Gil Serrancolí
Universitat Politecnica de Catalunya, Mechanical Engineering, Faculty Member
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Gil received his PhD in Biomedical Engineering from the Technical University of Catalonia in 2015. He did a six-month... moreGil received his PhD in Biomedical Engineering from the Technical University of Catalonia in 2015. He did a six-month PhD stay at the University of Florida (2012-2013). He worked in optimization and synergy approaches for studying muscle redundancy during walking. In 2015 and 2016 he worked as a postdoctoral researcher at KU Leuven (Belgium) developing predictive simulations based on direct collocation to estimate foot-ground and human-exoskeleton contact parameters and predict the collaborative movement of a subject with an exoskeleton. In September 2016 he got a position at the Department of Mechanical Engineering at the Technical University of Catalonia as Assistant Professor, and in 2021 as Associate Professor. In 2017 he was OpenSim Visiting Scholar. In 2020 he got a fellowship to do a research stay at Northwestern University (Illinois, USA). His current research lines are focused on biomechanical modeling, on integrating methods to obtain faster and more accurate biomechanical motion analysis results, and biomechanical predictive simulations based on optimal control. edit
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Background Despite favourable outcomes relatively few surgeons offer high tibial osteotomy (HTO) as a treatment option for early knee osteoarthritis, mainly due to the difficulty of achieving planned correction and reported soft tissue... more
Background Despite favourable outcomes relatively few surgeons offer high tibial osteotomy (HTO) as a treatment option for early knee osteoarthritis, mainly due to the difficulty of achieving planned correction and reported soft tissue irritation around the plate used to stablise the osteotomy. To compare the mechanical safety of a new personalised 3D printed high tibial osteotomy (HTO) device, created to overcome these issues, with an existing generic device, a case-control in silico virtual clinical trial was conducted. Methods Twenty-eight knee osteoarthritis patients underwent computed tomography (CT) scanning to create a virtual cohort; the cohort was duplicated to form two arms, Generic and Personalised, on which virtual HTO was performed. Finite element analysis was performed to calculate the stresses in the plates arising from simulated physiological activities at three healing stages. The odds ratio indicative of the relative risk of fatigue failure of the HTO plates betwee...
EMG analyses have several applications, such as identifying muscle excitation patterns during rehabilitation or training plans, or controlling EMG‐driven devices. However, experimental measurements can be time consuming or difficult to... more
EMG analyses have several applications, such as identifying muscle excitation patterns during rehabilitation or training plans, or controlling EMG‐driven devices. However, experimental measurements can be time consuming or difficult to obtain. This study presents a simple algorithm to predict EMG signals that can be applied in real time during running, given only the instantaneous vector of kinematics. We hypothesize that the factorization of the kinematics of the skeleton together with the EMG data of calibration subjects could be used to predict EMG data of another subject only using the kinematic information. The results showed that EMG signals of lower‐limb muscles can be predicted accurately in less than a second using this method. Correlation coefficients between predicted and experimental EMG signals were higher than 0.7 in 10 out of 11 muscles for most prediction trials and subjects, and their overall median value was higher than 0.8. These values confirm that this method could be used to accurately predict EMG signals in real time when only kinematics are measured.
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This study aimed to investigate the impact of a Mediterranean-style diet on weight loss effectiveness and sustainability in patients with obesity who underwent endoscopic bariatric therapies (EBT), relative to a protein diet plan. Thus,... more
This study aimed to investigate the impact of a Mediterranean-style diet on weight loss effectiveness and sustainability in patients with obesity who underwent endoscopic bariatric therapies (EBT), relative to a protein diet plan. Thus, 132 patients with obesity (BMI 30–40 kg/m2) who underwent EBT, were asked to follow a Mediterranean-style diet plan (n = 52) or a protein diet plan (n = 26) for six months. General linear models were used to compare outcome variables between dietary intervention groups. Results showed that participants who followed a Mediterranean-style diet plan lost 14.2% more weight (95% CI: 3.0; 25.3), compared with those who followed a protein diet plan. Additionally, following a Mediterranean-style diet plan was associated with the sustainability of weight loss. Note that three months after the end of the dietary intervention, the patients who followed a Mediterranean-style diet plan were still losing weight (−1.2 ± 3.0 kg), while those with a protein diet plan...
This supporting document contains more details about the experimental data, the smooth approximations, and the optimal control formulations. In addition, this document contains supporting figures and tables referred to in the main text.
