout a cycling session since muscles fatigue). In this paper, input-output data is exploited using a finite-time algorithm to estimate the target desired torque leveraging an estimate of the active torque produced by muscles via FES. The convergence rate of the finite-time algorithm can be adjusted by tuning selectable parameters. The cycle-rider system is modeled as a nonlinear, time-varying, state-dependent switched system to activate lower-limb muscles and an electric motor. To achieve cadence and torque tracking, nonlinear robust tracking controllers are designed for muscles and motor. A robust sliding mode controller is designed for the electric motor to track a desired constant cadence trajectory. Moreover, an integral torque feedback controller is designed to activate quadriceps, hamstrings, and gluteus muscle groups to track the desired torque trajectory computed by the finite-time algorithm. A Lyapunov-based stability analysis is developed to ensure exponential tracking of the closed-loop cadence error system and global uniformly ultimate bounded (GUUB) torque tracking. A discrete-time Lyapunov-based stability analysis leveraging a recent tool for finite-time systems is developed to ensure convergence and guarantee that the finite-time algorithm is Hölder continuous. The developed tracking controllers for the muscles and electric motor and finite-time algorithm to compute the desired torque are implemented in real-time during cycling experiments in seven able-bodied individuals. Multiple cycling trials are implemented with different gain parameters of the finite-time torque algorithm to compare tracking performance for all participants.
... Hence, researchers in the medical domain have been extensively using wearable robotic devices for rehabilitative training in order to rehabilitate injured people and help them regain mobility and quality of life (Chang et al. 2017;Grasmücke et al. 2017). Exoskeleton, a form of wearable robotic system, has been widely used and proved to be effective in assisting people who have suffered a stroke, spinal cord injury, and traumatic brain injury (Ikumi et al. 2017). ...
... (1) Rule-based classifier, including the FSM (Chang et al., 2017;Goršič et al., 2014;Ma et al., 2021;Grimes, 2005 Novak et al., 2013;Zhang, Fang, Liu, & Huang, 2011). The rule-based classifier principle can be described as follows: pre-given a set of all possible gait patterns and formulate judgment criteria for gait classifications and mutual conversions. ...
As a typical application of the human-computer interaction device, the lower limb exoskeleton has attracted many researchers' attention in recent years in an attempt to improve its functionality in human body assistance, augmentation, treatment, and protection. Essentially, the interaction between the lower limb exoskeleton and the subject is mainly realized through its sensing and control system. The sensing and control of lower limb exoskeletons will significantly affect the subject's actual wearing effect in lower extremity assistance or enhancement. However, due to the limitations of sensing and control techniques, the lower limb exoskeleton is still challenging to achieve a large-scale popularization and application. Therefore, this paper investigated the literature regarding the sensing and control of lower limb exoskeletons in recent years and studied the influences of different sensor signals and controller modeling on the exoskeleton performance. In addition, the current research challenges of insufficient stability and comfort in lower limb exoskeleton control are discussed, and possible innovative insights of functional material-based actuation, invasive and epidermal electronic sensing, and data-driven deep learning are analyzed in-depth. Some future research directions of the exoskeleton control are also provided to facilitate the further development of the exoskeleton control.
... Collecting plantar pressure information can distinguish swing and standing posture, identify walking gait [35], and monitor walking process [36]. By analysing the plantar pressure information, we can calculate the contact time between the foot and the ground and the time in the standing posture stage [37], identify the user's limb dynamic parameters [38], and judge the double standing posture, early swing, late swing, weight, and gait conversion [39]. In addition, plantar pressure can provide on/off signals to the controller or accurately compensate for the dynamic effects of torque measurement in swing motion [40]. ...
In recent decades, although the research on gait recognition of lower limb exoskeleton robot has been widely developed, there are still limitations in rehabilitation training and clinical practice. The emergence of interactive information fusion technology provides a new research idea for the solution of this problem, and it is also the development trend in the future. In order to better explore the issue, this paper summarizes gait recognition based on interactive information fusion of lower limb exoskeleton robots. This review introduces the current research status, methods, and directions for information acquisition, interaction, fusion, and gait recognition of exoskeleton robots. The content involves the research progress of information acquisition methods, sensor placements, target groups, lower limb sports biomechanics, interactive information fusion, and gait recognition model. Finally, the current challenges, possible solutions, and promising prospects are analysed and discussed, which provides a useful reference resource for the study of interactive information fusion and gait recognition of rehabilitation exoskeleton robots.
... For example, the user may want to indicate a desire to walk faster or simply that they would like to take a step. Current solutions include using push buttons to change modes or generate a step [40] or kinematic measures like forward trunk lean to initiate gait [41]. Push buttons are not a natural method for gait initiation, but erroneous trunk lean detection may also be problematic. ...
Technological advancements in robotic devices have the potential to transform human mobility through gait assistance. However, the integration of physical hardware and software control algorithms with users to assist with impaired gait poses several challenges, such as allowing the user to adopt a variety of gaits and the process for evaluating the efficacy and performance of these assistive devices. Here, I discuss some of the challenges in the development of assistive devices and the use of biomechanical concepts and tools for control and test validation. Several potential solutions are proposed through the case study of one project that aimed to provide gait assistance for individuals with a spinal cord injury. Further challenges and future directions are discussed, with emphasis that diverse perspectives and approaches in gait assistance will accelerate engineering solutions towards regaining mobility.
