Equilibrium Positions for UAV Flight by Dynamic Soaring

International Journal of Aerospace Engineering ◽

10.1155/2015/141906 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

Bingjie Zhu ◽

Zhongxi Hou ◽

Shangqiu Shan ◽

Xinzhu Wang

Keyword(s):

Equilibrium Position ◽

Mechanical Energy ◽

Inertial Force ◽

Value Theory ◽

Gradient Field ◽

Maximum Function ◽

Noninertial Frame ◽

Dynamic Soaring ◽

Extraction Mechanisms ◽

Positive Work

Dynamic soaring is a special flying technique designed to allow UAVs (unmanned aerial vehicles) to extract energy from wind gradient field and enable UAVs to increase the endurance. In order to figure out the energy-extraction mechanisms in dynamic soaring, a noninertial wind relative reference frame of aircraft is built. In the noninertial frame, there is an inertial force which is created by gradient wind field. When the wind gradient(GW)and the components of airspeed(vzvx)are positive, inertial force(F)makes positive work to the aircraft. In the meantime, an equilibrium position theory of dynamic soaring is proposed. At the equilibrium positions, the increased potential energy is greater than the wasted kinetic energy when the aircraft is flying upwards. The mechanical energy is increased in this way, and the aircraft can store energy for flight. According to the extreme value theory, contour line figures of the maximum function and the component of airspeed(vz)are obtained to find out the aircraft’s lifting balance allowance in dynamic soaring. Moreover, this equilibrium position theory can also help to conduct an aircraft to acquire energy from the environment constantly.

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Soaring energetics and glide performance in a moving atmosphere

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2015.0398 ◽

2016 ◽

Vol 371 (1704) ◽

pp. 20150398 ◽

Cited By ~ 17

Author(s):

Graham K. Taylor ◽

Kate V. Reynolds ◽

Adrian L. R. Thomas

Keyword(s):

Global Positioning System ◽

Inertial Measurement Unit ◽

Mechanical Energy ◽

Measurement Unit ◽

Cost Of Transport ◽

Inertial Measurement ◽

Dynamic Soaring ◽

Energy Flows ◽

Weak Evidence ◽

Global Positioning

Here, we analyse the energetics, performance and optimization of flight in a moving atmosphere. We begin by deriving a succinct expression describing all of the mechanical energy flows associated with gliding, dynamic soaring and thermal soaring, which we use to explore the optimization of gliding in an arbitrary wind. We use this optimization to revisit the classical theory of the glide polar, which we expand upon in two significant ways. First, we compare the predictions of the glide polar for different species under the various published models. Second, we derive a glide optimization chart that maps every combination of headwind and updraft speed to the unique combination of airspeed and inertial sink rate at which the aerodynamic cost of transport is expected to be minimized. With these theoretical tools in hand, we test their predictions using empirical data collected from a captive steppe eagle ( Aquila nipalensis ) carrying an inertial measurement unit, global positioning system, barometer and pitot tube. We show that the bird adjusts airspeed in relation to headwind speed as expected if it were seeking to minimize its aerodynamic cost of transport, but find only weak evidence to suggest that it adjusts airspeed similarly in response to updrafts during straight and interthermal glides. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’.

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Mechanical power and work of cat soleus, gastrocnemius and plantaris muscles during locomotion: possible functional significance of muscle design and force patterns.

