Design and Test of a Biomechanical Model for the Estimation of Knee Joint Angle During Indoor Rowing: Implications for FES-Rowing Protocols in Paraplegia

Functional electrical stimulation of lower limb muscles during rowing provides a means for the cardiovascular conditioning in paraplegia. The possibility of shaping stimulation profiles according to changes in knee angle, so far conceived as changes in seat position, may help circumventing open issues associated with muscle fatigue and movement coordination.Here we present a subject-specific biomechanical model for the estimation of knee joint angle during indoor rowing. Anthropometric measurements and foot and seat position are inputs to the model. We tested our model on two samples of elite rowers; 15 able-bodied and 11 participants in the Rio 2016 Paralympic games. Paralympic rowers presented minor physical disabilities (LTA-PD classification), enabling them to perform the full rowing cycle (with legs, trunks and arms). Knee angle was estimated from the rowing machine seat position, measured with a linear encoder and transmitted wirelessly to a computer. Key results indicate the root mean square error (RMSE) between estimated and measured angles did not depend on group and stroke rate (p>0.267). Significantly greater RMSE values were observed however within the rowing cycle (p<0.001), reaching on average 8deg in the mid-recovery phase. Differences between estimated and measured knee angle values resulted in slightly earlier (5%) detection of knee flexion, regardless of the group and stroke rate considered. Offset of knee extension, knee angle at catch and range of knee motion were identified equally well with our model and with inertial sensors. These results suggest our model describes accurately the movement of knee joint during indoor rowing

Effect of Inclined Rowing Machine on FES-Assisted Indoor Rowing Exercise Performance

Abstract – This paper describes the effect of inclined track in an indoor rowing machine on the rowing exercise for paraplegics. The indoor rowing exercise is introduced as a total body exercise for rehabilitation of function of lower extremities through the application of functional electrical stimulation (FES). A model of the machine is developed using the Visual Nastran (Vn4D) software environment. Nine different degrees of inclination are set. Fuzzy logic control is implemented to control the knee and elbow trajectories for each of the inclination angle. The generated level of electrical stimulations for activation of quadriceps and hamstrings muscles are recorded and analysed. The results show that the highest efficiency is achieved at 7 ° of inclination. In view of good results obtained, it is concluded that different angles of track inclination significantly affect the level of electrical stimulation required to assist paraplegics ’ indoor rowing exercise

Feasibility of Using Neuro-Fuzzy Subject-Specific Models for Functional Electrical Stimulation Induced Hand Movements

Functional Electrical Stimulation (FES) is a technique that artificially elicits muscle contractions and it is used to restore motor/sensory functions in both assistive and therapeutic applications. The use of multi-field surface electrodes is a novel popular approach in transcutaneous FES applications. Lately, hybrid systems that combine artificial neural networks and fuzzy logic have also been proposed for many applications in different areas. This paper presents the possibility of combining both approaches for obtaining subject-specific models of FES induced hand movements for grasping applications. Data of the hand and finger motion from two subjects affected by acquired brain injury were used to train two different approaches: coactive neuro-fuzzy inference system and recurrent fuzzy neural network. Preliminary results show that these approaches can be considered in modelling applications for their ability to learn and predict main characteristics of the system, as well as providing useful information from the original system that could be interpreted as subject-specific knowledge

Feedback control of cycling in spinal cord injury using functional electrical stimulation

