Imperial College London

DrRaviVaidyanathan

Faculty of EngineeringDepartment of Mechanical Engineering

Reader in Biomechatronics
 
 
 
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Contact

 

+44 (0)20 7594 7020r.vaidyanathan CV

 
 
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Location

 

717City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
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136 results found

Lai J, Nowlan NC, Vaidyanathan R, Visser GHA, Lees CCet al., 2020, The use of actograph in the assessment of fetal well-being, Journal of Maternal-Fetal and Neonatal Medicine, Vol: 33, Pages: 2116-2121, ISSN: 1476-4954

PURPOSE: Third trimester maternal perception of fetal movements is often used to assess fetal well-being. However, its true clinical value is unknown, primarily because of the variability in subjective quantification. The actograph, a technology available on most cardiotocograph machines, quantifies movements, but has never previously been investigated in relation to fetal health and existing monitoring devices. The objective of this study was to quantify actograph output in healthy third trimester pregnancies and investigate this in relation to other methods of assessing fetal well-being. METHODS: Forty-two women between 24 and 34 weeks of gestation underwent ultrasound scan followed by a computerized cardiotocograph (CTG). Post capture analysis of the actograph recording was performed and expressed as a percentage of activity over time. The actograph output results were analyzed in relation to Doppler, ultrasound and CTG findings expressed as z-score normalized for gestation. RESULTS: There was a significant association between actograph output recording and estimated fetal weight Z-score (R = 0.546, p ≤ .005). This activity was not related to estimated fetal weight. Increased actograph activity was negatively correlated with umbilical artery pulsatility index Z-score (R = -0.306, p = .049) and middle cerebral artery pulsatility index Z-score (R = -0.390, p = .011). CONCLUSION: Fetal movements assessed by the actograph are associated both with fetal size in relation to gestation and fetoplacental Doppler parameters. It is not the case that larger babies move more, however, as the relationship with actograph output related only to estimated fetal weight z-score. These findings suggest a plausible link between the frequency of fetal movements and established markers of fetal health. RATIONALE The objective of this study was to quantify actograph output in healthy third trimester pregnancies and investigate this in relation to other methods of assess

Journal article

Huo W, Angeles P, Tai Y, Pavese N, Wilson S, Hu M, Vaidyanathan Ret al., 2020, A heterogeneous sensing suite for multisymptom quantification of Parkinson’s disease, IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol: 28, Pages: 1397-1406, ISSN: 1534-4320

Parkinson’s disease (PD) is the second most common neurodegenerative disease affecting millions worldwide. Bespoke subject-specific treatment (medication or deep brain stimulation (DBS)) is critical for management, yet depends on precise assessment cardinal PD symptoms - bradykinesia, rigidity and tremor. Clinician diagnosis is the basis of treatment, yet it allows only a cross-sectional assessment of symptoms which can vary on an hourly basis and is liable to inter- and intra-rater subjectivity across human examiners. Automated symptomatic assessment has attracted significant interest to optimise treatment regimens between clinician visits, however, no wearable has the capacity to simultaneously assess all three cardinal symptoms. Challenges in the measurement of rigidity, mapping muscle activity outof-clinic and sensor fusion have inhibited translation. In this study, we address all through a novel wearable sensor system and learning algorithms. The sensor system is composed of a force-sensor, two inertial measurement units (IMUs) and four custom mechanomyography (MMG) sensors. The system was tested in its capacity to predict Unified Parkinson’s Disease Rating Scale (UPDRS) scores based on quantitative assessment of bradykinesia, rigidity and tremor in PD patients. 23 PD patients were tested with the sensor system in parallel with exams conducted by treating clinicians and 10 healthy subjects were recruited as a comparison control group. Results prove the system accurately predicts UPDRS scores for all symptoms (85.4% match on average with physician assessment) and discriminates between healthy subjects and PD patients (96.6% on average). MMG features can also be used for remote monitoring of severity and fluctuations in PD symptoms out-of-clinic. This closedloop feedback system enables individually tailored and regularly updated treatment, facilitating better outcomes for a very large patient population.

