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Van Der Kruk E, Geijtenbeek T. Is increased trunk flexion in standing up related to muscle weakness or pain avoidance in individuals with unilateral knee pain; a simulation study. Front Bioeng Biotechnol 2024; 12:1346365. [PMID: 38659645 PMCID: PMC11039967 DOI: 10.3389/fbioe.2024.1346365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/28/2024] [Indexed: 04/26/2024] Open
Abstract
The 'Timed Up and Go' test (TUG) is a widely used clinical tool for assessing gait and balance, relying primarily on timing as a measure. However, there are more observable biomechanical compensation strategies within TUG that are indicative of underlying neuromuscular issues and movement priorities. In individuals with unilateral knee osteoarthritis, an increased trunk flexion during TUG is a common phenomenon, often attributed to muscle weakness and/or pain avoidance. Unfortunately, it is difficult to differentiate between these underlying causes using experimental studies alone. This study aimed to distinguish between muscle weakness and pain avoidance as contributing factors, using predictive neuromuscular simulations of the sit-to-walk movement. Muscle weakness was simulated by reducing the maximum isometric force of the vasti muscles (ranging from 20% to 60%), while pain avoidance was integrated as a movement objective, ensuring that peak knee load did not exceed predefined thresholds (2-4 times body weight). The simulations demonstrate that a decrease in muscular capacity led to greater trunk flexion, while pain avoidance led to slower movement speeds and altered muscle recruitments, but not to greater trunk flexion. Our predictive simulations thus indicate that increased trunk flexion is more likely the result of lack of muscular reserve rather than pain avoidance. These findings align with reported differences in kinematics and muscle activations between moderate and severe knee osteoarthritis patients, emphasizing the impact of severe muscle weakness in those with advanced knee osteoarthritis. The simulations offer valuable insights into the mechanisms behind altered movement strategies, potentially guiding more targeted treatment.
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Affiliation(s)
- Eline Van Der Kruk
- Department of Biomechanical Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Delft, Netherlands
| | - Thomas Geijtenbeek
- Department of Biomechanical Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Delft, Netherlands
- Goatstream, Delft, Netherlands
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2
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Mandal D, Bovender T, Geil RD, Banerjee S. Surface Acoustic Waves (SAW) Sensors: Tone-Burst Sensing for Lab-on-a-Chip Devices. Sensors (Basel) 2024; 24:644. [PMID: 38276335 PMCID: PMC10819011 DOI: 10.3390/s24020644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/13/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
The article presents the design concept of a surface acoustic wave (SAW)-based lab-on-a-chip sensor with multifrequency and multidirectional sensitivity. The conventional SAW sensors use delay lines that suffer from multiple signal losses such as insertion, reflection, transmission losses, etc. Most delay lines are designed to transmit and receive continuous signal at a fixed frequency. Thus, the delay lines are limited to only a few features, like frequency shift and change in wave velocity, during the signal analysis. These facts lead to limited sensitivity and a lack of opportunity to utilize the multi-directional variability of the sensing platform at different frequencies. Motivated by these facts, a guided wave sensing platform that utilizes simultaneous tone burst-based excitation in multiple directions is proposed in this article. The design incorporates a five-count tone burst signal for the omnidirectional actuation. This helps the acquisition of sensitive long part of the coda wave (CW) signals from multiple directions, which is hypothesized to enhance sensitivity through improved signal analysis. In this article, the design methodology and implementation of unique tone burst interdigitated electrodes (TB-IDT) are presented. Sensing using TB-IDT enables accessing multiple frequencies simultaneously. This results in a wider frequency spectrum and allows better scope for the detection of different target analytes. The novel design process utilized guided wave analysis of the substrate, and selective directional focused interdigitated electrodes (F-IDT) were implemented. The article demonstrates computational simulation along with experimental results with validation of multifrequency and multidirectional sensing capability.
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Affiliation(s)
- Debdyuti Mandal
- Integrated Material Assessment and Predictive Simulation (iMAPS) Laboratory, Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, USA; (D.M.); (T.B.)
| | - Tally Bovender
- Integrated Material Assessment and Predictive Simulation (iMAPS) Laboratory, Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, USA; (D.M.); (T.B.)
| | - Robert D. Geil
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Sourav Banerjee
- Integrated Material Assessment and Predictive Simulation (iMAPS) Laboratory, Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, USA; (D.M.); (T.B.)