Journal of Experimental Biology ◽

10.1242/jeb.199.4.801 ◽

1996 ◽

Vol 199 (4) ◽

pp. 801-814 ◽

Cited By ~ 10

Author(s):

B I Prilutsky ◽

W Herzog ◽

T L Allinger

Keyword(s):

Electrical Activity ◽

Mechanical Energy ◽

Fibre Length ◽

Rate Of Change ◽

The Body ◽

Mechanical Power ◽

Step Cycle ◽

Extensor Muscles ◽

Work Done ◽

Positive Work

Electrical activity, forces, power and work of the soleus (SO), the gastrocnemius (GA) and the plantaris (PL) muscles were measured during locomotion in the cat in order to study the functional role of these ankle extensor muscles. Forces and electrical activity (EMG) of the three muscles were measured using home-made force transducers and bipolar, indwelling wire electrodes, respectively, for walking and trotting at speeds of 0.4 to 1.8 m s-1 on a motor-driven treadmill. Video records and a geometrical model of the cat hindlimb were used for calculating the rates of change in lengths of the SO, GA and PL muscles. The instantaneous maximum possible force that can be produced by a muscle at a given fibre length and the rate of change in fibre length (termed contractile abilities) were estimated for each muscle throughout the step cycle. Fibre lengths of the SO, GA and PL were calculated using a planar, geometrical muscle model, measured muscle forces and kinematics, and morphological measurements from the animal after it had been killed. Mechanical power and work of SO, GA and PL were calculated for 144 step cycles. The contribution of the positive work done by the ankle extensor muscles of one hindlimb to the increase of the total mechanical energy of the body (estimated from values in the literature) increased from 4-11% at speeds of locomotion of 0.4 and 0.8 m s-1 to 7-16% at speeds of 1.2 m s-1 and above. The relative contributions of the negative and positive work to the total negative and positive work done by the three ankle extensor muscles increased for GA, decreased for SO and remained about the same for PL, with increasing speeds of locomotion. At speeds of 0.4-0.8 m s-1, the positive work normalized to muscle mass was 7.5-11.0 J kg-1, 1.9-3.0 J kg-1 and 5.3-8.4 J kg-1 for SO, GA and PL, respectively. At speeds of 1.2-1.8 m s-1, the corresponding values were 9.8-16.7 J kg-1, 6.0-10.7 J kg-1 and 13.4-25.0 J kg-1. Peak forces of GA and PL increased and peak forces of SO did not change substantially with increasing speeds of locomotion. The time of decrease of force and the time of decrease of power after peak values had been achieved were much shorter for SO than the corresponding times for GA and PL at fast speeds of locomotion. The faster decrease in the force and power of SO compared with GA and PL was caused by the fast decrease of the contractile abilities and the activation of SO. The results of this study suggest that the ankle extensor muscles play a significant role in the generation of mechanical energy for locomotion.

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THE EFFECTS OF INCREASING INSOLE STIFFNESS ON FOOT AND ANKLE MECHANICS IN WALKING GAIT

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s101623722150023x ◽

2021 ◽

pp. 2150023

Author(s):

Li Jin

Keyword(s):

Ankle Joint ◽

Stance Phase ◽

Mechanical Energy ◽

Energy Generation ◽

Bending Stiffness ◽

Mechanical Work ◽

Compensatory Mechanism ◽

Walking Gait ◽

Normal Speed ◽

Positive Work

The energetic pattern of the foot–ankle system is critical in human walking gait. While some of the mechanical energy was dissipated due to foot segment deformation in walking stance phase. Increasing footwear insole bending stiffness was reported to restrict foot segment bending behavior and this was reported to reduce foot segment energy dissipation. While little is known whether increasing footwear insole bending stiffness would alter foot–ankle system mechanical work generation and absorption patterns. Two healthy subjects (one female, one male; age [Formula: see text] years, height [Formula: see text][Formula: see text]cm, weight [Formula: see text][Formula: see text]kg) participated in this study and they were asked to walk at self-selected normal speed with the same footwear (Nike Free RN Flyknit, 2017) in two different insole stiffness conditions: (i) normal shoe insole (NSI); (ii) carbon fiber insole (CFI). Paired sample [Formula: see text]-test was conducted between NSI and CFI for all outcome measures. No statistically significant differences in the outcome variables were found between the two insole conditions. While foot segment positive work and mechanical work ratio were 45.54% and 68.43% higher in CFI than in NSI condition, respectively; foot negative work was 25.02% lower in CFI than in NSI condition. However, ankle joint positive work and work ratio were around more than 10% higher in NSI than in CFI condition, and ankle peak positive power in NSI was 23.93% higher than in CFI condition. Additionally, foot–ankle system overall positive work and mechanical work ratio were both similar between NSI and CFI conditions. The findings indicate increasing footwear insole bending stiffness may influence foot segment and ankle joint energetic patterns in walking stance phase. And the mechanical energy generation compensatory mechanism may exist between foot segment and ankle joint. Specifically, a decreased foot segment energy generation tended to result in a higher amount of ankle joint positive work and peak power generation. This will be beneficial for maintaining a relatively consistent foot–ankle system overall energy generation and work ratio in response to altered insole stiffness and foot segment work during gait.