Journal article

Madgwick SOH, Wilson S, Turk R, Burridge J, Kapatos C, Vaidyanathan Ret al., 2020, An extended complementary filter (ECF) for full-body MARG orientation estimation, IEEE/ASME Transactions on Mechatronics, Pages: 1-1, ISSN: 1083-4435

Inertial sensing suites now permeate all forms of smart automation, yet a plateau exists in real-world derivation of global orientation. Magnetic field fluctuations and inefficient sensor fusion still inhibit deployment. We introduce a new algorithm, an Extended Complementary Filter (ECF), to derive 3D rigid body orientation from inertial sensing suites addressing these challenges. The ECF combines computational efficiency of classic complementary filters with improved accuracy compared to popular optimization filters. We present a complete formulation of the algorithm, including an extension to address the challenge of orientation accuracy in the presence of fluctuating magnetic fields. Performance is tested under a variety of conditions and benchmarked against the commonly used gradient decent (GDA) inertial sensor fusion algorithm. Results demonstrate improved efficiency, with the ECF achieving convergence 30% faster than standard alternatives. We further demonstrate an improved robustness to sources of magnetic interference in pitch and roll and to fast changes of orientation in the yaw direction. The ECF has been implemented at the core of a wearable rehabilitation system tracking movement of stroke patients for home telehealth. The ECF and accompanying magnetic disturbance rejection algorithm enables previously unachievable real-time patient movement feedback in the form of a full virtual human (avatar), even in the presence of magnetic disturbance. Algorithm efficiency and accuracy have also spawned an entire commercial product line released by the company x-io. We believe the ECF and accompanying magnetic disturbance routines are key enablers for future widespread use of wearable systems with the capacity for global orientation tracking

Journal article

Meagher C, Franco E, Turk R, Wilson S, Steadman N, McNicholas L, Vaidyanathan R, Burridge J, Stokes Met al., 2020, New advances in mechanomyography sensor technology and signal processing: validity and intrarater reliability of recordings from muscle, Journal of Rehabilitation and Assistive Technologies Engineering, Vol: 7, ISSN: 2055-6683

IntroductionThe Mechanical Muscle Activity with Real-time Kinematics project aims to develop a device incorporating wearable sensors for arm rehabilitation following stroke. These will record kinematic activity using inertial measurement units and mechanical muscle activity. The gold standard for measuring muscle activity is electromyography; however, mechanomyography offers an appropriate alterative for our home-based rehabilitation device. We have patent filed a new laboratory-tested device that combines an inertial measurement unit with mechanomyography. We report on the validity and reliability of the mechanomyography against electromyography sensors.MethodsIn 18 healthy adults (27–82 years), mechanomyography and electromyography recordings were taken from the forearm flexor and extensor muscles during voluntary contractions. Isometric contractions were performed at different percentages of maximal force to examine the validity of mechanomyography. Root-mean-square of mechanomyography and electromyography was measured during 1 s epocs of isometric flexion and extension. Dynamic contractions were recorded during a tracking task on two days, one week apart, to examine reliability of muscle onset timing.ResultsReliability of mechanomyography onset was high (intraclass correlation coefficient = 0.78) and was comparable with electromyography (intraclass correlation coefficient = 0.79). The correlation between force and mechanomyography was high (R2 = 0.94).ConclusionThe mechanomyography device records valid and reliable signals of mechanical muscle activity on different days.

Journal article

Hopkins M, Vaidyanathan R, McGregor AH, 2020, Examination of the performance characteristics of velostat as an in-socket pressure sensor, IEEE Sensors Journal, Vol: 20, Pages: 6992-7000, ISSN: 1530-437X

Velostat is a low-cost, low-profile electrical bagging material with piezoresistive properties, making it an attractive option for in-socket pressure sensing. The focus of this research was to explore the suitability of a Velostat-based system for providing real-time socket pressure profiles. The prototype system performance was explored through a series of bench tests to determine properties including accuracy, repeatability and hysteresis responses, and through participant testing with a single subject. The fabricated sensors demonstrated mean accuracy errors of 110 kPa and significant cyclical and thermal drift effects of up to 0.00715 V/cycle and leading to up to a 67% difference in voltage range respectively. Despite these errors the system was able to capture data within a prosthetic socket, aligning to expected contact and loading patterns for the socket and amputation type. Distinct pressure maps were obtained for standing and walking tasks displaying loading patterns indicative of posture and gait phase. The system demonstrated utility for assessing contact and movement patterns within a prosthetic socket, potentially useful for improvement of socket fit, in a low cost, low profile and adaptable format. However, Velostat requires significant improvement in its electrical properties before proving suitable for accurate pressure measurement tools in lower limb prosthetics.

