Florian Muijres | Wageningen University (original) (raw)

Papers by Florian Muijres

The Journal of Experimental Biology, Jul 15, 2019

Journal of Experimental Biology

ABSTRACTHabitat specialization can influence the evolution of animal movement in promoting diverg... more ABSTRACTHabitat specialization can influence the evolution of animal movement in promoting divergent locomotor abilities adapted to contrasting environmental conditions, differences in vegetation clutter or predatory communities. While the effect of habitat on the evolution of locomotion and particularly escape performance has been well investigated in terrestrial animals, it remains understudied in flying animals. Here, we investigated whether specialization of Morpho butterfly species into different vertical strata of the Amazonian forest affects the performance of upward escape flight manoeuvres. Using stereoscopic high-speed videography, we compared the climbing flight kinematics of seven Morpho species living either in the forest canopy or in the understory. We show that butterflies from canopy species display strikingly higher climbing speed and steeper ascent angle compared with understory species. Although climbing speed increased with wing speed and angle of attack, the hig...

CSH Protocols, Sep 27, 2022

After tracking the kinematics of a moving mosquito from video, one needs to convert the tracking ... more After tracking the kinematics of a moving mosquito from video, one needs to convert the tracking output into the kinematics data needed to answer the research question. Here, we provide general guidelines for how to do this by discussing how to quantify body position and orientation in the world reference frame and wing and leg orientation in the mosquito body reference frame. These guidelines should be adapted based on the goal of your research. To answer your research question, the resulting kinematics data must then be further analyzed. Because the nature of this analysis depends strongly on your specific research question, we refer to literature for designing these postprocessing routines.

Functional Ecology, Sep 21, 2017

CSH Protocols, Sep 27, 2022

Female mosquitoes of most species require a blood meal for egg development. When biting a human h... more Female mosquitoes of most species require a blood meal for egg development. When biting a human host to collect this blood meal, they can spread dangerous diseases such as malaria, yellow fever, or dengue. Researchers use videography to study many aspects of mosquito behavior, including in-flight host-seeking, takeoff, and landing behaviors, as well as probing and blood feeding, and more. Here, we introduce protocols on how to use videography to capture and analyze mosquito movements at high spatial and temporal resolution, in two and three dimensions.

CSH Protocols, Sep 27, 2022

In this protocol, we describe the basic design considerations and general method to set up a vide... more In this protocol, we describe the basic design considerations and general method to set up a videography system to study mosquito behavior. A basic videography system to study mosquito behavior requires one or more cameras with an optical lens, camera lighting, a calibration setup, and a system to record the video data or otherwise control the camera. Here, we define two types of systems: (1) a real-time videography-based tracking system for determining the position of multiple moving (flying) mosquitoes, and (2) a high-fidelity videography system that can track the detailed movements of body, wings, and legs of a single mosquito at high spatial and temporal resolutions. These high-fidelity trackers are divided into single-camera systems for studying two-dimensional (2D) movements, and multicamera systems that can reconstruct three-dimensional (3D) movements of the mosquito.

CSH Protocols, Sep 28, 2022

In this protocol, we discuss general techniques for tracking the three-dimensional (3D) locations... more In this protocol, we discuss general techniques for tracking the three-dimensional (3D) locations of the mosquito body, wings, legs, or other features of interest using videos. Tracking data must be acquired to produce detailed kinematics of moving mosquitoes. The software of focus for this protocol, DLTdv, was chosen for its widespread use and excellent support and because it is open-source. In addition, DLTdv allows both manual and automatic tracking. The automatic tracking can be done using a classic machine vision or machine-learning algorithm. The software supports both single-camera analysis and multicamera systems and can take advantage of sophisticated calibration algorithms, both for intrinsic lens distortion correction and for 3D DLT-based reconstruction. For this protocol, we assume all kinematic data is acquiredpost hocthrough video analysis.

CSH Protocols, Sep 28, 2022

Tracking mosquitoes in real time, as opposed to recording video files and performing the tracking... more Tracking mosquitoes in real time, as opposed to recording video files and performing the tracking step later, is useful for two reasons. The first is efficiency. Real-time tracking requires less storage because video images do not need to be saved and followed by a tracking step. The second is that tracking data can be used to interact with the animal in some way, such as triggering the approach of a looming object. In this protocol, we discuss the use of Braid, free software for performing real-time, multicamera, multianimal tracking. We describe a setup with four cameras capable of tracking the threedimensional (3D) position of mosquitoes at 100 frames per second in a volume of 30 cm × 30 cm × 60 cm with millimeter accuracy. The specific hardware configuration is flexible and can be substituted using different or additional components to adjust the tracking parameters as needed. MATERIALS It is essential that you consult the appropriate Material Safety Data Sheets and your institution's Environmental Health and Safety Office for proper handling of equipment and hazardous materials used in this protocol.

