Lateral Disturbance Research Articles

Simulation Analysis Based on Sodium-Cooled Fast Reactor Fuel Assembly Under Blockage Accident

This paper employs computational fluid dynamics to investigate the fuel assemblies within a sodium-cooled fast neutron reactor. To begin with, we developed computational models for seven wire spacer fuel rods under both normal operating conditions and transient blockage conditions. We conducted separate analyses to assess the impacts of normal operation, blockage thickness, and blockage area. This work allowed us to acquire data on the heat transfer properties and the flow field variations for the coolant, blockages, and fuel rods across different conditions. Subsequently, we leveraged these flow field alterations to examine the resulting temperature distributions. Analyses were conducted to evaluate the effects of normal operation, blockage thickness, and blockage area. The research acquired the heat transfer characteristics and flow field distribution variations of the coolant, blockages, and fuel rods under different operational conditions and utilized these variations to analyze the temperature distribution. Through research analysis, the following conclusions have been reached. Under normal operating conditions, the temperature and flow fields of the fuel components exhibit cyclic variations along the axial length, corresponding to the pitch of the wire spacers. Heat exchange between the internal and external subchannels occurs independently, which further substantiates that the incorporation of wire spacers strengthens lateral flow disturbances. This effect is more pronounced within the internal subchannels, thereby leading to a marked difference in the flow fields on either side of the wire spacers. In the case of blocked conditions, an increase in blockage thickness and area both lead to higher temperatures for the coolant, the blockages themselves, and the fuel rods. The temperature in the recirculation zone behind the blockages also rises with increasing blockage thickness and area, although the magnitude of this increase is not significant. After the onset of blockage conditions, the instantaneous temperature tends to increase. As time progresses, the instantaneous temperature fields following the blockage do not display greater fluctuations in temperature change than those observed after the system has stabilized. For the temperature parameters of the convective field, differences arising from an increase in blockage area are more significant than those caused by an increase in blockage thickness. When blockage area and blockage thickness are increased by the same multiple, an increase in blockage area results in a higher temperature peak. Increasing the area of blockage necessitates a longer duration for both the temperature and the velocity fields to revert to equilibrium.

Experimental Study on Railway Vehicle Lateral Performance under Different Lateral Disturbance

Experimental Study on Railway Vehicle Lateral Performance under Different Lateral Disturbance

Instability and breakup of rayleigh-plateau jets with capillary wave induced by electrowetting-on-dielectric

This paper discusses the lateral disturbances of vertical liquid flow enhancement using electrowetting-on-dielectric (EWOD) technique, which effectively reducing the breakup length of the liquid flow and minimizing the formation of satellite droplets. The EWOD technology is characterized by its minimal space occupation and low energy consumption. The successful implementation of the EWOD phenomenon relies on the formation of a three-phase contact line (TPCL) between the electrodes and the liquid, and the novel EWOD tube structure design provides an extended TPCL, enhancing the amplitude of capillary waves. Through experimental and theoretical analysis, this paper identifies key parameters affecting the liquid breakup process, such as the gap depth, angle of the EWOD tube, EWOD voltage amplitude, and frequency of the AC electrical signal. The research results indicate that the proposed EWOD tube responds rapidly and can consistently and stably manage liquid breakup and reduce the number of satellite droplets.

Planning trajectories for connected and automated vehicle platoon on curved roads: A two-dimensional cooperative approach

This paper presents a cooperative two-dimensional trajectory planning algorithm for connected and automated vehicle (CAV) platoons. Specifically, the proposed algorithm generates two-dimensional optimal trajectories for CAVs with car-following relationships cooperatively within a complex road geometry. By extending the simplified Newell’s car-following model, we propose a two-dimensional Newell’s car-following model as an equilibrium car-following policy for CAVs. Based on this, a multi-objective constrained optimization is systematically formulated under a Cartesian coordinate. Due to the constraint’s complexity, a new solving algorithm based on the rapid random tree (RRT) technique is proposed. To test the effectiveness of our proposed models and algorithm, numerical simulation experiments with a real-world road geometry are conducted. Results indicate that our proposed method is able to generate trajectories for CAV platoons which are close to the equilibrium condition with smooth controls, while avoiding road obstacles. We further extend the definition of a one-dimensional car-following control string stability to a two-dimensional case. By this definition, we find that the proposed method can achieve empirical two-dimensional string stability, ensuring that both lateral and longitudinal disturbances are attenuated through vehicular strings.