Journal article

Purnomo D, Richter F, Bonner M, Vaidyanathan R, Rein Get al., 2020, Role of optimisation method on kinetic inverse modelling of biomass pyrolysis at the microscale, Fuel: the science and technology of fuel and energy, Vol: 262, ISSN: 0016-2361

Biomass pyrolysis is important to biofuel production and fire safety. Inverse modelling is an increasingly used technique to find values for the kinetic parameters that control pyrolysis. The quality of kinetic inverse modelling depends on, in order of importance, the quality of the experimental data, the kinetic model, and the optimisation method used. Unlike the two former components, the optimisation method chosen, i.e. the combination of algorithm and objective function, is rarely discussed in the literature. This work compares the accuracy and efficiency of five commonly used advanced algorithms (Genetic Algorithm, AMALGAM, Shuffled Complex Evolution, Cuckoo Search, and Multi-Start Nonlinear Program) and a simple algorithm (a Random Search) to find the kinetic parameters for cellulose and wood pyrolysis at the microscale. These algorithms are combined with seven objective functions comprising concentrated and dispersed functions. The results show that for cellulose (simple chemistry) the use of an advanced optimisation algorithm is unnecessary, since a simple algorithm achieves similarly high accuracy with higher efficiency. However, for wood (complex chemistry) a combination of an advanced algorithm and a concentrated function greatly improve accuracy. Among the 25 possible combinations we investigated, Shuffled Complex Evolution with mean square error objective function performed best with 0.91% error in mass loss rate and 0.88 × 1013 CPU time. These findings can guide the selection of the best optimisation method to use in inverse modelling of kinetic parameters and ensuring both accuracy and efficiency.

Journal article

Russell F, Kormushev P, Vaidyanathan R, Ellison Pet al., 2020, The impact of ACL laxity on a bicondylar robotic knee and implications in human joint biomechanics, IEEE Transactions on Biomedical Engineering, ISSN: 0018-9294

Objective: Elucidating the role of structural mechanisms in the knee can improve joint surgeries, rehabilitation, and understanding of biped locomotion. Identification of key features, however, is challenging due to limitations in simulation and in-vivo studies. In particular the coupling of the patello-femoral and tibio-femoral joints with ligaments and its impact on joint mechanics and movement is not understood. We investigate this coupling experimentally through the design and testing of a robotic sagittal plane model. Methods: We constructed a sagittal plane robot comprised of: 1) elastic links representing cruciate ligaments; 2) a bi-condylar joint; 3) a patella; and 4) actuator hamstrings and quadriceps. Stiffness and geometry were derived from anthropometric data. 10° - 110° squatting tests were executed at speeds of 0.1 - 0.25Hz over a range of anterior cruciate ligament (ACL) slack lengths. Results: Increasing ACL length compromised joint stability, yet did not impact quadriceps mechanical advantage and force required for squat. The trend was consistent through varying condyle contact point and ligament force changes. Conclusion: The geometry of the condyles allows the ratio of quadriceps to patella tendon force to compensate for contact point changes imparted by the removal of the ACL. Thus the system maintains a constant mechanical advantage. Significance: The investigation uncovers critical features of human knee biomechanics. Findings contribute to understanding of knee ligament damage, inform procedures for knee surgery and orthopaedic implant design, and support design of trans-femoral prosthetics and walking robots. Results further demonstrate the utility of robotics as a powerful means of studying human joint biomechanics.

Journal article

Fadhil A, Kanneganti R, Gupta L, Eberle H, Vaidyanathan Ret al., 2019, Fusion of enhanced and synthetic vision system images for runway and horizon detection, Sensors, Vol: 19, Pages: 1-17, ISSN: 1424-8220

Networked operation of unmanned air vehicles (UAVs) demands fusion of information from disparate sources for accurate flight control. In this investigation, a novel sensor fusion architecture for detecting aircraft runway and horizons as well as enhancing the awareness of surrounding terrain is introduced based on fusion of enhanced vision system (EVS) and synthetic vision system (SVS) images. EVS and SVS image fusion has yet to be implemented in real-world situations due to signal misalignment. We address this through a registration step to align EVS and SVS images. Four fusion rules combining discrete wavelet transform (DWT) sub-bands are formulated, implemented, and evaluated. The resulting procedure is tested on real EVS-SVS image pairs and pairs containing simulated turbulence. Evaluations reveal that runways and horizons can be detected accurately even in poor visibility. Furthermore, it is demonstrated that different aspects of EVS and SVS images can be emphasized by using different DWT fusion rules. The procedure is autonomous throughout landing, irrespective of weather. The fusion architecture developed in this study holds promise for incorporation into manned heads-up displays (HUDs) and UAV remote displays to assist pilots landing aircraft in poor lighting and varying weather. The algorithm also provides a basis for rule selection in other signal fusion applications.