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3
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Price M, Huber ME, Hoogkamer W. Minimum effort simulations of split-belt treadmill walking exploit asymmetry to reduce metabolic energy expenditure. J Neurophysiol 2023; 129:900-913. [PMID: 36883759 PMCID: PMC10110733 DOI: 10.1152/jn.00343.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 02/15/2023] [Accepted: 02/28/2023] [Indexed: 03/09/2023] Open
Abstract
Walking on a split-belt treadmill elicits an adaptation response that changes baseline step length asymmetry. The underlying causes of this adaptation, however, are difficult to determine. It has been proposed that effort minimization may drive this adaptation, based on the idea that adopting longer steps on the fast belt, or positive step length asymmetry (SLA), can cause the treadmill to exert net-positive mechanical work on a bipedal walker. However, humans walking on split-belt treadmills have not been observed to reproduce this behavior when allowed to freely adapt. To determine if an effort-minimization motor control strategy would result in experimentally observed adaptation patterns, we conducted simulations of walking on different combinations of belt speeds with a human musculoskeletal model that minimized muscle excitations and metabolic rate. The model adopted increasing amounts of positive SLA and decreased its net metabolic rate with increasing belt speed difference, reaching +42.4% SLA and -5.7% metabolic rate relative to tied-belt walking at our maximum belt speed ratio of 3:1. These gains were primarily enabled by an increase in braking work and a reduction in propulsion work on the fast belt. The results suggest that a purely effort minimization driven split-belt walking strategy would involve substantial positive SLA, and that the lack of this characteristic in human behavior points to additional factors influencing the motor control strategy, such as aversion to excessive joint loads, asymmetry, or instability.NEW & NOTEWORTHY Behavioral observations of split-belt treadmill adaptation have been inconclusive toward its underlying causes. To estimate gait patterns when driven exclusively by one of these possible underlying causes, we simulated split-belt treadmill walking with a musculoskeletal model that minimized its summed muscle excitations. Our model took significantly longer steps on the fast belt and reduced its metabolic rate below tied-belt walking, unlike experimental observations. This suggests that asymmetry is energetically optimal, but human adaptation involves additional factors.
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Affiliation(s)
- Mark Price
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts, United States
| | - Meghan E Huber
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts, United States
| | - Wouter Hoogkamer
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
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Vega MM, Li G, Shourijeh MS, Ao D, Weinschenk RC, Patten C, Font-Llagunes JM, Lewis VO, Fregly BJ. Computational evaluation of psoas muscle influence on walking function following internal hemipelvectomy with reconstruction. Front Bioeng Biotechnol 2022; 10:855870. [PMID: 36246391 PMCID: PMC9559731 DOI: 10.3389/fbioe.2022.855870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 09/01/2022] [Indexed: 11/13/2022] Open
Abstract
An emerging option for internal hemipelvectomy surgery is custom prosthesis reconstruction. This option typically recapitulates the resected pelvic bony anatomy with the goal of maximizing post-surgery walking function while minimizing recovery time. However, the current custom prosthesis design process does not account for the patient's post-surgery prosthesis and bone loading patterns, nor can it predict how different surgical or rehabilitation decisions (e.g., retention or removal of the psoas muscle, strengthening the psoas) will affect prosthesis durability and post-surgery walking function. These factors may contribute to the high observed failure rate for custom pelvic prostheses, discouraging orthopedic oncologists from pursuing this valuable treatment option. One possibility for addressing this problem is to simulate the complex interaction between surgical and rehabilitation decisions, post-surgery walking function, and custom pelvic prosthesis design using patient-specific neuromusculoskeletal models. As a first step toward developing this capability, this study used a personalized neuromusculoskeletal model and direct collocation optimal control to predict the impact of ipsilateral psoas muscle strength on walking function following internal hemipelvectomy with custom prosthesis reconstruction. The influence of the psoas muscle was targeted since retention of this important muscle can be surgically demanding for certain tumors, requiring additional time in the operating room. The post-surgery walking predictions emulated the most common surgical scenario encountered at MD Anderson Cancer Center in Houston. Simulated post-surgery psoas strengths included 0% (removed), 50% (weakened), 100% (maintained), and 150% (strengthened) of the pre-surgery value. However, only the 100% and 150% cases successfully converged to a complete gait cycle. When post-surgery psoas strength was maintained, clinical gait features were predicted, including increased stance width, decreased stride length, and increased lumbar bending towards the operated side. Furthermore, when post-surgery psoas strength was increased, stance width and stride length returned to pre-surgery values. These results suggest that retention and strengthening of the psoas muscle on the operated side may be important for maximizing post-surgery walking function. If future studies can validate this computational approach using post-surgery experimental walking data, the approach may eventually influence surgical, rehabilitation, and custom prosthesis design decisions to meet the unique clinical needs of pelvic sarcoma patients.
