Roll Angular Velocity Research Articles

Improving the accuracy of a platformless inertial navigation system for an aircraft during rapid roll rotation

The article addresses the problem of enhancing the accuracy of an autonomous strapdown inertial navigation system (SINS) for aircraft with rapid rotation about their longitudinal axis. This rapid rotation stabilizes the aircraft's position along the longitudinal axis while imposing strict requirements on the roll gyroscope's scale factor (SF) error in the SINS. This is essential to ensure that the roll angle error remains on par with the pitch and yaw angle errors. A novel method for periodic correction of the roll gyroscope's SF within an autonomous SINS is proposed. The method utilizes signals from a single-axis indicator gyrostabilizer based on a microelectromechanical system (MEMS) gyroscope. The correction involves determining the numerical value of the roll gyroscope's SF error during flight and subsequently compensating for its influence on the roll angular velocity measurements. The functional scheme of the method is presented, along with formulas for calculating the correction coefficient. The efficiency of the proposed approach in improving the accuracy of the SINS is evaluated using a typical inertial module and an indicator gyrostabilizer with a MEMS gyroscope as an example. The method significantly enhances the accuracy of roll angular velocity and coordinate measurements in an autonomous SINS without requiring expensive precision gyroscopes.

Ballistic Fitting Impact Point Prediction Based on Improved Crayfish Optimization Algorithm

To solve the problem of difficulty in predicting the impact point clearly and promptly during projectile flight, this paper proposes an improved ballistic-impact-point prediction method. A certain type of high-spinning tailed projectile is taken as the research object for online real-time landing point prediction research. This study comprehensively utilizes the real-time radar measurement data and the geomagnetic data measured by the bomb-carried geomagnetic sensor. It applies the four-degree-of-freedom ballistic model to predict the landing point. First, the roll angular velocity is calculated based on the geomagnetic data, after which the radar real-time measurement data are segmentally fitted using the improved crayfish algorithm. Then, the fitted parameters are substituted into the four-degree-of-freedom ballistic model. Finally, the C-K method is used to identify the aerodynamic parameters, and the identified aerodynamic parameters are used for fallout prediction. The simulation results show a small deviation between the predicted and actual impact points using the improved ballistic-impact-point prediction method.

An aviation accident report data-driven approach to scenario design for a centrifuge-based dynamic flight simulator

The use of flight simulators in investigating an aviation incident or accident related to human errors has been identified as an important part of a strategy to improve safety. This study aimed to replicate a real flight of the MiG-29 aircraft using a centrifuge-based dynamic flight simulator and to determine the simulator’s accuracy in recreating in-flight aircraft performance. A 60-second recording of the real flight of the MiG-29 aircraft, captured by the flight data recorder, was chosen for replication in the HTC-07 human training centrifuge simulator. To evaluate how accurately the simulator replicates the performance of the aircraft, the linear accelerations and angular velocities acting on a pilot during the real flight were compared with those during the replication of that flight in the simulator. The fit of these parameters was assessed using the root mean square percentage error (RMSPE) and the correlation coefficient (r). The highest replication accuracy was achieved for the vertical component of the linear acceleration (RMSPE=2068; r=0.98), while the worst result was obtained for the longitudinal component (RMSPE=14205; r=0.31). Inaccuracies were much more pronounced for the angular velocity. The roll angular velocity had the lowest replication error (RMSPE=12640). However, its correlation with the recorded velocity during the real flight was very weak (r=-0.02). Despite some inaccuracies in replicating other components of the acceleration and angular velocity vectors, the HTC-07 simulator seems valuable for investigating aviation incidents or accidents related to human factors.