Journal article

Wilson S, Eberle H, Hayashi Y, Madgwick SOH, McGregor A, Jing X, Vaidyanathan Ret al., 2019, Formulation of a new gradient descent MARG orientation algorithm: Case study on robot teleoperation, Mechanical Systems and Signal Processing, Vol: 130, Pages: 183-200, ISSN: 0888-3270

We introduce a novel magnetic angular rate gravity (MARG) sensor fusion algorithm for inertial measurement. The new algorithm improves the popular gradient descent (Ê»Madgwick’) algorithm increasing accuracy and robustness while preserving computational efficiency. Analytic and experimental results demonstrate faster convergence for multiple variations of the algorithm through changing magnetic inclination. Furthermore, decoupling of magnetic field variance from roll and pitch estimation is proven for enhanced robustness. The algorithm is validated in a human-machine interface (HMI) case study. The case study involves hardware implementation for wearable robot teleoperation in both Virtual Reality (VR) and in real-time on a 14 degree-of-freedom (DoF) humanoid robot. The experiment fuses inertial (movement) and mechanomyography (MMG) muscle sensing to control robot arm movement and grasp simultaneously, demonstrating algorithm efficacy and capacity to interface with other physiological sensors. To our knowledge, this is the first such formulation and the first fusion of inertial measurement and MMG in HMI. We believe the new algorithm holds the potential to impact a very wide range of inertial measurement applications where full orientation necessary. Physiological sensor synthesis and hardware interface further provides a foundation for robotic teleoperation systems with necessary robustness for use in the field.

Journal article

Woodward R, Stokes M, Shefelbine S, Vaidyanathan Ret al., 2019, Segmenting mechanomyography measures of muscle activity phases using inertial data, Scientific Reports, Vol: 9, ISSN: 2045-2322

Electromyography (EMG) is the standard technology for monitoring muscle activity in laboratory environments, either using surface electrodes or fine wire electrodes inserted into the muscle. Due to limitations such as cost, complexity, and technical factors, including skin impedance with surface EMG and the invasive nature of fine wire electrodes, EMG is impractical for use outside of a laboratory environment. Mechanomyography (MMG) is an alternative to EMG, which shows promise in pervasive applications. The present study used an exerting squat-based task to induce muscle fatigue. MMG and EMG amplitude and frequency were compared before, during, and after the squatting task. Combining MMG with inertial measurement unit (IMU) data enabled segmentation of muscle activity at specific points: entering, holding, and exiting the squat. Results show MMG measures of muscle activity were similar to EMG in timing, duration, and magnitude during the fatigue task. The size, cost, unobtrusive nature, and usability of the MMG/IMU technology used, paired with the similar results compared to EMG, suggest that such a system could be suitable in uncontrolled natural environments such as within the home.

Journal article

Formstone L, Pucek M, Wilson S, Bentley P, McGregor A, Vaidyanathan Ret al., 2019, Myographic Information Enables Hand Function Classification in Automated Fugl-Meyer Assessment, 9th IEEE/EMBS International Conference on Neural Engineering (NER), Publisher: IEEE, Pages: 239-242, ISSN: 1948-3546

Conference paper

Harkin P, Vaidyanathan R, Morad S, 2019, Concentric joint connectors for form-changing space frames, 7th International Conference on Structural Engineering, Mechanics and Computation (SEMC), Publisher: CRC PRESS-BALKEMA, Pages: 977-982

Conference paper

Russell F, Vaidyanathan R, Ellison P, 2018, A kinematic model for the design of a bicondylar mechanical knee, 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob), Publisher: IEEE, Pages: 750-755