This thesis is concerned with the realisation of leg cycling by means of FES in SCI individuals with complete paraplegia. FES lower-limb cycling can be safely performed by paraplegics on static ergometers or recumbent tricycles. In this work, different FES cycling systems were developed for clinical and home use. Two design approaches have been followed. The first is based on the adaptation of commercially available recumbent tricycles. This results in devices which can be used as static trainers or for mobile cycling. The second design approach utilises a commercially available motorised ergometer which can be operated while sitting in a wheelchair. The developed FES cycling systems can be operated in isotonic (constant cycling resistance) or isokinetic mode (constant cadence) when used as static trainers. This represents a novelty compared to existing FES cycling systems. In order to realise isokinetic cycling, an electric motor is needed to assist or resist the cycling movement to maintain a constant cadence. Repetitive control technology is applied to the motor in this context to virtually eliminate disturbance caused by the FES activated musculature which are periodic with respect to the cadence. Furthermore, new methods for feedback control of the patient’s work rate have been introduced. A one year pilot study on FES cycling with paraplegic subjects has been carried out. Effective indoor cycling on a trainer setup could be achieved for long periods up to an hour, and mobile outdoor cycling was performed over useful distances. Power output of FES cycling was in the range of 15 to 20 W for two of the three subjects at the end of the pilot study. A muscle strengthening programme was carried out prior and concurrent to the FES cycling. Feedback control of FES assisted weight lifting exercises by quadriceps stimulation has been studied in this context

Analysis and control of FES-assisted paraplegic walking with wheel walker.

The number of people with spinal cord injury (SCI) is increasing every year and walking has been found to be the most exciting and important prospect to these patients to improve their quality of life. Many individuals with incomplete SCI have the potential to walk and everyone of them wants to try. Unfortunately up to now, there is less than one third of patients could walk again after SCI. Residual function, the orthotic support, energy expenditure, patient motivation and control technique are some of the factors that influence the walking outcome of spinal cord injured people. In this thesis, a series of studies are carried out to investigate the possibility of enhancing the performance of the functional electrical stimulation (PES) assisted paraplegic walking with wheel walker through the development and implementation of intelligent control technique and spring brake orthosis (SBO) with full utilization of the voluntary upper body effort. The main aim of this thesis is to enable individuals with complete paraplegia to walk again with maximum performance and the simplest approach as possible. Firstly, before simulation of the system can be made, it is important to select the right model to represent the actual plant. In this thesis, the development of a humanoid and wheel walker models are carried out using MSC.visualNastran4D (vN4D) software and this is integrated with Matlab Simulink® for simulation. The newly developed quadriceps and hamstrings muscle models from the series of experiments are used to represent subject muscles after comparison and validation with other two well-known muscle models are performed. Several experiments are conducted to investigate the effect of stimulation frequency and pulse-width in intermittent stimulation with isometric measurement from paraplegic subjects. The results from this work can serve as a guidance to determine the optimum stimulation parameters such as frequency and pulse-width to reduce muscle fatigue during PES application. The ability test is introduced to determine the maximum leg force that can be applied to the specific paraplegic subject during FES functional task with minimum chance of spasm and leg injury. Investigations are carried out on the control techniques implemented for FES walking with wheel walker. PID control and fuzzy logic control (FLC) are used to regulate the electrical stimulation required by the quadriceps and hamstrings muscles in order to perform the FES walking manoeuvre according to predefined walking trajectory. The body weight transfer is introduced to increase the efficiency of FES walking performance. The effectiveness of body weight transfer and control strategy to enhance the performance of FES walking and reduce stimulation pulses required is examined. Investigations are carried out on the effectiveness of spring brake orthosis (SBO) for FES assisted paraplegic walking with wheel walker. A new concept in hybrid orthotics provides solutions to the problems that affect current 'hybrid orthosis, including knee and hip flexion without relying on the withdrawal reflex or a powered actuator and foot-ground clearance without extra upper body effort. The use of SBO can also eliminate electrical stimulation pulses required by the hamstrings muscle for the same FES walking system. Further improvement of the FES walking system is achieved by introducing finite state control (FSC) to control the switching time between springs, brakes and electrical stimulation during FES assisted walking with wheel walker with the combInation of FLC to regulate the electrical stimulation required for the knee extension. The results show that FSC can be used to accurately control the switching time and improve the system robustness and stability

The development and evaluation of functional electrical stimulation rowing for health, exercise and sport for persons with spinal cord injury