The sprint running literature contains recommendations for how athletes should consider modifying their technique, yet, very few studies have documented their affect on performance. We used a musculoskeletal modelling and simulation... more
The sprint running literature contains recommendations for how athletes should consider modifying their technique, yet, very few studies have documented their affect on performance. We used a musculoskeletal modelling and simulation approach to initially perform a data-tracking simulation to evaluate the outputs against experimental data. A predictive simulation with limited constraints was then performed to assess the influence of technique modications on performance. The data-tracking simulation tracked the experimental data well, particularly the ground reaction forces (largest RMSE = 0.04 BW). The predictive simulation resulted in the model covering 2.79 m in 0.325 s through an increase in step frequency, and this was a time duration improvement of 6.9% in comparison to the athlete’s own performance. In this preliminary work we have managed to track experimental sprint running data, and provided a promising basis to further explore hypothetical modifications in technique.
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Neuromusculoskeletal models used to predict muscle and joint contact forces for a specific individual require specification of muscle-tendon, skeletal geometry, and neural control model parameter values. Though these parameter values... more
Neuromusculoskeletal models used to predict muscle and joint contact forces for a specific individual require specification of muscle-tendon, skeletal geometry, and neural control model parameter values. Though these parameter values should ideally be calibrated using in vivo data collected from the subject, they are often taken from generic models. This study explored the influence of three model calibration methods on predicted lower limb muscle and knee contact forces during walking. The calibrated model from each approach was used in a static optimization that predicted knee contact forces for six walking trials. The predictions were evaluated using knee contact forces measured in vivo from a subject implanted with a force-measuring knee replacement. The first calibration approach used muscle-tendon model parameter values (i.e., optimal muscle fiber lengths and tendon slack lengths) taken directly from the literature. The second approach calibrated muscle-tendon model parameter ...
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INTRODUCTION Musculoskeletal models and optimization methods are often combined to estimate joint contact and muscle forces during walking. However, important model parameter values that affect estimated joint contact and muscle forces... more
INTRODUCTION Musculoskeletal models and optimization methods are often combined to estimate joint contact and muscle forces during walking. However, important model parameter values that affect estimated joint contact and muscle forces cannot be measured in the clinic. Since internal body forces also cannot be measured clinically, the ability of existing neuromusculoskeletal modeling methods to predict joint contact and muscle forces accurately during walking remains unknown. Recently, experimental movement and imaging data collected from subjects implanted with force-measuring knee replacements have been made publicly available [1]. Using these data sets, Knee Grand Challenge competitors have developed subject-specific neuromusculoskeletal models and tested their ability to predict knee contact forces accurately over two walking cycles. Even when knee contact force data were used for model calibration, parameter values that worked well for the first walking cycle did not work well ...
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Nicos Haralabidis1,2, Gil Serrancolí3, Steffi Colyer1,2, Ian Bezodis4, Aki Salo5,1,2 and Dario Cazzola1,2 1Department for Health, University of Bath, UK 2CAMERA, University of Bath, UK 3Department of Mechanical Engineering, Universitat... more
Nicos Haralabidis1,2, Gil Serrancolí3, Steffi Colyer1,2, Ian Bezodis4, Aki Salo5,1,2 and Dario Cazzola1,2 1Department for Health, University of Bath, UK 2CAMERA, University of Bath, UK 3Department of Mechanical Engineering, Universitat Politècnica de Catalunya, Spain 4Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK 5KIHU Research Institute for Olympic Sports, Jyväskylä, Finland email: n.haralabidis@bath.ac.uk
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Distincio de "Travel Award" al treball presentat al 8th World Congress of Biomechanics, WCB 2018
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EMG ISB 2015-174 A COMPARATIVE STUDY OF THE MUSCLE SYNERGY PATTERNS IN HEALTHY AND ACL-DEFICIENT SUBJECTS Gil Serrancolí* 1, Joan C Monllau2, 3, 4, Josep M Font-Llagunes5 1Department of Mechanical Engineering and Biomedical Engineering... more
EMG ISB 2015-174 A COMPARATIVE STUDY OF THE MUSCLE SYNERGY PATTERNS IN HEALTHY AND ACL-DEFICIENT SUBJECTS Gil Serrancolí* 1, Joan C Monllau2, 3, 4, Josep M Font-Llagunes5 1Department of Mechanical Engineering and Biomedical Engineering Research Centre, Universitat Politècnica de Catalunya, 2Department of Orthopaedic Surgery, Hospital del Mar, 3ICATME, Hospital Universitari Quirón-Dexeus, 4 Universitat Autònoma de Barcelona, 5Department of Mechanical Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
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The knee anterior cruciate ligament (ACL) rupture is a common knee injury. Between 3 and 4 out of 1000 people have to be intervened every year [1,2]. There are some “standard” tests to perform the clinical evaluation, such as the Lachman... more
The knee anterior cruciate ligament (ACL) rupture is a common knee injury. Between 3 and 4 out of 1000 people have to be intervened every year [1,2]. There are some “standard” tests to perform the clinical evaluation, such as the Lachman and Pivot-Shift tests. However, the process could be quite subjective. Despite there are multiple devices to measure the instability of the knee [3], the measurement could be difficult to perform, not repeatable, or expensive. For example, the most common device to measure anterior-posterior (AP) translation is the arthrometer KT-1000, which is not practical to be used in the operating room since it must be sterilized every time of use. Kira accelerometer is used to measure the instability during a Pivot-Shift test; it actually measures the absolute acceleration of the tibia with respect to the ground, and the evaluation of the results is not obvious. Hoshino et al. [4] proposed an image-based method to measure the AP translation of the knee, one of...
