2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC)
Accurate identification of the intended hand movement from the surface Electromyography (sEMG) da... more Accurate identification of the intended hand movement from the surface Electromyography (sEMG) data is desired for effective control of myoelectric lower arm prostheses. This study improves the classification accuracy of hand gestures by using feature arrays, Kalman filter (KF), and a Softmax classifier. We use data from BioPatRec database to classify ten hand movements performed by 17 participants. The proposed classifier achieved 95.3% accuracy without KF, and 99.3% accuracy when KF was used to smooth the training data. Clinical Relevance-This feature-based classifier can classify 200k samples per second making it suitable for online implementation.
Prosthetic limbs hold a promise to renew the quality of life for the amputee. Neural commands are... more Prosthetic limbs hold a promise to renew the quality of life for the amputee. Neural commands are decoded via a classifier to generate control signals for the prosthetic devices. In the literature, many challenges and limitations have been identified that affect the prosthesis operation. One such drawback is muscle fatigue which degrades the surface electromyogram (sEMG) signals, and consequently, the performance of the deployed classification algorithm declines from 90% to 50% of average accuracy. We used a new technique using the Linear Discrimination Analysis (LDA) algorithm and the muscle synergy-based task discrimination (MSD) algorithm to improve the classification accuracy. In this technique, during muscles contraction/fatigue, we used the LDA algorithms in the beginning and the MSD algorithms later. The applied technique exhibited better movement classification performance during normal and muscle fatigue conditions. However, more work needs to be done to effectively solve t...
Journal of Speech, Language, and Hearing Research, 2006
Purpose The purpose of the present study was to test the hypothesis that talkers previously class... more Purpose The purpose of the present study was to test the hypothesis that talkers previously classified by Y.-C. Tsao and G. Weismer (1997) as habitually fast versus habitually slow would show differences in the way they manipulated articulation rate across the rate continuum. Method Thirty talkers previously classified by Tsao and Weismer (1997) as having habitually slow ( n = 15; 7 males, 8 females) and habitually fast ( n = 15; 8 males, 7 females) articulation rates produced a single sentence at 7 different rates, using a magnitude production paradigm. Hence, the participants were not randomly assigned to conditions. Results Quadratic regression functions relating measured to intended articulation rates were all statistically significant, and most important, there were significant differences between the slow and fast groups in the y intercepts of the functions, for both males and females. Conclusions This study provides a constructive replication of Tsao and Weismer (1997), showi...
International Journal of Electronics and Electrical Engineering
The study aims to develop an state estimation framework for the detection of stance and swing pha... more The study aims to develop an state estimation framework for the detection of stance and swing phases of gait cycle during walking on a perturbed platform, i.e. a slackline. We use Support Vector Machine (SVM) classifier for the detection of stance and swing phase in gait cycle. Surface Electromyography (EMG) data was recorded from nine different muscles in the lower extremity from five healthy subjects. The proposed structure utilizes the hypothesis of Muscle Synergies (MS) where the movement intent is modelled as hidden state of the state space framework. We employ time domain modeling of the neural drive that excites the task-dependent muscles. To cater for the naturally existing physiological bounds (the non-negative muscle activations), the state estimation process is executed using a constrained form of the Kalman filter. Principal Component Analysis (PCA) is used for dimensional reduction of reconstructed EMG signal. We evaluated performance of SVM classifier, and the detectio...
2017 IEEE Power & Energy Society General Meeting, 2017
Coherent groups of generators, i.e., machines with perfectly correlated rotor angles, play an imp... more Coherent groups of generators, i.e., machines with perfectly correlated rotor angles, play an important role in power system stability analysis. Traditionally, the coherency analysis is carried out offline, whereby the number of coherent groups of generators is determined in advance. We present an alternative real-time methodology for coherency detection based on modularity clustering of synchronization coefficient matrix. The proposed approach not only accomplishes real time coherency detection but also provides the network integrity indices (splitting, connectivity and modularity indices) for studying the dynamic behavior of the power system. Our methodology is simple, fast, and computationally attractive. A simulation case study on the IEEE 39 bus system consisting of 10 generators following a typical fault demonstrates the efficacy of our approach.
