Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> Based on recent studies of neuro-adaptive control, we tested a new iterative algorithm to generate custom training forces to "trick" subjects into altering their target-directed reaching movements to a prechosen movement as an after-effect of adaptation. The prechosen movement goal, a sinusoidal-shaped path from start to end point, was never explicitly conveyed to the subject. We hypothesized that the adaptation would cause an alteration in the feedforward command that would result in the prechosen movement. Our results showed that when forces were suddenly removed after a training period of 330 movements, trajectories were significantly shifted toward the prechosen movement. However, de-adaptation occurred (i.e., the after-effect "washed out") in the 50-75 movements that followed the removal of the training forces. A second experiment suppressed vision of hand location and found a detectable reduction in the washout of after-effects, suggesting that visual feedback of error critically influences learning. A final experiment demonstrated that after-effects were also present in the neighborhood of training-44% of original directional shift was seen in adjacent, unpracticed movement directions to targets that were 60/spl deg/ different from the targets used for training. These results demonstrate the potential for these methods for teaching motor skills and for neuro-rehabilitation of brain-injured patients. This is a form of "implicit learning," because unlike explicit training methods, subjects learn movements with minimal instructions, no knowledge of, and little attention to the trajectory. <s> BIB001 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> This investigation is one in a series of studies that address the possibility of stroke rehabilitation using robotic devices to facilitate “adaptive training.” Healthy subjects, after training in the presence of systematically applied forces, typically exhibit a predictable “after-effect.” A critical question is whether this adaptive characteristic is preserved following stroke so that it might be exploited for restoring function. Another important question is whether subjects benefit more from training forces that enhance their errors than from forces that reduce their errors. We exposed hemiparetic stroke survivors and healthy age-matched controls to a pattern of disturbing forces that have been found by previous studies to induce a dramatic adaptation in healthy individuals. Eighteen stroke survivors made 834 movements in the presence of a robot-generated force field that pushed their hands proportional to its speed and perpendicular to its direction of motion — either clockwise or counterclockwise. We found that subjects could adapt, as evidenced by significant after-effects. After-effects were not correlated with the clinical scores that we used for measuring motor impairment. Further examination revealed that significant improvements occurred only when the training forces magnified the original errors, and not when the training forces reduced the errors or were zero. Within this constrained experimental task we found that error-enhancing therapy (as opposed to guiding the limb closer to the correct path) to be more effective than therapy that assisted the subject. <s> BIB002 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> BackgroundIt is common for individuals with chronic disabilities to continue using the compensatory movement coordination due to entrenched habits, increased perception of task difficulty, or personality variables such as low self-efficacy or a fear of failure. Following our previous work using feedback distortion in a virtual rehabilitation environment to increase strength and range of motion, we address the use of visual feedback distortion environment to alter movement coordination patterns.MethodsFifty-one able-bodied subjects participated in the study. During the experiment, each subject learned to move their index finger and thumb in a particular target pattern while receiving visual feedback. Visual distortion was implemented as a magnification of the error between the thumb and/or index finger position and the desired position. The error reduction profile and the effect of distortion were analyzed by comparing the mean total absolute error and a normalized error that measured performance improvement for each subject as a proportion of the baseline error.ResultsThe results of the study showed that (1) different coordination pattern could be trained with visual feedback and have the new pattern transferred to trials without visual feedback, (2) distorting individual finger at a time allowed different error reduction profile from the controls, and (3) overall learning was not sped up by distorting individual fingers.ConclusionIt is important that robotic rehabilitation incorporates multi-limb or finger coordination tasks that are important for activities of daily life in the near future. This study marks the first investigation on multi-finger coordination tasks under visual feedback manipulation. <s> BIB003 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> We present an initial test of a technique for retrain- ing reaching skills in patients with poststroke hemiparesis, in which errors are temporarily magnified to encourage learning and compensation. Individuals with poststroke hemiparesis held a horizontal plane robotic manipulandum that could exert a variety of forces while recording patients' movements. We measured how well the patients recovered movement straight- ness in a single visit to the laboratory (~3 h). Following train- ing, we returned forces to zero for an additional 50 movements to discern if aftereffects lasted. We found that