SummaryBackground/ObjectiveThe number of patients paralysed due to stroke, spinal cord injury, or other related diseases is increasing. In order to improve the physical and mental health of these patients, robotic devices that can help them to regain the mobility to stand and walk are highly desirable. The aim of this study is to develop a wearable exoskeleton suit to help paralysed patients regain the ability to stand up/sit down (STS) and walk.MethodsA lower extremity exoskeleton named CUHK-EXO was developed with considerations of ergonomics, user-friendly interface, safety, and comfort. The mechanical structure, human-machine interface, reference trajectories of the exoskeleton hip and knee joints, and control architecture of CUHK-EXO were designed. Clinical trials with a paralysed patient were performed to validate the effectiveness of the whole system design.ResultsWith the assistance provided by CUHK-EXO, the paralysed patient was able to STS and walk. As designed, the actual joint angles of the exoskeleton well followed the designed reference trajectories, and assistive torques generated from the exoskeleton actuators were able to support the patient’s STS and walking motions.ConclusionThe whole system design of CUHK-EXO is effective and can be optimised for clinical application. The exoskeleton can provide proper assistance in enabling paralysed patients to STS and walk.

This paper introduces a wearable exoskeleton suit CUHK-EXO that can help paraplegic patients regain their mobility to stand up, sit down, and walk. An offline design and online modification (ODOM) algorithm is proposed for the exoskeleton to generate reference joint trajectories during walking assistance. First, reference trajectories of CUHK-EXO are designed offline based on motion capture data considering leg geometry constraints. Then the human-exoskeleton system (HES) including a pair of crutches is modeled as an eight-link system for analysis. Since the relative position of system center of pressure (COP) is an important factor to indicate system balance during walking, it is estimated in real-time and monitored for exoskeleton control. Based on the system COP position, this paper further proposes the reference trajectories online modification method for CUHK-EXO to counteract disturbances applied to the HES, and hence stabilize system balance in the walking assistance. Finally, walking tests are performed in both healthy subjects and a paraplegic patient to validate the effectiveness of the proposed ODOM algorithm. Testing results demonstrate that knowing the COP desired areas of the wearer, the exoskeleton CUHK-EXO can counteract perturbations and decrease the wearer's efforts, so as to maintain system balance with the ODOM algorithm.

No abstract

No abstract

SUMMARYIn this paper, we introduce a lower extremity exoskeleton CUHK-EXO that is developed to help paraplegic patients, who have lost the motor and sensory functions of their lower limbs to perform basic daily life motions. Since the sit-to-stand and stand-to-sit (STS) motion is the first step for paraplegic patients toward walking, analysis of the exoskeleton's applicability to the STS motion assistance is performed. First, the human-exoskeleton system (HES) is modeled as a five-link model during the STS motion, and the center of pressure (COP) on the ground and center of gravity of the whole system are calculated. Then, a description of the CUHK-EXO hardware design is presented, including the mechatronics design and actuator selection. The COP position is an important factor indicating system balance and wearer's comfort. Based on the COP position, a trajectory online modification algorithm (TOMA) is proposed for CUHK-EXO to counteract disturbances, stabilize system balance, and improve the wearer's comfort in the STS motion. The results of STS motion tests conducted with a paraplegic patient demonstrate that CUHK-EXO can provide a normal reference pattern and proper assistive torque to support the patient's STS motion. In addition, a pilot study is conducted with a healthy subject to verify the effectiveness of the proposed TOMA under external disturbances before future clinical trials. The testing results verify that CUHK-EXO can counteract disturbances, and help the wearer perform the STS motion safely and comfortably.