Estimation of Crosswind Disturbances for a Vehicle by LPV‐MHE and its Application to Disturbance Cancellation

Crosswinds and transverse slopes of the road surface affect the motion of a ground vehicle as disturbances. The objective of this paper is to develop a method for estimating crosswind disturbances and lateral force disturbances caused by transverse slopes of the road surface under the variation of the vehicle speed. Firstly, a dynamical model of a vehicle is described as a Linear Parameter‐Varying (LPV) system in which the value of the coefficient matrices vary with the vehicle velocity. Then, an algorithm to estimate the disturbance is derived based on Moving Horizon Estimation (MHE) and applied to the derived LPV system. Furthermore, a simple control law which counteracts the effects of the disturbances on the lateral velocity and the yaw rate in steady‐state based on the estimates of the disturbances is presented. The effectiveness of the proposed method is demonstrated by a numerical example. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Influence of aging on the relation between head control and hip joint kinematics during crossover stepping.

Falls in older individuals are a serious health issue in super-aged societies. The stepping reaction is an important postural strategy for preventing falls. This study aimed to reveal the characteristics of lateral stepping in response to mechanical disturbance by means of an analysis of the hip joint kinematics in the stepping leg and head stability during crossover steps. The participants included 11 healthy older and 13 younger individuals. An electromagnet-controlled disturbance-loading device induced crossover steps due to lateral disturbance. Responses were measured using a motion capture system and force plates. The righting reaction of the head was quantified by lateral displacement (sway), neck joint kinematics (angle displacement, angular velocity), and neck joint moment during crossover stepping. Moreover, the relationship between the neck lateral bending moment and angular velocity of hip flexion/adduction of the stepping leg was examined. The lateral head sway was significantly larger in the older participants (1.13±0.7 m/s2) than in the younger individuals (0.54±0.3 m/s2); whereas, the angle displacement (older -14.1±7.1 degree, young -8.3±4.5 degree) and angular velocity (older 9.9±6.6 degree/s, 41.2±27.7 degree/s) of the head were significantly lower in the older than in the younger participants. In both groups, the moment of neck lateral bending exhibited a significant negative correlation with the hip flexion angular velocity of the stepping leg. Correlation analysis also showed a significant negative correlation between the neck lateral bending moment and hip adduction angular velocity only in the older group (r = 0.71, p<0.01). In conclusion, older individuals increased instability in the lateral direction of the head and decreased righting angle displacement and angular velocity of the head during crossover steps. The correlation between neck moment and hip flexion/adduction angular velocity suggested a decrease in step speed due to increased neck muscle tone, which could be influenced by vestibulospinal reflexes.

Collaborative control of path tracking and roll stability in intelligent commercial vehicle: A minimax robust regulator based on Nash game

—Currently, most vehicles are generally equipped with roll stability control system or electronic stability control system to improve stability. However, when encountering emergency obstacle avoidance and similar conditions, roll stability control system may compete with path tracking control system for vehicle control, resulting in the inability to balance path tracking and roll stability. Therefore, a closed-loop feedback Nash game collaborative control method is proposed to solve the collaborative problem between the two control systems. Firstly, a fifth-order vehicle model with coupled yaw-roll dynamics is presented, which was extended to a vehicle-road closed-loop model based on lateral position, yaw angle and road preview information. Secondly, the path tracking control system and roll stability control system are regarded as two agents in the dynamic game control process. On this basis, a Nash game collaborative control strategy is designed by fully considering the control interaction between two game agents. Finally, considering the influence of uncertain disturbances, a finite-time minimax robust control strategy is proposed by using minimax optimization theory. Simulation and hardware in loop experiments show that the minimax robust regulator based on Nash game controller can effectively improve the path tracking and roll stability performance of vehicles. Moreover, the regulator improves the robustness of the system when it is subjected to bounded uncertain lateral disturbances.

Robotic realization of human perceptual changes with lateral balance task

Human motor learning affects not only motion pattern but also perception. On the basis of this idea, we investigated some human-balancing tasks to observe changes in the balance perception. We simulated one of the results to replay the human behavior. In this study, we aim to demonstrate the human adaptive behavior in a motor and sensory system using a robot in a real-world scenario. The subjective upright, i.e., the inclination angle was considered as upright, was evaluated as perception in a balance position, and its lateral shift was determined after a motor-learning task under lateral disturbances. The adaptation dynamics were defined based on our hypothesis that stated that the subjective upright tends to vary toward the posture in which balance can be best maintained. Consequently, the change in the subjective upright similar to the human result was reproduced using a two-link robot that was subjected to the same environmental condition as that in the human experiment.