Development and implementation of a new approach for posture control of a hexapod robot to walk in irregular terrains

AbstractThe adaptability of hexapods for various locomotion tasks, especially in rescue and exploration missions, drives their application. Unlike controlled environments, these robots need to navigate ever-changing terrains, where ground irregularities impact foothold positions and origin shifts in contact forces. This dynamic interaction leads to varying hexapod postures, affecting overall system stability. This study introduces a posture control approach that adjusts the hexapod’s main body orientation and height based on terrain topology. The strategy estimates ground slope using limb positions, thereby calculating novel limb trajectories to modify the hexapod’s angular position. Adjusting the hexapod’s height, based on the calculated slope, further enhances main body stability. The proposed methodology is implemented and evaluated on the ATHENA hexapod (All-Terrain Hexapod for Environment Adaptability). Control feasibility is assessed through dynamic analysis of the hexapod’s multibody model on irregular surfaces, using computational simulations in Gazebo software. Environmental complexity’s impact on hexapod stability is tested on both a ramp and uneven terrain. Independent analyses for each scenario evaluate the controller’s effect on roll and pitch angular velocities, as well as height variations. Results demonstrate the strategy’s suitability for both environments, significantly enhancing posture stability.

Research on Stability Control Algorithm of Distributed Drive Bus under High-Speed Conditions

Aiming at the instability problem of a four-wheel independent drive electric bus under high-speed conditions, this paper first designs a vehicle yaw stability controller based on a linear two-degree-of-freedom model and a linear quadratic programming (LQR) algorithm. A vehicle roll stability controller is then designed based on a linear three-degree-of-freedom model and a model predictive control algorithm (MPC). Moreover, a coordinated control rule based on the lateral load transfer rate (LTR) is designed for the coupled problem of yaw and roll dynamics. Finally, the effectiveness of the proposed control algorithm is verified by simulation. The obtained results show that when the vehicle is running at a high speed of 90 km/h, the stability control algorithm can control the yaw rate tracking error within 0.05 rad/s. In addition, the control algorithm can reduce the maximum amplitude of the side slip angle, the maximum value of the roll angle, the maximum value of the roll angular velocity, and the amplitude of the lateral acceleration by more than 96%, 81.1%, 65.0%, and 11.1%, respectively.

Flight test of flying wing aircraft controlled by dual synthetic jets at Ma0.2

To explore the application potential of zero-mass-flux dual synthetic jets in flight control of flying wing aircraft (FWA), dual synthetic jet actuators (DSJAs) are integrated into a FWA and flight tests without deflections of rudders are firstly carried out to verify the viability of DSJAs to manipulate three-axis attitudes at a cruising speed of 70 m/s. Two active flow control methods of circulation control and reverse jet control performed by DSJAs are utilized to execute the three-axis control. Novel flight control effectors based on DSJAs are designed and achieve the integration with the FWA. Flight tests show that three-axis flight control is realized by DSJAs distributed in different locations. The maximum roll, pitch and yaw angular velocities are 10.12°/s, 6.17°/s and 8.38°/s respectively. The work initially verifies rudderless flight control ability of DSJAs at a cruising speed of 70 m/s and the control ability will be improved by the further optimization of DSJAs.

Articulated vehicle rollover detection and active control based on center of gravity position metric

In this study, the adaptive adjustment technology, based on an Attitude and Heading Reference System, is applied to loaders, aiming to improve the rollover protection performance of articulated engineering vehicles. A dynamic rollover stability index for loaders is developed, coupling the roll angular velocity and the slope and height of the center of gravity. A nonlinear predictive model of the material weight is built, in order to attain the height of the center of gravity. An adaptive attitude adjustment system is proposed, totally based on electro-hydraulic proportional control technology, to adjust the attitude of the working system, so as to achieve a higher threshold value of the vehicle’s anti-tip performance. Finally, the rollover stability index and control methods, as proposed in this article, are validated using experiments. The boundary values that trigger the system’s operation are reduced to ensure safety, while the validation results prove that the proposed method is effective.

Novel model predictive control-based motion cueing algorithm for compensating centrifugal acceleration in KUKA robocoaster-based driving simulators.

