Yaw Response Research Articles

Shaping the Ship Yaw Response by the State-Space Feedback Gain

Ship autopilots are usually designed based on PID controller because of the simplicity and the ease of construct. However its performance in various environmental conditions is not as good as desired. This disadvantage can be decreased by designing a linear state space feedback controller. This paper presents the utility of the state-space feedback controller to stabilize the system and shaping its response as desired. The simulation results for a 4DOF ship with real parameters show the effectiveness of the feedback controller in comparison with ordinary PID ship autopilots.

Bicycle steering and roll responses

This article investigates the effects of different steering geometries on the steering response, system stability and frequency response of bicycles. A computer model was developed using Simulink™. The model simulates different bicycle designs allowing several different steering geometries to be quantified in terms of performance. It was validated by data available in literature and from an experimental investigation conducted with a bicycle fitted with steering and roll sensors. Three key variables were examined in detail: the head tube angle, front fork rake and bicycle speed. Their actual importance was determined by systematically changing each key variable one at a time while keeping all other terms constant. Large variations in roll and yaw responses show how sensitive bicycles are to small changes in head tube angles and rake dimensions. At higher speeds, the observed steering responses support the common observation that bicycles are more stable and easier to ride at higher speeds. These simulations show the importance of correctly designing a bicycle’s steering geometry in order to optimise steering performance and the sensitivity of bicycles to small changes in geometry.

A Fuzzy-Active Force Control Architecture Based in Characterizing Nonlinear Systems’ Behavior

This paper presents Active Force Control (AFC) based architecture in characterizing the twin rotor multi-input multi-output (MIMO) system (TRMS). The proposed architecture is expected to produce an optimum control gains in both pitch and yaw responses by introducing decoupling function between pitch and yaw responses. The internal change corresponds to coupling effects, gust and wind turbulence are very difficult to compensate by the classical PID control, but both of them are stamped out as AFC scheme is implemented into the control strategy. The performance of TRMS is further optimized by the realization of hybrid strategy in which an artificial intelligence Fuzzy Logic is integrated into the control architecture.

An olfactory circuit increases the fidelity of visual behavior.

Multimodal integration allows neural circuits to be activated in a behaviorally context-specific manner. In the case of odor plume tracking by Drosophila, an attractive odorant increases the influence of yaw-optic flow on steering behavior in flight, which enhances visual stability reflexes, resulting in straighter flight trajectories within an odor plume. However, it is not well understood whether context-specific changes in optomotor behavior are the result of an increased sensitivity to motion inputs (e.g., through increased visual attention) or direct scaling of motor outputs (i.e., increased steering gain). We address this question by examining the optomotor behavior of Drosophila melanogaster in a tethered flight assay and demonstrate that whereas olfactory cues decrease the gain of the optomotor response to sideslip optic flow, they concomitantly increase the gain of the yaw optomotor response by enhancing the animal's ability to follow transient visual perturbations. Furthermore, ablating the mushroom bodies (MBs) of the fly brain via larval hydroxyurea (HU) treatment results in a loss of olfaction-dependent increase in yaw optomotor fidelity. By expressing either tetanus toxin light chain or diphtheria toxin in gal4-defined neural circuits, we were able to replicate the loss of function observed in the HU treatment within the lines expressing broadly in the mushroom bodies, but not within specific mushroom body lobes. Finally, we were able to genetically separate the yaw responses and sideslip responses in our behavioral assay. Together, our results implicate the MBs in a fast-acting, memory-independent olfactory modification of a visual reflex that is critical for flight control.

Prediction of icing effects on the lateral/directional stability and control of light airplanes

The accumulation of ice on an airplane in flight is one of the leading contributing factors to general aviation accidents, and to date only relatively sophisticated methods based on detailed empirical data and flight data exist for its analysis. This paper develops a methodology and simulation tool for a preliminary yet accurate evaluation of airplane dynamical response and stability and control characteristics due to icing. It uses only basic mass properties, configuration, and propulsion data, together with known icing data obtained for similar configurations. Existing icing data for a light airplane is suitably modified and applied to a non-real-time, six degree-of-freedom simulation model of a different but similar light airplane, developed from empirical data and Data Compendium methods. The component build-up method is used to implement icing effects on the wing alone, horizontal tail alone, and various unequal distributions of combined wing and horizontal tail icing as well as ice accretion on only one half of the wing. Results presented in the paper are limited to the roll axis and yaw axis maneuvers with various levels and distributions of ice accretion show that the methodology captures the basic detrimental effects of ice accretion on roll and yaw response and lateral stability, in addition to the sensitivity of pilot control response.