Journal of Fluid Mechanics, Jan 26, 2023

The fluid dynamics of insect wings and the fins and tails of fish are governed by vortex wake int... more The fluid dynamics of insect wings and the fins and tails of fish are governed by vortex wake interactions, which are strongly related to the wing, fins and tail kinematics. By modeling the kinematics of these wings, fins and tails as a two-dimensionally flapping foil, the influence of the kinematics on the vortex wake interactions is studied. This is done by varying the non-dimensional advance ratio -which describes the amount of foil chord lengths traveled during one falling cycle- and keeping the other independent variables constant. The vortex wake interactions in the wake of the flapping foil as a function of the advance ratio were studied with so-called soap-film tunnel technique: a planar film of soap runs down between two wires at constant flow velocity. In this soap-film the vorticity field in the wake of the flapping foil can directly be visualized using a high speed camera and monochromatic illumination. Different vortex wake pattern domains were found for various advance ratios. This shows that the vortex wake interactions are strongly related to the advance ratio as well as the behavior of the Leading Edge Vortex (LEV). At low advance (Less)

Social Science Research Network, 2022

bioRxiv (Cold Spring Harbor Laboratory), Mar 8, 2019

Most fish species use fast starts to escape from predators. Zebrafish larvae perform effective fa... more Most fish species use fast starts to escape from predators. Zebrafish larvae perform effective fast starts immediately after hatching. They use a C-start, where the body curls into a C-shape, and then unfolds to accelerate. These escape responses need to fulfil a number of functional demands, under the constraints of the fluid environment and the larva's body shape. Primarily, the larvae need to generate sufficient escape speed in a wide range of possible directions, in a short-enough time. In this study, we examined how the larvae meet these demands. We filmed fast starts of zebrafish larvae with a unique five-camera setup with high spatiotemporal resolution. From these videos, we reconstructed the three-dimensional swimming motion with an automated method and from these data calculated resultant hydrodynamic forces and, for the first time, 3D torques. We show that zebrafish larvae reorient mostly in the first stage of the start by producing a strong yaw torque, often without using the pectoral fins. This reorientation is expressed as the body angle, a measure that represents the rotation of the complete body, rather than the commonly used head angle. The fish accelerates its centre of mass mostly in stage 2 by generating a considerable force peak while the fish "unfolds". The escape direction of the fish correlates strongly with the amount of body

Frontiers in Robotics and AI, 2022

Natural fliers utilize passive and active flight control strategies to cope with windy conditions... more Natural fliers utilize passive and active flight control strategies to cope with windy conditions. This capability makes them incredibly agile and resistant to wind gusts. Here, we study how insects achieve this, by combining Computational Fluid Dynamics (CFD) analyses of flying fruit flies with freely-flying robotic experiments. The CFD analysis shows that flying flies are partly passively stable in side-wind conditions due to their dorsal-ventral wing-beat asymmetry defined as wing-stroke dihedral. Our robotic experiments confirm that this mechanism also stabilizes free-moving flapping robots with similar asymmetric dihedral wing-beats. This shows that both animals and robots with asymmetric wing-beats are dynamically stable in sideways wind gusts. Based on these results, we developed an improved model for the aerodynamic yaw and roll torques caused by the coupling between lateral motion and the stroke dihedral. The yaw coupling passively steers an asymmetric flapping flyer into t...

This dataset contains 10,005 landing manoeuvres of bumblebees observed in three different light c... more This dataset contains 10,005 landing manoeuvres of bumblebees observed in three different light conditions and in the presence of two different landing patterns. This dataset supplements the text in the manuscript titled: "Bumblebees land rapidly and robustly using a sophisticated modular flight control strategy".

Flying animals often encounter winds during visually guided landings. However, how winds affect t... more Flying animals often encounter winds during visually guided landings. However, how winds affect their flight control strategy during landing is unknown. Here, we investigated how sidewind affects the landing strategy, sensorimotor control, and landing performance of foraging bumblebees (Bombus terrestris). For this, we trained a hive of bumblebees to forage in a wind tunnel, and used high-speed stereoscopic videography to record 19,421 landing flight maneuvers in six sidewind speeds (0 to 3.4 m s−1), which correspond to winds encountered in nature. Bumblebees landed less often in higher windspeeds, but the landing duration from free flight was not increased by wind. We then tested how bumblebees adjusted their landing control to compensate for the adverse effects of sidewind on landing. This showed that the landing strategy in sidewind was similar to that in still air, but with important adaptations. In the highest windspeeds, more hover phases occurred than during landings in still...