The washout motion cueing algorithm (MCA) is a critical element in driving simulators, designed to faithfully reproduce precise motion cues while minimizing false cues during simulation processes, particularly deceptive translational and rotational cues. To enhance motion sensation accuracy and optimize the use of available workspace, model predictive control (MPC) has been employed to develop innovative motion cueing algorithms. While most MCAs have been tailored for the Steward motion platform, there has been a recent adoption of the motion platform based on KUKA Robocoaster as an economical option for driving simulators. However, leveraging the full potential of the KUKA Robocoaster requires trajectory conversion of the motion base. Thus, this research proposes a novel MCA specifically designed for the KUKA Robocoaster-based motion platform, utilizing large planar circular motion to simulate lateral movement for drivers. Nonetheless, circular motion introduces disruptive centrifugal forces, which can be mitigated through proper pitch-tilted angles. The novel MPC generates simulated motion that accurately follows the lateral specific force target and effectively maintains the roll angular velocity below its threshold value. Additionally, it compensates for disturbing centrifugal acceleration by implementing pitch rotational motion, ensuring the pitch angular velocity remains below its threshold. Simulation tasks conducted on the motion platform, focusing solely on lateral acceleration, demonstrate the successful elimination of false motion cues in both the roll/sway and pitch/surge channels. The proposed innovative MPC solution offers an original approach to motion cueing algorithms in KUKA Robocoaster-based driving simulators. It enables the exploitation of the KUKA Robocoaster platform's capabilities while delivering accurate and immersive motion cues to drivers during simulation experiences.

Self-rolling and circling of a conical liquid crystal elastomer rod on a hot surface

Self-oscillation refers to the steady-state periodic motion maintained by the mutual coupling of parts within system itself, which can compensate for damping dissipation through periodically absorbing energy from non-periodic external stimuli. Recent experiments have demonstrated that the uneven thermal contraction in the cylindrical rod can drive its forward self-rolling on a hot surface. In current paper, by introducing a cone angle to the rod, we fabricate a conical liquid crystal elastomer (LCE) rod to investigate its rolling on a hot surface. Our experiments show that the thermally-responsive conical LCE rod can self-roll and circle on a flat hot surface at a uniform temperature. We propose a thermomechanical model to elucidate the mechanism of self-rolling and circling and calculate the rolling and circling angular velocities of the conical LCE rod. The theoretical results demonstrate that the rolling angular velocity depends on the Biot number, cone angle, rod length and heat inflow. The theoretical predictions are proved to be consistent with the experimental results. The self-rolling and circling of the conical LCE rod can retrace its original position through a curved trajectory, offering the benefit of circumventing extensive heated surfaces and maneuvering around obstacles or traps. Such self-rolling and circling system based on conical LCE rod may constitute novel designs for self-cleaning sweepers, energy harvesters, active machinery, mass transport devices and so on.

Flight control of a flying wing aircraft based on circulation control using synthetic jet actuators

To achieve the nice stealth performance and aerodynamic maneuverability of a Flying Wing Aircraft (FWA), a longitudinal aerodynamic control technology based on circulation control using trailing-edge synthetic jet actuators was proposed without the movement of rudders. Effects on the longitudinal aerodynamic characteristics of a small-sweep FWA were investigated. Then, flight tests were carried out to verify the control abilities, providing a novel technology for the design of a future rudderless FWA. Results show that synthetic jets could narrow the dead zone area, improve the flow velocity near the trailing edge, and then move the trailing-edge separation point and the leading-edge stagnation point downwards, which make the effective Attack of Angle (AOA) increase, thereby enhancing the pressure envelope area. Circulation control based on synthetic jets could improve the lift, drag and nose-down moment. The variations of lift and nose-down moment decrease with the growth of AOA caused by the improved reverse pressure gradient and the weakened circulation control efficiency. Finally, synthetic jet actuators were integrated into the trailing edge of a small-sweep FWA, which could realize the roll and pitch control without deflections of rudders during the cruise stage, and the maximum roll and pitch angular velocity are 12.64 (°)/s and 8.51 (°)/s, respectively.

Controlled roll rotation of a microparticle in a hydro-thermophoretic trap.

In recent years, there has been a growing interest in controlling the motion of microparticles inside and outside a focused laser beam. A hydro-thermophoretic trap was recently reported [Nalupurackal et al., Soft Matter 18, 6825 (2022)], which can trap and manipulate microparticles and living cells outside a laser beam. Briefly, a hydro-thermophoretic trap works by the competition between thermoplasmonic flows due to laser heating of a substrate and thermophoresis away from the hotspot of the laser. Here, we extend that work to demonstrate the controlled roll rotation of a microparticle in a hydro-thermophoretic trap using experiments and theory. We experimentally measure the roll angular velocity of the trapped particle. We predict this roll rotation from theoretical computation of the fluid flow. The expression for the angular velocity fits the experimental data. Our method has potential applications in microrheology by employing a different mode of rotation.