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.At the beginning of this project it was known that functional electrical stimulation (FES) rowing was technically feasible, but no studies on health benefits had been conducted and it was unclear what levels of fitness could be reliably attained by spinal cord injured (SCI) users. This thesis shows that training with the first-generation of the FES-rowing system (RowStim II), seven paraplegics achieved high V02peak values (21.0 - 27.9 ml-kg-1-min-1) and a significant (10%) increase in V02peak. This was also found to significantly improve insulin sensitivity and leptin levels but it had no significant effect on lipid profiles or body composition, possibly caused by technological limitations of the RowStim 11. However, training volumes were positively correlated with improvements in lipid profile and body composition. This motivated further technical development of the RowStim to enable paraplegics to train harder and longer. The development included a more stable seat configuration with redesigned trunk retaining straps, a rigid low friction carriage/brake system, improved leg stabiliser, improved stimulation control and a gravity-assisted return phase. This RowStim III has enabled paraplegics to participate in the British (2004, 2005 and 2006) and World Indoor Rowing Championships (2006). The rowers have achieved higher exercise intensities (26.8 -31.0 ml. kg- I .min-1) and increased exercise volumes (1,150 kcal-week-1) with the RowStim III. Such levels of physical activity, which are difficult to achieve for paraplegics using traditional exercises, are correlated with significant health benefits in the able-bodied. Preliminary results suggest that perfusion of the quadriceps muscle during FES-rowing might limit the exercise time in novice rowers. Other preliminary data from pressure mapping indicate that there is a dynamic pattern during FES-rowing, which might reduce the risk for pressure sores during FES-rowing. This thesis shows that FES-rowing is now a rapidly developing exercise modality, which has been shown to enable safe and well-tolerated exercise for individuals with SCI. It can offer unprecedented levels of cardiovascular fitness, competitive challenges and potentially important health benefits

Controle rítmico para aplicações de estimulação elétrica funcional usando modelos musculoesqueléticos detalhados

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2017.O objetivo principal deste trabalho é projetar novos controladores para exercícios rítmicos assistidos por FES, como ciclismo e remo. Este trabalho faz parte de um esforço de pesquisa mais amplo baseado na reabilitação de SCI com base em princípios de neuro-engenharia e robótica integrados com fisioterapia orientada. Uma estrutura básica para simulação de modelos musculoesqueléticos detalhados foi desenvolvida para acelerar a prototipagem de novas estratégias de controle. O controle básico possui um controlador de estado finito no nível superior e um controlador de nível inferior que calcula a intensidade da ativação dos músculos. Um controlador com primitivas de movimento com base na dinâmica de atratores foi desenvolvido para o exercício de remo e osciladores acoplados foram adicionados aos controladores para exercícios de remo e ciclismo. Além disso, algoritmos genéticos foram utilizados para estimar os parâmetros dos controladores, minimizar o nível geral da estimulação elétrica aplicada e aumentar a robustez em ambientes com configurações diferentes. No caso do exercício de ciclismo, os mesmos parâmetros foram utilizados em simulações com ruído, fadiga, diferentes cargas e escalas. Além da avaliação de desempenho, a eficiência do gasto energético metabólico dos modelos musculoesqueléticos também foi calculada como método alternativo para comparar diferentes aplicações FES. Os resultados demonstraram que a adição de osciladores acoplados aumentou a eficiência em ambos os exercícios. Além disso, o ciclismo assistido por FES parece ser mais adequado para participantes com deficiência motora que têm músculos fracos e baixa resistência devido à sua menor ativação muscular e ao gasto de energia metabólica. O remo assistido por FES pode ser usado depois para melhorar a potência dos músculos.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).The main objective of this work concerns the design of new controllers for rhythmic exercises assisted by functional electrical stimulation (FES), such as cycling and rowing. This work is part of a broader research effort targeting spinal cord injury rehabilitation based on principles of neuro-engineering and robotics integrated with goal-directed physical therapy. We developed a basic framework for simulation of detailed musculoskeletal models to accelerate the prototyping of new control strategies. The basic control features a higher level finite state controller and a lower level controller which calculates the activation level of the muscles. A controller with motor primitives based on attractor dynamics was developed for the rowing exercise, and coupled oscillators were added to controllers of both cycling and rowing exercises. Furthermore, we used genetic algorithms to estimate the controllers parameters, minimize the overall level of applied electrical stimulation and increase the robustness in environments with different configurations. In the case of the cycling exercise, we used the same parameters in simulations with noise, fatigue, different loads, and scales. Besides the performance evaluation, we also calculated the efficiency of the metabolic energy expenditure of the musculoskeletal models as an alternative method to compare different FES applications. Results demonstrated that the addition of coupled oscillators increased the efficiency in both exercises. Also, FES cycling seems to be more suitable for participants with motor disabilities who have weak muscles and low endurance due to its lower muscle activation and metabolic energy expenditure. FES rowing can be used later for improving the power of the muscles