Vertical torque responses to vestibular stimulation in standing humans

The effects of electrical vestibular stimulation upon movement and perception suggest two evoked sensations: head roll and inter-aural linear acceleration. The head roll vector causes walking subjects to turn in a direction dependent on head pitch, requiring generation of torque around a vertical axis. Here the effect of vestibular stimulation upon vertical torque (T(z)) was investigated during quiet stance. With the head tilted forward, square-wave stimuli applied to the mastoid processes evoked a polarity-specific T(z) response accompanied by trunk yaw. Stochastic vestibular stimulation (SVS) was used to investigate the effect of head pitch with greater precision; the SVS–T(z) cross-correlation displayed a modulation pattern consistent with the head roll vector and this was also reflected by changes in coherence at 2–3 Hz. However, a separate response at 7–8 Hz was unaffected by head pitch. Head translation (rather than rotation) had no effect upon this high frequency response either, suggesting it is not caused by a sense of body rotation induced by an inter-aural acceleration vector offset from the body. Instead, high coherence between medio-lateral shear force and T(z) at the same frequency range suggests it is caused by mechanical coupling to evoked medio-lateral sway. Consistent with this explanation, the 7–8 Hz response was attenuated by 90 deg head roll or yaw, both of which uncouple the inter-aural axis from the medio-lateral sway axis. These results demonstrate two vertical torque responses to electrical vestibular stimulation in standing subjects. The high frequency response can be attributed to mechanical coupling to evoked medio-lateral sway. The low frequency response is consistent with a reaction to a sensation of head roll, and provides a novel method for investigating proprioceptive-vestibular interactions during stance.

Use of a Vertical Wind Turbine in an Offshore Floating Wind Farm

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 21705, ’Use of a Vertical Wind Turbine in an Offshore Floating Wind Farm,’ by Marc Cahay and Eric Luquiau, Technip, and Charles Smadja and Frederic Silvert, Nenuphar, originally prepared for the 2011 Offshore Technology Conference, Houston, 2-5 May. The paper has not been peer reviewed. With 2.0 GW already installed and more than 50.0 GW planned in Europe by 2020, as reported by the European Wind-Energy Association, the installation of bottom-mounted offshore wind turbines in very shallow water (less than 40 m) is now well established. The foundation and the offshore installation costs represent approximately 50% of the total development cost of an offshore wind farm, and this proportion increases with the water depth. Hence, floating wind turbines are the solution for deep offshore. Vertiwind Project Coming from a strong and complementary partnership of utilities, industrials, and academics, the Vertiwind project plans to build, install, and operate, in real offshore conditions, a full-scale floating vertical-axis wind turbine (VAWT) of 2 MW. This is a real step change in the technology compared with most offshore wind turbines with horizontal axes. The floater concept retained is of a semisubmersible design and is called “multifloater.” It skillfully combines an out-of-the-wave excitation response, a shallow draft to facilitate fabrication, and a very simple installation procedure requiring only one or two tugs. The VAWT is located in the center of the floater, ensuring that the center of gravity, the buoyancy, and the convergence point of the mooring lines are all on the same axis. This geometrical property highly reduces the sway and yaw response of the floater subject to noncolinearity or heading variation of wave and wind. Because of the architecture and underlying principles of this Darrieus turbine, the power production is not affected by the inclination of the turbine axis relative to the wind direction as a result of the floater motions. The turbine design is carried out in parallel with the floater. It integrates, at an early stage, all requirements of the offshore environment in terms of loads, accessibility, and ease of maintenance. The complete unit will be anchored to the seabed and linked to the network by a compliant subsea cable.

Stochastic rocket dynamics under random nozzle side loads: Ornstein-Uhlenbeck boundary layer separation and its coarse grained connection to side loading and rocket response