Prototype sensor system for analyzing frailty in older people: a pilot study

Introduction: Frailty syndrome is characterized by reduced physical and cognitive reserves, making older people vulnerable to adverse events. This study describes a prototype sensor system developed for assessing frailty through physiological parameters and frailty markers. Methods: A prototype combining four sensors in network and a software package was developed and tested in four long-term care facility senior residents of both sexes, aged 60 and older, showing no locomotive syndrome or severe cognitive impairment. Three of them were frail and able to walk without aid (P1), holding onto the wall (P2) or with a cane (P3), and a non-frail participant (P4) walked without aid. Results: Regarding mean acceleration, P1 and P4 showed the lowest and highest values, respectively, on the antero-posterior axis; P4 had the lowest value on the medio-lateral axis; and P3 presented the highest value on the vertical axis. All participants showed similar roll angular velocity; P4 presented the lowest pitch angular velocity; and P1 and P4 had the highest mean yaw angular velocity. A sarcopenic participant (P2) exhibited the lowest force of muscle contraction. Conclusion: The device has potential to detect frailty markers for adverse outcomes in older people, such as postural instability and increased risk of falls.

Adaptive neural control for coordinated rolling motion of vessels with zero speed via composite learning

An intelligent control method under the backstepping and dynamic surface control (DSC) design framework is proposed in this article. The proposed method is aiming at solving the problem of coordinated rolling motion control of the supply and receiving vessels with internal dynamic uncertainty, unknown external nonlinear disturbance, input saturation, and unmeasurable rolling angular velocity. In the control design, a neural-based state observer is constructed to generate the unmeasurable rolling angular velocity, which achieves a separate design from the control law. To compensate the input saturation effect, a second-order auxiliary dynamic system (ADS) is designed, and its states are inset into the transformation of coordinates required by backstepping. To realize the accurate reconstruction of the neural network for the dynamic uncertainty, the adaptive neural and nonlinear disturbance observer (NDO) are used to reconstruct the internal dynamic uncertainty and unknown external disturbance, respectively. And then the serial–parallel estimation model is introduced to establish a predictor of the system state, and a composite adaptive learning law is designed, which includes the velocity error and predictor error. As a result, the idea of classification reconstruction is developed. Finally, an adaptive neural composite learning coordinated rolling motion control solution is developed. Lyapunov stability analysis shows that all signals in the closed-loop control system are bounded. The effectiveness of the control solution is verified by the simulations.

Qualitative Modelling the Dancing Volvox with Two-Body System: Comparing Simple Mechanics with Observation Video

Volvox cells normally construct a spherical colony of hundred of cells and moving together to perform their basic needs. More than moving a single colony, two attached volvox colonies can ‘dance’ and move together. This system can be modeled as a two-body system, where its center of mass (COM) is performing simple translational (TRAN) motion, while the two colonies center is rotating around the COM with roll (ROLL) or spin (SPIN) motions. From the available observation video, about 10 s or 325 frames can be isolatedfor Sobel edge detection to get a clear picture of the dancing motion of two volvox colonies. It has been observed that the dancing volvox has a superposition motion of the other motion (TRAN, ROLL, SPIN), which has been compared qualitatively with the simple mechanics model of the two-body system. From the model, the translational velocityis about 1.25 m/s, and its roll and spin angular velocity are about 0.785 and 3.063 rad/s, respectively. The results of the study concluded that the mode of motion of the two Volvox colonies was a combination of spin and translational motion.

