Biomechanical Study of Gait Rehabilitation Robot The 16th International Conference on Biomedical Engineering Biomechanical Study of Gait Rehabilitation Robot Hsiao-ju Cheng1, Pavithra Thangavel2, Gong Chen1, Vidhaya S2, Haoyong Yu1 1Department of Biomedical Engineering, NUS, Singapore 2Department of Biomedical Engineering, VIT University, Vellore, India 7th December 2016

Biomechanical Study of Gait Rehabilitation Robot Introduction Conventional Gait Rehabilitation Robot-assisted Gait Rehabilitation http://www.clickittefaq.com/wp-content/uploads/2016/06/Stroke-patients.jpg http://www.irehab.com.my/images/Lokomat.jpg High demand on manpower Physical demand for therapists Inconsistency Bulky and heavy Expensive Not suitable for home-based exercise Introduction

Biomechanical Study of Gait Rehabilitation Robot Robot Design Human-robot interface controller Intelligent control strategy  Overground gait rehabilitation [1] G. Chen, P. Qi, Z. Guo and H. Yu, “Gait-Event-Based Synchronization Method for Gait Rehabilitation Robots via a Bio-inspired Adaptive Oscillator,” IEEE Transactions on Biomedical Engineering, accepted on 25 August 2016. [2] G. Chen, P. Qi, Z. Guo and H. Yu, "Mechanical Design and Evaluation of a Compact Portable Knee–ankle–foot Robot for Gait Rehabilitation", Mechanism and Machine Theory, vol. 103, pp. 51-64, 2016. [3] G. Chen, H. Yu, “A Portable Powered Knee-Ankle-Foot Orthosis,” ASME Transactions Journal of Medical Devices, 8(2): 020927, 2014. [4] H. Yu, S. Huang, Gong Chen, N. Thakor, “Control Design of a Novel Compliant Actuator for Rehabilitation Robots,” Mechatronics, 23(8): 1072-1083, 2013. Introduction

Mechanical Design Modular design Bilateral structure Compact and portable Light weight (< 4Kg) Compliant and backdrivable Length adjustable (Height of subject: 158~186cm) Introduction

Biomechanical Study of Gait Rehabilitation Robot Novel SEA Design Compact: 230 x 78 x 43 mm Weight: 0.85 Kg Power: 120 W Low-force range: 0~240N force resolution: 0.0092 N High-force range: 240~1128 N Force resolution: 5.6 N Add one for gait phase detection Introduction

Control Strategy Gait-event-based synchronization method (based on hidden Markov model) Introduction

Control Strategy (Cont.) Adaptive Oscillator Robot Assistive Method     SEA controller Introduction

Biomechanical Study of Gait Rehabilitation Robot Aim To evaluate the performance and effectiveness of the exoskeleton by biomechanical analysis with assistive support To determine the feasibility of the exoskeleton in healthy subjects Introduction

Biomechanical Study of Gait Rehabilitation Robot Experimental Setup Task: 10 m overground walking Conditions: Free walking (FW) Zero force (ZF) Assistive condition (AS) EMG  sEMG Methods

Experimental Video Methods

Biomechanical Study of Gait Rehabilitation Robot Data Collection Surface electromyography (sEMG) Sampling rate: 1000 Hz Tibialis Anterior (TA) Gastrocnemius Lateralis (GL) Rectus Femoris (RF) Semitendinosus (SM) Kinetics data: knee assistive torque Kinematic data: knee joint angle Gait phases and events by inertia measurement unit (IMU) Elaborate function of muscles Methods

Data Processing Processed by MATLAB (The MathWorks, Inc., US) sEMG: Normalized by using the isometric maximal voluntary contraction (MVIC) method percentage of the acquired MVC Statistics analysis for three studied parameters Repeated measures analysis of variance (ANOVA) Least significant difference (LSD) method α = 0.05 Methods

Participants 10 healthy male volunteers Age: 25.3 ± 3.12 years Weight: 71.3 ± 8.94 kg Height :1.74 ±0.07 m Signed the informed consent forms (granted by NUS-IRB) Methods

Kinetics & Kinematics Analysis Biomechanical Study of Gait Rehabilitation Robot Kinetics & Kinematics Analysis http://clinicalgate.com/wp-content/uploads/2015/03/F000146f014-002-9781455709779.jpg Mean knee torque Mean knee angle FW: Free Walking ZF: Zero Force AS: Assistive Condition With assistive torque  knee joint angle is closer to normal walking Results & Discussion

Biomechanical Study of Gait Rehabilitation Robot sEMG Analysis FW: Free Walking ZF: Zero Force AS: Assistive Condition TA: Tibialis Anterior GL: Gastrocnemius Lateralis RF: Rectus Femoris SM: Semitendinosus *: P < 0.05 **: P < 0.01 After wearing the exoskeleton, the muscle activities increased Providing assistive torque, the muscle activities significantly decreased  Assistive torque does help subjects to lower the loading of the exoskeleton Results & Discussion

Biomechanical Study of Gait Rehabilitation Robot Conclusion Experiments on the effect of the exoskeleton on lower limb kinematics and muscle activity during walking in healthy subjects Significant reduction in muscle activity and improvement in the knee joint angle with assistive support The exoskeleton is capable of providing assistance and the implemented control strategy is effective  Suitable for future clinical trials Conclusion

Acknowledgement Supervisor: Dr. Haoyong Yu Labmates: Gong Chen Pavithra Thangavel Francisco Anaya Reyes Ashwin Narayan Gokhan Mert Yagli Jen-Shuan Chang Funding agency and collaborators: http://www.bioeng.nus.edu.sg/biorob/index.html