Abstract-We have developed a haptic-based approach for retraining of interjoint coordination following stroke called time-independent functional training (TIFT) and implemented this mode in the ARMin III robotic exoskeleton. The ARMin III robot was developed by Drs. Robert Riener and Tobias Nef at the Swiss Federal Institute of Technology Zurich (Eidgenossische Technische Hochschule Zurich, or ETH Zurich), in Zurich, Switzerland. In the TIFT mode, the robot maintains arm movements within the proper kinematic trajectory via haptic walls at each joint. These arm movements focus training of interjoint coordination with highly intuitive real-time feedback of performance; arm movements advance within the trajectory only if their movement coordination is correct. In initial testing, 37 nondisabled subjects received a single session of learning of a complex pattern. Subjects were randomized to TIFT or visual demonstration or moved along with the robot as it moved though the pattern (time-dependent [TD] training). We examined visual demonstration to separate the effects of action observation on motor learning from the effects of the two haptic guidance methods. During these training trials, TIFT subjects reduced error and interaction forces between the robot and arm, while TD subject performance did not change. All groups showed significant learning of the trajectory during unassisted recall trials, but we observed no difference in learning between groups, possibly because this learning task is dominated by vision. Further testing in stroke populations is warranted.

Aim This study investigated the presence of inter-limb activity at the elbow joint in individuals with childhood-onset hemiparesis, including spontaneous mirror movements during unilateral tasks and the ability to suppress them during bilateral tasks. Method Eighteen individuals with hemiparesis were divided into three categories of injury timing: before birth (PRE-natal), around the time of birth (PERI-natal), and after 6 months of age (POST-natal). Individuals with hemiparesis, as well as 12 typically developing peers, participated in unilateral and bilateral elbow flexion and extension tasks completed at maximal and submaximal effort while muscle activity was monitored and motor output was quantified by two multiple degrees-of-freedom load cells. Results Significantly higher levels of paretic elbow flexion were found only in the PRE- and PERI-natal groups during the flexion of the non-paretic limb, which was modulated by effort level in both unilateral and bilateral tasks. Interpretation The bilateral activation of elbow flexors in the PRE-/PERI-natal groups indicates potential use of a common cortical command source to drive both upper extremities, while the POST-natal/typically developing groups’ flexors appear to receive input from different supraspinal structures.

After a stroke abnormal joint coordination of the arm may limit functional movement and recovery. To aid in training inter-joint movement coordination a haptic guidance method for functional driven rehabilitation after stroke called Time Independent Functional Training (TIFT) has been developed for the ARMin III robot. The mode helps retraining inter-joint coordination during functional movements, such as putting an object on a shelf, pouring from a pitcher, and sorting objects into bins. A single chronic stroke subject was tested for validation of the modality. The subject was given 1.5 hrs of robotic therapy twice a week for 4 weeks. The therapy and the results of training the single stroke subject are discussed. The subject showed a decrease in training joint error for the sorting task across training sessions and increased self-selected movement time in training. In kinematic reaching analysis the subject showed improvements in range of motion and joint coordination in a reaching task, as well as improvements in supination-pronation range of motion at the wrist.

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