Designing A Rehabilitation-Purposed No-Direct-Contact Collaborative
Robotic System For Stroke Patients
Authors: Wei Liyan , Cheng Wenxuan , Luo Zhengzheng , Kit Yu Mo , Hiu Tung Chan , Ma Zhengtao , Zhang Yaqi , Jia Wang Stephen 
Published: July 2023

Different from the traditional rehabilitation methods, rehabilitation
robots can provide repetitive and meaningful tasks that make the
rehabilitation process smarter and more efficient during upper extremity
rehabilitation for stroke patients. Therefore, rehabilitation robots are
often used to assist patients during their rehabilitation training. From a
robotic system perspective, it needs to sense the user's various needs to
provide real-time assistance and allow the user to trust the robot. This
means that the system must be able to monitor and process the user's level
of fatigue. The analysis of EMG signals is used as a criterion to determine
the level of muscle fatigue. At the same time, the degree of intervention
that stroke patients receive during the rehabilitation process is also a
challenge(Fang et al. 2017). For instance, the current rehabilitation robots
often help the user to complete the rehabilitation training by means of end
traction, the robot is attached to the user's arm, pulling the arm to
complete the training. This approach could reduce muscle fatigue and
increase the efficiency of rehabilitation.Even though direct contact and
traction have been proven in studies to help patients perform better in
rehabilitation, from a general HSI perspective, the degree of direct
traction assistance may reduce the patient's sense of independence which
affects their cognitive and motor function. This paper proposes a
No-Direct-Contact Collaborative (NDCC) robotic-arm system that assists
patients with physical game tasks. The NDCC system means that the robotic
arm doesn't directly touch and hold the patient's upper limb as traditional
robots would, but rather works in a cooperative way to complete the task,
picking up and moving objects together with patients when they need. The
purpose of the NDCC system is to avoid excessive interference to the patient
during rehabilitation training, which is beneficial to the patient's
cognitive and motor function recovery. In recent years, there has been a
gradual increase in the use of robotic systems to assist in rehabilitation
exercises for stroke patients and different kinds of interaction have been
proposed. (Janssen et al. 2017) suggested that “interactive, engaging
game-based rehabilitation tools, which match the abilities of the
participant, could provide variation and attractiveness, thereby
facilitating recovery of residual motor and cognitive function.” For
instance, HarmonySHR system provides end-traction assistance at different
recovery stages to complete rehabilitation exercises. With game elements
embedded in rehabilitation systems, older patients are not only more
attached to the training process but also can train their cognitive controls
that “allow them to interact with our complex environment in a goal-directed
manner (Anguera et al.2013)”. Therefore, the robotic arm is a “guide” rather
than a “teammate.” In our research, it has been possible to collect and
process the user's EMG signal during the task in real-time and convert it to
RMS (Root Mean Square), and use Huskylens sensors to enable the robotic arm
to track the position of the user's upper limb in real-time. The proposed
study will be verified through two types of experiments, including Expert
Participation and User Experience Experiments, giving designers a new
direction to think about the degree of interaction and intervention between
robots and stroke patients. In future studies, feedback from the user's EMG
signal data and Patient's Rehabilitation Questionnaire (Fang et al. 2017)
will be collected and analyzed. The physiological state of the upper limb
will be determined by examining the EMG signal. The Patient's Rehabilitation
Questionnaire will also be given to the user, aiming to assess the user's
cognitive status and sense of independence under the two different
assistance methods.