A long-standing, though ill-understood problem in rocket dynamics, rocket response to random, altitude-dependent nozzle side-loads, is investigated. Side loads arise during low altitude flight due to random, asymmetric, shock-induced separation of in-nozzle boundary layers. In this paper, stochastic evolution of the in-nozzle boundary layer separation line, an essential feature underlying side load generation, is connected to random, altitude-dependent rotational and translational rocket response via a set of simple analytical models. Separation line motion, extant on a fast boundary layer time scale, is modeled as an Ornstein-Uhlenbeck process. Pitch and yaw responses, taking place on a long, rocket dynamics time scale, are shown to likewise evolve as OU processes. Stochastic, altitude-dependent rocket translational motion follows from linear, asymptotic versions of the full nonlinear equations of motion; the model is valid in the practical limit where random pitch, yaw, and roll rates all remain small. Computed altitudedependent rotational and translational velocity and displacement statistics are compared against those obtained using recently reported high fidelity simulations [Srivastava, Tkacik, and Keanini, J. Applied Phys., 108, 044911 (2010)]; in every case, reasonable agreement is observed. As an important prelude, evidence indicating the physical consistency of the model introduced in the above article is first presented: it is shown that the study's separation line model allows direct derivation of experimentally observed side load amplitude and direction densities. Finally, it is found that the analytical models proposed in this paper allow straightforward identification of practical approaches for: i) reducing pitch/yaw response to side loads, and ii) enhancing pitch/yaw damping once side loads cease.

横傾斜を含む線形応答モデルによる船舶操縦性の検討

Many researches have been done about the effect of a steering motion on roll motion, as the turning motion sometimes introduces a capsizing of ship and makes serious disasters. On the contrary, the researches of the effect of a roll motion on the manoeuvrability are very few, and the mechanism is not clear. In 1970s after the construction of a high-speed container ship, it began to be pointed out that the navigation difficulty arises with such ships, and then the research on the latter was started. Eda1), Hirano2) and Sohn3)respectively proposed the mathematical models of manoeuvring motion including the roll motion, and pointed out that the course-keeping ability becomes worse and the turning radius becomes smaller when ship speed increases. This tendency becomes remarkable with lower GM. In these researches, although the turning motions were well simulated using each mathematical model,the mechanism or structure of the roll effect on the manoeuvrability has not been clarified yet.In this paper, the author introduces the rudder to yaw response equation from the simple linear mathematical model, and has clarified the following principal structure regarding to the effect of the roll motion on ship manoeuvrability. 1) The turning moment Yφφ and Nφφ induced by the roll angle become the key parameter that strongly affects the course-keeping and turning abilities of ship. This tendency becomes remarkable when roll angle becomes larger by the lower GM and higher Froude number.2) For a high-speed merchant ship whose (N'φ -Y'φl'β) becomes larger in negative due to the large bulbous bow for example, the larger negative (N'φ -Y'φl'β) makes the less stability on course and the stronger turning ability, which may make the smaller turning radius and the larger overshoot angle in Z-manoeuvre.3) On the other hand, when (N'φ -Y'φl'β) is a positive value, it becomes a phenomenon completely contrary to the above.

曳船・被曳船系の針路安定性と運動応答

曳船・被曳船系の針路安定性と運動応答

Prediction of Icing Effects on the Coupled Dynamic Response of Light Airplanes

Most methods for the preliminary safety and performance evaluation of airplane dynamical response, stability characteristics, and climb performance in icing conditions require relatively sophisticated methods, based on detailed empirical data and existing flight data. This paper extends a pitch axis 3-degree-of-freedom methodology to the fully coupled, 6-degree-of-freedom case. It evaluates various levels of icing severity and addresses distributed icing with unequal ice distribution between wing halves on the coupled pitch, roll, and yaw responses. The important aspect of dynamic response sensitivity to pilot control input with the autopilot disabled is also highlighted. Using only basic mass properties, configuration, propulsion data, and known icing data from a similar configuration, icing effects are applied to the 6-degree-of-freedom dynamics of a nonreal-time simulation model of a different, but similar, light airplane. Results presented in the paper for a series of simulated climb maneuvers and cruise disturbances with equal or unequal ice levels between wing halves show that the methodology captures the basic effects of ice accretion on the coupled pitch, roll, and yaw responses and the sensitivity of the dynamic response to pilot control inputs.

Design and Characterization of Artificial Haircell Sensor for Flow Sensing With Ultrahigh Velocity and Angular Sensitivity

We report the development of an artificial hair cell (AHC) sensor with design inspired by biological hair cells. The sensor consists of a silicon cantilever beam with a high-aspect-ratio cilium attached at the distal end. Sensing is based on silicon piezoresistive strain gauge at the base of the cantilever. The cilium is made of photodefinable SU-8 epoxy and can be up to 700-mum tall. In this paper, we focus on flow-sensing applications. We have characterized the performance of the AHC sensor both in water and in air. For underwater applications, we have characterized the sensor under two flow conditions: steady-state laminar flow (dc flow) and oscillatory flow (ac flow). The detection limit of the sensor under ac flow in water is experimentally established to be below 1 mm/s. A best case angular resolution of 2.16deg is also achieved for the sensor's yaw response in air.