Bulletin of the American Physical Society, Mar 10, 2008

Birds, bats and insects have provided inspiration for human-designed small-scale flying machines,... more Birds, bats and insects have provided inspiration for human-designed small-scale flying machines, and while insects have long been known to rely on unsteady separated flows for their above-average aerodynamic performance at small-scale, the details of air flows over bird and bat wings have been harder to elucidate, mainly because of the extra complexity and precautions required in live experiments. Here we report on the first experiments of the airflow around a bat wing in free (but trained) flight in a low-turbulence wind tunnel. The aerodynamics of fixed wings at these Reynolds numbers are notoriously sensitive to small disturbances of the initially laminar, attached boundary layer, but these flight experiments show that the instantaneous flow fields around the flapping wing bear almost no resemblance to an equivalent fixed-wing experiment. The circulation increment due to the presence of a strong leading-edge vortex is estimated to provide a significant fraction of the total lift. Implications for the design and control of micro-air vehicles are considered.

Animal Biotelemetry, Jul 15, 2023

Background Biologgers have contributed greatly to studies of animal movement, behaviours and phys... more Background Biologgers have contributed greatly to studies of animal movement, behaviours and physiology. Accelerometers, among the various on-board sensors of biologgers, have mainly been used for animal behaviour classification and energy expenditure estimation. However, a general principle for the combined sampling duration and frequency for different taxa is lacking. In this study, we evaluated whether Nyquist-Shannon sampling theorem applies to accelerometer-based classification of animal behaviour and energy expenditure approximation. To evaluate the influence of accelerometer sampling frequency on behaviour classification, we annotated accelerometer data from seven European pied flycatchers (Ficedula hypoleuca) freely moving in aviaries. We also used simulated data to systematically evaluate the combined effect of sampling duration and sampling frequency on the performance of estimating signal frequency and amplitude.

Integrative and Comparative Biology, 2011

The Journal of Experimental Biology, Jul 15, 2019

Journal of Experimental Biology

ABSTRACTHabitat specialization can influence the evolution of animal movement in promoting diverg... more ABSTRACTHabitat specialization can influence the evolution of animal movement in promoting divergent locomotor abilities adapted to contrasting environmental conditions, differences in vegetation clutter or predatory communities. While the effect of habitat on the evolution of locomotion and particularly escape performance has been well investigated in terrestrial animals, it remains understudied in flying animals. Here, we investigated whether specialization of Morpho butterfly species into different vertical strata of the Amazonian forest affects the performance of upward escape flight manoeuvres. Using stereoscopic high-speed videography, we compared the climbing flight kinematics of seven Morpho species living either in the forest canopy or in the understory. We show that butterflies from canopy species display strikingly higher climbing speed and steeper ascent angle compared with understory species. Although climbing speed increased with wing speed and angle of attack, the hig...

CSH Protocols, Sep 27, 2022

After tracking the kinematics of a moving mosquito from video, one needs to convert the tracking ... more After tracking the kinematics of a moving mosquito from video, one needs to convert the tracking output into the kinematics data needed to answer the research question. Here, we provide general guidelines for how to do this by discussing how to quantify body position and orientation in the world reference frame and wing and leg orientation in the mosquito body reference frame. These guidelines should be adapted based on the goal of your research. To answer your research question, the resulting kinematics data must then be further analyzed. Because the nature of this analysis depends strongly on your specific research question, we refer to literature for designing these postprocessing routines.

Functional Ecology, Sep 21, 2017

CSH Protocols, Sep 27, 2022

Female mosquitoes of most species require a blood meal for egg development. When biting a human h... more Female mosquitoes of most species require a blood meal for egg development. When biting a human host to collect this blood meal, they can spread dangerous diseases such as malaria, yellow fever, or dengue. Researchers use videography to study many aspects of mosquito behavior, including in-flight host-seeking, takeoff, and landing behaviors, as well as probing and blood feeding, and more. Here, we introduce protocols on how to use videography to capture and analyze mosquito movements at high spatial and temporal resolution, in two and three dimensions.