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This study utilized a novel two-level optimization method to evaluate how availability of in vivo knee contact force data affects calibration of muscle-tendon model parameter values for walking. An outer-level calibration optimization... more
This study utilized a novel two-level optimization method to evaluate how availability of in vivo knee contact force data affects calibration of muscle-tendon model parameter values for walking. An outer-level calibration optimization adjusts muscle-tendon and synergy control model parameter values, while an inner-level muscle force optimization adjusts muscle activations using the current model parameter values. The outer-level optimization is formulated using two approaches – one that matches in vivo knee contact force data (Approach A), and one that does not (Approach B). This methodology makes it possible to evaluate how well model parameter values are defined when knee contact force data are not available. The experimental data used in this study came from the 4th Grand Challenge Competition to Predict In Vivo Knee Loads [1]. The subject wore an instrumented knee implant in his right leg. An inverse dynamic analysis of six gait trials was carried out in OpenSim [2]. A lower-lim...
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Predictive simulations of walking have a high potential to improve our understanding of walking control. A common approach is to formulate predictive simulations as optimal control problems. Yet, these problems are computationally... more
Predictive simulations of walking have a high potential to improve our understanding of walking control. A common approach is to formulate predictive simulations as optimal control problems. Yet, these problems are computationally expensive and hard to solve due to the stiffness and nonlinearity of the musculoskeletal dynamics. These difficulties limit the abilities of researchers to perform predictive simulations using complex musculoskeletal models in a reasonable time. In this study, we address these difficulties by combining computationally efficient numerical methods including direct collocation and automatic differentiation when performing predictive muscle-driven simulations of 3D walking. Additionally, we exploit this computational efficiency to examine different objective functions.
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Recent work has demonstrated how the size of an animal can affect neural control strategies, showing that passive viscoelastic limb properties have a significant role in determining limb movements in small animals but are less important... more
Recent work has demonstrated how the size of an animal can affect neural control strategies, showing that passive viscoelastic limb properties have a significant role in determining limb movements in small animals but are less important in large animals. We extend that work to consider effects of mechanical scaling on the maintenance of joint integrity; i.e., the prevention of aberrant contact forces within joints that might lead to joint dislocation or cartilage degradation. We first performed a literature review to evaluate how properties of ligaments responsible for joint integrity scale with animal size. Although we found that the cross-sectional area of the anterior cruciate ligament generally scaled with animal size, as expected, the effects of scale on the ligament’s mechanical properties were less clear, suggesting potential adaptations in passive contributions to the maintenance of joint integrity across species. We then analyzed how the neural control of joint stability is...