all subjects showed immediate benefit from the training, although 3 of the 10 subjects did not retain these benefits for the remainder of the experiment. We discuss how these approaches demonstrate great potential for rehabilitation tools that augment error to facilitate functional recovery. <s> BIB004 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> Cerebellar symptoms areextremely disabling, andarecommoninpatients withMultiple Sclerosis (MS);atpresent, noeffective treatments areavailable. Thispilot study aimsatdeveloping andassessing anovel robottherapy protocol, aimedattherehabilitation of subjects withMS andimpaired coordination. Subjects performed planarreaching movementswhilegrasping thehandle ofarobotic manipulandum, whichgenerated forces thateither reduced orenhanced thepatterns of curvature ofthesubjects' movements, observed atthe beginning ofeachsession. Therefore, theprotocol was designed to adaptto eachpatient, and to the improvements - ifany- fromsession tosession. We tested atotal offoursubjects, withclinically defined MS andcerebellar symptoms attheupperlimb. Eachsubject wentthrough twoblocks ofsessions, fourerror-reducing andfourerror-enhancing (2sessions/week). Allsubjects displayed apreserved ability toadapttothe robot-generated forces. Moreover, after training, their movementsbecamefaster, smoother, andwitha more symmetric speedprofile. Oversessions, weobserved an improved sensorimotor performance andareduction of cerebellar symptoms. Theseresults support theclaim thatrehabilitation, ingeneral, and adaptive robot training inparticular maybebeneficial tosubjects with MS andimpaired coordination. <s> BIB005 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> The present study is aimed at developing new rehabilitation protocols to be used in post-stroke robotic-aided therapy. In the recent past, it has been suggested that the use of robotic training forces that enhance error instead of reducing it, could stimulate new learning and feedback strategies at the base of an effective motor recovery. Starting from these findings, in this work two different robotic-aided therapies were compared: the first was based on the constraint induced movement therapy, the second employed an unstable training force field increasing path errors performed by the subjects. The results shows that the use of the unstable divergent force field can increase the recovery, especially in people with mild level of impairment. <s> BIB006 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> BackgroundCerebellar symptoms are extremely disabling and are common in Multiple Sclerosis (MS) subjects. In this feasibility study, we developed and tested a robot therapy protocol, aimed at the rehabilitation of incoordination in MS subjects.MethodsEight subjects with clinically defined MS performed planar reaching movements while grasping the handle of a robotic manipulandum, which generated forces that either reduced (error-reducing, ER) or enhanced (error-enhancing, EE) the curvature of their movements, assessed at the beginning of each session. The protocol was designed to adapt to the individual subjects' impairments, as well as to improvements between sessions (if any). Each subject went through a total of eight training sessions. To compare the effect of the two variants of the training protocol (ER and EE), we used a cross-over design consisting of two blocks of sessions (four ER and four EE; 2 sessions/week), separated by a 2-weeks rest period. The order of application of ER and EE exercises was randomized across subjects. The primary outcome measure was the modification of the Nine Hole Peg Test (NHPT) score. Other clinical scales and movement kinematics were taken as secondary outcomes.ResultsMost subjects revealed a preserved ability to adapt to the robot-generated forces. No significant differences were observed in EE and ER training. However over sessions, subjects exhibited an average 24% decrease in their NHPT score. The other clinical scales showed small improvements for at least some of the subjects. After training, movements became smoother, and their curvature decreased significantly over sessions.ConclusionsThe results point to an improved coordination over sessions and suggest a potential benefit of a short-term, customized, and adaptive robot therapy for MS subjects. <s> BIB007 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> Recent research has suggested that enhanced retraining for stroke patients using haptics (robotic forces) and graphics (visual display) to generate a practice environment that can artificially enhance error rather than reducing it, can stimulate new learning and foster accelerated recovery. We present an evaluation of early results of this novel post-stroke robotic-aided therapy trial that incorporates these ideas in a large VR system and simultaneously employs the patient, the therapist, and the technology to accomplish effective therapy. <s> BIB008 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> The paper investigates the impact of the integration of the visual error augmentation training method with the assist-as-needed training method in robot-assisted rehabilitation training of the upper extremity. A robot-assisted rehabilitation system is developed that integrates an assistive controller, which can provide robotic assistance to the participant as and when needed, with a visual error augmentation mechanism, which amplifies the tracking error to heighten the participant's motivation to improve tracking accuracy. A crossover study is designed to evaluate the impact of the integration of the visual error augmentation method with the assist-as-needed training method. Experimental results on unimpaired participants demonstrate improved performance has