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Affiliation(s)
- Marleny M. Vega
- Rice Computational Neuromechanics Lab, Department of Mechanical Engineering, Rice University, Houston, TX, United States
| | - Geng Li
- Rice Computational Neuromechanics Lab, Department of Mechanical Engineering, Rice University, Houston, TX, United States
| | - Mohammad S. Shourijeh
- Rice Computational Neuromechanics Lab, Department of Mechanical Engineering, Rice University, Houston, TX, United States
| | - Di Ao
- Rice Computational Neuromechanics Lab, Department of Mechanical Engineering, Rice University, Houston, TX, United States
| | - Robert C. Weinschenk
- Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Carolynn Patten
- Biomechanics, Rehabilitation, and Integrative Neuroscience (BRaIN) Lab, UC Davis School of Medicine, Sacramento, CA, United States
- UC Davis Center for Neuroengineering and Medicine, University of California, Davis, CA, United States
- VA Northern California Health Care System, Martinez, CA, United States
| | - Josep M. Font-Llagunes
- Biomechanical Engineering Lab, Department of Mechanical Engineering and Research Centre for Biomedical Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
- Health Technologies and Innovation, Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Valerae O. Lewis
- Department of Orthopaedic Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Benjamin J. Fregly
- Rice Computational Neuromechanics Lab, Department of Mechanical Engineering, Rice University, Houston, TX, United States
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Wright JG, Amin MN, Meena GG, Schmidt H, Hawkins AR. Optofluidic Flow-Through Biosensor Sensitivity - Model and Experiment. J Lightwave Technol 2021; 39:3330-3340. [PMID: 34177078 PMCID: PMC8224397 DOI: 10.1109/jlt.2021.3061872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We present a model and simulation for predicting the detected signal of a fluorescence-based optical biosensor built from optofluidic waveguides. Typical applications include flow experiments to determine pathogen concentrations in a biological sample after tagging relevant DNA or RNA sequences. An overview of the biosensor geometry and fabrication processes is presented. The basis for the predictive model is also outlined. The model is then compared to experimental results for three different biosensor designs. The model is shown to have similar signal statistics as physical tests, illustrating utility as a pre-fabrication design tool and as a predictor of detection sensitivity.
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Affiliation(s)
- Joel G Wright
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT, 84602, USA
| | - Md Nafiz Amin
- School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Gopikrishnan G Meena
- School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Holger Schmidt
- School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Aaron R Hawkins
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT, 84602, USA
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Van Wouwe T, Ting LH, De Groote F. Interactions between initial posture and task-level goal explain experimental variability in postural responses to perturbations of standing balance. J Neurophysiol 2020; 125:586-598. [PMID: 33326357 DOI: 10.1152/jn.00476.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Postural responses to similar perturbations of standing balance vary widely within and across subjects. Here, we identified two sources of variability and their interactions by combining experimental observations with computational modeling: differences in posture at perturbation onset across trials and differences in task-level goals across subjects. We first collected postural responses to unpredictable backward support-surface translations during standing in 10 young adults. We found that maximal trunk lean in postural responses to backward translations were highly variable both within subjects (mean of ranges = 28.3°) and across subjects (range of means = 39.9°). Initial center of mass (COM) position was correlated with maximal trunk lean during the response, but this relation was subject specific (R2 = 0.29-0.82). We then used predictive simulations to assess causal relations and interactions with task-level goal. Our simulations showed that initial posture explains the experimentally observed intrasubject variability with a more anterior initial COM position increasing the use of the hip strategy. Differences in task-level goal explain observed intersubject variability with prioritizing effort minimization leading to ankle strategies and prioritizing stability leading to hip strategies. Interactions between initial posture and task-level goal explain observed differences in intrasubject variability across subjects. Our findings suggest that variability in initial posture due to increased sway as observed in older adults might increase the occurrence of less stable postural responses to perturbations. Insight in factors causing movement variability will advance our ability to study the origin of differences between groups and conditions.NEW & NOTEWORTHY Responses to perturbations of standing balance vary both within and between individuals. By combining experimental observations with computational modeling, we identified causes of observed kinematic variability in healthy young adults. First, we found that trial-by-trial differences in posture at perturbation onset explain most of the kinematic variability observed within subjects. Second, we found that differences in prioritizing effort versus stability explained differences in the postural response as well as differences in trial-by-trial variability across subjects.
