A Modified Kinematic Model of Shoulder Complex Based on Vicon Motion Capturing System: Generalized GH Joint with Floating Centre

Abstract

<jats:p>Due to the complex coupling motion of shoulder mechanism, only a small amount of quantitative information is available in the existing literature, although various kinematic models of the shoulder complex have been proposed. This study focused on the specific motion coupling relationship between glenohumeral (GH) joint center displacement variable quantity relative to the thorax coordinate system and humeral elevation angle to describe the shoulder complex. The mechanism model of shoulder complex was proposed with an algorithm designed. Subsequently, twelve healthy subjects performed right arm raising, lowering, as well as raising and lowering (RAL) movements in sixteen elevation planes, and the motion information of the markers attached to the thorax, scapula, and humerus was captured by using Vicon motion capturing system. Then, experimental data was processed and the generalized GH joint with floating center was quantized. Simultaneously, different coupling characteristics were detected during humerus raising as well as lowering movements. The motion coupling relationships in different phases were acquired, and a modified kinematic model was established, with the description of overall motion characteristics of shoulder complex validated by comparing the results with a prior kinematic model from literature, showing enough accuracy for the design of upper limb rehabilitation robots.</jats:p>

Patient-Specific Exercises with the Development of an End-Effector Type Upper Limb Rehabilitation Robot

“…In addition, stroke is becoming the leading cause of permanent disabilities worldwide, with over 15 million new cases each year and 50 million stroke survivors [ 3 ]; more than two-third of all patients affected by stroke have impaired upper limb motor function and have difficulty in independently performing ADLs [ 4 ]. Evidence has suggested that upper limb motor skills can be improved by following rehabilitation interventions [ 5 ], which attracts more and more scholars engaged in upper limb rehabilitation robot (ULRR) research [ 6 , 7 ], for the ULRRs have the potential to provide intensive rehabilitation consistently for a longer duration [ 8 ] irrespective of the skills and fatigue level of the therapist.…”

“…There are two types of ULRRs that have been studied the most, the exoskeleton type and end-effector type [ 9 ]. For the exoskeleton-based ULRR, the robots can resemble human limbs as they are connected to patients at multiple points and their joint axes match with human joint axes; training of specific muscles by controlling joint movements at calculated torques is possible, and the number of anatomical movements can exceed six; typical exoskeleton ULRRs are SUEFUL-7 [ 10 ], CADEN-7 [ 11 ], ARMin III [ 12 ], L-EXOS [ 13 ], ExoRob [ 14 ], RUPERT [ 15 , 16 ], BONES [ 17 ], ULEL [ 18 ], and Limpact [ 19 ]; nonetheless, increasing the number of movement parts increases the number of device modules, so the system setup becomes difficult; moreover, since the shoulder has a variable joint center, the mechanical design and control algorithms become more complicated [ 7 ]. By comparison, the end-effector type ULRRs are connected to patients at one distal point, and their joints do not match with human joints; force generated at the distal interface changes the positions of other joints simultaneously, making isolated movement of a single joint difficult [ 20 , 21 ]; the advantages of the end-effector type ULRRs are that they have a simple structure and less complex control algorithms and can avoid abnormal motion and posture of the target anatomical joints and specific muscles; typical end-effector type ULRRs are MIT-Manus [ 22 ], AMES [ 23 ], iPAM [ 24 ], PASCAL [ 25 ], Fourier M2 [ 26 ], EEULRebot [ 27 ], hCAAR [ 28 ], PARM [ 29 ], CASIA-ARM [ 30 ], Sophia-3 [ 31 ], and BULReD [ 2 , 32 ].…”

“…Recent study found that the end-effector type ULRR intervention is better than the exoskeleton type ULRR intervention with regard to activity and participation among chronic stroke patients with moderate-to-severe impairment of upper extremity function after four weeks of intervention [ 9 ]. In addition, research studies have shown that the shoulder complex of upper limb is very complex, and it is difficult to design an exoskeleton type ULRR that is compatible with the upper limb of users because the glenohumeral joint moves with the functional relevance of the shoulder girdle during humeral elevation and the glenohumeral joint has three degrees of freedom (DOFs) with axes intersecting perpendicularly in the glenohumeral joint center, which is obviously a spherical joint and can be regarded with a generalized glenohumeral joint with floating center [ 7 , 33 ]. Also, the end-effector type ULRRs focus more on the rehabilitation of the combined motion of upper limb chain and assist the patient to perform collaborative tasks; they are safer compared with exoskeletons because they are not in direct contact with the human body.…”

Mathematical Analysis and Motion Capture System Utilization Method for Standardization Evaluation of Tracking Objectivity of 6-DOF Arm Structure for Rehabilitation Training Exercise Therapy Robot

“…Therefore, an in-depth analysis of shoulder movement is essential for understanding the mechanism of SR robots. Various studies on the mechanism of shoulder movement have been conducted [ 11 , 12 , 13 , 14 , 15 , 16 ].…”

“…In particular, the shoulder elevation and depression phases, and the movement coupling relationship between the displacement of the glenohumeral (GH) joint center with respect to the thoracic coordinate system and elevation of the humerus was investigated. As a result, a new design model for an upper extremity rehabilitation robot consistent with the actual situation of the human body structure was developed [ 16 ].…”