CSH Protocols, Sep 27, 2022

In this protocol, we describe the basic design considerations and general method to set up a vide... more In this protocol, we describe the basic design considerations and general method to set up a videography system to study mosquito behavior. A basic videography system to study mosquito behavior requires one or more cameras with an optical lens, camera lighting, a calibration setup, and a system to record the video data or otherwise control the camera. Here, we define two types of systems: (1) a real-time videography-based tracking system for determining the position of multiple moving (flying) mosquitoes, and (2) a high-fidelity videography system that can track the detailed movements of body, wings, and legs of a single mosquito at high spatial and temporal resolutions. These high-fidelity trackers are divided into single-camera systems for studying two-dimensional (2D) movements, and multicamera systems that can reconstruct three-dimensional (3D) movements of the mosquito.

CSH Protocols, Sep 28, 2022

In this protocol, we discuss general techniques for tracking the three-dimensional (3D) locations... more In this protocol, we discuss general techniques for tracking the three-dimensional (3D) locations of the mosquito body, wings, legs, or other features of interest using videos. Tracking data must be acquired to produce detailed kinematics of moving mosquitoes. The software of focus for this protocol, DLTdv, was chosen for its widespread use and excellent support and because it is open-source. In addition, DLTdv allows both manual and automatic tracking. The automatic tracking can be done using a classic machine vision or machine-learning algorithm. The software supports both single-camera analysis and multicamera systems and can take advantage of sophisticated calibration algorithms, both for intrinsic lens distortion correction and for 3D DLT-based reconstruction. For this protocol, we assume all kinematic data is acquiredpost hocthrough video analysis.

CSH Protocols, Sep 28, 2022

Tracking mosquitoes in real time, as opposed to recording video files and performing the tracking... more Tracking mosquitoes in real time, as opposed to recording video files and performing the tracking step later, is useful for two reasons. The first is efficiency. Real-time tracking requires less storage because video images do not need to be saved and followed by a tracking step. The second is that tracking data can be used to interact with the animal in some way, such as triggering the approach of a looming object. In this protocol, we discuss the use of Braid, free software for performing real-time, multicamera, multianimal tracking. We describe a setup with four cameras capable of tracking the threedimensional (3D) position of mosquitoes at 100 frames per second in a volume of 30 cm × 30 cm × 60 cm with millimeter accuracy. The specific hardware configuration is flexible and can be substituted using different or additional components to adjust the tracking parameters as needed. MATERIALS It is essential that you consult the appropriate Material Safety Data Sheets and your institution's Environmental Health and Safety Office for proper handling of equipment and hazardous materials used in this protocol.

Journal of Fluid Mechanics, Jan 26, 2023

The fluid dynamics of insect wings and the fins and tails of fish are governed by vortex wake int... more The fluid dynamics of insect wings and the fins and tails of fish are governed by vortex wake interactions, which are strongly related to the wing, fins and tail kinematics. By modeling the kinematics of these wings, fins and tails as a two-dimensionally flapping foil, the influence of the kinematics on the vortex wake interactions is studied. This is done by varying the non-dimensional advance ratio -which describes the amount of foil chord lengths traveled during one falling cycle- and keeping the other independent variables constant. The vortex wake interactions in the wake of the flapping foil as a function of the advance ratio were studied with so-called soap-film tunnel technique: a planar film of soap runs down between two wires at constant flow velocity. In this soap-film the vorticity field in the wake of the flapping foil can directly be visualized using a high speed camera and monochromatic illumination. Different vortex wake pattern domains were found for various advance ratios. This shows that the vortex wake interactions are strongly related to the advance ratio as well as the behavior of the Leading Edge Vortex (LEV). At low advance (Less)

Social Science Research Network, 2022

bioRxiv (Cold Spring Harbor Laboratory), Mar 8, 2019

Most fish species use fast starts to escape from predators. Zebrafish larvae perform effective fa... more Most fish species use fast starts to escape from predators. Zebrafish larvae perform effective fast starts immediately after hatching. They use a C-start, where the body curls into a C-shape, and then unfolds to accelerate. These escape responses need to fulfil a number of functional demands, under the constraints of the fluid environment and the larva's body shape. Primarily, the larvae need to generate sufficient escape speed in a wide range of possible directions, in a short-enough time. In this study, we examined how the larvae meet these demands. We filmed fast starts of zebrafish larvae with a unique five-camera setup with high spatiotemporal resolution. From these videos, we reconstructed the three-dimensional swimming motion with an automated method and from these data calculated resultant hydrodynamic forces and, for the first time, 3D torques. We show that zebrafish larvae reorient mostly in the first stage of the start by producing a strong yaw torque, often without using the pectoral fins. This reorientation is expressed as the body angle, a measure that represents the rotation of the complete body, rather than the commonly used head angle. The fish accelerates its centre of mass mostly in stage 2 by generating a considerable force peak while the fish "unfolds". The escape direction of the fish correlates strongly with the amount of body