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Department for Health, University of Bath, UK 2CAMERA-Centre for the Analysis of Motion, Entertainment Research and Applications, University of Bath, UK 3Department of Mechanical Engineering, Universitat Politècnica de Catalunya, Spain... more
Department for Health, University of Bath, UK 2CAMERA-Centre for the Analysis of Motion, Entertainment Research and Applications, University of Bath, UK 3Department of Mechanical Engineering, Universitat Politècnica de Catalunya, Spain 4Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, Wales 5KIHU Research Institute for Olympic Sports, Jyväskylä, Finland Email: N.Haralabidis@bath.ac.uk
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Musculoskeletal simulations can be useful to have a better understanding of the forces involved in human movements and their interactions with the environment. Recent advancements in the integration of algorithmic differentiation tools in... more
Musculoskeletal simulations can be useful to have a better understanding of the forces involved in human movements and their interactions with the environment. Recent advancements in the integration of algorithmic differentiation tools in powerful dynamic engines allow the simulations, based on the resolution of an optimal control problem, to be much faster than using traditional methods to compute derivatives, such as finite differences. The formulation of the optimal control problem could also have an impact on the convergence of the optimization (regarding number of iterations and computational time), especially when some variables are very sensitive to small changes of design variables. In this study we present how the use of algorithmic differentiation [1] can help to analyse the influence of slightly different formulations on the convergence of an optimization framework [2] to calibrate contact models (foot-ground and subject exoskeleton) and then predict movement with their f...
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Biomechanical simulation and modelling approaches have the possibility to make a meaningful impact within applied sports settings, such as sprinting. However, for this to be realised, such approaches must first undergo a thorough... more
Biomechanical simulation and modelling approaches have the possibility to make a meaningful impact within applied sports settings, such as sprinting. However, for this to be realised, such approaches must first undergo a thorough quantitative evaluation against experimental data. We developed a musculoskeletal modelling and simulation framework for sprinting, with the objective to evaluate its ability to reproduce experimental kinematics and kinetics data for different sprinting phases. This was achieved by performing a series of data-tracking calibration (individual and simultaneous) and validation simulations, that also featured the generation of dynamically consistent simulated outputs and the determination of foot-ground contact model parameters. The simulated values from the calibration simulations were found to be in close agreement with the corresponding experimental data, particularly for the kinematics (average root mean squared differences (RMSDs) less than 1.0° and 0.2 cm...
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Physics-based predictive simulations of human movement have the potential to support personalized medicine, but large computational costs and difficulties to model control strategies have limited their use. We have developed a... more
Physics-based predictive simulations of human movement have the potential to support personalized medicine, but large computational costs and difficulties to model control strategies have limited their use. We have developed a computationally efficient optimal control framework to predict human gaits based on optimization of a performance criterion without relying on experimental data. The framework generates three-dimensional muscle-driven simulations in 36 min on average—more than 20 times faster than existing simulations—by using direct collocation, implicit differential equations and algorithmic differentiation. Using this framework, we identified a multi-objective performance criterion combining energy and effort considerations that produces physiologically realistic walking gaits. The same criterion also predicted the walk-to-run transition and clinical gait deficiencies caused by muscle weakness and prosthesis use, suggesting that diverse healthy and pathological gaits can em...
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Algorithmic differentiation (AD) is an alternative to finite differences (FD) for evaluating function derivatives. The primarily aim of this study was to demonstrate the computational benefits of using AD instead of FD in OpenSim-based... more
Algorithmic differentiation (AD) is an alternative to finite differences (FD) for evaluating function derivatives. The primarily aim of this study was to demonstrate the computational benefits of using AD instead of FD in OpenSim-based optimal control simulations. The secondary aim was to evaluate computational choices including different AD tools, different linear solvers, and the use of first- or second-order derivatives. First, we enabled the use of AD in OpenSim through a custom source code transformation tool and through the operator overloading tool ADOL-C. Second, we developed an interface between OpenSim and CasADi to perform optimal control simulations. Third, we evaluated computational choices through simulations of perturbed balance, two-dimensional predictive simulations of walking, and three-dimensional tracking simulations of walking. We performed all simulations using direct collocation and implicit differential equations. Using AD through our custom tool was between ...
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Objectives Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in... more
Objectives Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in particular, stimulation of healing at the osteotomy site. This study used finite element (FE) analysis to investigate the effect of plate design and bridging span on interfragmentary movement (IFM) and the influence of fracture healing on plate stress and potential failure. Materials and Methods A 10° opening wedge HTO was created in a composite tibia. Imaging and strain gauge data were used to create and validate FE models. Models of an intact tibia and a tibia implanted with a custom HTO plate using two different bridging spans were validated against experimental data. Physiological muscle forces and different stages of osteotomy gap healing simulating up to six weeks postoperatively were then incorporated. Predictions of plate stress and IFM for the cust...
