Framework and Implications of Virtual Neurorobotics

Despite decades of societal investment in artificial learning systems, truly “intelligent” systems have yet to be realized. These traditional models are based on input-output pattern optimization and/or cognitive production rule modeling. One response has been social robotics, using the interaction of human and robot to capture important cognitive dynamics such as cooperation and emotion; to date, these systems still incorporate traditional learning algorithms. More recently, investigators are focusing on the core assumptions of the brain “algorithm” itself—trying to replicate uniquely “neuromorphic” dynamics such as action potential spiking and synaptic learning. Only now are large-scale neuromorphic models becoming feasible, due to the availability of powerful supercomputers and an expanding supply of parameters derived from research into the brain's interdependent electrophysiological, metabolomic and genomic networks. Personal computer technology has also led to the acceptance of computer-generated humanoid images, or “avatars”, to represent intelligent actors in virtual realities. In a recent paper, we proposed a method of virtual neurorobotics (VNR) in which the approaches above (social-emotional robotics, neuromorphic brain architectures, and virtual reality projection) are hybridized to rapidly forward-engineer and develop increasingly complex, intrinsically intelligent systems. In this paper, we synthesize our research and related work in the field and provide a framework for VNR, with wider implications for research and practical applications

Development of a mechatronic system for the mirror therapy

This paper fits into the field of research concerning robotic systems for rehabilitation. Robotic systems are going to be increasingly used to assist fragile persons and to perform rehabilitation tasks for persons affected by motion injuries. Among the recovery therapies, the mirror therapy was shown to be effective for the functional recovery of an arm after stroke. In this paper we present a master/slave robotic device based on the mirror therapy paradigm for wrist rehabilitation. The device is designed to orient the affected wrist in real time according to the imposed motion of the healthy wrist. The paper shows the kinematic analysis of the system, the numerical simulations, an experimental mechatronic set-up, and a built 3D-printed prototype

Evaluation of upper extremity robot-assistances in subacute and chronic stroke subjects

<p>Abstract</p> <p>Background</p> <p>Robotic systems are becoming increasingly common in upper extremity stroke rehabilitation. Recent studies have already shown that the use of rehabilitation robots can improve recovery. This paper evaluates the effect of different modes of robot-assistances in a complex virtual environment on the subjects' ability to complete the task as well as on various haptic parameters arising from the human-robot interaction.</p> <p>Methods</p> <p>The MIMICS multimodal system that includes the haptic robot HapticMaster and a dynamic virtual environment is used. The goal of the task is to catch a ball that rolls down a sloped table and place it in a basket above the table. Our study examines the influence of catching assistance, pick-and-place movement assistance and grasping assistance on the catching efficiency, placing efficiency and on movement-dependant parameters: mean reaching forces, deviation error, mechanical work and correlation between the grasping force and the load force.</p> <p>Results</p> <p>The results with groups of subjects (23 subacute hemiparetic subjects, 10 chronic hemiparetic subjects and 23 control subjects) showed that the assistance raises the catching efficiency and pick-and-place efficiency. The pick-and-place movement assistance greatly limits the movements of the subject and results in decreased work toward the basket. The correlation between the load force and the grasping force exists in a certain phase of the movement. The results also showed that the stroke subjects without assistance and the control subjects performed similarly.</p> <p>Conclusions</p> <p>The robot-assistances used in the study were found to be a possible way to raise the catching efficiency and efficiency of the pick-and-place movements in subacute and chronic subjects. The observed movement parameters showed that robot-assistances we used for our virtual task should be improved to maximize physical activity.</p

Design of a series visco-elastic actuator for multi-purpose rehabilitation haptic device

<p>Abstract</p> <p>Background</p> <p>Variable structure parallel mechanisms, actuated with low-cost motors with serially added elasticity (series elastic actuator - SEA), has considerable potential in rehabilitation robotics. However, reflected masses of a SEA and variable structure parallel mechanism linked with a compliant actuator result in a potentially unstable coupled mechanical oscillator, which has not been addressed in previous studies.</p> <p>Methods</p> <p>The aim of this paper was to investigate through simulation, experimentation and theoretical analysis the necessary conditions that guarantee stability and passivity of a haptic device (based on a variable structure parallel mechanism driven by SEA actuators) when in contact with a human. We have analyzed an equivalent mechanical system where a dissipative element, a mechanical damper was placed in parallel to a spring in SEA.</p> <p>Results</p> <p>The theoretical analysis yielded necessary conditions relating the damping coefficient, spring stiffness, both reflected masses, controller's gain and desired virtual impedance that needs to be fulfilled in order to obtain stable and passive behavior of the device when in contact with a human. The validity of the derived passivity conditions were confirmed in simulations and experimentally.</p> <p>Conclusions</p> <p>These results show that by properly designing variable structure parallel mechanisms actuated with SEA, versatile and affordable rehabilitation robotic devices can be conceived, which may facilitate their wide spread use in clinical and home environments.</p

