A Sitting Balance Training Robot for Trunk Rehabilitation of Acute and Subacute Stroke Patients

Objective: to test the stability of a sitting balance training robot and to verify the physiological effects on trunk muscles during the robot training. Method: fundamental experiment and robot test experiment were conducted. EMG and kinematic data were recorded from six healthy subjects and five stroke patients. Three pairs of trunk muscles were included in our observation. They are erector spinae (ES), rectus abdominis (RA) and external oblique (EO). Results: contralateral ES was more engaged in actively bending while ipsilateral ES in passively tilting. Healthy subjects activated ES when sitting and lateral bending, while stroke patients activated EO and RA in addition to ES. Resisting against pushing force at bending posture had a similar activation on ES, comparing with passively tilting by the robot. EMG amplitude of ES in actively bending experiment is similar to that in passively tilting on the robot. Conclusion: This robot could activate the erector spinaes of subjects in the lateral bending motion. The stroke patients have weak ES in comparison with healthy subjects. ES is a proper reflector of trunk motions and can be further studied to evaluate trunk capacity of patients.