scholarly journals Hybrid Impedance-Admittance Control for Upper Limb Exoskeleton Using Electromyography

2020 ◽  
Vol 10 (20) ◽  
pp. 7146
Author(s):  
Lucas D. L. da Silva ◽  
Thiago F. Pereira ◽  
Valderi R. Q. Leithardt ◽  
Laio O. Seman ◽  
Cesar A. Zeferino
Keyword(s):  
Upper Limb ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Hybrid Control ◽  
Impedance Control ◽  
Robotic Arm ◽  
Average Error ◽  
Acceptable Error ◽  
Upper Limb Exoskeleton ◽  
Input Signals

Exoskeletons are wearable mobile robots that combine various technologies to enable limb movement with greater strength and endurance, being used in several application areas, such as industry and medicine. In this context, this paper presents the development of a hybrid control method for exoskeletons, combining admission and impedance control based on electromyographic input signals. A proof of concept of a robotic arm with two degrees of freedom, mimicking the functions of a human’s upper limb, was built to evaluate the proposed control system. Through tests that measured the discrepancy between the angles of the human joint and the joint of the exoskeleton, it was possible to determine that the system remained within an acceptable error range. The average error is lower than 4.3%, and the robotic arm manages to mimic the movements of the upper limbs of a human in real-time.

scholarly journals A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

2021 ◽  
Vol 11 (13) ◽  
pp. 5865
Author(s):  
Muhammad Ahsan Gull ◽  
Mikkel Thoegersen ◽  
Stefan Hein Bengtson ◽  
Mostafa Mohammadi ◽  
Lotte N. S. Andreasen Struijk ◽  
...  
Keyword(s):  
Upper Limb ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Trajectory Tracking Control ◽  
Upper Limb Exoskeleton ◽  
And Performance ◽  
Physically Disabled People ◽  
Human Upper Limb

Wheelchair mounted upper limb exoskeletons offer an alternative way to support disabled individuals in their activities of daily living (ADL). Key challenges in exoskeleton technology include innovative mechanical design and implementation of a control method that can assure a safe and comfortable interaction between the human upper limb and exoskeleton. In this article, we present a mechanical design of a four degrees of freedom (DOF) wheelchair mounted upper limb exoskeleton. The design takes advantage of non-backdrivable mechanism that can hold the output position without energy consumption and provide assistance to the completely paralyzed users. Moreover, a PD-based trajectory tracking control is implemented to enhance the performance of human exoskeleton system for two different tasks. Preliminary results are provided to show the effectiveness and reliability of using the proposed design for physically disabled people.

scholarly journals Postural Synergy-Based Exoskeleton Reproducing Natural Human Movements to Improve Upper Limb Motor Control after Stroke

2020 ◽  
Author(s):  
Chang He ◽  
Cai-Hua Xiong ◽  
Ze-Jian Chen ◽  
Wei Fan ◽  
Xiao-Lin Huang
Keyword(s):  
Motor Control ◽  
Upper Limb ◽  
Degrees Of Freedom ◽  
Response Rate ◽  
Human Movement ◽  
Interaction Force ◽  
Human Anatomy ◽  
Clinical Trial Registration ◽  
Upper Limb Exoskeleton ◽  
Human Movements