Nonlinear dynamics of flexible diaphragm coupling’s rotor system during maneuvering flight

In this paper, the flexible multi-diaphragm coupling which is used as flexible power transmission shaft of the aeroengine accessory is taken as the research object, and the coupling stiffness matrix and axial nonlinear stiffness of the diaphragms are considered in the coupling rotor system. On this basis, in order to consider the influence of aircraft maneuvering load, in non-inertial system the bending-pendular-axial coupled differential equations of flexible diaphragm coupling were established by Lagrange method. The modal characteristics of the flexible diaphragm coupling were analyzed and compared with the finite element solutions, and the correctness of model is verified. Runge-Kutta method is used to solve and analyze the influence of different maneuvering flight conditions on the vibration characteristics of the flexible diaphragm coupling. The research indicates that the coupling between diaphragm’s axial and radial stiffness leads to the right shift of resonant region, the increase of resonance peak value, and the nonlinear characteristics of amplitude-frequency curve such as jump and multi-value. In the non-inertial system, only the installation distance a of the flexible diaphragm coupling along the wingspan leads to the increase of the axial deformation offset of the flexible diaphragm coupling in the rolling flight state. The increase of climbing or diving angular velocity makes the flexible diaphragm coupling’s vibration changes from single period to multi-period, bifurcation or chaos state; With the increase of diving angular velocity and rolling angular velocity, the axial critical speed gradually increases; Each flight condition not only affects the vibration characteristics, but also causes the axial, radial and angular deformation of the flexible diaphragm coupling to a certain extent. This study provided a theoretical basis and method for the design and analysis of diaphragm coupling.

Multi-dimensional prediction method based on Bi-LSTMC for ship roll

When ships sail in the sea, they will move irregularly due to the influence of strong wind, waves and other complex marine environment. Among them, the ship roll is very important to the safety of ship navigation. In order to ensure navigation safety, it is necessary to predict the ship roll effectively and accurately in advance to provide a basis for ship advance control. Aiming at the problem that traditional methods and machine learning methods are not accurate for ship roll prediction, a single input single output (SISO) and multiple input single output (MISO) ship roll prediction methods based on deep learning are proposed, and the influence of input variables on the ship roll prediction model is studied. Firstly, a single input Bi-LSTMC ship roll prediction method is proposed. The network takes the advantage of LSTM time series prediction and combines convolution kernel to extract cross time features. Then the analysis and test results of six different single input prediction models are given based on real ship data. Secondly, a deep bidirectional feature network with multiple inputs of ship roll angle, roll angular velocity, relative wind speed, relative wind direction, turning angle and rudder angle is proposed for ship roll prediction. The network uses Bi-LSTM to extract forward and reverse information respectively, and introduces two Bi-LSTMC branch structures to explore the deep features between multiple input data to improve the accuracy of ship roll prediction. Finally, four error indexes were used to evaluate the proposed single input and multiple input ship roll prediction algorithms on real ship data. The applicable conditions of the single input and multiple input ship roll prediction algorithms are obtained, and the effectiveness of the proposed algorithms are also verified.

The hydrodynamics of self-rolling locomotion driven by the flexible pectoral fins of 3-D bionic dolphin

The novel autonomous rolling performance is realized by the pair of pectoral fins of a three-dimensional(3-D) bionic dolphin in this paper numerically. 3-D Navier–Stokes equations are employed to simulate the viscous fluid around the bionic dolphin. The effect of self-rolling manoeuvrability is explored using the dynamic mesh technology and user-defined function (UDF). By varying the parameter ratios, the interaction of flexible pectoral fins is divided into two motion modes, amplitude differential and frequency differential mode. As the primary driving source, the differential motion of a pair of pectoral fins can effectively provide the rolling torque, and the trajectory of the entire rolling process is approximately the clockwise spiral. The results demonstrate that the rolling angular velocity and driving torque in the steady state can be improved by increasing parameter ratios, and the rolling efficiency can reach the maximum under the optimal parameter ratio. Meanwhile, different parameter ratios do not affect the rolling radius of the self-rolling dolphin. The evolution process around the pair of pectoral fins is shown by the flow structures in self-rolling swimming, reasonably revealing that self-rolling locomotion is produced by the pressure and wake vortices surrounding the pair of pectoral fins, and the wake structures depend primarily on the variation of parameter ratio. It properly turns out that the application of the pair of pectoral fins can realize the self-rolling performance through parameter differential modes.

Movement smoothness in chronic post-stroke individuals walking in an outdoor environment-A cross-sectional study using IMU sensors.