Switching Longitudinal and Lateral Semi-decoupled Active Disturbance Rejection Control for Unmanned Ground Vehicles

In this paper, a switching longitudinal and lateral semi-decoupled active disturbance rejection control (ADRC) strategy is proposed for motion control of unmanned ground vehicles (UGVs). To characterize the coupling property between longitudinal and lateral dynamics, a switching longitudinal and lateral semi-coupled model is first developed. By utilizing the switching method, a so-called “two-stage ADRC” strategy is presented. It has two forms before and after the transition instant such that the boundedness premise for the derivative of the total disturbance can be removed. With the designed two-stage ADRC, a longitudinal and lateral semi-decoupled controller is then suggested to solve the motion control problem of UGVs. Finally, both stability analysis and comparison results are given to demonstrate the effectiveness and robustness of the proposed control strategy.

Free Gait Generation of Quadruped Robots via Impulse-Based Feasibility Analysis

Online gait adaptation is crucial for improving the dynamic performance of quadruped locomotion systems, while current approaches often adopt the predefined periodic gait pattern. This article proposes a free gait generation algorithm that only takes the robot state as input. Specifically, we introduce the feasible impulse polytope, which takes into account both linear and angular momentum impulses acting on the body in a prediction horizon. This naturally leads us to formulate a leg capability metric related to the effect of take-off and touch-down on the body motion. Then, gait sequence, take-off timing, and touch-down location can be automatically adjusted online as long as a metric threshold is given. To cope with rough terrain, a series of quadratic programming problems are established for online pose optimization under mild assumptions. Furthermore, we fully integrate the proposed algorithms with the robot control and estimation framework for real-time implementation. We first validate our approach with the quadruped robot SCIT-Dog through locomotion with speed changes, on stairs and slopes, and under lateral disturbances. Besides, a push-recovery experiment is established to show the superiority of the proposed approach over the baseline method with prespecified gait patterns. Experiment results verify the ability of the proposed algorithms to achieve autonomous gait transitions in response to various emergencies.

Study on the lateral thermal disturbances of three parallel embankments on permafrost along the Gonghe-Yushu Engineering Corridor in China

The mutual thermal disturbance of built structures along narrow permafrost engineering corridors has become an evident influencing factor on the thermal stability of frozen soil engineering. To analyse the mutual thermal disturbance of the built structures along a permafrost engineering corridor in the Qinghai-Tibet Plateau, three parallel permafrost embankments (along the G214 Highway and the first- and second-stage projects of the Gonghe-Yushu Highway in the Gonghe-Yushu Engineering Corridor) were chosen as the research sites. These three highways were built at different times following different standards; thus, complicated lateral thermal disturbances occurred among the three parallel embankments. The embankment distress investigations, typical section drilling, and ground temperature observations were used for analysis. Then, the thermal distress and service status were analyzed under the mutual thermal disturbances of the three embankments. The continuous wave settlements and inclination deformations were relatively developed due to the remarkable mutual thermal disturbances from the shorter distances among the three embankments. Moreover, missing or poor drainage systems further aggravated the mutual thermal disturbances. The monitored data revealed that the transverse thermal disturbances weakened the cooling effects of several special structures to a certain degree; these structures included the ventiduct embankments and crushed-rock embankments. A thermal disturbance simulation model for the three parallel permafrost embankments was proposed and included the assignment of the general influence, core influence, and severe influence zones of the thermal disturbance. The computed results showed that the general influence zones and core influence zones under the three embankments were linked together after 3 and 10 years of construction, respectively, on the Gonghe-Yushu Highway. After 50 years, a vast thermal influence area almost 100 m wide and 20 m deep would form under the three embankments. The thermal disturbances at different distances between embankments were also analyzed using this model; the distances between G214 and the first-phase project of the Gonghe-Yushu Highway were inferred to be more than 15 m and 20 m between the first- and second-phase projects of the Gonghe-Yushu Highway, respectively.