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Though walking impairments are prevalent in society, clinical treatments are often ineffective at restoring lost function. For this reason, researchers have begun to explore the use of patient-specific computational walking models to... more
Though walking impairments are prevalent in society, clinical treatments are often ineffective at restoring lost function. For this reason, researchers have begun to explore the use of patient-specific computational walking models to develop more effective treatments. However, the accuracy with which models can predict internal body forces in muscles and across joints depends on how well relevant model parameter values can be calibrated for the patient. This study investigated how knowledge of internal knee contact forces affects calibration of neuromusculoskeletal model parameter values and subsequent prediction of internal knee contact and leg muscle forces during walking. Model calibration was performed using a novel two-level optimization procedure applied to six normal walking trials from the Fourth Grand Challenge Competition to Predict In Vivo Knee Loads. The outer-level optimization adjusted time-invariant model parameter values to minimize passive muscle forces, reserve act...
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Mechanical Engineering, Biomechanical Engineering, Mathematics, Biomedical Engineering, Biomechanics, and 15 moreSensitivity Analysis, Medicine, Gait, Humans, Computer Simulation, Calibration, Male, Muscles, Electromyography, Aged, Reproducibility of Results, Muscle contraction, Sensitivity and Specificity, Neuromuscular Junction, and Knee Joint
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Mechanical Engineering, Biomedical Engineering, Biomechanics, Medicine, Physical Medicine and Rehabilitation, and 15 moreAnterior Cruciate Ligament, Humans, Walking, Clinical Biomechanics, Female, Male, Young Adult, Muscles, Electromyography, Middle Aged, Adult, Muscle Synergies, Joint Instability, Knee Joint, and Case Control Studies
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The human body is an over-actuated multi-body system, as each joint degree of freedom can be controlled by more than one muscle. Solving the force-sharing problem (i.e. finding out how the resultant joint torque is shared among the... more
The human body is an over-actuated multi-body system, as each joint degree of freedom can be controlled by more than one muscle. Solving the force-sharing problem (i.e. finding out how the resultant joint torque is shared among the muscles actuating that joint) calls for an optimization process where a cost function, representing the strategy followed by the central nervous system to activate muscles, is minimized. The main contribution of the present study has been the particular formulation of that cost function for the case of the pathological gait of a single subject suffering from anterior cruciate ligament rupture. Our hypothesis was that the central nervous system does not weight equally the muscles when trying to compensate for a lower limb injury during gait (in contrast to what is the usual practice for healthy gait where all muscles are weighted equally). This hypothesis is supported by the fact that muscle activity in injured individuals differs from that of healthy subj...
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Forging dies are crucial in forging to manufacture accurate workpieces. These dies are generally made of AISI H steel series and hardened and tempered medium carbon alloy steel. Dies are processed by using high-speed milling + polishing... more
Forging dies are crucial in forging to manufacture accurate workpieces. These dies are generally made of AISI H steel series and hardened and tempered medium carbon alloy steel. Dies are processed by using high-speed milling + polishing or electrical discharge machining + polishing. The surface quality of the workpiece depends on the surface properties of these dies, where surface roughness, material hardness, and wear evolution of their surfaces are critical aspects to consider. This research analyzes different wire electrical discharge machining surface conditions combined with polishing treatment to describe their influence on friction and wear. Wire electrical discharge machining defines the disks’ surface properties in finishing and roughing conditions, and polishing treatment varies in time and paper sand depending on the roughness. Abbott-Firestone curves and Rsk-Rku roughness parameters characterize the surface roughness of each studied configuration. Room temperature pin-on...
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There are widely used standard clinical tests to estimate the instability of an anterior cruciate ligament (ACL) deficient knee by assessing the translation of the tibia with respect to the femur. However, the assessment of those tests... more
There are widely used standard clinical tests to estimate the instability of an anterior cruciate ligament (ACL) deficient knee by assessing the translation of the tibia with respect to the femur. However, the assessment of those tests could be quite subjective. The goal of this study is to present a universally affordable open-source Android application that is easy and quick. Moreover, it provides the possibility for a quantitative and objective analysis of that instability. The anterior–posterior knee translation of seven subjects was assessed using the open-source Android application developed. A single Android smartphone and the placement of three green skin adhesives are all that is required to use it. The application was developed using the image-processing features of the open-source OpenCV Library. An open-source Android application was developed to measure anterior–posterior (AP) translation in ACL-deficient subjects. The application identified differences in the AP transl...