BackgroundWalking speed is often used in the clinic to assess the level of gait impairment following stroke. Nonetheless, post-stroke individuals may employ the same walking speed but at a distinct movement quality. The main objective of this study was to explore a novel movement quality metric, the estimation of gait smoothness by the spectral arc length (SPARC), in individuals with a chronic stroke displaying mild/moderate or severe motor impairment while walking in an outdoor environment. Also, to quantify the correlation between SPARC, gait speed, motor impairment, and lower limb spasticity focused on understanding the relationship between the movement smoothness metric and common clinical assessments.MethodsThirty-two individuals with a chronic stroke and 32 control subjects participated in this study. The 10 meters walking test (10 MWT) was performed at the self-selected speed in an outdoor environment. The 10 MWT was instrumented with an inertial measurement unit system (IMU), which afforded the extraction of trunk angular velocities (yaw, roll, and pitch) and subsequent SPARC calculation.ResultsMovement smoothness was not influenced by gait speed in the control group, indicating that SPARC may constitute an additional and independent metric in the gait assessment. Individuals with a chronic stroke displayed reduced smoothness in the yaw and roll angular velocities (lower SPARC) compared with the control group. Also, severely impaired participants presented greater variability in smoothness along the 10 MWT. In the stroke group, a smoother gait in the pitch angular velocity was correlated with lower limb spasticity, likely indicating adaptive use of spasticity to maintain the pendular walking mechanics. Conversely, reduced smoothness in the roll angular velocity was related to pronounced spasticity.ConclusionsIndividuals with a chronic stroke displayed reduced smoothness in the yaw and roll angular velocities while walking in an outdoor environment. The quantification of gait smoothness using the SPARC metric may represent an additional outcome in clinical assessments of gait in individuals with a chronic stroke.

Can Variations of Vehicle Driving Status Provide Accurate Predictors of Discomfort? A Study on the Actual Driving Test

The ride comfort of bus passengers is a critical factor that is recognized to attract greater ridership towards a sustainable public transport system. However, it is challenging to predict bus passenger comfort due to the complex non-linear interaction among various factors. In an application-based study, 18 real driving tests were conducted to analyze the correlation between factors induced by motion sickness and the driving status of the vehicle. We used the user’s feedback module (UFM) to record the feelings of passengers, and the six degrees of freedom (6-df) motion parameters were obtained by the accelerometer in the micro electro mechanical system (MEMS) of the smartphone. Then, the data were discriminated and analyzed, and thresholds of the variables affecting the discomfort of passengers in different conditions were obtained. Finally, we established a prediction model of motion sickness duration based on the driving status of vehicles. The result shows that passenger’s comfort is most sensitive to vertical acceleration changes when the vehicle is decelerated, and the duration of motion sickness (DMS) can be effectively predicted (79.8%) by the vehicle’s lateral acceleration, roll, and pitch angular velocity indicators. The findings of this study provide insights into the potential theoretical basis for policymakers to improve the adjustment of the driving strategies and path trajectory of city buses.

Influence of Attitude Parameters on Image Quality of Very High-Resolution Satellite Telescopes

The image quality of very high-resolution satellite telescopes (VHRSTs) is affected by several factors, including optics, detector, pointing accuracy errors, attitude stability errors, and altitude variations. The charge-coupled devices with a time delay and integration (TDI) feature play a significant role along with the satellite attitude parameters in characterizing the VHRST image quality. The imperfection of the satellite control system to maintain the required pointing accuracy and attitude stability can lead to severe degradation in the quality of the acquired imagery. Hence, it is required to investigate their impacts carefully during the satellite preliminary design phase. In this article, the combined effect of the TDI steps, satellite attitude parameters, and orbital altitude variations on the image quality are investigated in detail. The results show that the image quality in the along- and cross-track directions are affected seriously in certain situations by the roll and pitch angular velocity bias. Furthermore, the proposed mathematical model in this article reveals that total modulation transfer function (MTF), as an image quality metric, is affected severely by the satellite altitude variation, particularly when employing a high number of TDI steps. For example, for a given scenario, when employing TDI steps of 64, the mathematical results show that the effect of a satellite altitude variation of 10 km will result in a 65% reduction in total system MTF.