D. S. V. Bandara

Developments in hardware systems of active upper-limb exoskeleton robots

The very first application of active exoskeleton robot was to provide external power to a soldier so that he can carry additional weight than his strength. Since then this technology has focused on developing systems for assisting and augmenting human power. Later this technology is expanded into other applications such as limb rehabilitation and tele-operations. Exoskeleton research is still a growing area and demands multi-disciplinary approaches in solving complex technical issues. In this paper, the developments of active upper-limb exoskeleton robots are reviewed. This paper presents the major developments occurred in the history, the key milestones during the evolution and major research challenges in the present day context of hardware systems of upper-limb exoskeleton robots. Moreover, the paper provides a classification, a comparison and a design overview of mechanisms, actuation and power transmission of most of the upper-limb exoskeleton robots that have been found in the literature. A brief review on the control methods of upper-limb exoskeleton robots is also presented. At the end, a discussion on the future directions of the upper-limb exoskeleton robots was included. Reviews developments of active upper-limb exoskeleton robots.Presents major developments of exoskeleton hardware systems occurred in history.Identifies major research challenges in exoskeleton robots.Provides a classification, a comparison and a design overview of mechanisms and actuation.Presents future directions in upper-limb exoskeleton robots.

A brief review on upper extremity robotic exoskeleton systems

Robotic exoskeleton systems are one of the highly active areas in recent robotic research. These systems have been developed significantly to be used for the human power augmentation, robotic rehabilitation, human power assist, and haptic interaction in virtual reality. Unlike the robots used in industry, the robotic exoskeleton systems should be designed with special consideration since they directly interact with human user. In the mechanical design of these systems, movable ranges, safety, comfort wearing, low inertia, and adaptability should be especially considered. Controllability, responsiveness, flexible and smooth motion generation, and safety should especially be considered in the controllers of exoskeleton systems. Furthermore, the controller should generate the motions in accordance with the human motion intention. This paper briefly reviews the upper extremity robotic exoskeleton systems. In the short review, it is focused to identify the brief history, basic concept, challenges, and future development of the robotic exoskeleton systems. Furthermore, key technologies of upper extremity exoskeleton systems are reviewed by taking state-of-the-art robot as examples.

Recent Trends in EMG-Based Control Methods for Assistive Robots

Any person would like to spend his or her entire life time as an individual without becoming a dependant person by any means. Nonetheless, there are several instances where a human being would fail to achieve this due to physical problems which preventing him/her from acting as an individual. In most cases, after a stroke, brain or orthopedic trauma, brain damage due to an accident or a cognitive disease the victim will definitely have to undergo physical or cognitive rehabilitation in order to get him used to changed body conditions. In modern society, a considerable percentage of population is physically weak due to aging, congenital diseases, physical diseases and occupational hazards [1, 2]. Such people need a dexterous assistive methodology to regain the normal activities of daily living (ADL). Not only they, those with a missing limb (e.g. due to an amputation), should also be furnished with necessary aids which would enable them to regain the individuality. The development of proper devices for the purpose of rehabilitation, human power assistance and as replacements to body parts has a long history [3, 4] which has reached a high point due to recent developments in technology, such as robotics, biomedical signal processing, soft computing and advances in sensors and actuators over the past few decades. With many advances, capabilities and potential, still biological signal based control has a long way to go before reaching the realm of professional and commercial applications [5].

An under-actuated mechanism for a robotic finger

Robotic hands can be applied in different applications such as prosthesis, humanoid robots, industrial robotic manipulators and other kinds of robotic arms. Introduction of robotic technology into the field of prosthesis has resulted a higher quality of life for amputees. In this paper an under-actuated mechanism which has the self-adaptation ability is proposed to be used in the fingers of the hand prosthesis. The mechanism is a modification of the cross bar mechanism and it shows grasping adaptation ability for different geometries. In addition the mechanism is capable to generate dexterous grasping patterns making a paradigm shift from the conventional linkage mechanisms used for fingers which only has the capability for the grasping. Kinematic analysis, mathematical simulation and computer simulations were carried out to evaluate the effectiveness of the mechanism. Furthermore a new parameter, degree of adaptation is introduced to evaluate the performance of the under-actuated finger mechanisms.