Usability of Upper Limb Electromyogram Features as Muscle Fatigue Indicators for Better Adaptation of Human-Robot Interactions

Human-robot interaction (HRI) is the process of humans and robots working together to accomplish a goal with the objective of making the interaction beneficial to humans. Closed loop control and adaptability to individuals are some of the important acceptance criteria for human-robot interaction systems. While designing an HRI interaction scheme, it is important to understand the users of the system and evaluate the capabilities of humans and robots. An acceptable HRI solution is expected to be adaptable by detecting and responding to the changes in the environment and its users. Hence, an adaptive robotic interaction will require a better sensing of the human performance parameters. Human performance is influenced by the state of muscular and mental fatigue during active interactions. Researchers in the field of human-robot interaction have been trying to improve the adaptability of the environment according to the physical state of the human participants. Existing human-robot interactions and robot assisted trainings are designed without sufficiently considering the implications of fatigue to the users. Given this, identifying if better outcome can be achieved during a robot-assisted training by adapting to individual muscular status, i.e. with respect to fatigue, is a novel area of research. This has potential applications in scenarios such as rehabilitation robotics. Since robots have the potential to deliver a large number of repetitions, they can be used for training stroke patients to improve their muscular disabilities through repetitive training exercises. The objective of this research is to explore a solution for a longer and less fatiguing robot-assisted interaction, which can adapt based on the muscular state of participants using fatigue indicators derived from electromyogram (EMG) measurements. In the initial part of this research, fatigue indicators from upper limb muscles of healthy participants were identified by analysing the electromyogram signals from the muscles as well as the kinematic data collected by the robot. The tasks were defined to have point-to-point upper limb movements, which involved dynamic muscle contractions, while interacting with the HapticMaster robot. The study revealed quantitatively, which muscles were involved in the exercise and which muscles were more fatigued. The results also indicated the potential of EMG and kinematic parameters to be used as fatigue indicators. A correlation analysis between EMG features and kinematic parameters revealed that the correlation coefficient was impacted by muscle fatigue. As an extension of this study, the EMG collected at the beginning of the task was also used to predict the type of point-to-point movements using a supervised machine learning algorithm based on Support Vector Machines. The results showed that the movement intention could be detected with a reasonably good accuracy within the initial milliseconds of the task. The final part of the research implemented a fatigue-adaptive algorithm based on the identified EMG features. An experiment was conducted with thirty healthy participants to test the effectiveness of this adaptive algorithm. The participants interacted with the HapticMaster robot following a progressive muscle strength training protocol similar to a standard sports science protocol for muscle strengthening. The robotic assistance was altered according to the muscular state of participants, and, thus, offering varying difficulty levels based on the states of fatigue or relaxation, while performing the tasks. The results showed that the fatigue-based robotic adaptation has resulted in a prolonged training interaction, that involved many repetitions of the task. This study showed that using fatigue indicators, it is possible to alter the level of challenge, and thus, increase the interaction time. In summary, the research undertaken during this PhD has successfully enhanced the adaptability of human-robot interaction. Apart from its potential use for muscle strength training in healthy individuals, the work presented in this thesis is applicable in a wide-range of humanmachine interaction research such as rehabilitation robotics. This has a potential application in robot-assisted upper limb rehabilitation training of stroke patients

