90 research outputs found

    Review of control strategies for robotic movement training after neurologic injury

    Get PDF
    There is increasing interest in using robotic devices to assist in movement training following neurologic injuries such as stroke and spinal cord injury. This paper reviews control strategies for robotic therapy devices. Several categories of strategies have been proposed, including, assistive, challenge-based, haptic simulation, and coaching. The greatest amount of work has been done on developing assistive strategies, and thus the majority of this review summarizes techniques for implementing assistive strategies, including impedance-, counterbalance-, and EMG- based controllers, as well as adaptive controllers that modify control parameters based on ongoing participant performance. Clinical evidence regarding the relative effectiveness of different types of robotic therapy controllers is limited, but there is initial evidence that some control strategies are more effective than others. It is also now apparent there may be mechanisms by which some robotic control approaches might actually decrease the recovery possible with comparable, non-robotic forms of training. In future research, there is a need for head-to-head comparison of control algorithms in randomized, controlled clinical trials, and for improved models of human motor recovery to provide a more rational framework for designing robotic therapy control strategies

    A Systematic Review of Bilateral Upper Limb Training Devices for Poststroke Rehabilitation

    Get PDF

    An Industrial Robot-Based Rehabilitation System for Bilateral Exercises

    Get PDF
    Robot-assisted rehabilitation devices can provide intensive and precise task-based training that differs from clinician-facilitated manual therapy. However, industrial robots are still rarely used in rehabilitation, especially in bilateral exercises. The main purpose of this research is to develop and evaluate the functionality of a bilateral upper-limb rehabilitation system based on two modern industrial robots. A `patient-cooperative' control strategy is developed based on an adaptive admittance controller, which can take into account patients' voluntary efforts. Three bilateral training protocols (passive, active, and self) are also proposed based on the system and the control strategy. Experimental results from 10 healthy subjects show that the proposed system can provide reliable bilateral exercises: the mean RMS values for the master error and the master-slave error are all less than 1.00 mm and 1.15 mm respectively, and the mean max absolute values for the master error and the master-slave error are no greater than 6.11 mm and 6.73 mm respectively. Meanwhile, the experimental results also confirm that the recalculated desired trajectory can present the voluntary efforts of subjects. These experimental findings suggest that industrial robots can be used in bilateral rehabilitation training, and also highlight the potential applications of the proposed system in further clinical practices

    Active robotic training improves locomotor function in a stroke survivor

    Full text link
    Abstract Background Clinical outcomes after robotic training are often not superior to conventional therapy. One key factor responsible for this is the use of control strategies that provide substantial guidance. This strategy not only leads to a reduction in volitional physical effort, but also interferes with motor relearning. Methods We tested the feasibility of a novel training approach (active robotic training) using a powered gait orthosis (Lokomat) in mitigating post-stroke gait impairments of a 52-year-old male stroke survivor. This gait training paradigm combined patient-cooperative robot-aided walking with a target-tracking task. The training lasted for 4-weeks (12 visits, 3 × per week). The subject’s neuromotor performance and recovery were evaluated using biomechanical, neuromuscular and clinical measures recorded at various time-points (pre-training, post-training, and 6-weeks after training). Results Active robotic training resulted in considerable increase in target-tracking accuracy and reduction in the kinematic variability of ankle trajectory during robot-aided treadmill walking. These improvements also transferred to overground walking as characterized by larger propulsive forces and more symmetric ground reaction forces (GRFs). Training also resulted in improvements in muscle coordination, which resembled patterns observed in healthy controls. These changes were accompanied by a reduction in motor cortical excitability (MCE) of the vastus medialis, medial hamstrings, and gluteus medius muscles during treadmill walking. Importantly, active robotic training resulted in substantial improvements in several standard clinical and functional parameters. These improvements persisted during the follow-up evaluation at 6 weeks. Conclusions The results indicate that active robotic training appears to be a promising way of facilitating gait and physical function in moderately impaired stroke survivors.http://deepblue.lib.umich.edu/bitstream/2027.42/112853/1/12984_2011_Article_375.pd

    Impairment and Compensation in Dexterous Upper-Limb Function After Stroke. From the Direct Consequences of Pyramidal Tract Lesions to Behavioral Involvement of Both Upper-Limbs in Daily Activities