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Affiliation(s)
- Tom Van Wouwe
- Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Lena H Ting
- W.H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia.,Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, Georgia
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7
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Al Borno M, Hicks JL, Delp SL. The effects of motor modularity on performance, learning and generalizability in upper-extremity reaching: a computational analysis. J R Soc Interface 2020; 17:20200011. [PMID: 32486950 PMCID: PMC7328389 DOI: 10.1098/rsif.2020.0011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 05/06/2020] [Indexed: 11/12/2022] Open
Abstract
It has been hypothesized that the central nervous system simplifies the production of movement by limiting motor commands to a small set of modules known as muscle synergies. Recently, investigators have questioned whether a low-dimensional controller can produce the rich and flexible behaviours seen in everyday movements. To study this issue, we implemented muscle synergies in a biomechanically realistic model of the human upper extremity and performed computational experiments to determine whether synergies introduced task performance deficits, facilitated the learning of movements, and generalized to different movements. We derived sets of synergies from the muscle excitations our dynamic optimizations computed for a nominal task (reaching in a plane). Then we compared the performance and learning rates of a controller that activated all muscles independently to controllers that activated the synergies derived from the nominal reaching task. We found that a controller based on synergies had errors within 1 cm of a full-dimensional controller and achieved faster learning rates (as estimated from computational time to converge). The synergy-based controllers could also accomplish new tasks-such as reaching to targets on a higher or lower plane, and starting from alternative initial poses-with average errors similar to a full-dimensional controller.
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Affiliation(s)
- Mazen Al Borno
- Department of Bioengineering and Mechanical Engineering, Stanford University, Stanford, CA, USA
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Nguyen VQ, LaPre AK, Price MA, Umberger BR, Sup FC. Inclusion of actuator dynamics in simulations of assisted human movement. Int J Numer Method Biomed Eng 2020; 36:e3334. [PMID: 32170995 DOI: 10.1002/cnm.3334] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 09/14/2019] [Accepted: 03/08/2020] [Indexed: 06/10/2023]
Abstract
Simulation of musculoskeletal systems using dynamic optimization is a powerful approach for studying the biomechanics of human movements and can be applied to human-robot interactions. The simulation results of human movements augmented by robotic devices may be used to evaluate and optimize the device design and controller. However, simulations are limited by the accuracy of the models which are usually simplified for computation efficiency. Typically, the powered robotic devices are often modeled as massless, ideal torque actuators that is without mass and internal dynamics, which may have significant impacts on the simulation results. This article investigates the effects of including the mass and internal dynamics of the device in simulations of assisted human movement. The device actuator was modeled in various ways with different detail levels. Dynamic optimization was used to find the muscle activations and actuator commands in motion tracking and predictive simulations. The results showed that while the effects of device mass and inertia can be small, the electrical dynamics of the motor can significantly impact the results. This outcome suggests the importance of using an accurate actuator model in simulations of human movement augmented by assistive devices. NOVELTY: Demonstrating the effects of including mass and internal dynamics of the actuator in simulations of assisted human movement A new OpenSim electric motor actuator class to capture the electromechanical dynamics for use in simulation of human movement assisted by powered robotic devices.