Learning new movements after paralysis: Results from a home-based study

open8siBody-machine interfaces (BMIs) decode upper-body motion for operating devices, such as computers and wheelchairs. We developed a low-cost portable BMI for survivors of cervical spinal cord injury and investigated it as a means to support personalized assistance and therapy within the home environment. Depending on the specific impairment of each participant, we modified the interface gains to restore a higher level of upper body mobility. The use of the BMI over one month led to increased range of motion and force at the shoulders in chronic survivors. Concurrently, subjects learned to reorganize their body motions as they practiced the control of a computer cursor to perform different tasks and games. The BMI allowed subjects to generate any movement of the cursor with different motions of their body. Through practice subjects demonstrated a tendency to increase the similarity between the body motions used to control the cursor in distinct tasks. Nevertheless, by the end of learning, some significant and persistent differences appeared to persist. This suggests the ability of the central nervous system to concurrently learn operating the BMI while exploiting the possibility to adapt the available mobility to the specific spatio-temporal requirements of each task.openPierella, Camilla; Abdollahi, Farnaz; Thorp, Elias; Farshchiansadegh, Ali; Pedersen, Jessica; Seanez-Gonzalez, Ismael; Mussa-Ivaldi, Ferdinando A.; Casadio, MauraPierella, Camilla; Abdollahi, Farnaz; Thorp, Elias; Farshchiansadegh, Ali; Pedersen, Jessica; Seanez-Gonzalez, Ismael; Mussa-Ivaldi, Ferdinando A.; Casadio, Maur

Effect of visual distraction and auditory feedback on patient effort during robot-assisted movement training after stroke

<p>Abstract</p> <p>Background</p> <p>Practicing arm and gait movements with robotic assistance after neurologic injury can help patients improve their movement ability, but patients sometimes reduce their effort during training in response to the assistance. Reduced effort has been hypothesized to diminish clinical outcomes of robotic training. To better understand patient slacking, we studied the role of visual distraction and auditory feedback in modulating patient effort during a common robot-assisted tracking task.</p> <p>Methods</p> <p>Fourteen participants with chronic left hemiparesis from stroke, five control participants with chronic right hemiparesis and fourteen non-impaired healthy control participants, tracked a visual target with their arms while receiving adaptive assistance from a robotic arm exoskeleton. We compared four practice conditions: the baseline tracking task alone; tracking while also performing a visual distracter task; tracking with the visual distracter and sound feedback; and tracking with sound feedback. For the distracter task, symbols were randomly displayed in the corners of the computer screen, and the participants were instructed to click a mouse button when a target symbol appeared. The sound feedback consisted of a repeating beep, with the frequency of repetition made to increase with increasing tracking error.</p> <p>Results</p> <p>Participants with stroke halved their effort and doubled their tracking error when performing the visual distracter task with their left hemiparetic arm. With sound feedback, however, these participants increased their effort and decreased their tracking error close to their baseline levels, while also performing the distracter task successfully. These effects were significantly smaller for the participants who used their non-paretic arm and for the participants without stroke.</p> <p>Conclusions</p> <p>Visual distraction decreased participants effort during a standard robot-assisted movement training task. This effect was greater for the hemiparetic arm, suggesting that the increased demands associated with controlling an affected arm make the motor system more prone to slack when distracted. Providing an alternate sensory channel for feedback, i.e., auditory feedback of tracking error, enabled the participants to simultaneously perform the tracking task and distracter task effectively. Thus, incorporating real-time auditory feedback of performance errors might improve clinical outcomes of robotic therapy systems.</p

The Effect of Sensory Experience and Movement Observation on Motor Adaptation to Novel Force Perturbations