been achieved in the integrated training session. <s> BIB009 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> Background ::: Robot-generated deviating forces during multijoint reaching movements have been applied to investigate motor control and to tune neuromotor adaptation. Can the application of force to limbs improve motor learning? In this framework, the response to altered dynamic environments of children affected by primary dystonia has never been studied. <s> BIB010 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> Feedback is an important element in motor learning during rehabilitation therapy following stroke. The objective of this pilot study was to better understand the effect of position feedback during task-oriented reach training of the upper limb in people with chronic stroke. Five subjects participated in the training for 30 minutes three times a week for 6 weeks. During training, subjects performed reaching movements over a predefined path. When deviation from this path occurred, shoulder and elbow joints received position feedback using restraining forces. We recorded the amount of position feedback used by each subject. During pre- and posttraining assessments, we collected data from clinical scales, isometric strength, and workspace of the arm. All subjects showed improvement on one or several kinematic variables during a circular motion task after training. One subject showed improvement on all clinical scales. Subjects required position feedback between 7.4% and 14.7% of training time. Although augmented feedback use was limited, kinematic outcome measures and movement performance during training increased in all subjects, which was comparable with other studies. Emphasis on movement errors at the moment they occur may possibly stimulate motor learning when movement tasks with sufficiently high levels of difficulty are applied. <s> BIB011 </s> Error Augmented Robotic Rehabilitation of the Upper Limb - A Review <s> Intervention Modalities <s> To study the effects of different feedback error amplification methods on a subject's upper-limb motor learning and affect during a point-to-point reaching exercise, we developed a real-time controller for a robotic manipulandum. The reaching environment was visually distorted by implementing a thirty degrees rotation between the coordinate systems of the robot's end-effector and the visual display. Feedback error amplification was provided to subjects as they trained to learn reaching within the visually rotated environment. Error amplification was provided either visually or through both haptic and visual means, each method with two different amplification gains. Subjects' performance (i.e., trajectory error) and self-reports to a questionnaire were used to study the speed and amount of adaptation promoted by each error amplification method and subjects' emotional changes. We found that providing haptic and visual feedback promotes faster adaptation to the distortion and increases subjects' satisfaction with the task, leading to a higher level of attentiveness during the exercise. This finding can be used to design a novel exercise regimen, where alternating between error amplification methods is used to both increase a subject's motor learning and maintain a minimum level of motivational engagement in the exercise. In future experiments, we will test whether such exercise methods will lead to a faster learning time and greater motivation to pursue a therapy exercise regimen. <s> BIB012
The main concept of the intervention behind all the reviewed studies was that a user was positioned in front of a computer screen while a robotic manipulandum was attached to/held by the participant's upper limb. A target would be displayed while visual feedback about the current position of the arm was provided to the user. The user was asked to perform movements towards Year published Number of publications predefined targets while the system responded to the users' movement by augmenting any error. In some of the reviewed studies BIB001 BIB005 BIB006 BIB007 BIB010 haptic error augmenting algorithms were compared against other types of haptic algorithms namely, error reducing haptic algorithms. Error reducing algorithms are adaptive assistive algorithms which apply forces towards the optimal trajectory when a threshold of error is reached. In the aforementioned studies the two different types of haptic algorithms were either administered to different trial groups or in the same group but in different stages of the trial in order for a comparison between the two training modalities to be feasible. There was one study BIB011 where restraining forces only occurred when a certain amount of error was reached in order to provide position feedback to the user. In this case the forces were turned off when the user didn't exceed a predefined error threshold. There was great variance in the number of sessions and the total exercise time the participants undertook, among the studies. In several cases the total intervention time was administered in one session  BIB002 BIB003 BIB010 BIB012 while in others the number of sessions varied from a minimum of 2 sessions BIB009 BIB011 ) to a maximum 10 sessions BIB006 . Moreover, the total time of exercise administered varied significantly from as little as 90 minutes BIB012 to as much as 20hours BIB006 . Additionally, some studies induced a washout component in the practice regime either by including a washout cycle in the practice session where the perturbative forces were gradually removed BIB001 BIB004 BIB010 , or by setting a washout period between trials where no practice was undertaken BIB006 BIB008 BIB009 . Table 2 provides an overview on the practice schemes administered in the reviewed studies.