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Affiliation(s)
- Vinh Q Nguyen
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts, USA
| | | | - Mark A Price
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts, USA
| | - Brian R Umberger
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Frank C Sup
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts, USA
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Koelewijn AD, Dorschky E, van den Bogert AJ. A metabolic energy expenditure model with a continuous first derivative and its application to predictive simulations of gait. Comput Methods Biomech Biomed Engin 2018; 21:521-531. [PMID: 30027769 DOI: 10.1080/10255842.2018.1490954] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Whether humans minimize metabolic energy in gait is unknown. Gradient-based optimization could be used to predict gait without using walking data but requires a twice differentiable metabolic energy model. Therefore, the metabolic energy model of Umberger et al. ( 2003 ) was adapted to be twice differentiable. Predictive simulations of a reaching task and gait were solved using this continuous model and by minimizing effort. The reaching task simulation showed that energy minimization predicts unrealistic movements when compared to effort minimization. The predictive gait simulations showed that objectives other than metabolic energy are also important in gait.
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Affiliation(s)
- Anne D Koelewijn
- a Department of Mechanical Engineering , Cleveland State University , 1960 E 24th St , Cleveland , OH , 44115 , USA
| | - Eva Dorschky
- b Department of Computer Science , Friedrich-Alexander-Universität Nürnberg , Erlangen , Germany
| | - Antonie J van den Bogert
- a Department of Mechanical Engineering , Cleveland State University , 1960 E 24th St , Cleveland , OH , 44115 , USA
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Van Leeuwen SR, Baranoski GVG. Elucidating the contribution of Rayleigh scattering to the bluish appearance of veins. J Biomed Opt 2018; 23:1-17. [PMID: 29405048 DOI: 10.1117/1.jbo.23.2.025001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/04/2018] [Indexed: 05/26/2023]
Abstract
The bluish appearance of veins located immediately beneath the skin has long been a topic of interest for biomedical optics researchers. Despite this interest, a thorough identification of the specific optical processes responsible for this phenomenon remains to be achieved. We employ controlled in silico experiments to address this enduring open problem. Our experiments, which are supported by measured data available in the scientific literature, are performed using first-principles models of light interaction with human skin and blood. Using this investigation approach, we quantitatively demonstrate that Rayleigh scattering caused by collagen fibrils present in the papillary dermis, a sublayer of the skin, can play a pivotal role in the bluish appearance of veins as suggested by previous works in this area. Moreover, also taking color perception aspects into account, we systematically assess the effects of variations in fibril radius and papillary dermis thickness on the coloration of veins under different illuminants. Notably, this assessment indicates that Rayleigh scattering elicited by reticulin fibrils, another type of fibril found in the papillary dermis, is unlikely to significantly contribute to the bluish appearance of veins. By strengthening the current understanding of light attenuation mechanisms affecting the appearance of skin and blood, our investigation contributes to the development of more effective technologies aimed at the noninvasive measurement of the physiological properties of these tissues.
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Affiliation(s)
- Spencer R Van Leeuwen
- University of Waterloo, Natural Phenomena Simulation Group, School of Computer Science, Waterloo, Canada
| | - Gladimir V G Baranoski
- University of Waterloo, Natural Phenomena Simulation Group, School of Computer Science, Waterloo, Canada
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Abstract
A theoretical model of avian flight is developed which simulates wing motion through a class of methods known as predictive simulation. This approach uses numerical optimization to predict power-optimal kinematics of avian wings in hover, cruise, climb and descent. The wing dynamics capture both aerodynamic and inertial loads. The model is used to simulate the flight of the pigeon, Columba livia, and the results are compared with previous experimental measurements. In cruise, the model unearths a vast range of kinematic modes that are capable of generating the required forces for flight. The most efficient mode uses a near-vertical stroke-plane and a flexed-wing upstroke, similar to kinematics recorded experimentally. In hover, the model predicts that the power-optimal mode uses an extended-wing upstroke, similar to hummingbirds. In flexing their wings, pigeons are predicted to consume 20% more power than if they kept their wings full extended, implying that the typical kinematics used by pigeons in hover are suboptimal. Predictions of climbing flight suggest that the most energy-efficient way to reach a given altitude is to climb as steeply as possible, subjected to the availability of power.
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Affiliation(s)
- Ben Parslew
- Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M60 1QD, UK
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