In this paper we present a design methodology for a bicondylar joint that mimics many of the physical mechanisms in the human knee. We replicate the elastic ligaments and sliding and rolling joint surfaces. As a result the centre of rotation and moment arm from the quadriceps changes as a function of flexion angle in a similar way to the human knee. This leads to a larger moment arm in the centre of motion, where it is most needed for high load tasks, and a smaller moment arm at the extremes, reducing the required actuator displacement. This is anticipated to improve performance:weight ratio in legged devices for tasks such as stair accent and sit-to-stand. In the design process ligament attachment positions, femur profile and ligament lengths were taken from cadaver studies. This information was then used as inputs to a simplified kinematic computer model in order to design a valid profile for a tibial condyle. A physical model was then tested on a custom built squatting robot. It was found that although ligament lengths deviated from the designed values the robot moment arm still matched the model to within 6.1% on average. This shows that the simplified model is an effective design tool for this type of joint. It is anticipated that this design, when employed in walking robots, prostheses or exoskeletons, will improve the high load task capability of these devices. In this paper we have outlined and validated a design method to begin to achieve this goal.

Conference paper

Caulcrick C, Russell F, Wilson S, Sawade C, Vaidyanathan Ret al., 2018, Unilateral Inertial and Muscle Activity Sensor Fusion for Gait Cycle Progress Estimation, Pages: 1151-1156, ISSN: 2155-1774

© 2018 IEEE. This paper introduces a method which uses feedforward neural networks (FNNs) for estimating gait cycle progress using data recorded from inertial and muscle activity sensors attached to one side of the lower body. Three-axis inertial measurement unit (IMU) readings from accelerometers and gyroscopes located above the outer ankle and knee were fused with mechanomyogram (MMG) sensor readings from across major muscle groups on the left leg. Validation was against ground truth gathered concurrently with VICON motion capture. The performance was characterised by rms error (Erms) and max error (Emax), averaged across four cross-validated trials, and enhanced by adjusting number of sliding window frames and hidden layer neurons. The final configuration estimated gait cycle progress with Erms of 1.6% and Emax of 6.8%. This demonstrates promise for such a method to be used for control of unilateral robotic prostheses and exoskeletons, providing state estimation of gait progress from low power sensors limited to one side of the lower body.

Conference paper

Needham APH, Paszkiewicz FP, Alias MFM, Wilson S, Dehghani-Sanij AA, Khoo BC, Vaidyanathan Ret al., 2018, Subject-independent data pooling in classification of gait intent using mechanomyography on a transtibial amputee, IEEE International Conference on Robotics and Automation (ICRA), Publisher: IEEE COMPUTER SOC, Pages: 1806-1811, ISSN: 1050-4729

Conference paper

Russell F, Zhu Y, Hey W, Vaidyanathan R, Ellison Pet al., A biomimicking design for mechanical knee joints, Bioinspiration and Biomimetics, Vol: 13, ISSN: 1748-3182

In this paper we present a new bioinspired bicondylar knee joint that requires a smaller actuator size when compared to a constant moment arm joint. Unlike existing prosthetic joints, the proposed mechanism replicates the elastic, rolling and sliding elements of the human knee. As a result, the moment arm that the actuators can impart on the joint changes as function of the angle, producing the equivalent of a variable transmission. By employing a similar moment arm—angle profile as the human knee the peak actuator force for stair ascent can be reduced by 12% compared to a constant moment arm joint addressing critical impediments in weight and power for robotics limbs. Additionally, the knee employs mechanical 'ligaments' containing stretch sensors to replicate the neurosensory and compliant elements of the joint. We demonstrate experimentally how the ligament stretch can be used to estimate joint angle, therefore overcoming the difficulty of sensing position in a bicondylar joint.

Journal article

Lai J, Woodward R, Alexandrov Y, Munnee QA, Lees CC, Vaidyanathan R, Nowlan NCet al., 2018, Performance of a wearable acoustic system for fetal movement discrimination, PLoS ONE, Vol: 13, ISSN: 1932-6203

Fetal movements (FM) are a key factor in clinical management of high-risk pregnancies such as fetal growth restriction. While maternal perception of reduced FM can trigger self-referral to obstetric services, maternal sensation is highly subjective. Objective, reliable monitoring of fetal movement patterns outside clinical environs is not currently possible. A wearable and non-transmitting system capable of sensing fetal movements over extended periods of time would be extremely valuable, not only for monitoring individual fetal health, but also for establishing normal levels of movement in the population at large. Wearable monitors based on accelerometers have previously been proposed as a means of tracking FM, but such systems have difficulty separating maternal and fetal activity and have not matured to the level of clinical use. We introduce a new wearable system based on a novel combination of accelerometers and bespoke acoustic sensors as well as an advanced signal processing architecture to identify and discriminate between types of fetal movements. We validate the system with concurrent ultrasound tests on a cohort of 44 pregnant women and demonstrate that the garment is capable of both detecting and discriminating the vigorous, whole-body ‘startle’ movements of a fetus. These results demonstrate the promise of multimodal sensing for the development of a low-cost, non-transmitting wearable monitor for fetal movements.

