Search Results (23)

Background and Objectives: Adequate peri-implant soft tissue dimensions are essential for health, hygiene, and esthetics. When ridge volume is sufficient, phenotype modification may avoid bone grafting. This case report describes a pedicled roll flap performed concurrently with single-stage implant placement after spontaneous socket healing, without bone substitute, and assesses soft-tissue stability with serial intraoral scans. Clinical case: A single-tooth edentulous site underwent prosthetically driven, fully guided implant placement. A modified roll flap with vertical and palatal incisions was prepared; the de-epithelialized crestal connective tissue was elevated and rolled into a buccal envelope to augment thickness. No graft material was used. A provisional crown conditioned the emergence profile. Follow-up included photographs, radiographs, and intraoral scan superimpositions at 2 weeks, 3–4 months, 8 months, and 14 months after implant treatment. Healing was uneventful. Buccal soft-tissue thickness increased, keratinized mucosa was preserved, and midfacial levels remained stable. Emergence profile and papillae integrated harmoniously. Crestal bone levels were stable radiographically. Digital scans corroborated soft-tissue thickness maintenance. No donor-site morbidity occurred. Conclusions: In healed sockets with adequate bone, a modified pedicled roll flap at implant placement can thicken the peri-implant phenotype and achieve stable esthetic integration without bone substitutes. Full article

This study presents the design, control, and flight experiments of a motor-directly-driven flapping-wing micro air vehicle with extension springs (MDD-FWMAVES). The flapping wing actuation utilizes the resonance of a linear extension spring and a flapping wing. The analysis results of the proposed MDD-FWMAVES revealed a resonant frequency of 19.59 Hz for the flapping-wing mechanism, and actual flapping experiments confirmed this to be 20 Hz. Using a six-axis load cell, we demonstrated the ability to generate roll, pitch, and yaw moments for attitude control based on wing flapping variations. All roll, pitch, and yaw moments were linearly proportional to the wing flapping variations. MEMS gyroscopes and accelerometers were used to measure roll, pitch, and yaw angular velocities and the gravity. A complementary filter was applied to these measurements to obtain the roll and pitch angles required for attitude control. A microprocessor, two motor drive circuits, one MEMS gyroscope/accelerometer, and one EEPROM for flight data storage were implemented on a single, ultra-compact electronic control board and mounted on the MDD-FWMAVES. Simple roll and pitch PD controllers were implemented on this electronic control board, and the controlled flight feasibility of the MDD-FWMAVES was explored. Flight tests demonstrated stable hovering for approximately 6 s. While yaw control was not achieved, the onboard feedback control system demonstrated stable roll and pitch control. Therefore, the MDD-FWMAVES holds the potential to be developed into a high-performance flapping-wing micro air vehicle if its flight system and controller are improved. Full article

This paper presents FWStab, a specialized video stabilization dataset tailored for flapping-wing platforms. The dataset encompasses five typical flight scenarios, featuring 48 video clips with intense dynamic jitter. The corresponding Inertial Measurement Unit (IMU) sensor data are synchronously collected, which jointly provide reliable support for multimodal modeling. Based on this, to address the issue of poor image acquisition quality due to severe vibrations in aerial vehicles, this paper proposes a multi-modal signal fusion video stabilization framework. This framework effectively integrates image features and inertial sensor features to predict smooth and stable camera poses. During the video stabilization process, the true camera motion originally estimated based on sensors is warped to the smooth trajectory predicted by the network, thereby optimizing the inter-frame stability. This approach maintains the global rigidity of scene motion, avoids visual artifacts caused by traditional dense optical flow-based spatiotemporal warping, and rectifies rolling shutter-induced distortions. Furthermore, the network is trained in an unsupervised manner by leveraging a joint loss function that integrates camera pose smoothness and optical flow residuals. When coupled with a multi-stage training strategy, this framework demonstrates remarkable stabilization adaptability across a wide range of scenarios. The entire framework employs Long Short-Term Memory (LSTM) to model the temporal characteristics of camera trajectories, enabling high-precision prediction of smooth trajectories. Full article

