A Bird-Inspired Perching Landing Gear System1

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Paul M. Nadan ◽  
Tatiana M. Anthony ◽  
Duncan M. Michael ◽  
Jeffrey B. Pflueger ◽  
Manik S. Sethi ◽  
...  
Keyword(s):  
Computational Model ◽  
Minimum Weight ◽  
Landing Gear ◽  
Contact Forces ◽  
Gear System ◽  
Prototype System ◽  
Cross Sectional ◽  
Modeling Simulation ◽  
Working Principle ◽  
Shape And Size

Abstract The design, modeling, simulation, and testing of a landing gear system that enables a UAV to perch on an object or surface is presented here. The working principle of the landing gear is inspired by the anatomy of birds that grasp and perch as tendons in their legs and feet are tensioned. In a similar fashion, as the UAV sets down on a structure, its weight tensions a cable which actuates opposing, flexible, multi-segment feet to enclose the target. To analyze the grasping capability of the design, a hybrid empirical–computational model is developed that can be used to simulate the kinematics of the system as it grasps objects of various cross-sectional shapes and sizes. The model relates the curvature of the feet to the displacement and tension of the cable tendon. These quantities are then related to the weight of the UAV through the leg geometry. It also evaluates enclosure and calculates contact forces to quantitatively characterize the grasp. Results demonstrate how the model can be used by designers to determine how a UAV can perch upon a structure of a given shape and size. If perched, the minimum weight required to maintain its position is calculated. A prototype system was fabricated, analyzed, and tested on a radio-controlled hexacopter. Experiments show that the landing gear enables the hexacopter to land, perch, and takeoff from a variety of objects. Finally, we begin to investigate the scalability of the concept with a smaller, lighter design.

Computational Design of a Bird-Inspired Perching Landing Gear Mechanism

2018 ◽  
Author(s):  
Paul M. Nadan ◽  
Christopher L. Lee
Keyword(s):  
Computational Model ◽  
Cross Section ◽  
Computational Design ◽  
Landing Gear ◽  
Model Based ◽  
Small Uav ◽  
Gear Mechanism ◽  
Working Principle

To support the design of a mechanism with two opposing, underactuated, multi-segmented feet that enables a small UAV to grasp and perch upon a branch or similar structure, a hybrid empirical-computational model has been developed that can be used to predict whether the mechanism can kinematically grasp structures with a range of cross-section shapes and sizes in various orientations and to quantify the forces exerted by the grasp. The model, based on experimentally-determined parameters, relates the curvature of the feet to the displacement and tension of the cable tendon which is related in turn to the weight of the UAV. The working principle of the landing gear follows the anatomy of birds that grasp and perch as tendons in their legs and feet are tensioned. Results demonstrate how the model can be used to simulate and evaluate grasping in order to determine the size and weight of a UAV for landing and perching upon a range of target structures.

scholarly journals Robust force and displacement control of an active landing gear for vibration reduction at touchdown and during taxiing

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Mehran Pirooz ◽  
Seyed Hossein Mirmahdi ◽  
Ahmad Reza Khoogar
Keyword(s):  
Control System ◽  
Force Control ◽  
Direct Method ◽  
Landing Gear ◽  
Gear System ◽  
Displacement Control ◽  
Robust Nonlinear Control ◽  
Control Loops ◽  
Tire Force ◽  
The Mathematical Model

AbstractIn this paper, a new approach is proposed to control the dynamic response of a landing gear system subjected to runway force, both on heavy landing conditions and at the taxiing process. The mathematical model of the system is used in a way that covers nonlinear dynamics characteristics of landing gear and nonlinear/nonaffine property of the external actuator. The operation of the landing gear system and its components are described briefly. The desired control system includes two different interior loops for displacement and force control. The inner loop determines the actuator force and the outer loop performs the displacement control. A lumped uncertainty is considered in both displacement and force control loops that represent uncertainties including parametric errors, measurement noises, unmodeled dynamics, disturbance due to runway excitation, and other disturbances. The direct method of Lyapunov is utilized for asymptotic stability analysis of the robust nonlinear control system (RNCS). This system is simulated in MATLAB software and the performance of the proposed controller is analyzed exactly. Besides, the results are compared with a passive system and conventional PID control. The comparison indicates that RNCS works better and more precisely. This method can reduce vibrations at touchdown and taxiing and effectively overcome uncertainty and provide well aircraft handling by decreasing the changes in tire force.