Why Birds and Miniscale Airplanes Need No Vertical Tail

The vertical tail is a typical component of the aerodynamic configuration of airplanes, existing with any kind of vehicle. In contrast, there is no bird which possesses a vertical tail. This is a striking difference between birds and airplanes with regard to the ability of flight. The functions of the vertical tail are considered in this paper, including issues of flight dynamics as well as control and trim. It is shown that there are unique relationships for the flight mechanics of small flying objects, like birds and miniscale airplanes, and for their aerodynamic configuration so that they need no vertical tail. It turns out that small flying objects can have an adequate level of dynamic yaw response capability (Dutch roll frequency) even if their static aerodynamic stability is very small. Furthermore, it is shown that the wing alone can provide the required aerodynamic yawing moment if it has appropriate features. For identifying these features, results from flow simulation using a sophisticated aerodynamic method are presented. For this purpose, a modern and efficient aerodynamic method was used for modeling the fluid flow around complex geometries and for computing the forces and moments with high precision. Other dynamics issues dealt with concern the damping characteristics in the yaw axis. It is shown that there is a reduction in the required aerodynamic damping capability with a decrease in the size. As a result, the wing alone can generate the required level of yaw damping. Furthermore, the effects on the spiral mode are treated. It is shown that the abandoning of the vertical tail is only of partial influence. The control and trim issues dealt with concern asymmetrical flight for which a yawing moment capability is usually required. It is shown how it is possible to cope with such flight conditions without needing a vertical tail. Aerodynamic configurations needing no vertical tail are an issue which is of relevance for technical applications. From the characteristics of birds, it can be learned how such configurations and the related benefits may be used for airplanes. This is of particular significance for miniscale airplanes the size of which is considered to range from configurations comparable with large birds to micro air vehicles with a length of some centimeters.

Responses of Reticulospinal Neurons in the Lamprey to Lateral Turns

When swimming, the lamprey maintains a definite orientation of its body in the vertical planes, in relation to the gravity vector, as the result of postural vestibular reflexes. Do the vestibular-driven mechanisms also play a role in the control of the direction of swimming in the horizontal (yaw) plane, in which the gravity cannot be used as a reference direction? In the present study, we addressed this question by recording responses to lateral turns in reticulospinal (RS) neurons mediating vestibulospinal reflexes. In intact lampreys, the activity of axons of RS neurons was recorded in the spinal cord by implanted electrodes. Vestibular stimulation was performed by periodical turns of the animal in the yaw plane (60 degrees peak to peak). It was found that the majority of responding RS neurons were activated by the contralateral turn. By removing one labyrinth, we found that yaw responses in RS neurons were driven mainly by input from the contralateral labyrinth. We suggest that these neurons, when activated by the contralateral turn, will elicit the ipsilateral turn and thus will compensate for perturbations of the rectilinear swimming caused by external factors. It is also known that unilateral eye illumination elicits a contralateral turn in the yaw plane (negative phototaxis). We found that a portion of RS neurons were activated by the contralateral eye illumination. By eliciting an ipsilateral turn, these neurons could mediate the negative phototaxis.

Accident assessment of vehicles on long-span bridges in windy environments

Currently, there are very few systematic analyses of vehicle performance on bridges in windy environments. There are thus no scientific data to support bridge management in this regard, such as when to close traffic on bridges. This paper presents a framework of vehicle accident analysis model on long-span bridges in windy environments. In the accompanying paper, a three-dimensional analysis of the coupled bridge–vehicle–wind system is developed. Each vehicle is modeled as a combination of several rigid bodies, axle mass blocks, springs, and dampers. Dynamic interaction analysis is then conducted on the vehicle–bridge system to predict the “global” bridge and vehicle dynamic responses without considering accident occurrences. The results of the global bridge–vehicle vibrations serve as the basis for the present accident analysis of the “local” vehicle vibrations. With the global vibrations as inputs of the accident model, the lateral response, yaw response of the vehicle, and the reaction forces of each individual wheel are obtained and the stability condition of the vehicles are analyzed. The vehicle accidents on long-span bridges are then identified with given accident criteria. The developed framework can be used in not only analyzing the vehicle performance on highways and on bridges, but also in predicting useful information for emergency preparedness agencies in developing evacuation plans.