The endpoint stiffness, i.e., stiffness displayed by the wrist amid perturbations to the arm, has... more The endpoint stiffness, i.e., stiffness displayed by the wrist amid perturbations to the arm, has been used to assess the mechanical stability of the arm posture. The aim of this study is to develop an algorithm to optimally realize a desired end-point stiffness by minimizing muscle forces. The neuro-muscular behavior of the human arm during posture maintenance tasks is approximated by a two-link eight-muscle arm model. The model parameters reflect physiological data taken from published literature. The endpoint stiffness is shown to be a linear function of muscle activations. It is shown that the problem to minimize muscle activations while satisfying torque constraint at the joints can be solved by using non-negative least-squares method. Alternatively, linear programming can be used for this purpose. The biomechanical model is used to demonstrate how endpoint stiffness of desired magnitude, orientation, and eccentricity can be synthesized by activating arm muscles with minimal en...
A First Course in Control System Design discusses control systems design from a model-based persp... more A First Course in Control System Design discusses control systems design from a model-based perspective as applicable to single-input single-output systems. The emphasis in this book is on understanding and applying the techniques that enable the design of effective control systems. The book covers the time-domain and the frequency-domain design methods, as well as the design of continuous-time and discrete-time systems.
2018 IEEE International Conference on Industrial Technology (ICIT)
This study addresses the sensorless speed control of a permanent magnet DC motor using non-ideal ... more This study addresses the sensorless speed control of a permanent magnet DC motor using non-ideal voltage and current sensors. A Proportional-Integral-Derivative (PID) type speed controller with Kalman Filter (KF) estimator was used and Integral of Absolute Error (IAE), peak overshoot and settling time were chosen as performance indices. Though KF helped reduce the noise, the PID controller gains tuned via MATLAB resulted in large peak overshoot and IAE with a relatively long settling time. In comparison, a Fuzzy Logic Controller (FLC) based PID (FLC-PID), tuned using genetic algorithms (GA), reduced the settling times by 75.98%, and the IAE and the maximum overshoot by 56.2% and 97.89% respectively. Compared to the conventional PID without KF, the FLC-PID radically improved the reference command speed tracking and sudden load changes disturbance rejection for the dc motor model.
2018 IEEE Biomedical Circuits and Systems Conference (BioCAS)
The organization of encoded motor modules or motor primitives in the central nervous system and t... more The organization of encoded motor modules or motor primitives in the central nervous system and their combination leads to different aspects of natural motor behavior. It is believed that neural stimulation of these coded sections activates specific groups of muscles to achieve a behavioral goal. We use the muscle synergy (MS) hypothesis to compare activation patterns during overground walking and slackline walking for a small group of highly proficient slackliners and beginners. Synchronous MS were extracted using factor analysis (FA) for rhythmic and arrhythmic repertoire of movement. The results revealed no significant difference between slackliners and non-slackliners as the extracted synergies were dependent on the variability of the task. Besides, the shared dimensional space revealed the task-specific higher loading of the quadriceps muscles for walking with such postural constraints.
2019 IEEE 7th International Conference on Smart Energy Grid Engineering (SEGE)
$A$ grid-connected wind turbine system is considered for power system studies. The wind turbine w... more $A$ grid-connected wind turbine system is considered for power system studies. The wind turbine with doubly fed induction generator (DFIG) is modeled in MATLAB/Simulink. The fifth-order system is divided into two third-order systems representing in direct and quadrature components. Sliding mode controllers are designed for the nominal system to output rotor voltages. The Super-twisting scheme is adopted to eliminate the chattering in the switching relay. A three-phase fault on the grid side with 150 msec. duration time is applied to test the reliability of the closed-loop system. Computer simulation results show that the control system effectively clears the fault and maintains the stability of the system.
2019 IEEE 15th International Conference on Control and Automation (ICCA), 2019
Balancing over a tight rope or slackline is a challenging task as the stabilizing moments must be... more Balancing over a tight rope or slackline is a challenging task as the stabilizing moments must be internally generated by moving the arms. In this study, we use a two-segment biomechanical model of the subject to investigate postural stability and control during the balancing task on slackline. The assumed model has three degree of freedom (DoF), including slackline displacement, body orientation, and the arm rotation that also generates the stabilizing torque. We assume vestibular sensing of the body rotation rate and emulate a neural estimator in the brain that reconstructs the missing state variables. We employ linear matrix inequality (LMI) framework to design the controller-estimator to stabilize the proposed biomechanical model. The nonlinear model is then simulated to ensure postural stability during the execution of balancing task over slackline.