scholarly journals The influence of muscle pennation angle and cross-sectional area on contact forces in the ankle joint

2016 ◽  
Vol 52 (1) ◽  
pp. 12-23 ◽  
Author(s):  
Ran S Sopher ◽  
Andrew A Amis ◽  
D Ceri Davies ◽  
Jonathan RT Jeffers
Keyword(s):  
Pennation Angle ◽  
Muscle Architecture ◽  
Cross Sectional Area ◽  
Contact Forces ◽  
Sectional Area ◽  
Muscle Forces ◽  
Cross Sectional ◽  
Contact Loads ◽  
The Mean ◽  
And Function

Data about a muscle’s fibre pennation angle and physiological cross-sectional area are used in musculoskeletal modelling to estimate muscle forces, which are used to calculate joint contact forces. For the leg, muscle architecture data are derived from studies that measured pennation angle at the muscle surface, but not deep within it. Musculoskeletal models developed to estimate joint contact loads have usually been based on the mean values of pennation angle and physiological cross-sectional area. Therefore, the first aim of this study was to investigate differences between superficial and deep pennation angles within each muscle acting over the ankle and predict how differences may influence muscle forces calculated in musculoskeletal modelling. The second aim was to investigate how inter-subject variability in physiological cross-sectional area and pennation angle affects calculated ankle contact forces. Eight cadaveric legs were dissected to excise the muscles acting over the ankle. The mean surface and deep pennation angles, fibre length and physiological cross-sectional area were measured. Cluster analysis was applied to group the muscles according to their architectural characteristics. A previously validated OpenSim model was used to estimate ankle muscle forces and contact loads using architecture data from all eight limbs. The mean surface pennation angle for soleus was significantly greater (54%) than the mean deep pennation angle. Cluster analysis revealed three groups of muscles with similar architecture and function: deep plantarflexors and peroneals, superficial plantarflexors and dorsiflexors. Peak ankle contact force was predicted to occur before toe-off, with magnitude greater than five times bodyweight. Inter-specimen variability in contact force was smallest at peak force. These findings will help improve the development of experimental and computational musculoskeletal models by providing data to estimate force based on both surface and deep pennation angles. Inter-subject variability in muscle architecture affected ankle muscle and contact loads only slightly. The link between muscle architecture and function contributes to the understanding of the relationship between muscle structure and function.

Design and dynamic analysis of landing gear system in vertical takeoff and vertical landing reusable launch vehicle

2018 ◽  
Vol 233 (10) ◽  
pp. 3700-3713
Author(s):  
Ming Zhang ◽  
Dafu Xu ◽  
Shuai Yue ◽  
Haifeng Tao
Keyword(s):  
General Scheme ◽  
Surface Friction ◽  
Launch Vehicle ◽  
Landing Gear ◽  
Gear System ◽  
Extreme Condition ◽  
Response Characteristics ◽  
Reusable Launch Vehicle ◽  
Vertical Landing ◽  
Vertical Takeoff

Landing gear system is a key part of the implementation of reusable vertical takeoff and vertical landing launch vehicle, where its buffing performance is directly related to the vehicle whether it can land safely or stably. According to the reusable launch vehicle general scheme, outrigger landing legs are designed, and the hydraulic absorber is used for the landing gear system. Meanwhile, a scaling principle prototype of landing gear system is developed, and the landing impact test is carried out. A dynamic simulation model of the landing vehicle has been set up, researching the influence of parameters, such as the horizontal velocity, initial inclination, surface friction coefficient, and pitch angular velocity on the landing performance. Four kinds of extreme conditions are identified, and dynamic response characteristics of landing system under each extreme condition are conducted. The simulation results are in good agreement with the experimental data. The buffing performance of the vehicle meets the design requirements, which provides a reference for the design of landing gear system of the vehicle.