On a daily basis, humans capably and effortlessly interact with their surrounding environment through the performance of accurate movements. Movements are often perturbed through the physical influence of the surrounding environment, interaction with objects, or injury, yet adaptation is both rapid and flexible. When adapting, humans are informed by their direct trial-and-error movement experience, incrementally updating predictive control on the next movement; how the brain processes sensed errors into adaptation is not fully known. We may also learn to move through the observation of the movements of others, as visually observed movement information may be transformed into motor memories that influence subsequent motor command; the neural computations underlying such a learning process are not well understood. In this thesis, I aimed to further understand how people incrementally update their predictive motor control in novel haptic environments as a function of sensation during action and during observation. Theories of motor learning suggest that adaptation scales with the size of experienced error. Previous studies have indicated the relationship between adaptation and sensed error can be modulated by statistics of the perturbing environment. In Chapter 2, we considered how the duration of experienced force perturbations might modulate adaptive strategy and found that people becomes increasingly sensitive to kinematic and dynamic sensory signals when experiencing perturbations of decreasing duration. We further found that subjects experiencing pulsatile forces adapted their steady-state feedforward prediction of dynamics with a persistently mismatched breadth when compared to the duration of experienced forces, but learned to closely match the experienced duration of full-movement forces. In the next two sections, we considered the learning effects of movement observation. In Chapter 3, we newly designed and implemented an experimental paradigm in which movement and observation were interleaved, varying the strength of perturbations and associated kinematics from trial-to-trial. Based on previous descriptions of long-term learning by observing, we hypothesized that incremental adaptation would be corrective with respect to observed errors but more modest in magnitude than gains from physical practice. Instead, we found that the incremental adaptive response of movement observation generally countered the direction of experienced forces and was similar in magnitude to the response following action, but was not error-corrective with respect to real-valued signals. Previous research had established an initial advantage when adapting to novel dynamics following observation but the learning processes influencing this effect were unknown. In Chapter 4, we newly demonstrated that the long-term movement observation resulted in adaptive changes in feedforward predictive dynamics. We found that observation generated a small, but significant, compensatory change in reach dynamics that could be characterized by a learned scaling of perturbation-appropriate kinematic signals, suggesting a transformation of visual inputs into a neural representation of environment dynamics

Evaluation and reaching trainning with trunk restraint in post-stroke hemiparetic patients

Orientador: Antonio Guilhermo Borges NetoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas.Resumo: O acidente vascular cerebral (AVC) é reconhecido como uma das maiores causas de morbidade e mortalidade. Seqüelas decorrentes deste evento podem levar à incapacidade motora e déficits de leves a severos. Para classificar melhor a disfunção sensitivo-motora, o equilíbrio e as habilidades para as atividades de vida diária (AVD's), escalas de avaliações quantitativas e qualitativas estão sendo amplamente utilizadas. O objetivo do Artigo 1 foi verificar a correlação existente entre a Escala de Fugl-Meyer (FM), Escala de Equilíbrio de Berg (EEB) e Índice de Barthel (IB). Foram recrutados 20 pacientes com diagnóstico de AVC crônico, que passaram pelas avaliações por cerca de uma hora. Os resultados demonstraram que a FM se correlaciona positivamente com o IB e a EEB, mostrando que, quando utilizadas em conjunto, classificam de forma esclarecedora o quadro físico geral do paciente com AVC. Após o AVC, o comprometimento da função do membro superior é a seqüela mais comum, podendo ser permanente. Os movimentos de alcance feitos com o membro superior hemiparético são freqüentemente acompanhados por movimentos compensatórios de tronco e cintura-escapular. O uso da terapia de restrição de tronco visa evitar a movimentação compensatória de tronco, propiciando o desenvolvimento de padrões motores mais próximos do normal no braço afetado. Através do uso de escalas de mensuração clínica, foram observados os benefícios da terapia de restrição de tronco em 11 sujeitos com seqüela de AVC que passaram por 20 sessões de treinamento (Artigo 2). Em um segundo estudo (Artigo 3), 20 sujeitos foram recrutados e divididos em dois grupos de treinamento (20 sessões): Grupo com Tronco Restrito (GTR - treinamento de alcance com o tronco restrito) e o Grupo com Tronco Livre (GTL - treinamento de alcance sem restrição de tronco, enfatizando o uso da orientação verbal). O objetivo foi verificar os benefícios a longo prazo do treinamento de alcance tarefa-específica associado à terapia de restrição de tronco, utilizando como instrumentos de medida as escalas clínicas (Escala Modificada de Ashworth, FM, IB e EEB) e a avaliação cinemática do movimento (deslocamento, velocidade, angulação). As avaliações foram divididas em três momentos: a primeira foi realizada na admissão (PRÉ); a segunda, no final do período total de treinamento (PÓS) e a terceira, três meses após o término do tratamento (RET). O treinamento tarefa-específica associado à terapia de restrição de tronco (GTR) mostrou-se eficaz a longo prazo para a melhora dos movimentos articulares ativos de ombro e cotovelo, além de propiciar melhora no planejamento interno do movimento. Em contrapartida, o uso contínuo da restrição provocou dependência aos pacientes e não foi eficaz na redução dos graus adicionais de liberdade (tronco) a longo prazo. Apesar do treinamento baseado em orientações verbais (GTL) ter sido mais eficaz na retenção do tronco, não houve melhora significativa nas amplitudes articulares voluntárias de membro superior. Acredita-se que os pacientes que passaram por este tipo de tratamento ficaram mais atentos ao recrutamento anormal de graus adicionais de liberdade e não exploraram de forma efetiva as combinações multiarticulares presentes membro superior.Abstract: Stroke is recognized as one of the major causes of morbidity and mortality. Sequels deriving from this event may lead to motor disability and from mild to severe deficits. In order to better classify sensory-motor dysfunction, balance and ability to perform activities of daily living (ADL), quantitative and qualitative evaluation scales have been used. The aim of Article 1 was to verify the correlation between the Fugl-Meyer Assessment Scale (FM), Berg Balance Scale (BBS) and Barthel Index (BI). Twenty chronic stroke patients were submitted to an evaluation that spent approximately one hour. The results demonstrated that the FM was positively correlated with the BBS and BI, showing that when they are employed together, make it possible to design the general clinical performance of the stroke patient. After stroke, upper limb function impairment is the most common sequel that could lead to permanent dysfunction. Reaching movements made with hemiparetic upper limbs are often followed by compensatory trunk and shoulder-girdle movements. The use of the trunk restraint therapy aims at avoiding the compensatory trunk movement providing the development of normal motor patterns in the affected upper limb. The benefits of the trunk restraint therapy could be observed through the clinical measures scales in eleven stroke subjects that performed twenty training sessions (Article 2). In another study (Article 3), twenty patients were recruited and divided into two training groups (20 sessions): Trunk restraint group (TRG - reaching training with trunk restraint) and trunk free group (TFG - reaching training without trunk restraint, providing emphasis in the verbal cue). The aim was to verify the long term benefits of the task-specific training with trunk restraint using the clinical scales (Modified Ashworth Scale, FM, BI and BBS) and the kinematic analysis (displacement, velocity, angles) like evaluation tools. The evaluations were performed in three phases: the first, in admission time (PRE test); the second, after the end of the treatment (POST test); and the third, three months after the completed treatment (retention test - RET test). Task-specific training associated with the trunk restraint therapy (TRG) proved to be a long-term effective treatment in the enhancement of shoulder and elbow active joint range, as well as in the improvement of the internal planning of the movement. However, the continuous use of restraint may have caused dependence to the patients and was not efficient in long term reduction of the additional degrees of freedom (trunk). Although the verbal cue training (TFG) was more effective in the trunk retention, there was no significant improvement in the upper limb joint ranges. Therefore patients who sustained this type of treatment developed more attention in the abnormal recruitment of the additional degrees of freedom, and did not efficiently explore the multi-joint combinations presented in the upper limb.DoutoradoCiencias BiomedicasDoutor em Ciências Médica

