The usability assessment focuses on the actual use of the proposed rehabilitation system to clarify issues users would face in actual system operation, thus providing a reference for subsequent system improvement.

This study protocol was approved by the institutional review board of Chang Gung Medical Foundation. The usability assessment focuses on the actual use of the proposed rehabilitation system to clarify issues users would face in actual system operation, thus providing a reference for subsequent system improvement. Pre-testing and formal testing were conducted at Chang Gung Memorial Hospital at Taoyuan. The pre-test was conducted on five healthy participants, while the formal testing was conducted on 12 participants (4 stroke patients, 4 caregivers, and 4 therapists). The healthy participants were aged 20-70 years old and had no physical disabilities; the stroke patients had normal cognitive and language skills, stable stroke status, no fractures in the upper limbs in the previous three months, and minimal or no upper limb spasticity with Modified Ashworth Scale of 0 or 1; the occupational therapists should had work experience in the hospital for more than one year.

Prior to the experiment, the subject provided basic biographical information. The investigators then explained the experimental process and demonstrated the operation of the device. For usability assessment, the subject operated the device under the instruction by the researchers, during which problems observed and questions asked were recorded. Following device operation, the subjects filled the system usability scale (SUS) questionnaire that obtained subjective evaluations and recommendations for the device. Experimental instrument consisted of the rehabilitation device, video cameras, still image cameras, digital voice recorders, questionnaires and observational recording forms.

The results of the SUS questionnaire were analyzed using SPSS (IBM Corp., Armonk, NY, USA). The split-half method was used for reliability analysis and one-sample t test for comparison.

Inclusion Criteria:

• Had previous experience using rehabilitation equipment.

Exclusion Criteria:

• Cognitive deficits or psychiatric illness.