Journal article

Hasan MM, Wei S, Vaidyanathan R, 2018, Estimation of RFID Tag Population Size by Gaussian Estimator, IEEE International Conference on Communications (ICC) / Workshop on Integrating UAVs into 5G, Publisher: IEEE, ISSN: 1550-3607

Conference paper

Admiraal M, Wilson S, Vaidyanathan R, 2017, Improved Formulation of the IMU and MARG Orientation Gradient Descent Algorithm for Motion Tracking in Human-Machine Interfaces, IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems (MFI), Publisher: IEEE, Pages: 403-410

Conference paper

Ma Y, Liu Y, Fin R, Yuan X, Sekha R, Wilson S, Vaidyanathan Ret al., 2017, Hand Gesture Recognition with Convolutional Neural Networks for the Multimodal UAV Control, Workshop on Research, Education and Development of Unmanned Aerial Systems (RED-UAS), Publisher: IEEE, Pages: 198-203

Conference paper

Wilson S, Vaidyanathan R, 2017, Upper-Limb Prosthetic Control using Wearable Multichannel Mechanomyography, International Conference on Rehabilitation Robotics (ICORR), Publisher: IEEE, Pages: 1293-1298, ISSN: 1945-7898

Conference paper

Russell F, Gao L, Ellison P, Vaidyanathan Ret al., 2017, Challenges in using Compliant Ligaments for Position Estimation within Robotic Joints, 2017 International Conference on Rehabilitation Robotics (ICORR), Publisher: IEEE, ISSN: 1945-7901

The mechanical advantages of bio-inspired condylar robotic knee joints for use in prosthetics or rehabilitation has been argued extensively in literature. A common limitation of these designs is the difficulty of estimating joint angle and therefore accurately controlling the joint. Furthermore, the potential role of ligament-like structures in robotic knees is not very well established. In this work, we investigate the role of compliant stretch sensing ligaments and their integration into a condylar robotic knee. Simulations and experiments are executed out in order to establish whether measurement of stretch in these structures can be used to produce a new feedback controller for joint position. We report results from a computer model, as well as the design and construction of a robotic knee that show, for a chosen condyle shape, ligament stretch is a function of muscle force and joint velocity as well as joint angle. We have developed a genetic algorithm optimised controller incorporating ligament feedback that demonstrates improved performance for a desired joint angle in response to step inputs. The controller showed marginal improvement in response to a cyclic command signal and further investigation is required in order to use these measurements in robust control, nevertheless we believe these results demonstrate the that ligament-like structures have the potential to improve the performance of robotic knees for prosthetics and rehabilitation devices.

Conference paper

Martineau T, Vaidyanathan R, 2017, Studying the Implementation of Iterative Impedance Control for Assistive Hand Rehabilitation using an Exoskeleton, International Conference on Rehabilitation Robotics (ICORR), Publisher: IEEE, Pages: 1500-1505, ISSN: 1945-7898

Conference paper

Woodward R, Shefelbine S, Vaidyanathan R, 2017, Pervasive monitoring of motion and muscle activation: inertial and mechanomyography fusion, IEEE/ASME Transactions on Mechatronics, Vol: 22, Pages: 2022-2033, ISSN: 1083-4435

Muscle activity and human motion are useful pa-rameters to map the diagnosis, treatment, and rehabilitation ofneurological and movement disorders. In laboratory and clinicalenvironments, electromyography (EMG) and motion capturesystems enable the collection of accurate, high resolution data onhuman movement and corresponding muscle activity. However,controlled surroundings limit both the length of time and thebreadth of activities that can be measured. Features of movement,critical to understanding patient progress, can change duringthe course of a day and daily activities may not correlate to thelimited motions examined in a laboratory. We introduce a systemto measure motion and muscle activity simultaneously over thecourse of a day in an uncontrolled environment with minimalpreparation time and ease of implementation that enables dailyusage. Our system combines a bespoke inertial measurement unit(IMU) and mechanomyography (MMG) sensor, which measuresthe mechanical signal of muscular activity. The IMU can collectdata continuously, and transmit wirelessly, for up to 10 hours.We describe the hardware design and validation and outline thedata analysis (including data processing and activity classificationalgorithms) for the sensing system. Furthermore, we presenttwo pilot studies to demonstrate utility of the system, includingactivity identification in six able-bodied subjects with an accuracyof 98%, and monitoring motion/muscle changes in a subjectwith cerebral palsy and of a single leg amputee over extendedperiods (∼5 hours). We believe these results provide a foundationfor mapping human muscle activity and corresponding motionchanges over time, providing a basis for a range of novelrehabilitation therapies.