Frontiers in Robotics and AI, 2022

Natural fliers utilize passive and active flight control strategies to cope with windy conditions... more Natural fliers utilize passive and active flight control strategies to cope with windy conditions. This capability makes them incredibly agile and resistant to wind gusts. Here, we study how insects achieve this, by combining Computational Fluid Dynamics (CFD) analyses of flying fruit flies with freely-flying robotic experiments. The CFD analysis shows that flying flies are partly passively stable in side-wind conditions due to their dorsal-ventral wing-beat asymmetry defined as wing-stroke dihedral. Our robotic experiments confirm that this mechanism also stabilizes free-moving flapping robots with similar asymmetric dihedral wing-beats. This shows that both animals and robots with asymmetric wing-beats are dynamically stable in sideways wind gusts. Based on these results, we developed an improved model for the aerodynamic yaw and roll torques caused by the coupling between lateral motion and the stroke dihedral. The yaw coupling passively steers an asymmetric flapping flyer into t...

This dataset contains 10,005 landing manoeuvres of bumblebees observed in three different light c... more This dataset contains 10,005 landing manoeuvres of bumblebees observed in three different light conditions and in the presence of two different landing patterns. This dataset supplements the text in the manuscript titled: "Bumblebees land rapidly and robustly using a sophisticated modular flight control strategy".

Flying animals often encounter winds during visually guided landings. However, how winds affect t... more Flying animals often encounter winds during visually guided landings. However, how winds affect their flight control strategy during landing is unknown. Here, we investigated how sidewind affects the landing strategy, sensorimotor control, and landing performance of foraging bumblebees (Bombus terrestris). For this, we trained a hive of bumblebees to forage in a wind tunnel, and used high-speed stereoscopic videography to record 19,421 landing flight maneuvers in six sidewind speeds (0 to 3.4 m s−1), which correspond to winds encountered in nature. Bumblebees landed less often in higher windspeeds, but the landing duration from free flight was not increased by wind. We then tested how bumblebees adjusted their landing control to compensate for the adverse effects of sidewind on landing. This showed that the landing strategy in sidewind was similar to that in still air, but with important adaptations. In the highest windspeeds, more hover phases occurred than during landings in still...

Bulletin of the American Physical Society, Mar 10, 2008

Birds, bats and insects have provided inspiration for human-designed small-scale flying machines,... more Birds, bats and insects have provided inspiration for human-designed small-scale flying machines, and while insects have long been known to rely on unsteady separated flows for their above-average aerodynamic performance at small-scale, the details of air flows over bird and bat wings have been harder to elucidate, mainly because of the extra complexity and precautions required in live experiments. Here we report on the first experiments of the airflow around a bat wing in free (but trained) flight in a low-turbulence wind tunnel. The aerodynamics of fixed wings at these Reynolds numbers are notoriously sensitive to small disturbances of the initially laminar, attached boundary layer, but these flight experiments show that the instantaneous flow fields around the flapping wing bear almost no resemblance to an equivalent fixed-wing experiment. The circulation increment due to the presence of a strong leading-edge vortex is estimated to provide a significant fraction of the total lift. Implications for the design and control of micro-air vehicles are considered.

Animal Biotelemetry, Jul 15, 2023

Background Biologgers have contributed greatly to studies of animal movement, behaviours and phys... more Background Biologgers have contributed greatly to studies of animal movement, behaviours and physiology. Accelerometers, among the various on-board sensors of biologgers, have mainly been used for animal behaviour classification and energy expenditure estimation. However, a general principle for the combined sampling duration and frequency for different taxa is lacking. In this study, we evaluated whether Nyquist-Shannon sampling theorem applies to accelerometer-based classification of animal behaviour and energy expenditure approximation. To evaluate the influence of accelerometer sampling frequency on behaviour classification, we annotated accelerometer data from seven European pied flycatchers (Ficedula hypoleuca) freely moving in aviaries. We also used simulated data to systematically evaluate the combined effect of sampling duration and sampling frequency on the performance of estimating signal frequency and amplitude.

Integrative and Comparative Biology, 2011