Nghiên cứu điều khiển robot phục hồi chức năng chi dưới sử dụng cơ nhân tạo

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MINISTRY OF EDUCATION AND TRAINING

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

DINH VAN VUONG

STUDY ON CONTROL OF A PAM-BASED LOWER-LIMB

REHABILITATION ROBOT

DOCTOR DISSERTATION ON CONTROL ENGINEERING AND AUTOMATION

Hanoi - 2024

MINISTRY OF EDUCATION AND TRAINING

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

DINH VAN VUONG

STUDY ON CONTROL OF A PAM-BASED LOWER-LIMB

1 Assoc.Prof.Dr Duong Minh Duc

2 Dr Dao Quy Thinh

Hanoi - 2024

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DECLARATION

I certify that this is my research work under the guidance of my supervisor and scientists References used in the Dissertation have been fully cited The data and results in the Dissertation are truthful and have never been published by other authors

Hanoi, February , 2024

Supervisor Dissertation Author

1 Assoc.Prof.Dr Duong Minh Duc Dinh Van Vuong

2 Dr Dao Quy Thinh

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ACKNOWLEDGMENTS

The author would like to express his sincere gratitude to his supervisors, Assoc.Prof.Dr Duong Minh Duc and Dr Dao Quy Thinh, for their dedicated guidance throughout his Dissertation, from forming ideas to step-by-step planning to completing the Dissertation

The author would like to express this deep gratitude to the Department of Automation Engineering – School of Electrical Engineering and Electronics (Hanoi University of Science and Technology) for providing him with a favorable research environment and the necessary facilities for his Dissertation Moreover, the author also received valuable and practical contributions and exchanges from Assoc.Prof.Dr Tran Trong Minh, Assoc.Prof.Dr Nguyen Tung Lam, and Dr Nguyen Danh Huy about his research content during the Dissertation process

In addition, the author would like to express his sincere gratitude to the leadership of the Hanoi College of High Technology, the Faculty of Electrical and Electronics Engineering leaders, and his colleagues, who facilitated the time for him to participate in the research

The author would like to thank all research members at the WSR Laboratory They were the ones who always accompanied, encouraged, and supported him in research and experiments

Finally, the author would like to express his sincere gratitude to his family, especially his wife, Nguyen Thi Doan Trang, and other relatives for their understanding and encouragement throughout all his steps to complete this study

Hanoi, February , 2024

Dissertation Author

Dinh Van Vuong

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ABSTRACT

suffering from work accidents, traffic accidents, strokes, and disabilities in the world Many people face difficulties with daily living activities, which becomes increasingly difficult if they do not receive appropriate rehabilitation training The rehabilitation process can help patients slow the rate of function loss and improve motion rehabilitation However, the traditional rehabilitation process is often expensive and takes a long time The number of doctors and medical staff, especially physical therapists, is increasingly lacking Rehabilitation robots can reduce the burden on physical therapy doctors and assist patients

in exercising regularly at any time However, upper limb rehabilitation training involves more complex movements and degrees of freedom However, the lower limb rehabilitation process must bear the load of the entire body weight Therefore, besides providing appropriate exercise methods for patients, supporting the patient is also very important According to a report on treadmill exercise therapy based on the "spinal motion rule" by

spinal cord injury (SCI) improve their motion function more quickly than traditional rehabilitation methods Currently, most rehabilitation systems are still in the research and development stage Therefore, researching the application of robots to replace humans in medical care, especially rehabilitation, has become an inevitable trend today, not only in developed countries but worldwide

Recently, a lower limb rehabilitation robot system called the BK-Gait has been developed at the Hanoi University of Science and Technology laboratory The BK-Gait system includes a treadmill, a body weight support system, and a lower limb rehabilitation robot The lower limb rehabilitation robot is a two-degree-of-freedom robot The detailed structure of the lower limb rehabilitation robot includes the following: Pneumatic artificial muscles (PAMs) are McKibben artificial muscles with a diameter of 1.0 inches, similar to human muscles These pneumatic artificial muscles can reach a maximum contraction level

of 30% compared to muscle length The ITV−2030−212S−X26 electric proportional control

sensor measures the joint angle, and the Myrio−1900 controller controls the robot

