A New Algorithm to Estimate Glenohumeral Joint Location Based on Scapula Rhythm.

This work analyzes the human shoulder complex workspace by introducing a new method to estimate the intraarticulation location of the glenohumeral (GH) joint. The proposed algorithm is based on the hypothesis of the GH joint remaining fixed during the first 30 degrees of shoulder elevation. This part of any vertical movement is considered to estimate the center of spherical motions CoS) where the humeral head is located.For the experimental results, six subjects performed 5 cycles of 12 different movements in different planes. The data are collected using motion capture, for various landmarks of the shoulder girdle. With the proposed method, estimating the location of GH is possible for any motion of the shoulder girdle complex. In order to complete the kinematic model of the shoulder complex, PCA is used to identify a relation between the shoulder joints. This technique indicates that the shoulder complex can be modeled using two degrees of freedom (DOFs) to locate the spherical GH joint. The overall shoulder model can generate any possible vertical motion of the human shoulder.

A task-based design methodology for robotic exoskeletons.

INTRODUCTION: This study is aimed at developing a task-based methodology for the design of robotic exoskeletons. This is in contrast to prevailing research efforts, which attempt to mimic the human limb, where each human joint is given an exoskeleton counter-joint. Rather, we present an alternative systematic design approach for the design of exoskeletons that can follow the complex three-dimensional motions of the human body independent of anatomical measures and landmarks. With this approach, it is not necessary to know the geometry of the targeted limb but rather to have a description of its motion at the point of attachment. METHODS: The desired trajectory of the targeted limb has been collected through a motion capture system from a healthy subject. Then, an approximate dimensional synthesis has been employed to specify the size of the mechanism and its location with respect to the limb, while generating the desired trajectory. The procedure for this method, from motion capture to kinematic synthesis to mechanism selection and optimization, is validated with an illustrative example. RESULTS: The proposed method resulted an exoskeleton which follows the desired trajectory of the human limb without any need of aligning its joint to the corresponding human joints. CONCLUSION: A method to design lower mobility exoskeletons for specific sets of human motion is presented; the approach result an exoskeleton with lesser actuation system while generating complex 3D limb motions, which in turn results a lighter exoskeletons. It also avoids a need to align each robotic joint axis with its human counterpart.

Single degree-of-freedom exoskeleton mechanism design for thumb rehabilitation.

This paper presents the kinematic design of a spatial, 1-degree-of-freedom closed linkage to be used as an exoskeleton for thumb motion. Together with an already-designed finger mechanism, it forms a robotic device for hand therapy. The goal for the exoskeleton is to generate the desired grasping and pinching path of the thumb with one degree of freedom, rather than using a system actuating all its joints independently. In addition to the path of the thumb, additional constraints are added in order to control the position and size of the exoskeleton, reducing physical and sensory interference with the user.

Design of a prosthetic hand with remote actuation.

One of the main issues of prosthetic hands is to be able to fulfill all the specifications about speed, torque, weight and inertia while placing all the components within the prosthetic hand. This is especially true when full dexterity is required in the prosthesis. In this paper, a new design for a prosthetic hand is presented, which uses remote actuation in order to satisfy most of those requirements. The actuators are to be located in the back of the subject and the transmission is implemented via cables. Other characteristics of this new prosthetic hand include torque limitation and the possibility of switching between underactuated and fully actuated functions.

Design of an exoskeleton as a finger-joint angular sensor.

Estimation of joint angles for human joints is important for many applications in Bioengineering. Most of the existing angular joint sensors rely on the assumption of the knowledge of the type of motion and location of the joint. This paper presents a new design for the measurement of finger joint angular motion. The design presented here consists of an exoskeleton, designed to fit the finger motion, in which we can relate the angular displacement of its links to the change in orientation of the phalanx under consideration. Unlike other designs, the exoskeleton does not need any information about the actual anatomy and dimensions of the hand in order to provide with the angular information. The design is to be used in myoelectrical signal identification.

Single degree-of-freedom exoskeleton mechanism design for finger rehabilitation.

This paper presents the kinematic design of a single degree-of-freedom exoskeleton mechanism: a planar eight-bar mechanism for finger curling. The mechanism is part of a finger-thumb robotic device for hand therapy that will allow users to practice key pinch grip and finger-thumb opposition, allowing discrete control inputs for playing notes on a musical gaming interface. This approach uses the mechanism to generate the desired grasping trajectory rather than actuating the joints of the fingers and thumb independently. In addition, the mechanism is confined to the back of the hand, so as to allow sensory input into the palm of the hand, minimal size and apparent inertia, and the possibility of placing multiple mechanisms side-by-side to allow control of individual fingers.

A hybrid adaptive control strategy for a smart prosthetic hand.

This paper presents a hybrid of a soft computing technique of adaptive neuro-fuzzy inference system (ANFIS) and a hard computing technique of adaptive control for a two-dimensional movement of a prosthetic hand with a thumb and index finger. In particular, ANFIS is used for inverse kinematics, and the adaptive control is used for linearized dynamics to minimize tracking error. The simulations of this hybrid controller, when compared with the proportional-integral-derivative (PID) controller showed enhanced performance. Work is in progress to extend this methodology to a five-fingered, three-dimensional prosthetic hand.