R. A. R. C. Gopura

SUEFUL-7: A 7DOF upper-limb exoskeleton robot with muscle-model-oriented EMG-based control

This paper proposes an electromyography (EMG) signal based control method for a seven degrees of freedom (7DOF) upper-limb motion assist exoskeleton robot (SUEFUL-7). The SUEFUL-7 is able to assist the motions of shoulder vertical and horizontal flexion/extension, shoulder internal/external rotation, elbow flexion/extension, forearm supination/pronation, wrist flexion/extension, and wrist radial/ulnar deviation of physically weak individuals. In the proposed control method, an impedance controller is applied to the muscle-model-oriented control method by considering the end effecter force vector. Impedance parameters are adjusted in real time by considering the upper-limb posture and EMG activity levels. Experiments have been performed to evaluate the effectiveness of the proposed robotic system.

Mechanical designs of active upper-limb exoskeleton robots: State-of-the-art and design difficulties

Active upper-limb exoskeleton robots have been developing from 1960s. In recent years, the mechanical designs and control algorithms of active upper-limb exoskeleton robots were developed significantly. This paper reviews the state-of-the-art of active upper-limb exoskeleton robots that are applied in the areas of rehabilitation and assistive robotics. In addition, the main requirements of the active upper-limb exoskeleton robot are identified and the mechanical designs of existing active upper-limb exoskeleton robot are classified. The design difficulties of an active upper-limb exoskeleton robot are discussed.

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.

EMG-based control of an exoskeleton robot for human forearm and wrist motion assist

We have been developing exoskeleton robots for assisting the motion of physically weak individuals such as elderly or slightly disabled in daily life. In this paper we propose an EMG-based control of a three degree of freedom (3-DOF) exoskeleton robot for the forearm pronation/supination motion, wrist flexion/extension motion and ulnar/radial deviation. The paper describes the hardware design of the exoskeleton robot and the control method. The skin surface electromyographic (EMG) signals of muscles in forearm of the exoskeletons user and the hand force/forearm torque are used as input information for the proposed controller. By applying the skin surface EMG signals as main input signals to the controller, automatic control of the robot can be realized without manipulating any other equipment. Fuzzy control method has been applied to realize the natural and flexible motion assist. An experiment has been performed to evaluate the proposed exoskeleton robot.

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.

Development of a 6DOF Exoskeleton Robot for Human Upper-Limb Motion Assist

The upper-limb motions are essential to perform the daily activities. This paper proposes a six degree of freedom (6DOF) upper-limb motion power assist exoskeleton robot for shoulder vertical and horizontal flexion/extension motion, elbow flexion/extension motion, forearm supination/pronation motion, wrist flexion/extension motion and wrist radial/ulnar deviation motion. The axes offset of wrist joint and the moving center of rotation (CR) of shoulder joint are applied in the hardware design of the exoskeleton robot. The robot is named as SUEFUL-6 to indicate 6DOF Saga University Exoskeleton For Upper-Limb. The paper describes the anatomy details of upper-limb towards the development of the exoskeleton robot and the hardware design of the exoskeleton robot. Experiments have been performed to evaluate the effectiveness of the hardware design of the proposed exoskeleton robot.

Control methodologies for upper limb exoskeleton robots

An exoskeleton robot is kind of a man-machine system which mostly uses combination of human intelligence and machine power. These robotic systems are used for different applications such as rehabilitation, human power amplification, motion assistance, virtual reality etc. Successful operation of an exoskeleton robot depends on correct selection of design and control methodologies. This paper reviews control methodologies used in upper limb exoskeleton robots. In the review, the control methods used in the exoskeleton robots are classified into three categories: control system based on human biological signal, nonbiological signal and platform independent control system. Different types of control methods under each category are compared and reviewed.

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].

Development of an exoskeleton robot for human wrist and forearm motion assist

Exoskeleton is an external structural mechanism with joints and links corresponding to those of the human body. It transmits torques from actuators through rigid exoskeletal links to the human joints when it is worn. We have been developing exoskeleton robots for assisting the motion of physically weak individuals such as elderly or slightly disabled in daily life. In this paper we propose a three degree of freedom (3DOF) exoskeleton robot for the forearm pronation/supination motion, wrist flexion/ extension motion and ulnar/radial deviation. The paper describes wrist anatomy toward the development of the robot, the hardware design of the exoskeleton (mechanical structure and mechanism, sensors and actuators, power transmission and safety aspects) and potential control methods. Force control using force/torque sensors located at wrist and forearm and electromyographic (EMG) signals based control using skin surface EMG signals of forearm and wrist muscles are the potential control methods for the robot. Experiments have been performed to evaluate the proposed exoskeleton.

6-REXOS: Upper Limb Exoskeleton Robot with Improved pHRI

Close interaction can be observed between an exoskeleton robot and its wearer. Therefore, appropriate physical human-robot interaction (pHRI) should be considered when designing an exoskeleton robot to provide safe and comfortable motion assistance. Different features have been used in recent studies to enhance the pHRI in upper-limb exoskeleton robots. However, less attention has been given to integrating kinematic redundancy into upper-limb exoskeleton robots to improve the pHRI. In this context, this paper proposes a six-degrees-of-freedom (DoF) upper-limb exoskeleton robot (6-REXOS) for the motion assistance of physically weak individuals. The 6-REXOS uses a kinematically different structure to that of the human lower arm, where the exoskeleton robot is worn. The 6-REXOS has four active DoFs to generate the motion of the human lower arm. Furthermore, two flexible bellow couplings are attached to the wrist and elbow joints to generate two passive DoFs. These couplings not only allow translational motion in wrist and elbow joints but also a redundancy in the robot. Furthermore, the compliance of the flexible coupling contributes to avoiding misalignments between human and robot joint axes. The redundancy in the 6-REXOS is verified based on manipulability index, minimum singular value, condition number and manipulability ellipsoids. The 6-REXOS and a four-DoF exoskeleton robot are compared to verify the manipulation advantage due to the redundancy. The four-DoF exoskeleton robot is designed by excluding the two passive DoFs of the 6-REXOS. In addition, a kinematic model is proposed for the human lower arm to validate the performance of the 6-REXOS. Kinematic analysis and simulations are carried out to validate the 6-REXOS and human-lower-arm model.