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Comparison of mechanical energy profiles of passive and active below-knee prostheses: A case study

Prosthetics and Orthotics International ◽

10.1177/0309364613513298 ◽

2014 ◽

Vol 39 (2) ◽

pp. 150-156 ◽

Cited By ~ 9

Author(s):

Kota Z Takahashi ◽

John R Horne ◽

Steven J Stanhope

Keyword(s):

Power Analysis ◽

Peak Power ◽

Mechanical Energy ◽

Lower Limbs ◽

Biomechanical Analysis ◽

Knee Prostheses ◽

Prosthetic Limb ◽

Energy Profiles ◽

Positive Work

Background: With the recent technological advancements of prosthetic lower limbs, there is currently a great desire to objectively evaluate existing prostheses. Using a novel biomechanical analysis, the purpose of this case study was to compare the mechanical energy profiles of anatomical and two disparate prostheses: a passive prosthesis and an active prosthesis. Case description and methods: An individual with a transtibial amputation who customarily wears a passive prosthesis (Elation, Össur) and an active prosthesis (BiOM, iWalk, Inc.) and 11 healthy subjects participated in an instrumented gait analysis. The total mechanical power and work of below-knee structures during stance were quantified using a unified deformable segment power analysis. Findings and outcomes: Active prosthesis generated greater peak power and total positive work than passive prosthesis and healthy anatomical limbs. Conclusion: The case study will enhance future efforts to objectively evaluate prosthetic functions during gait in individuals with transtibial amputations. Clinical relevance A prosthetic limb should closely replicate the mechanical energy profiles of anatomical limbs. The unified deformable (UD) analysis may be valuable to facilitate future clinical prescription and guide fine adjustments of prosthetic componentry to optimize gait outcomes.

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Informational Reinterpretation of the Mechanics Notions and Laws

Entropy ◽

10.3390/e22060631 ◽

2020 ◽

Vol 22 (6) ◽

pp. 631 ◽

Cited By ~ 2

Author(s):

Edward Bormashenko

Keyword(s):

Single Particle ◽

Equivalence Principle ◽

Inertial Force ◽

Constant Speed ◽

Informational Content ◽

Rectilinear Motion ◽

Inertial Forces ◽

Noninertial Frame ◽

Rest State ◽

Isobaric Expansion

The informational re-interpretation of the basic laws of the mechanics exploiting the Landauer principle is suggested. When a physical body is in rest or it moves rectilinearly with the constant speed, zero information is transferred; thus, the informational affinity of the rest state and the rectilinear motion with a constant speed is established. Inertial forces may be involved in the erasure/recording of information. The analysis of the minimal Szilard thermal engine as seen from the noninertial frame of references is carried out. The Szilard single-particle minimal thermal engine undergoes isobaric expansion relative to accelerated frame of references, enabling the erasure of 1 bit of information. The energy ΔQ spent by the inertial force for the erasure of 1 bit of information is estimated as Δ Q ≅ 5 3 k B T ¯ , which is larger than the Landauer bound but qualitatively is close to it. The informational interpretation of the equivalence principle is proposed: the informational content of the inertial and gravitational masses is the same.

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