GENTLE/A - Adaptive Robotic Assistance for Upper-Limb Rehabilitation

Advanced devices that can assist the therapists to offer rehabilitation are in high demand with the growing rehabilitation needs. The primary requirement from such rehabilitative devices is to reduce the therapist monitoring time. If the training device can autonomously adapt to the performance of the user, it can make the rehabilitation partly self-manageable. Therefore the main goal of our research is to investigate how to make a rehabilitation system more adaptable. The strategy we followed to augment the adaptability of the GENTLE/A robotic system was to (i) identify the parameters that inform about the contribution of the user/robot during a human-robot interaction session and (ii) use these parameters as performance indicators to adapt the system. Three main studies were conducted with healthy participants during the course of this PhD. The first study identified that the difference between the position coordinates recorded by the robot and the reference trajectory position coordinates indicated the leading/lagging status of the user with respect to the robot. Using the leadlag model we proposed two strategies to enhance the adaptability of the system. The first adaptability strategy tuned the performance time to suit the user’s requirements (second study). The second adaptability strategy tuned the task difficulty level based on the user’s leading or lagging status (third study). In summary the research undertaken during this PhD successfully enhanced the adaptability of the GENTLE/A system. The adaptability strategies evaluated were designed to suit various stages of recovery. Apart from potential use for remote assessment of patients, the work presented in this thesis is applicable in many areas of human-robot interaction research where a robot and human are involved in physical interaction

Multimodal series elastic actuator for human-machine interaction with applications in robot-aided rehabilitation

Series elastic actuators (SEAs) are becoming an elemental building block in collaborative robotic systems. They introduce an elastic element between the mechanical drive and the end-effector, making otherwise rigid structures compliant when in contact with humans. Topologically, SEAs are more amenable to accurate force control than classical actuation techniques, as the elastic element may be used to provide a direct force estimate. The compliant nature of SEAs provides the potential to be applied in robot-aided rehabilitation. This thesis proposes the design of a novel SEA to be used in robot-aided musculoskeletal rehabilitation. An active disturbance rejection controller is derived and experimentally validated and multiobjective optimization is executed to tune the controller for best performance in human-machine interaction. This thesis also evaluates the constrained workspaces for individuals experiencing upper-limb musculoskeletal disorders. This evaluation can be used as a tool to determine the kinematic structure of devices centred around the novel SEA