2019 2nd International Conference of Intelligent Robotic and Control Engineering (IRCE)
The research about modelling complex mechanical system have been developed rapidly. Newtonian, La... more The research about modelling complex mechanical system have been developed rapidly. Newtonian, Lagrangian and Bond graph method were considered the most useful methods, but involves a high level of geometry, orientation and interconnection between segments. The motivation for this research is to use a modelling-simulation framework to achieve three aims: (a) establish a dynamic model soccer kicking behavior in SimMechanics, (b) synthesize PID and LQR controller for the model and (c) to optimize the dynamic stability and performance during the said movement. The rigid body model is driven by torque actuators at the joints. This modeling framework mimics the kicking action of a soccer player under different regimes. We compared the performance of PID and LQR controller to regulate the kick action. Though the PID controller needed less time to achieve the steady state, the LQR controller could adopt to various task requirements as well as optimized the energy expenditures. The dynamic simulations carried out in this study leads to further investigation of kicking action by utilizing the outside, and inside area of foot for kick action (the Magnus effect).
The human motor system is a complex neuro-musculo sensory system that needs further investigation... more The human motor system is a complex neuro-musculo sensory system that needs further investigations of neuro-muscular commands and sensory-motor coupling to decode movement execution. Some researchers suggest that the central nervous system (CNS) activates a small set of modules termed muscle synergies to simplify motor control. Further, these modules form functional building blocks of movement as they can explain the neurophysiological characteristics of movements. We can identify and extract these muscle synergies from electromyographic signals (EMG) recorded in the laboratory by using linear decomposition algorithms, such as principal component analysis (PCA) and non-Negative Matrix Factorization Algorithm (NNMF). For the past three decades, the hypothesis of muscle synergies has received considerable attention as we attempt to understand and apply the concept of muscle synergies in clinical settings and rehabilitation. In this article, we first explore the concept of muscle syner...
International Journal of Mechanical Engineering and Robotics Research
A quadrotor unmanned aerial vehicle (UAV) controller distributes the pitch, roll and yaw commands... more A quadrotor unmanned aerial vehicle (UAV) controller distributes the pitch, roll and yaw commands to individual propellers. This paper explores fault-tolerant control of a quadrotor UAV using delayed feedback and Divided State Feedback Control (DSFC). Initially, a Sliding Mode Controller (SMC) for the quadrotor UAV is designed to obtain sustained performance in the presence of actuator faults. The SMC performance deteriorates considerably in the presence of delayed sensory feedback from the UAV. A DSFC is then used to restore effectiveness of the device controller. The proposed control structure delivers improved stabilization, robustness and transient response in the presence of actuator faults. Computer simulations are presented to illustrate the effectiveness of our hybrid control scheme.
It is hypothesised that specific groups of muscles aka muscle synergies (MSs) are combined by the... more It is hypothesised that specific groups of muscles aka muscle synergies (MSs) are combined by the central nervous system to control a wide repertoire of movements and also simplify motor control. Therefore, studying MSs during human locomotion is of significance, as it may reveal neuromuscular strategies for postural stability. In this study, the authors aimed to use the hypothesis of MSs to identify specific muscle co-activations during overground walking and slacklining where postural perturbations were generated by the participants rather than being externally controlled. Nine participants were asked to walk overground and on a slackline while they recorded myoelectric activity of their leg muscles. They extracted synergies from the electromyography signals in the two tasks using factor analysis. The results showed adaptation in the shared MSs structure during walking on the slackline and these shared MSs across participants were recruited flexibly to meet the demand for stability. The modulation of synergies suggests adaptive neuromuscular strategies for stability while walking on a slackline. Specifically, higher activation of quadriceps during slacklining suggests a crouched gait to facilitate balance. During overground walking, lower leg muscles revealed higher activation compared to slacklining to support a more consistent toe-off during the stance phase.
The Physiological studies illustrate that human sit-to-stand STS movement consists of different p... more The Physiological studies illustrate that human sit-to-stand STS movement consists of different phases that are distinguishable by their kinematics constraints and stability requirements. We propose to use a fuzzy TSK biomechanical model to analyze, integrate, and study biomechanical STS movement. The fuzzy model combines two local linear models defined at the initiation and termination points of STS using Gaussian membership functions that operate on measurement of knee flexion. Further, we develop TSK fuzzy controllers that employ H2 and H∞ optimal control techniques for effective regulation of biomechanical STS. The fuzzy controllers similarly combine knowledge from local linear optimal controllers via membership functions. Our simulation results show that fuzzy TSK modeling is useful for the synthesis of STS movement because of its relevance with physiological principles and the use of localized control strategies for the joint torques.