Contribution in Optimization of Honeycomb Abradable Seals Structure

2021 ◽  
Author(s):  
P. Pathak ◽  
D. Dzhurinskiy ◽  
A. Elkin ◽  
P. Shornikov ◽  
S. Dautov ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Energy Demand ◽  
Mechanical Performance ◽  
Minimum Weight ◽  
Innovative Technology ◽  
Element Analysis ◽  
Cross Sectional ◽  
Spray System ◽  
Seal Design ◽  
Temperature Capability

Abstract The abradable coatings had significantly enhanced turbomachinery performance by acting as a sacrificial seal between rotating blades and stationary casing. Further improvement in seal design to meet the higher energy demand and increase the service time has been the key challenges to solve in the gas turbine industry. Honeycomb seals have become the industry standard clearance seal technique due to their unique design and high structural strength with minimum weight. The present study proposes a concept to form a thermal shock resistance structure to achieve higher temperature capability and improve the reliability of abradable seal structures. A cavity layer of honeycomb seal structure made of SS 321 alloy was coated with advanced high-temperature ZrO2+7.5%Y2O3+4% polyester seal material using TriplexPro-210 plasma spray system. The integrity of a seal structure was assessed by a cross-sectional analysis and evaluation of the coating microstructure. Additionally; the microhardness test was performed to estimate coating fracture toughness; and Object-Oriented Finite Element analysis was used to assess its thermo-mechanical performance. The concept proposed in this study should be further validated to develop the most capable innovative technology for advanced gas turbine abradable seal structures.

Dynamic Computational Model of the Human Spinal Cord Connectome

2019 ◽  
Vol 31 (2) ◽  
pp. 388-416 ◽  
Author(s):  
Jeffrey E. Arle ◽  
Nicolae Iftimia ◽  
Jay L. Shils ◽  
Longzhi Mei ◽  
Kristen W. Carlson
Keyword(s):  
Spinal Cord ◽  
Computational Model ◽  
Cell Types ◽  
Neural Circuitry ◽  
Simulation Software ◽  
Cross Sectional ◽  
Human Spinal Cord ◽  
Starting Point ◽  
The Many ◽  
Future Work

Connectomes abound, but few for the human spinal cord. Using anatomical data in the literature, we constructed a draft connectivity map of the human spinal cord connectome, providing a template for the many calibrations of specialized behavior to be overlaid on it and the basis for an initial computational model. A thorough literature review gleaned cell types, connectivity, and connection strength indications. Where human data were not available, we selected species that have been studied. Cadaveric spinal cord measurements, cross-sectional histology images, and cytoarchitectural data regarding cell size and density served as the starting point for estimating numbers of neurons. Simulations were run using neural circuitry simulation software. The model contains the neural circuitry in all ten Rexed laminae with intralaminar, interlaminar, and intersegmental connections, as well as ascending and descending brain connections and estimated neuron counts for various cell types in every lamina of all 31 segments. We noted the presence of highly interconnected complex networks exhibiting several orders of recurrence. The model was used to perform a detailed study of spinal cord stimulation for analgesia. This model is a starting point for workers to develop and test hypotheses across an array of biomedical applications focused on the spinal cord. Each such model requires additional calibrations to constrain its output to verifiable predictions. Future work will include simulating additional segments and expanding the research uses of the model.

scholarly journals Design of a Crashworthy Cable-Driven Four-Bar Link Robotic Landing Gear System

2020 ◽  
Vol 57 (2) ◽  
pp. 224-244
Author(s):  
Claudio V. Di Leo ◽  
Benjamin León ◽  
Jake Wachlin ◽  
Martin Kurien ◽  
Arjun Krishnan ◽  
...  
Keyword(s):  
Landing Gear ◽  
Gear System
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