Satellite Internet of Things (IoT) terminals face design constraints regarding low power consumption and light control. These constraints pose a significant collision risk when utilizing traditional random-access protocols, making it challenging to meet the system throughput requirements. Auxiliary beam schemes based on conventional beam formation suffer from the problem of the auxiliary beam shape being limited by the fixed directional map. This leads to the problem of limited throughput enhancement. In this paper, an auxiliary beam weight optimization method for satellite IoT capacity enhancement is proposed. By increasing the number of main flap roll-off bands, the success rate of collision signal separation is increased. It is possible to improve the system access performance. The simulation results indicate that the proposed method can significantly improve the system throughput performance. Furthermore, it can withstand some direction of arrival (DOA) estimation errors and amplitude–phase errors. Robustness is possessed. Full article

The study aimed to evaluate changes in buccal gingival contour following implant surgery using the simultaneous roll technique on Seibert class I defects, as determined by 3D intraoral scan data. Three patients requiring implant placement were recruited, and implants were placed using the roll flap technique. Digital impressions of the surgical site were obtained with a 3D intraoral scanner before surgery, after suture removal, and 4 months postoperatively. The results showed an overall increase in buccal gingival contour, with a maintained increase in soft tissue contour after 4 months. The study concluded that 3D scanning is a suitable method for assessing small changes in gingival contour, making it ideal for evaluating these changes. The roll flap technique was also found to effectively enhance the buccal gingival contour and soft tissue appearance around the implant collar. Full article

This paper presents an innovative active monitoring strategy to manage asymmetry in aircraft flaps. Complex mechanical systems like high-lift devices may undergo a wide range of faults, such as a broken transmission torsion bar or wear and tear on control surface actuators just to name a few. These faults can alter the surface symmetry between the two sides of the wing, potentially leading to dangerous conditions. The proposed relative dynamic position control technique provides a more effective monitoring method to detect and identify flap asymmetry. Once the faulty side has been identified, the system activates the wingtip brakes to halt the uncontrolled flap. The remaining functional flap is then moved to match the braking point of the failed flap, reducing the asymmetry. This approach effectively manages the unwanted roll moment caused by flap asymmetry, thereby partially restoring the aircraft’s maneuverability post-failure. The proposed monitoring technique has been subjected to extensive testing under various operational and failure conditions with the use of a mathematical model, with both new and worn actuators, and considering a wide range of possible failure scenarios. Full article

Birds have remarkable flight capabilities due to their adaptive wing morphology. However, studying live birds is time-consuming and laborious, and obtaining information about the complete wingbeat cycle is difficult. To address this issue and provide a complete dataset, we recorded comprehensive motion capture wing trajectory data from five free-flying pigeons (Columba livia). Five key motion parameters are used to quantitatively characterize wing kinematics: flapping, sweeping, twisting, folding and bending. In addition, the forelimb skeleton is mapped using an open-chain three-bar mechanism model. By systematically evaluating the relationship of joint degrees of freedom (DOFs), we configured the model as a 3-DOF shoulder, 1-DOF elbow and 2-DOF wrist. Based on the correlation analysis between wingbeat kinematics and joint movement, we found that the strongly correlated shoulder and wrist roll within the stroke plane cause wing flap and bending. There is also a strong correlation between shoulder, elbow and wrist yaw out of the stroke plane, which causes wing sweep and fold. By simplifying the wing morphing, we developed three flapping wing robots, each with different DOFs inside and outside the stroke plane. This study provides insight into the design of flapping wing robots capable of mimicking the 3D wing motion of pigeons. Full article