Journal article

Burridge JH, Lee ACW, Turk R, Stokes M, Whitall J, Vaidyanathan R, Clatworthy P, Hughes A-M, Meagher C, Franco E, Yardley Let al., 2017, Telehealth, Wearable Sensors, and the Internet: Will They Improve Stroke Outcomes Through Increased Intensity of Therapy, Motivation, and Adherence to Rehabilitation Programs?, JOURNAL OF NEUROLOGIC PHYSICAL THERAPY, Vol: 41, Pages: S32-S38, ISSN: 1557-0576

Journal article

Angeles P, Tai Y, Pavese N, Vaidyanathan Ret al., 2017, Assessing Parkinson's disease motor symptoms using supervised learning algorithms, 21st International Congress of Parkinson's Disease and Movement Disorders, Publisher: WILEY, ISSN: 0885-3185

Conference paper

Angeles P, Tai Y, Pavese N, Wilson S, vaidyanathan Ret al., Automated assessment of symptom severity changes during deep brain stimulation (DBS) therapy for Parkinson's disease., Publisher: Institute of Electrical and Electronics Engineers Inc., ISSN: 1945-7901

Conference paper

Wilson S, Vaidyanathan R, 2017, Gesture recognition through classification of acoustic muscle sensing for prosthetic control, Pages: 637-642, ISSN: 0302-9743

© Springer International Publishing AG 2017. In this paper we present the initial evaluation of a new upper limb prosthetic control system to be worn on the residual limb, which is capable of identifying hand gestures through muscle acoustic signatures (mechanomyography, or MMG) measured from the upper arm. We report the development of a complete system consisting of a bespoke inertial measurement unit (IMU) to monitor arm motion and a skin surface sensor capturing acoustic muscle activity associated with digit movement. The system fuses the orientation of the arm with the synchronized output of six MMG sensors, which capture the low frequency vibrations produced during muscle contraction, to determine which hand gesture the user is making. Twelve gestures split into two test categories were examined, achieving a preliminary average accuracy of 89% on the offline examination, and 68% in the real time tests.

Conference paper

Lai J, Nowlan N, Vaidyanathan R, Shaw C, Lees Cet al., 2016, Fetal movements as a predictor of health, Acta Obstetricia et Gynecologica Scandinavica, Vol: 95, Pages: 968-975, ISSN: 1600-0412

The key determinant to a fetus maintaining its health is through adequate perfusion and oxygen transfer mediated by the functioning placenta. When this equilibrium is distorted, a number of physiological changes including reduced fetal growth occur to favour survival. Technologies have been developed to monitor these changes with a view to prolong intrauterine maturity whilst reducing the risks of stillbirth. Many of these strategies involve complex interpretation, for example Doppler ultrasound for fetal blood flow and computerisedcomputerized analysis of fetal heart rate changes. However, even with these modalities of fetal assessment to determine the optimal timing of delivery, fetal movements remain integral to clinical decision making. In high risk cohorts with fetal growth restriction, the manifestation of a reduction in perceived movements may warrant an expedited delivery. Despite this, there remains has been little evolution in the development of technologies to objectively define evaluate normal fetal movement behavior for behavior, and where there has, there has been no linkage to clinical useapplication. In tThis review we is an attempt to understand synthesize currently available literature on the value of fetal movement analysis as a method of assessing fetal wellbeing, and show how interdisciplinary developments in this area may aid in improvements to clinical outcomes.

Journal article

Jameel ASMM, Mace M, Wang S, Vaidyanathan R, Al Mamun KAet al., 2016, Predicting Movement and Laterality From Deep Brain Local Field Potentials, 1st International Conference on Medical Engineering, Health Informatics and Technology (MediTec), Publisher: IEEE

Conference paper

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