    Get PDF
    Impairments in dexterous upper limb function are a significant cause of disability following stroke. While the physiological basis of movement deficits consequent to a lesion in the pyramidal tract is well demonstrated, specific mechanisms contributing to optimal recovery are less apparent. Various upper limb interventions (motor learning methods, neurostimulation techniques, robotics, virtual reality, and serious games) are associated with improvements in motor performance, but many patients continue to experience significant limitations with object handling in everyday activities. Exactly how we go about consolidating adaptive motor behaviors through the rehabilitation process thus remains a considerable challenge. An important part of this problem is the ability to successfully distinguish the extent to which a given gesture is determined by the neuromotor impairment and that which is determined by a compensatory mechanism. This question is particularly complicated in tasks involving manual dexterity where prehensile movements are contingent upon the task (individual digit movement, grasping, and manipulation…) and its objective (placing, two step actions…), as well as personal factors (motivation, acquired skills, and life habits…) and contextual cues related to the environment (presence of tools or assistive devices…). Presently, there remains a lack of integrative studies which differentiate processes related to structural changes associated with the neurological lesion and those related to behavioral change in response to situational constraints. In this text, we shall question the link between impairments, motor strategies and individual performance in object handling tasks. This scoping review will be based on clinical studies, and discussed in relation to more general findings about hand and upper limb function (manipulation of objects, tool use in daily life activity). We shall discuss how further quantitative studies on human manipulation in ecological contexts may provide greater insight into compensatory motor behavior in patients with a neurological impairment of dexterous upper-limb function

    Augmented visual, auditory, haptic, and multimodal feedback in motor learning: A review

    Get PDF
    It is generally accepted that augmented feedback, provided by a human expert or a technical display, effectively enhances motor learning. However, discussion of the way to most effectively provide augmented feedback has been controversial. Related studies have focused primarily on simple or artificial tasks enhanced by visual feedback. Recently, technical advances have made it possible also to investigate more complex, realistic motor tasks and to implement not only visual, but also auditory, haptic, or multimodal augmented feedback. The aim of this review is to address the potential of augmented unimodal and multimodal feedback in the framework of motor learning theories. The review addresses the reasons for the different impacts of feedback strategies within or between the visual, auditory, and haptic modalities and the challenges that need to be overcome to provide appropriate feedback in these modalities, either in isolation or in combination. Accordingly, the design criteria for successful visual, auditory, haptic, and multimodal feedback are elaborate

    Neuroplastic Changes Following Brain Ischemia and their Contribution to Stroke Recovery: Novel Approaches in Neurorehabilitation

    Get PDF
    Ischemic damage to the brain triggers substantial reorganization of spared areas and pathways, which is associated with limited, spontaneous restoration of function. A better understanding of this plastic remodeling is crucial to develop more effective strategies for stroke rehabilitation. In this review article, we discuss advances in the comprehension of post-stroke network reorganization in patients and animal models. We first focus on rodent studies that have shed light on the mechanisms underlying neuronal remodeling in the perilesional area and contralesional hemisphere after motor cortex infarcts. Analysis of electrophysiological data has demonstrated brain-wide alterations in functional connectivity in both hemispheres, well beyond the infarcted area. We then illustrate the potential use of non-invasive brain stimulation (NIBS) techniques to boost recovery. We finally discuss rehabilitative protocols based on robotic devices as a tool to promote endogenous plasticity and functional restoration

    Lower Limb Motor Coordination and Rehabilitation Facilitated through Self- Assist.

    Full text link
    Self-assisted rehabilitation of neurological injury through patient-operated telerobots offers potential benefits over traditional therapy including increased patient involvement, improved timing coordination, and better sensory information. Bimanual self-assist has been clinically shown to demonstrate greater improvements in range of motion and functional recovery than traditional therapy alone. This dissertation generalizes self-assist to lower limb rehabilitation with upper limb assistance, providing a scientific foundation for the mechanisms of self-assist. Through a series of experiments using electromechanical devices under real-time control, we have demonstrated that upper limb involvement enhances lower limb performance, improves anticipation of assistance, and maintains muscle activation. A critical concern to assistive rehabilitation is the degree to which subjects are capable of coordinating lower limb effort with the assisting effort. In a study involving lower limb disturbance rejection with neurologically intact subjects (n = 12), we found that subjects exhibit improved anticipation and compensation when externally applied loads are self-generated as opposed to generated by an outside agent. The centralized control inherent in self-assist ensures that assisting forces are expected, and even anticipated, compared to assisting forces from an external agent, such as a therapist or computer. Multi-limb control can represent a significantly increased challenge in motor planning and execution over single limb control. We evaluated the tradeoffs associated with multi-limb control in motor tasks with neurologically intact subjects (n = 7 separated into two experiments). The benefits of adding an upper limb, including increased strength and dexterity, seem to offset any detriments associated with increased control requirements, as evidenced by performance improvements relative to single limb control. In a final motor coordination study, hemiparetic subjects (n = 15) practiced dorsiflexing the impaired ankle with no assistance, upper limb self-assist, computer-assist, and experimenter-assist. We found that any assistance can be used to improve task performance, but self-assist, through improved information and awareness, maintains subject muscle recruitment and effort.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/61566/1/danekk_1.pd