Flapping-wing micro air vehicles (FWMAVs) have gained much attention from researchers due to their exceptional performance at low Reynolds numbers. However, the limited understanding of active aerodynamic modulation in flying creatures has hindered their maneuverability from reaching that of their biological counterparts. In this article, experimental investigations were conducted to examine the effect of the bilateral amplitude asymmetry of flexible flapping wings. A reduced bionic model featuring bat-like wings is built, and a dimensionless number $\Delta {\mathsf{\Phi }}^{*}$ is introduced to scale the degree of bilateral amplitude asymmetry in flapping motion. The experimental results suggest that the bilateral amplitude–asymmetric flapping motion primarily induces maneuvering control forces of coupling roll moment and yaw moment. Also, roll moment and yaw moment have a good linear relationship. To achieve more efficient maneuvers based on this asymmetric motion, it is advisable to maintain $\Delta {\mathsf{\Phi }}^{*}$ within the range of 0 to 0.4. The magnitude of passive pitching deformation during the downstroke is significantly greater than that during the upstroke. The phase of the peak of the passive pitching angle advances with the increase in flapping amplitude, while the valleys lag. And the proportion of pronation and supination in passive pitching motion cannot be adjusted by changing the flapping amplitude. These findings have important practical relevance for regulating turning maneuvers based on amplitude asymmetry and help to understand the active aerodynamic modulation mechanism through asymmetric wing kinematics. Full article

Penile augmentation using filler injections is gaining popularity; however, complications such as foreign body reactions can arise, leading to issues like penile ulceration and necrosis, subsequently necessitating reconstruction. The existing method of the reconstruction of the penis is primarily aimed at filling the deficit. In this paper, we describe a case in which a scrotal flap and autologous augmentation were utilized to treat a soft tissue defect caused by a delayed infection following a penile filler injection. The patient, a 41-year-old male, had received an Aquafilling^® (Biomedica, Prague, Czech Republic) filler injection seven years earlier and later developed a delayed infection. After debridement, the penile defect spanned the entire shaft, and the circumference of the flaccid penis was 7.5 cm. Using a bilateral scrotal flap technique, the lower margins of both flaps were rolled inward after de-epithelialization to achieve autologous augmentation. Over the three-month post-surgery follow-up, neither infections nor flap necrosis were observed. The penile circumference increased to 12 cm, and the patient reported high satisfaction with the outcome. This new surgical technique can be widely applied as treatment for a variety of penile defects. Full article

This article aims to numerically study the hydrodynamic performance of the bionic dolphin equipped with a pair of rigid pectoral fins. We use dynamic-grid technology and user-defined functions to simulate a novel butterfly-mode flapping propulsion of the fins. This pattern of propulsion is composed of three angular degrees of freedom including the pitch angle ϕ_p, the azimuth angle ϕ_a and the roll angle ϕ_r, which can be divided into four stages for analysis within a single cycle. The stroke of one single pectoral fin can be approximated as an ellipse trajectory, where the amplitudes of ϕ_a and ϕ_p, respectively, determine the major and minor axes of the ellipse. The fluid dynamics involved in the specific butterfly pattern is mathematically formulated, and numerical simulation is conducted to investigate the propulsion quantitatively. The results show that the dolphin with a higher water striking frequency f can acquire higher propulsion speed and efficiency. Furthermore, the shape of the ellipse trajectory under different conditions could also have different propulsion effects. The periodic generation and disappearance of vortex structures in the butterfly flapping mode show the evolution process of fluid flow around a pair of pectoral fins, which reveals the influence of motion parameters on fluid dynamics under different working conditions. Full article

A key challenge in flapping-wing micro air vehicle (FWMAV) design is to generate high aerodynamic force/torque for improving the vehicle’s maneuverability. This paper presents a bio-inspired hover-capable flapping-wing micro air vehicle, named RoboFly.S, using a cross-tail wing to adjust attitude. We propose a novel flapping mechanism composed of a two-stage linkage mechanism, which has a large flapping angle and high reliability. Combined with the experimentally optimized wings, this flapping mechanism can generate more than 34 g of lift with a total wingspan of 16.5 cm, which is obviously superior to other FWMAVs of the same size. Aerodynamic force/torque measurement systems are used to observe and measure the flapping wing and aerodynamic data of the vehicle. RoboFly.S realizes attitude control utilizing the deflection of the cross-tail wing. Through the design and experiments with tail wing parameters, it is proved that this control method can generate a pitch torque of 2.2 N·mm and a roll torque of 3.55 N·mm with no loss of lift. Flight tests show that the endurance of RoboFly.S can reach more than 2.5 min without interferences. Moreover, the vehicle can carry a load of 3.4 g for flight, which demonstrates its ability to carry sensors for carrying out tasks. Full article