2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC)
Accurate identification of the intended hand movement from the surface Electromyography (sEMG) da... more Accurate identification of the intended hand movement from the surface Electromyography (sEMG) data is desired for effective control of myoelectric lower arm prostheses. This study improves the classification accuracy of hand gestures by using feature arrays, Kalman filter (KF), and a Softmax classifier. We use data from BioPatRec database to classify ten hand movements performed by 17 participants. The proposed classifier achieved 95.3% accuracy without KF, and 99.3% accuracy when KF was used to smooth the training data. Clinical Relevance-This feature-based classifier can classify 200k samples per second making it suitable for online implementation.
Prosthetic limbs hold a promise to renew the quality of life for the amputee. Neural commands are... more Prosthetic limbs hold a promise to renew the quality of life for the amputee. Neural commands are decoded via a classifier to generate control signals for the prosthetic devices. In the literature, many challenges and limitations have been identified that affect the prosthesis operation. One such drawback is muscle fatigue which degrades the surface electromyogram (sEMG) signals, and consequently, the performance of the deployed classification algorithm declines from 90% to 50% of average accuracy. We used a new technique using the Linear Discrimination Analysis (LDA) algorithm and the muscle synergy-based task discrimination (MSD) algorithm to improve the classification accuracy. In this technique, during muscles contraction/fatigue, we used the LDA algorithms in the beginning and the MSD algorithms later. The applied technique exhibited better movement classification performance during normal and muscle fatigue conditions. However, more work needs to be done to effectively solve t...
Journal of Speech, Language, and Hearing Research, 2006
Purpose The purpose of the present study was to test the hypothesis that talkers previously class... more Purpose The purpose of the present study was to test the hypothesis that talkers previously classified by Y.-C. Tsao and G. Weismer (1997) as habitually fast versus habitually slow would show differences in the way they manipulated articulation rate across the rate continuum. Method Thirty talkers previously classified by Tsao and Weismer (1997) as having habitually slow ( n = 15; 7 males, 8 females) and habitually fast ( n = 15; 8 males, 7 females) articulation rates produced a single sentence at 7 different rates, using a magnitude production paradigm. Hence, the participants were not randomly assigned to conditions. Results Quadratic regression functions relating measured to intended articulation rates were all statistically significant, and most important, there were significant differences between the slow and fast groups in the y intercepts of the functions, for both males and females. Conclusions This study provides a constructive replication of Tsao and Weismer (1997), showi...
International Journal of Electronics and Electrical Engineering
The study aims to develop an state estimation framework for the detection of stance and swing pha... more The study aims to develop an state estimation framework for the detection of stance and swing phases of gait cycle during walking on a perturbed platform, i.e. a slackline. We use Support Vector Machine (SVM) classifier for the detection of stance and swing phase in gait cycle. Surface Electromyography (EMG) data was recorded from nine different muscles in the lower extremity from five healthy subjects. The proposed structure utilizes the hypothesis of Muscle Synergies (MS) where the movement intent is modelled as hidden state of the state space framework. We employ time domain modeling of the neural drive that excites the task-dependent muscles. To cater for the naturally existing physiological bounds (the non-negative muscle activations), the state estimation process is executed using a constrained form of the Kalman filter. Principal Component Analysis (PCA) is used for dimensional reduction of reconstructed EMG signal. We evaluated performance of SVM classifier, and the detectio...
2017 IEEE Power & Energy Society General Meeting, 2017
Coherent groups of generators, i.e., machines with perfectly correlated rotor angles, play an imp... more Coherent groups of generators, i.e., machines with perfectly correlated rotor angles, play an important role in power system stability analysis. Traditionally, the coherency analysis is carried out offline, whereby the number of coherent groups of generators is determined in advance. We present an alternative real-time methodology for coherency detection based on modularity clustering of synchronization coefficient matrix. The proposed approach not only accomplishes real time coherency detection but also provides the network integrity indices (splitting, connectivity and modularity indices) for studying the dynamic behavior of the power system. Our methodology is simple, fast, and computationally attractive. A simulation case study on the IEEE 39 bus system consisting of 10 generators following a typical fault demonstrates the efficacy of our approach.