Abstract Background: Upper limb exoskeletons have drawn significant attention in neurorehabilitation because of anthropomorphic mechanical structure analogous to human anatomy. Whereas, the training movements are typically underorganized because most exoskeletons only control the movement of the hand in space, without considering rehabilitation of joint motion, particularly inter-joint postural synergy. The purposes of this study were to explore the application of a postural synergy-based exoskeleton (Armule) reproducing natural human movements for robot-assisted neurorehabilitation and to preliminarily assess its effect on patients' upper limb motor control after stroke. Methods: We developed a novel upper limb exoskeleton based on the concept of postural synergy, which provided five degrees of freedom (DOF) , natural human movements of the upper limb. Eight participants with hemiplegia due to a first-ever, unilateral stroke were recruited and included. They participated in exoskeleton therapy sessions 45 minutes/day, 5 days/week for 4 weeks, with passive/active training under anthropomorphic trajectories and postures. The primary outcome was the Fugl-Meyer Assessment for Upper Extremities (FMA-UE). The secondary outcomes were the Action Research Arm Test(ARAT), modified Barthel Index (mBI) , and exoskeleton kinematic as well as interaction force metrics: motion smoothness in the joint space, postural synergy error, interaction force smoothness, and the intent response rate. Results: After the 4-weeks intervention, all subjects showed significant improvements in the following clinical measures: the FMA-UE ( p =0.02), the ARAT ( p =0.003), and the mBI score ( p <0.001). Besides, all subjects showed significant improvements in motion smoothness ( p =0.004), postural synergy error ( p =0.014), interaction force smoothness ( p =0.004), and the intent response rate ( p =0.008). Conclusions: The subjects were well adapted to our device that assisted in completing functional movements with natural human movement characteristics. The results of the preliminary clinical intervention indicate that the Armule exoskeleton improves individuals’ motor control and activities of daily living (ADL) function after stroke, which might be associated with kinematic and interaction force optimization and postural synergy modification during functional tasks. Clinical trial registration: ChiCTR, ChiCTR1900026656; Date of registration: October 17, 2019. http://www.chictr.org.cn/showproj.aspx?proj=44420

Integrating a Grasp Exoskeleton Into a String-Based Interface for Human-Scale Interactions

2008 ◽  
Vol 8 (4) ◽  
Author(s):  
Rasul Fesharakifard ◽  
Maryam Khalili ◽  
Laure Leroy ◽  
Alexis Paljic ◽  
Philippe Fuchs
Keyword(s):  
Virtual Environments ◽  
Degrees Of Freedom ◽  
Force Feedback ◽  
Control Method ◽  
Hybrid Control ◽  
Force Sensor ◽  
Virtual Objects ◽  
Rotary Encoder ◽  
Human Scale ◽  
Novel Design

A grasp exoskeleton actuated by a string-based platform is proposed to provide the force feedback for a user’s hand in human-scale virtual environments. The user of this interface accedes to seven active degrees of freedom in interaction with virtual objects, which comprises three degrees of translation, three degrees of rotation, and one degree of grasping. The exoskeleton has a light and ergonomic structure and provides the grasp gesture for five fingers. The actuation of the exoskeleton is performed by eight strings that are the parallel arms of the platform. Each string is connected to a block of motor, rotary encoder, and force sensor with a novel design to create the necessary force and precision for the interface. A hybrid control method based on the string’s tension measured by the force sensor is developed to resolve the ordinary problems of string-based interface. The blocks could be moved on a cubic frame around the virtual environment. Finally the results of preliminary experimentation of interface are presented to show its practical characteristics. Also the interface is mounted on an automotive model to demonstrate its industrial adaptability.

scholarly journals Eyes-Free Tongue Gesture and Tongue Joystick Control of a Five DOF Upper-Limb Exoskeleton for Severely Disabled Individuals

2021 ◽  
Vol 15 ◽  
Author(s):  
Mostafa Mohammadi ◽  
Hendrik Knoche ◽  
Mikkel Thøgersen ◽  
Stefan Hein Bengtson ◽  
Muhammad Ahsan Gull ◽  
...  
Keyword(s):  
Visual Feedback ◽  
Upper Limb ◽  
Degrees Of Freedom ◽  
Continuous Control ◽  
Clinical Case Study ◽  
Upper Limb Exoskeleton ◽  
Control Interface ◽  
Cord Injury ◽  
First Time