    Self-Powered Robots to Reduce Motor Slacking During Upper-Extremity Rehabilitation: A Proof of Concept Study

    Get PDF
    Background: Robotic rehabilitation is a highly promising approach to recover lost functions after stroke or other neurological disorders. Unfortunately, robotic rehabilitation currently suffers from motor slacking , a phenomenon in which the human motor system reduces muscle activation levels and movement excursions, ostensibly to minimize metabolic- and movement-related costs. Consequently, the patient remains passive and is not fully engaged during therapy. To overcome this limitation, we envision a new class of body-powered robots and hypothesize that motor slacking could be reduced if individuals must provide the power to move their impaired limbs via their own body (i.e., through the motion of a healthy limb). Objective: To test whether a body-powered exoskeleton (i.e. robot) could reduce motor slacking during robotic training. Methods: We developed a body-powered robot that mechanically coupled the motions of the user\u27s elbow joints. We tested this passive robot in two groups of subjects (stroke and able-bodied) during four exercise conditions in which we controlled whether the robotic device was powered by the subject or by the experimenter, and whether the subject\u27s driven arm was engaged or at rest. Motor slacking was quantified by computing the muscle activation changes of the elbow flexor and extensor muscles using surface electromyography. Results: Subjects had higher levels of muscle activation in their driven arm during self-powered conditions compared to externally-powered conditions. Most notably, subjects unintentionally activated their driven arm even when explicitly told to relax when the device was self-powered. This behavior was persistent throughout the trial and did not wane after the initiation of the trial. Conclusions: Our findings provide novel evidence indicating that motor slacking can be reduced by self-powered robots; thus demonstrating promise for rehabilitation of impaired subjects using this new class of wearable system. The results also serve as a foundation to develop more sophisticated body-powered robots (e.g., with controllable transmissions) for rehabilitation purposes

    Bimanual wheelchair propulsion by people with severe hemiparesis after stroke

    Get PDF
    Purpose: Individuals who require manual wheelchairs after stroke are typically taught to ambulate with compensatory propulsion (i.e., using their non-paretic arm and foot), risking disuse of the paretic arm. We investigated whether stroke survivors can instead ambulate in a bimanual, lever-driven wheelchair that requires the paretic arm to contribute half the propulsive input. Materials and methods: Seventeen individuals with chronic stroke and severe hemiparesis (upper extremity Fugl–Meyer scores between 10 and 24) participated across two experiments. In the first experiment, participants (n = 12) ambulated in straight paths. In the second experiment, participants (n = 12) also performed turns, using an improved version of the wheelchair that incorporated handbrakes. Twelve unimpaired controls also completed the second experiment. Motion capture and EMG were used to compare biomechanics between groups. Results: Altogether, 15 of 17 participants with stroke could ambulate 30 m in straight paths, and 9 of 12 could turn 1800° entirely under the power of their paretic arm. Participants with stroke exhibited largely healthy biomechanics, with minimal shoulder hiking/leaning or trunk inclination. Their arm muscle EMG patterns were similar to those used by unimpaired participants, excepting delayed elbow extensor activation. Conclusions: Individuals with severe arm impairment in the chronic stage of stroke retain sufficient strength and coordination with their paretic arm to manoeuvre bimanual, lever-driven wheelchairs. We suggest bimanual, lever-driven propulsion should be explored in stroke rehabilitation practice as an alternative to compensatory wheelchair propulsion, as it has the potential to exercise healthy movement synergies, which may in turn help drive use-dependent motor recovery.Implications for rehabilitation Severe arm impairment arising after stroke does not generally eliminate the motor dexterity needed to bimanually propel a manual wheelchair, provided that the wheelchair is modified to remove the requirement to grasp and release the push rim. Such exercise appears a good candidate to facilitate rehabilitation outcomes because it depends on alternating muscle activity and improving elbow extension. Such wheelchair propulsion involves largely normal biomechanics; shoulder hiking and leaning are absent and trunk inclination is rare
    • …
    corecore