The endpoint stiffness, i.e., stiffness displayed by the wrist amid perturbations to the arm, has... more The endpoint stiffness, i.e., stiffness displayed by the wrist amid perturbations to the arm, has been used to assess the mechanical stability of the arm posture. The aim of this study is to develop an algorithm to optimally realize a desired end-point stiffness by minimizing muscle forces. The neuro-muscular behavior of the human arm during posture maintenance tasks is approximated by a two-link eight-muscle arm model. The model parameters reflect physiological data taken from published literature. The endpoint stiffness is shown to be a linear function of muscle activations. It is shown that the problem to minimize muscle activations while satisfying torque constraint at the joints can be solved by using non-negative least-squares method. Alternatively, linear programming can be used for this purpose. The biomechanical model is used to demonstrate how endpoint stiffness of desired magnitude, orientation, and eccentricity can be synthesized by activating arm muscles with minimal en...
A First Course in Control System Design discusses control systems design from a model-based persp... more A First Course in Control System Design discusses control systems design from a model-based perspective as applicable to single-input single-output systems. The emphasis in this book is on understanding and applying the techniques that enable the design of effective control systems. The book covers the time-domain and the frequency-domain design methods, as well as the design of continuous-time and discrete-time systems.
2018 IEEE International Conference on Industrial Technology (ICIT)
This study addresses the sensorless speed control of a permanent magnet DC motor using non-ideal ... more This study addresses the sensorless speed control of a permanent magnet DC motor using non-ideal voltage and current sensors. A Proportional-Integral-Derivative (PID) type speed controller with Kalman Filter (KF) estimator was used and Integral of Absolute Error (IAE), peak overshoot and settling time were chosen as performance indices. Though KF helped reduce the noise, the PID controller gains tuned via MATLAB resulted in large peak overshoot and IAE with a relatively long settling time. In comparison, a Fuzzy Logic Controller (FLC) based PID (FLC-PID), tuned using genetic algorithms (GA), reduced the settling times by 75.98%, and the IAE and the maximum overshoot by 56.2% and 97.89% respectively. Compared to the conventional PID without KF, the FLC-PID radically improved the reference command speed tracking and sudden load changes disturbance rejection for the dc motor model.
2018 IEEE Biomedical Circuits and Systems Conference (BioCAS)
The organization of encoded motor modules or motor primitives in the central nervous system and t... more The organization of encoded motor modules or motor primitives in the central nervous system and their combination leads to different aspects of natural motor behavior. It is believed that neural stimulation of these coded sections activates specific groups of muscles to achieve a behavioral goal. We use the muscle synergy (MS) hypothesis to compare activation patterns during overground walking and slackline walking for a small group of highly proficient slackliners and beginners. Synchronous MS were extracted using factor analysis (FA) for rhythmic and arrhythmic repertoire of movement. The results revealed no significant difference between slackliners and non-slackliners as the extracted synergies were dependent on the variability of the task. Besides, the shared dimensional space revealed the task-specific higher loading of the quadriceps muscles for walking with such postural constraints.
2019 IEEE 7th International Conference on Smart Energy Grid Engineering (SEGE)
$A$ grid-connected wind turbine system is considered for power system studies. The wind turbine w... more $A$ grid-connected wind turbine system is considered for power system studies. The wind turbine with doubly fed induction generator (DFIG) is modeled in MATLAB/Simulink. The fifth-order system is divided into two third-order systems representing in direct and quadrature components. Sliding mode controllers are designed for the nominal system to output rotor voltages. The Super-twisting scheme is adopted to eliminate the chattering in the switching relay. A three-phase fault on the grid side with 150 msec. duration time is applied to test the reliability of the closed-loop system. Computer simulation results show that the control system effectively clears the fault and maintains the stability of the system.
2019 IEEE 15th International Conference on Control and Automation (ICCA), 2019
Balancing over a tight rope or slackline is a challenging task as the stabilizing moments must be... more Balancing over a tight rope or slackline is a challenging task as the stabilizing moments must be internally generated by moving the arms. In this study, we use a two-segment biomechanical model of the subject to investigate postural stability and control during the balancing task on slackline. The assumed model has three degree of freedom (DoF), including slackline displacement, body orientation, and the arm rotation that also generates the stabilizing torque. We assume vestibular sensing of the body rotation rate and emulate a neural estimator in the brain that reconstructs the missing state variables. We employ linear matrix inequality (LMI) framework to design the controller-estimator to stabilize the proposed biomechanical model. The nonlinear model is then simulated to ensure postural stability during the execution of balancing task over slackline.