Spinal cord injury can leave the affected individual severely disabled with a low level of independence and quality of life. Assistive upper-limb exoskeletons are one of the solutions that can enable an individual with tetraplegia (paralysis in both arms and legs) to perform simple activities of daily living by mobilizing the arm. Providing an efficient user interface that can provide full continuous control of such a device—safely and intuitively—with multiple degrees of freedom (DOFs) still remains a challenge. In this study, a control interface for an assistive upper-limb exoskeleton with five DOFs based on an intraoral tongue-computer interface (ITCI) for individuals with tetraplegia was proposed. Furthermore, we evaluated eyes-free use of the ITCI for the first time and compared two tongue-operated control methods, one based on tongue gestures and the other based on dynamic virtual buttons and a joystick-like control. Ten able-bodied participants tongue controlled the exoskeleton for a drinking task with and without visual feedback on a screen in three experimental sessions. As a baseline, the participants performed the drinking task with a standard gamepad. The results showed that it was possible to control the exoskeleton with the tongue even without visual feedback and to perform the drinking task at 65.1% of the speed of the gamepad. In a clinical case study, an individual with tetraplegia further succeeded to fully control the exoskeleton and perform the drinking task only 5.6% slower than the able-bodied group. This study demonstrated the first single-modal control interface that can enable individuals with complete tetraplegia to fully and continuously control a five-DOF upper limb exoskeleton and perform a drinking task after only 2 h of training. The interface was used both with and without visual feedback.

scholarly journals Control method of the wearable manipulator based on EMG signals

Mechanik ◽  
2018 ◽  
Vol 91 (7) ◽  
pp. 582-584
Author(s):  
Jarosław Jankowski ◽  
Klaudiusz Ziemek
Keyword(s):  
Neural Networks ◽  
Upper Limb ◽  
Control Method ◽  
Detection Algorithm ◽  
Upper Limb Exoskeleton ◽  
Research Procedure ◽  
Electromyographic Signal ◽  
Preliminary Research

Human integration with the exoskeleton, so that it correctly reflects the intentions of the user, requires the use of an appropriate control method containing an intent detection algorithm. The article presents the assumptions concerning the construction of the upper limb exoskeleton, the preliminary research procedure and the pre-developed methods of controlling the assistance manipulator based on the analysis of the electromyographic signal (EMG) characteristics and the use of neural networks.

scholarly journals Development of Multifunctional Myoelectric Hand Prosthesis System with Easy and Effective Mode Change Control Method Based on the Thumb Position and State

2021 ◽  
Vol 11 (16) ◽  
pp. 7295
Author(s):  
Sung-Yoon Jung ◽  
Seung-Gi Kim ◽  
Joo-Hyung Kim ◽  
Se-Hoon Park
Keyword(s):  
Upper Limb ◽  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Effective Control ◽  
Hand Gestures ◽  
Mode Change ◽  
Hand Prosthesis ◽  
Six Dof ◽  
Flexion And Extension

Commercial multi-degrees-of-freedom (multi-DOF) myoelectric hand prostheses can perform various hand gestures and grip motions using multiple DOFs. However, as most upper limb amputees have less than two electromyogram (EMG) signals generated at the amputation site, it is difficult to control various hand gestures and grip motions using multi-DOF myoelectric hand prostheses. This paper proposes a multifunctional myoelectric hand prosthesis system that uses only two EMG sensors while improving the convenience of upper limb amputees in everyday life. The proposed system comprises a six-DOF myoelectric hand prosthesis and an easy and effective control algorithm that enables upper limb amputees to perform various hand gestures and grip motions. More specifically, the hand prosthesis has a multi-DOF five-finger mechanism and a small controller that can be mounted inside the hand, allowing it to perform various hand gestures and grip motions. The control algorithm facilitates four grip motions and four gesture motions using the adduction and abduction positions of the thumb, the flexion and extension state of the thumb, and three EMG signals (co-contraction, flexion, and extension) generated using the two EMG sensors. Experimental results indicate that the proposed system is a versatile, flexible, and effective hand prosthesis system for upper limb amputees.

scholarly journals External Robotic Arm vs. Upper Limb Exoskeleton: What Do Potential Users Need?

2019 ◽  
Vol 9 (12) ◽  
pp. 2471 ◽  
Author(s):  
Hyung Seok Nam ◽  
Han Gil Seo ◽  
Ja-Ho Leigh ◽  
Yoon Jae Kim ◽  
Sungwan Kim ◽  
...  
Keyword(s):  
Upper Limb ◽  
Robotic Arm ◽  
Functional Impairments ◽  
End User ◽  
Robotic Arms ◽  
Upper Limb Exoskeleton ◽  
Phone Calls ◽  
Survey Results ◽  
Robotic Devices ◽  
Bilateral Impairment