A velocity dependent effective angle method for calibration of X-probes at low velocities

A velocity dependent effective angle (VDEA) method for the calibration of yaw response of hot-wire X-probes at low flow velocities (0.5–6 m/s) is presented. Comparisons with a full velocity vs. yaw-angle method (Osterlund 1999) in a smooth wall channel flow indicate that there is only moderate advantage in using the latter method, which is considerably more laborious. Comparisons with direct numerical simulations (DNS) (Moser et al. 1999) and the more common fixed effective angle method (FEA) show that the VDEA method significantly improves estimates of Reynolds stresses compared to the FEA method.

航空機における横揺れ補償操舵への時間進みビジュアル・キューの効果(人間機械システム・HMI(3),OS3 人間機械システム,ヒューマンインターフェース)

When a human pilot controls aircraft, he relies on visual cues and motion cues. Especially visual cues are great part of information required for control. We thought of modifying the movement of the outside visual field. That is, pilot observes a virtual visual cue which is added a first-order lead compensation to the real roll response of aircraft. In this study we prepared two tasks, roll compensatory control task and holding flight path task. We investigate the effect of virtual visual cue using a fixed-based flight simulator. As a result, in a roll compensatory control task, pilot controls aircraft easier without getting task performance worse. But in a holding flight path task, pilot didn't control aircraft easier. Although only roll response is important cue in roll compensatory control task. In holding flight path task, not only roll response but also yaw response plays a great role. That shows that it is necessary to modify the dutch-roll oscillation component in the yaw response.

Dynamic Behaviour of Tension Leg Platform under Impulsive Loading

In the literature on dynamics of tension leg platforms (TLPs), the effect offrequently occurring environmental forces, such as those arising due to wave, wind, current, tide, etc. has given the due consideration. However, less probable forces, such as that arising due to collision ofship with iceberg or any huge sea creature, etc., have not been considered in the study. Such small duration impact forces, usually termed as impulsive forces, may take four possible shapes: (i) rectangular, (ii) sinusoidal, (iii) triangular, and (iv) half-triangular. In the present study, response ofTLP has been obtained for all these four shaped impulsive forces. The result ofthe analyses shows that there is a dramatic change in surge, heave, and yaw responses of TLP due to such forces. In addition, a comparative study to find the most influencing impulsive force out of these four has also been conducted.

Modelling the Yaw Behaviour of a Small Wind Turbine

This paper develops a mathematical model for a small wind turbine responding to changes in the wind direction. Here “small” implies that the turbine has a tail fin. Good yaw behaviour, in terms of tracking the changes in wind direction, is necessary to maximize power extraction. However large rates of change of yaw can lead to large stresses in the turbine components. The unsteady tail fin loads are more complex than implied by the “pseudo-static” assumption that the steady-state lift and drag act instantaneously. The aerodynamic model is applied first to data obtained from a 5 kW experimental turbine when it was not extracting power, because this almost removes the effect of the blades from the yaw behaviour. MATLAB's systems identification toolbox was used to optimise the fit of the model parameters to the data. The resulting values of a number of the parameters are shown to be in good agreement with earlier wind tunnel tests of the tail fin design. Some details of the comparisons, mainly in terms of the higher frequency components, suggest the need to characterise similarly the dynamics of wind vanes. When the turbine was extracting power, the flexible blades were deflected backwards by the aerodynamic loads. A blade element analysis suggests that the stabilizing moment due to this “coning” does not alter the form of the yaw response equation. The optimised fit of the model equations gave changes in the parameters broadly in agreement with the blade element analysis, but the quasi-steady analysis did not predict the measured increase in the damping associated with power extraction.

Eigenstructure versus optimal control for decoupling

Abstract A study about how to design a control law that not only keeps following a reference attitude but also maintains attitude decoupling due to the vehicle manoeuvres has been performed. A control law was designed for a satellite launcher vehicle using eigenstructure assignment and optimal control method in order that the vehicle tracks a reference attitude and also to decouple the yaw response from roll and pitch manoeuvres and to decouple the pitch response from roll and yaw manoeuvres. It has been noticed that in order to achieve this objective it is necessary to use a linear coupled model to design the control law instead of the usual linear uncoupled model used to design the tracking control law. The design was based on a complete linear coupled model obtained from the complete vehicle non-linear model by linearisation at each trajectory point. A comparison of the system stability working with both control laws has also been performed. After all, the design was assessed with the vehicle time varying non-linear model showing a good performance and robustness. The used design method is explained and a case study for the Brazilian satellite launcher VLS is reported. By the end of the work some suggestions about how to implement this control law have also been studied.