In the scope of this research We focus on the following tasks:

• Building a two-degree-of-freedom pneumatic artificial muscle-based exoskeleton robot for the human's lower-limb rehabilitation

• Developing trajectory tracking control function for a prototype robot by employing some advanced control strategies

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• Integrating an impedance control function into a robot by using neural networks to approximate the interaction force of humans to the robot

The Dissertation content is presented in four chapters and a conclusion:

• Chapter 1: Overview of the rehabilitation systems

• Chapter 2: Modeling and control of PAMs

• Chapter 3: Trajectory tracking control of the BK-Gait orthosis

• Chapter 4: Impedance control of the BK-Gait orthosis

• Conclusions and Recommendations

1 The Necessity of the Dissertation

Nowadays, millions worldwide are limited in their ability to move, which makes them face many difficulties in their daily activities The process of physical therapy for the rehabilitation system can help the patients improve their recovery and assist therapists by supporting them in performing repetitive movements in the rehabilitation process However, traditional physical therapy takes time and requires highly trained physical therapists In addition, each patient requires different rehabilitation exercises, which require more physical therapists at different levels

Shortly, rehabilitation robot systems are being researched and developed worldwide

to replace physical therapists gradually Robots can assist patients systematically in performing preprogrammed rehabilitation exercises At the same time, robots can assist with long-term training without getting tired However, as robots interact directly with humans, safety is always a top priority in designing and controlling rehabilitation robots In addition, the robot's actuators must also be flexibly controlled to make patients feel most comfortable during training and avoid causing injury to the patient Recently, the rehabilitation system using pneumatic artificial muscles has attracted much attention from researchers due to the similarity between PAM and human muscles The PAM is lightweight and has a higher power-to-weight ratio than motorized transmission devices

Moreover, PAM is quite flexible and suitable for robots that interact with humans, such as rehabilitation robots Several prototype systems of rehabilitation robots have been developed at research centres worldwide But, most of the above systems are still in the early stages of development Furthermore, the "Assist-As-Needed" (AAN) function is indispensable for a rehabilitation robot to support patients flexibly, depending on their level

of interaction with the system Therefore, a robot must have sufficient rigidity to guide the patient's limb along the designated trajectory and estimate the patient's level of disability to provide the necessary support In summary, all rehabilitation robot systems that use pneumatic artificial muscles domestically and internationally are only currently in the

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laboratory and have not been commercialized So, the potential for research and

development is enormous Based on this reality, we have chosen the topic of "Study on

Control of a PAM-based Lower-limb Rehabilitation Robot"

2 Purpose of the research

The purpose of this Dissertation only focuses on the study of control lower-limb robotic orthosis:

• Building a two-degree-of-freedom pneumatic artificial muscle-based exoskeleton robot for the human's lower-limb rehabilitation

• Developing trajectory tracking control function for a prototype robot by employing some advanced control strategies

• Integrating an impedance control function into a robot by using neural networks to approximate the interaction force of humans to the robot

3 Objectives and scope of research

a Research objective

The research objective is the BK-Gait 2-DOF robotic orthosis that covers hip and knee joints The robotic orthosis is actuated by pneumatic artificial muscles in an antagonistic configuration

b Scope of research

The research scope of this Dissertation focuses only on the study of controlled limb robotic orthosis Therefore, the research project will be performed based on theoretical foundations and experiments:

lower-• The model parameters are collected based on the pneumatic artificial muscle (PAM) with the antagonistic configuration of the BK-Gait 2-DOF robotic orthosis

• All measurements, control algorithms, and experimental results are performed and verified by experiments on the lower-limb rehabilitation robot model (BK-Gait) at Hanoi University of Science and Technology

• A mathematical model with two muscles having an antagonistic configuration will

be built to describe the system's dynamic characteristics The model parameters will

The proposed controllers will be performed through experiments with the fabricated robot

