Usability Evaluation of Motorized Arm Support (MARS) for Robot-Assisted Upper-Limb Training

Injury to the brain caused by Stroke often results in weakness in the arm, which leads to difficulty in performing activities of daily living. It is possible to regain these functions by high-intensity therapy. One of the important techniques used in therapy is providing adaptive arm weight support. Existing passive devices for weight support, also used at home, are simple and inexpensive but do not have sensors that could make therapy fun and engaging through the concept of therapy by games. In addition, these devices are unable to automatically adapt weight support as the user recovers ability. Rehabilitation robots, on the other hand, address all these problems but are very expensive and complex for home settings. Thus, a simple, compact device is needed that enhances motivation through therapy by games with the potential for home therapy. Motorized Arm Support (MARS) is such a device being developed to satisfy these conditions. An important step in the development of the device after the technical developments is obtaining feedback about the device’s usability for performing different types of arm training from clinicians, therapists, and stroke survivors and making suitable modifications to the device.

 Objectives

To understand clinical expectations of a rehabilitation robot that provides arm weight support from clinicians and stroke survivors.

 Methods:

After the preliminary version of MARS is developed, it is shown to clinicians to understand the clinical usefulness of its features (Part 1). Suggestions are also obtained for new features that could be added to MARS. Based on the feedback, design modifications are made to the device and usability is evaluated using the system usability scale by testing the device with clinicians (Part 2a) and stroke survivors (Part 2b). The following section discuss Part 2b of the usability study with stroke survivors

Stroke survivors with weakness in the arm who:

a.      are above 18 years of age

b.     can understand instructions

c.      could perform small movements with robot support

are included in the study.

Patients with problems in the shoulder, such as pain, are excluded from the study. A therapist performs baseline assessments on stroke survivors, such as the Fugl-Meyer Assessment (FMA), and the Box and Block Test (BBT), to understand the impact of Stroke. Horizontal work area and grip strength are also measured to understand the usefulness of arm weight support in increasing the range of motion and grip strength, respectively. Clinicians and stroke survivors evaluate the usability of MARS using the System Usability Scale. Intervention includes moving the arm to play games and performing ADL activities in virtual or real life with arm weight support provided by the robot. Hand grasp is also trained for subjects with hand functions.