Jacobian matrix and kinematic dexterity analysis of human upper limb motion

In order to understand the kinematic characteristics and manipulation ability of human upper limb, a kinematic model of the right upper limb was built according to limb's anatomical structure analysis and upper limb motion description method proposed by the International Society of Biomechanics. In this model, the motions of sternoclavicular joint, glenohumeral joint as well as elbow joint were involved, and the motions of acromioclavicular joint and scapulothoraci joint were equivalently replaced by the motion of shoulder gridle. Based on the motion coupling of upper limb joints, the Jacobian matrix describing the velocity relationship between limb joints and limb wrist point was derived, and the kinematic dexterity of the right upper limb moving in coronal plane, sagittal plane and horizontal plane were analyzed. The results show that the number of independent joint parameters which impact wrist point movement is less than that of the natural axes of the upper limb, and the velocity Jacobian matrix has three different structures corresponding to the value region changing of elevation angle; When the upper limb moves in these three special planes, the dexterity index values of extension configurations of the upper limb are smaller than those of inflexion configurations, and human upper limb obtains better kinematic dexterity.