2019 2nd International Conference of Intelligent Robotic and Control Engineering (IRCE)
The research about modelling complex mechanical system have been developed rapidly. Newtonian, La... more The research about modelling complex mechanical system have been developed rapidly. Newtonian, Lagrangian and Bond graph method were considered the most useful methods, but involves a high level of geometry, orientation and interconnection between segments. The motivation for this research is to use a modelling-simulation framework to achieve three aims: (a) establish a dynamic model soccer kicking behavior in SimMechanics, (b) synthesize PID and LQR controller for the model and (c) to optimize the dynamic stability and performance during the said movement. The rigid body model is driven by torque actuators at the joints. This modeling framework mimics the kicking action of a soccer player under different regimes. We compared the performance of PID and LQR controller to regulate the kick action. Though the PID controller needed less time to achieve the steady state, the LQR controller could adopt to various task requirements as well as optimized the energy expenditures. The dynamic simulations carried out in this study leads to further investigation of kicking action by utilizing the outside, and inside area of foot for kick action (the Magnus effect).
The human motor system is a complex neuro-musculo sensory system that needs further investigation... more The human motor system is a complex neuro-musculo sensory system that needs further investigations of neuro-muscular commands and sensory-motor coupling to decode movement execution. Some researchers suggest that the central nervous system (CNS) activates a small set of modules termed muscle synergies to simplify motor control. Further, these modules form functional building blocks of movement as they can explain the neurophysiological characteristics of movements. We can identify and extract these muscle synergies from electromyographic signals (EMG) recorded in the laboratory by using linear decomposition algorithms, such as principal component analysis (PCA) and non-Negative Matrix Factorization Algorithm (NNMF). For the past three decades, the hypothesis of muscle synergies has received considerable attention as we attempt to understand and apply the concept of muscle synergies in clinical settings and rehabilitation. In this article, we first explore the concept of muscle syner...
International Journal of Mechanical Engineering and Robotics Research
A quadrotor unmanned aerial vehicle (UAV) controller distributes the pitch, roll and yaw commands... more A quadrotor unmanned aerial vehicle (UAV) controller distributes the pitch, roll and yaw commands to individual propellers. This paper explores fault-tolerant control of a quadrotor UAV using delayed feedback and Divided State Feedback Control (DSFC). Initially, a Sliding Mode Controller (SMC) for the quadrotor UAV is designed to obtain sustained performance in the presence of actuator faults. The SMC performance deteriorates considerably in the presence of delayed sensory feedback from the UAV. A DSFC is then used to restore effectiveness of the device controller. The proposed control structure delivers improved stabilization, robustness and transient response in the presence of actuator faults. Computer simulations are presented to illustrate the effectiveness of our hybrid control scheme.
It is hypothesised that specific groups of muscles aka muscle synergies (MSs) are combined by the... more It is hypothesised that specific groups of muscles aka muscle synergies (MSs) are combined by the central nervous system to control a wide repertoire of movements and also simplify motor control. Therefore, studying MSs during human locomotion is of significance, as it may reveal neuromuscular strategies for postural stability. In this study, the authors aimed to use the hypothesis of MSs to identify specific muscle co-activations during overground walking and slacklining where postural perturbations were generated by the participants rather than being externally controlled. Nine participants were asked to walk overground and on a slackline while they recorded myoelectric activity of their leg muscles. They extracted synergies from the electromyography signals in the two tasks using factor analysis. The results showed adaptation in the shared MSs structure during walking on the slackline and these shared MSs across participants were recruited flexibly to meet the demand for stability. The modulation of synergies suggests adaptive neuromuscular strategies for stability while walking on a slackline. Specifically, higher activation of quadriceps during slacklining suggests a crouched gait to facilitate balance. During overground walking, lower leg muscles revealed higher activation compared to slacklining to support a more consistent toe-off during the stance phase.
The Physiological studies illustrate that human sit-to-stand STS movement consists of different p... more The Physiological studies illustrate that human sit-to-stand STS movement consists of different phases that are distinguishable by their kinematics constraints and stability requirements. We propose to use a fuzzy TSK biomechanical model to analyze, integrate, and study biomechanical STS movement. The fuzzy model combines two local linear models defined at the initiation and termination points of STS using Gaussian membership functions that operate on measurement of knee flexion. Further, we develop TSK fuzzy controllers that employ H2 and H∞ optimal control techniques for effective regulation of biomechanical STS. The fuzzy controllers similarly combine knowledge from local linear optimal controllers via membership functions. Our simulation results show that fuzzy TSK modeling is useful for the synthesis of STS movement because of its relevance with physiological principles and the use of localized control strategies for the joint torques.
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