Recently, inspired by the flippers of humpback whales, researchers have been widely studying leading-edge tubercles for use as passive flow control devices. In this research, we numerically investigated the effects of leading-edge tubercles on a three-dimensional flapping foil coupled with rolling and pitching motions. Appropriate spanwise flexibility is considered to mimic the real flapping motion of humpback whales, and the profile of the angle of attack was analyzed in a representative section under the effects of spanwise flexibility. The motion of flexible foils was decomposed into rigid motion and flexible deflection by using the sliding mesh and dynamic mesh methods, respectively. Then, the hydrodynamic performance of the flexible flapping foils was estimated by solving the unsteady Reynolds Averaged Navier–Stokes equations. The effects of the shape and kinematic parameters on thrust, power consumption, and propulsive efficiency were studied and the mechanism behind these effects was investigated. A maximum efficiency loss of 19.4% was observed for the sharpest tubercle shape. Although the hydrodynamic advantages of leading-edge tubercles were not observed in the present study, the tendency of flow separation over peaking sections was suppressed under low angles of attacks. The results suggest that leading-edge tubercles are more suitable for foils with steady or quasi-steady motions, such as propellers or turbines. Full article

After a short overview of the COLIBRI project, this paper considers the cycle-averaged flight dynamics of a flapping-wing robot near hovering, taking advantage of the weak coupling between the roll and pitch axes. The system is naturally unstable; it needs to be stabilized actively, which requires an attitude reconstruction. Due to the flapping of the wings, the system is subject to a strong periodic noise at the flapping frequency and its higher harmonics; the resulting axial forces and pitch moments are characterized from experimental data. The flapping noise propagates to the six-axis Inertial Measurement Unit (IMU) consisting of three accelerometers and three gyros. The paper is devoted to attitude reconstruction in the presence of flapping noise representative of flight conditions. Two methods are considered: (i) the complementary filter based on the hovering assumption and (ii) a full-state dynamic observer (Kalman filter). Unlike the complementary filter, the full-state dynamic observer allows the reconstruction of the axial velocity, allowing us to control the hovering without any additional sensor. A numerical simulation is conducted to assess the merit of the two methods using experimental noise data obtained with the COLIBRI robot. The paper discusses the trade-off between noise rejection and stability. Full article

The design of a flapping fins stabilization system for yachts at anchor (zero speed conditions) is presented in this study. The solution presented in this manuscript took inspiration from a solution proposed for the design of a biologically inspired flapping UAV. Although the application was different, we used the same principles and methodology to design and study the stabilization mechanism discussed hereafter. The proposed system uses flapping fins to damp the roll oscillations of the vessel, and when the stabilization system is retracted, the surface of each of the fins is flush with the hull, thus offering minimum resistance when the ship is in cruise conditions. The unsteady forces of the flapping fins were computed using computational fluid dynamics, and they were used as input to conduct the structural and durability study of the proposed mechanism. The vessel’s response to roll perturbations was also studied, using a multi-body dynamics approach. From the results obtained, and the design specifications defined, it was found that the response of the stabilization system was acceptable, and that the mechanism could withstand the inertial and hydrodynamic loads. Full article

In this paper, we propose a platform for an insect-like flapping winged micro aerial vehicle with a resonant wing-driving system using extension springs (FMAVRES). The resonant wing-driving system is constructed using an extension spring instead of the conventional helical or torsion spring. The extension spring can be mounted more easily, compared with a torsion spring. Furthermore, the proposed resonant driving system has better endurance compared with systems with torsion springs. Using a prototype FMAVRES, it was found that torques generated for roll, pitch, and yaw control are linear to control input signals. Considering transient responses, each torque response as an actuator is modelled as a simple first-order system. Roll, pitch, and yaw control commands affect each other. They should be compensated in a closed loop controller design. Total weight of the prototype FMAVRES is 17.92 g while the lift force of it is 21.3 gf with 80% throttle input. Thus, it is expected that the new platform of FMAVRES could be used effectively to develop simple and robust flapping MAVs. Full article