Nonlinear robust control of functional electrical stimulation system for paraplegia

The study was directed towards enhancing Functional Electrical Stimulation (FES) for sit-to-stand movement restoration in paraplegia subjects. The scarcity of FES assistive devices was due to the inability of the developed equipment to attain clinical acceptance. Applications of control systems have shown fruitful results. And based on the literature, further improvements in model, trajectory and control systems are needed. Model with a higher level of accuracy and continuous as well as bump-free trajectories are essential ingredients for better control systems. The control systems can be enhanced by giving considering to changes in mass of the subject, disturbance rejection and stability. Hence, the comprehensive control scheme is necessary for this application as well as a better model and trajectory. In modelling an additional joint has been considered to improve the accuracy. In trajectory planning, the six-order polynomial has been used to refine the desired trajectory. The comprehensive control systems have been designed with consideration of robustness, disturbance rejection, and stability. Three nonlinear control approaches have been investigated; the Sliding Mode Control (SMC), Feedback Linearisation Control (FLC), and Back-Stepping Control (BSC). Results reveal improvements in the accuracy of the kinematic model by 24%, and the dynamic model by 47%. The trajectory planning parameters are continuous, and not susceptible to jerks or spikes. Execution time enhanced by 11%, the upper and lower terminal velocities improved by 16.9% and 20.9% respectively. The system response without disturbance shows good results with the SMC, FLC, and BSC. Revelations by robustness examination also maintain remarkable enhancements in the parameters with both 53% and 126% mass. The results for disturbance rejection examinations with fatigue, spasm, tremor, and combined disturbance effects showed sustenance of refinement in the response parameters. Therefore, indicating improvements despite the changes to the system. The BSC showed the best performance, followed by the FLC, and the SMC. Hence, the BSC is recommended for such systems

The development and evaluation of functional electrical stimulation rowing for health, exercise and sport for persons with spinal cord injury

At the beginning of this project it was known that functional electrical stimulation (FES) rowing was technically feasible, but no studies on health benefits had been conducted and it was unclear what levels of fitness could be reliably attained by spinal cord injured (SCI) users. This thesis shows that training with the first-generation of the FES-rowing system (RowStim II), seven paraplegics achieved high V02peak values (21.0 - 27.9 ml-kg-1-min-1) and a significant (10%) increase in V02peak. This was also found to significantly improve insulin sensitivity and leptin levels but it had no significant effect on lipid profiles or body composition, possibly caused by technological limitations of the RowStim 11. However, training volumes were positively correlated with improvements in lipid profile and body composition. This motivated further technical development of the RowStim to enable paraplegics to train harder and longer. The development included a more stable seat configuration with redesigned trunk retaining straps, a rigid low friction carriage/brake system, improved leg stabiliser, improved stimulation control and a gravity-assisted return phase. This RowStim III has enabled paraplegics to participate in the British (2004, 2005 and 2006) and World Indoor Rowing Championships (2006). The rowers have achieved higher exercise intensities (26.8 -31.0 ml. kg- I .min-1) and increased exercise volumes (1,150 kcal-week-1) with the RowStim III. Such levels of physical activity, which are difficult to achieve for paraplegics using traditional exercises, are correlated with significant health benefits in the able-bodied. Preliminary results suggest that perfusion of the quadriceps muscle during FES-rowing might limit the exercise time in novice rowers. Other preliminary data from pressure mapping indicate that there is a dynamic pattern during FES-rowing, which might reduce the risk for pressure sores during FES-rowing. This thesis shows that FES-rowing is now a rapidly developing exercise modality, which has been shown to enable safe and well-tolerated exercise for individuals with SCI. It can offer unprecedented levels of cardiovascular fitness, competitive challenges and potentially important health benefits.EThOS - Electronic Theses Online ServiceGBUnited Kingdo