Robotic devices that practically assist activities of daily living (ADL) are scarce. The aim of this study was to investigate practical demands of potential users of external robotic arms and upper limb exoskeletons for assistance in ADL. A survey was performed in rehabilitation clinics in individuals with functional impairments in the upper extremity, divided into unilateral (UIG, n = 24) and bilateral impairment groups (BIG, n = 24). Descriptive analyses were performed for current dependency, objective importance, and subjective necessity of the 18 ADLs by using a 5-point Likert scale. Overall, handling foods, dressing, and moving close items were highly necessary functions for both robot types. The UIG demonstrated a high demand for self-exercise using exoskeletons, whereas one-hand ADLs showed low necessity. In the UIG, the exoskeleton had significantly higher demands than the external robotic arm in washing face (p = 0.005) and brushing teeth (p = 0.007). The subjects in the BIG replied that cleaning desks and eating are highly necessary abilities for the external robotic arm; and transfer and wheelchair control, for exoskeletons. In the BIG, the exoskeleton showed significantly higher necessity than the external robotic arms in dressing (p = 0.010), making phone calls (p = 0.026), using a smartphone (p = 0.011), and writing (p = 0.005). The practical demands of potential users were affected by laterality and robot type. Further robot developments should involve essential functions based on the survey results to meet end-user needs.

Modelling and Control of a Translational Robotic Arm

2020 ◽  
Author(s):  
Bin Wei
Keyword(s):  
Computer Simulation ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Process Analysis ◽  
Robotic Arm ◽  
Control Analysis ◽  
Pick And Place ◽  
Final Design ◽  
Car Wash ◽  
End Effectors

Abstract The objective of this paper is to design and model a translational robotic arm that is simple and cheap to manufacture while maintaining good functionality. Once the robotic arm is designed, the control analysis and computer simulation are conducted. When selecting the material used for the parts, the density and strength of are considered. This paper covers the design process, analysis and computer simulation of a robotic arm. The final design is a 4-DOF (degrees of freedom) pick and place robot. This robot has 1 prismatic joint and 3 revolute joints. The arm is designed to be used in multiple applications such as pick and place, car wash, chalkboard erasers, etc. Forward kinematics is used to calculate the end effectors position and orientation based on the positions of each joint. The Lagrange general method is used to come up with the equation of motion. Also, the control method selected for this robot was nonlinear decoupling PD control.

Hybrid adaptive impedance-leader-follower control for multi-arm coordination manipulators

2016 ◽  
Vol 43 (1) ◽  
pp. 112-120 ◽  
Author(s):  
Xiangyu Liu ◽  
Ping Zhang ◽  
Guanglong Du
Keyword(s):  
Control Algorithm ◽  
Control Method ◽  
Hybrid Control ◽  
Impedance Control ◽  
Content Type ◽  
Control Framework ◽  
Coordination System ◽  
Error Accumulation ◽  
Arm Coordination ◽  
Multiple Manipulators

Purpose – The purpose of this paper is to provide a hybrid adaptive impedance-leader-follower control algorithm for multi-arm coordination manipulators, which is significant for dealing with the problems of kinematics inconsistency and error accumulation of interactive force in multi-arm system. Design/methodology/approach – This paper utilized a motion mapping theory in Cartesian space to establish a centralized dynamic leader-follower control algorithm which helped to reduce the possibility of kinematics inconsistency for multiple manipulators. A virtual linear spring model (VLSM) was presented based on a recognition approach of characteristic marker. This paper accomplished an adaptive impedance control algorithm based on the VLSM, which took into account the non-rigid contact characteristic. Experimentally demonstrated results showed the proposed algorithm guarantees that the motion and interactive forces asymptotically converge to the prescribed values. Findings – The hybrid control method improves the accuracy and reliability of multi-arm coordination system, which presents a new control framework for multiple manipulators. Practical implications – This algorithm has significant commercial applications, as a means of controlling multi-arm coordination manipulators that could serve to handle large objects and assemble complicated objects in industrial and hazardous environment. Originality/value – This work presented a new control framework for multiple coordination manipulators, which can ensure consistent kinematics and reduce the influence of error accumulation, and thus can improve the accuracy and reliability of multi-arm coordination system.

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