A multi-DoF anthropomorphic transradial prosthetic arm

An anthropomorphic transradial prosthetic arm is proposed in this paper. In order to generate the wrist flexion/extension and ulna/radial deviation, a novel wrist mechanism is proposed based on the parallel prismatic manipulators. It is expected to realize high speed operation, higher positional accuracy and anthropomorphic features using the proposed mechanism. The prosthetic arm consists of an under-actuated hand as the terminal device. The hand mechanism is capable of providing the grasping adaptation. With the intention of verifying the effectiveness of the mechanisms in motion generation, motion simulation and kinematic analysis are carried out.

Development of a multi-DoF transhumeral robotic arm prosthesis

An anthropomorphic transhumeral robotic arm prosthesis is proposed in this study. It is capable of generating fifteen degrees-of-freedom, seven active and eight passive. In order to realize wrist motions, a parallel manipulator-based mechanism is proposed. It simulates the human anatomical structure and generates motions in two axes. The hand-of-arm prosthesis consists of under-actuated fingers with intrinsic actuation. The finger mechanism is capable of generating three degrees of freedom, and it exhibits the capability of adjusting the joint angles passively according to the geometry of the grasping object. Additionally, a parameter to evaluate finger mechanisms is introduced, and it measures the adoptability of a finger mechanism. In order to verify the mechanisms efficacy in terms of motion generation, motion simulation and kinematic analysis were carried out. Results demonstrated that the mechanisms are capable of generating the required motions.

Towards Control of a Transhumeral Prosthesis with EEG Signals

Robotic prostheses are expected to allow amputees greater freedom and mobility. However, available options to control transhumeral prostheses are reduced with increasing amputation level. In addition, for electromyography-based control of prostheses, the residual muscles alone cannot generate sufficiently different signals for accurate distal arm function. Thus, controlling a multi-degree of freedom (DoF) transhumeral prosthesis is challenging with currently available techniques. In this paper, an electroencephalogram (EEG)-based hierarchical two-stage approach is proposed to achieve multi-DoF control of a transhumeral prosthesis. In the proposed method, the motion intention for arm reaching or hand lifting is identified using classifiers trained with motion-related EEG features. For this purpose, neural network and k-nearest neighbor classifiers are used. Then, elbow motion and hand endpoint motion is estimated using a different set of neural-network-based classifiers, which are trained with motion information recorded using healthy subjects. The predictions from the classifiers are compared with residual limb motion to generate a final prediction of motion intention. This can then be used to realize multi-DoF control of a prosthesis. The experimental results show the feasibility of the proposed method for multi-DoF control of a transhumeral prosthesis. This proof of concept study was performed with healthy subjects.

A prosthetic hand with self-adaptive fingers

Prosthetic hand is an artificial device which replaces the missing hand of an amputee. In this research, a multi-functional prosthetic hand with self-adaptation ability is proposed. The prosthetic hand enables user to grasp different objects by performing cylindrical grasp, hook grasp, lateral pinch and tip pinch and palmar pinch. Finger mechanism of the proposed prosthesis is capable of generating passively different flexion/extension angles for a proximal interphalangeal (PIP) joint and a distal interphalangeal (DIP) joint for each flexion angle of metacarpophalangeal (MCP) joint. In addition, DIP joint is capable of generating passively different angles for the same angle of PIP joint. The design includes thumb opposition/apposition in addition to its flexion/extension. Finger has an under-actuation mechanism using one actuator to drive all proximal, middle and distal phalanxes. Kinematic analysis of the finger has been carried out to verify the required range of motions of the joints. Simulations and experiments verify the effectiveness of the proposed hand prosthesis.