5 The scientific and practical significance of the Dissertation

a Scientific significance

The scientific significance of this Dissertation is to build trajectory-tracking control and impedance control algorithms for actuators and robot systems using PAM-based actuators that are accurate and suitable for rehabilitation applications

b Practical significance

The practical significance of this Dissertation is to build a rehabilitation system for the human lower limb with trajectory tracking and impedance control functions with good precision and applicability to rehabilitation systems in practice

6 The Contributions of the Dissertation

This study mainly presents the control algorithms for a low-limb rehabilitation system

by combining theoretical research and experimental verification The main contributions of the Dissertation:

• Building a two-degree-of-freedom pneumatic artificial muscle-based exoskeleton robot for the human's lower-limb rehabilitation

• Developing trajectory tracking control function for a prototype robot by employing some advanced control strategies

• Integrating an impedance control function into a robot by using neural networks to approximate the interaction force of humans to the robot

7 Structure of the Dissertation

The Dissertation is structured into Chapters and a conclusion as follows:

• Chapter 1 Overview of the Rehabilitation Systems: This Chapter provides an

overview of the rehabilitation robot system It highlights that the global research and development efforts in rehabilitation robots are substantial due to their notable advantages over traditional rehabilitation methods However, most research on robotic rehabilitation systems using artificial muscles is limited to the laboratory and

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has not been commercialized This indicates a significant potential for further research and development in the field

• Chapter 2 Modeling and Control of PAMs: This Chapter overviews pneumatic

artificial muscles and the popular methods for modeling artificial muscles After that,

we built a mathematical model for a PAM-based actuator Finally, we will apply advanced control algorithms to build a trajectory-tracking controller for a PAM-based actuator Multiple experiment scenarios will be performed to verify the effectiveness of these controllers

• Chapter 3 Trajectory Tracking Control of the BK-Gait Orthosis: This Chapter

focuses on improving the control system for the BK-Gait lower-limb robotic orthosis Firstly, we will build a mathematical model for the BK-Gait lower-limb robotic orthosis Next, we will apply advanced control algorithms to build a trajectory-tracking controller for BK-Gait lower-limb robotic orthosis Finally, multiple experiment scenarios will be performed to verify the effectiveness of the built controller

• Chapter 4 Impedance Control of the BK-Gait Orthosis: In this Chapter, a neural

network-based method is chosen to estimate the patient's recovery, an essential factor for a gait training robot system powered by pneumatic artificial muscles The estimated patient recovery will be used as the control signal for the impedance controller to improve joint compliance coefficients

• Conclusions and Recommendations: This section summarizes the results achieved

in the Dissertation, the main contributions, and proposes future research directions

Hip PAMs

Knee PAMs Hip Joint

Knee Joint

0.005 0.01 0.015 0.02 0.025 0.03

Root-mean-square Error

0.70 1.80

2.80 3.50

0.80

2.50

3.30 3.90

0.1Hz without Load 0.5Hz without Load 0.1Hz Load 0.5Hz Load

Root-mean-square Error

5.00

5.90

6.60 7.10

5.50 6.40 6.70

0 1 2 3 4 5 6 7 8 -25

0 5 10 15 20 25 30 -25

1.54

2.32 2.60

4.26 4.66

0 1 2 3 4 5

0 1 2 3 4 5 6 7 8 -25

4.26 4.66

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

COM

O

O COM

RMSE value of two ESO

0.92

1.08

1.53 1.75

1.27 1.60

2.34 2.66

Hip Jo

int

Hip Jo

int (Disturbance)

Knee Joint

ee Joint (Disturbance)0

0 1 2 3 4 5 6 7 8 -15

0 1 2 3 4 5 6 7 8 -10

1.52

1.20 2.10

1.23 1.96 1.98

Kn Jo(Load) 0

3.45 4.49 4.39

8.12

Hip Jo(wi

ut load)

Jo (wi

ut load) Hip Jo(Load)

Knee

nt (Lo

ad)0

1 2 3 4 5 6 7 8

0 2 4 6 8 10 12 -10

0 2 4 6 8 10 12 -30

0 2 4 6 8 10 12 14 16 18 20 -2

0 2 4 6 8 10 12 -30

0 2 4 6 8 10 12 0

Root-mean-square Tracking Error

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5

0 0.5 1 1.5 2 2.5 3 3.5 4