Energy-optimal Speed Regulation for CAVs in Urban Mixed Traffic with Induced Lane Changes

Existing urban energy-optimal vehicle speed regulation (eco-driving) studies were mostly carried out on single-lane roads or did not consider lane changes, delivering overidealized eco-driving results. In addition to lane changes that every vehicle may encounter on roads, the eco-driving connected automated vehicles (CAVs) are subject to induced types of lane changes of manually-driven vehicles (MVs), a cut-in of an MV to the front of a CAV from an adjacent lane, and an escape of an MV from behind a CAV to an adjacent lane. So far, very few studies have considered the impact of lane changes while designing the ecodriving strategies and evaluated the eco-driving performance with respect to lane-changing disturbances in credible simulation environments; and almost no existing work has addressed both lateral and longitudinal disturbances for eco-driving. This paper has developed a generic and deployable eco-driving strategy for CAVs under a unified rolling-horizon optimal control framework that can deal with both longitudinal and lateral disturbances of MVs without assuming communications between CAVs and MVs. The performance of this disturbance-rejection eco-driving strategy was thoroughly evaluated with regard to a multilane urban network, using the microscopic traffic simulator SUMO. The strategy was demonstrated very effective and robust, and similar results were little reported before.

Sliding behaviors of the trapezoidal roof rock block under a lateral dynamic disturbance

The surrounding rock of underground space is always affected by external dynamic disturbance from the side position, such as blasting vibration from a stope at the same level or seismic waves from adjacent strata. A series of laboratory tests, numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral disturbance. Firstly, the experiments on trapezoidal key block under various clamping loads and disturbance were conducted, followed by numerical simulations using the fast Lagrangian analysis of continua (FLAC3D). Then, based on the conventional wave propagation model and the classical shear-slip constitutive model, a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key block. The results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide (without instability). Meanwhile, when the key block was disturbed to fall, two types of instability process may appear as immediate type or delayed type. In addition, the propagation of stress waves in the block system exhibited obvious low-velocity and low-frequency characteristics, resulting in the friction reduction effect appearing at the contact interface, which is the essential reason for the sliding of rock blocks. The results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rock-falling disasters.

Vibration Control of a Multi-Disc Rotor System with Active Lateral Bearings and Disturbance Estimation

A rotor system used in a wide range of engineering applications generally consists of a rotor shaft, multiple discs, blades and other essential components, generating a multi-disc rotor arrangement. System uncertainties caused by unbalanced discs and disc mass variation, compounded with external disturbances under different operating conditions, can lead to a variation in rotor-dynamic characteristics with multiple structural resonances, potentially causing an excessive level of rotor lateral vibration. Therefore, to effectively suppress lateral vibration for such a multi-disc rotor system, an active vibration control approach using active lateral bearings with disturbance estimation is presented in this work. The utilized active lateral bearings can generate necessary bearing displacement regulations to eliminate the bearing forces so to effectively control the lateral vibration of the rotor system. The disturbance estimation approach is used to estimate the unknown uncertainties associated with the system's internal dynamics and external disturbances affecting the rotor system, incorporating an extended state observer (ESO). Utilizing the total disturbance estimated by the ESO to cancel out the effects of the disturbance using active lateral bearings, the rotor lateral vibration can be satisfactorily suppressed with sufficient control robustness against uncertainties in the rotor internal dynamics, particularly associated with the degree of mass unbalance of rotor discs, demonstrating the effectiveness of the active vibration control approach for suppressing vibration in a rotor system.

Comparison of two preserved cartilage iliac crest cortical-cancellous bone blocks graft harvesting techniques in children: A prospective, double-blind, randomized clinical trial

PurposeTo compare donor-site morbidity for alveolar bone grafting results following cartilage-preserving outer and inner cortico-cancellous iliac crest (OCIC and ICIC) bone block grafting in children. Materials and methodsPatients were randomly divided into two groups and prospectively reviewed. In the OCIC and ICIC groups, cortico-cancellous bone blocks were harvested at outer and inner iliac crest respectively. Patient characteristics and surgical parameters were compared; pain intensity and duration, lateral femoral cutaneous nerve (LFCN) injury, gait disturbance, scar and contour satisfaction were analysed postoperatively. ResultsForty-nine consecutive patients (OCIC, 24; ICIC, 25) were included. There were no significant differences in patient characteristics or donor-site surgical parameters. The mean pain score on the first post-operative day was significantly lower in the OCIC group (3.75±1.70) than in the ICIC group (5.20±2.08) (p=0.012). The pain duration was similar in the two groups (median: 5 days). Temporary LFCN injury only occurred in 3 patients in the ICIC group. Postoperatively, the duck and circle gaits were observed in the OCIC and ICIC groups, respectively. There were no significant differences in the claudication duration, scar and contour satisfaction between the groups. ConclusionOCIC bone graft harvesting is marginally advantageous in children due to less early postoperative donor-site pain and a lower risk of nerve damage.

Lane-changing control for hybrid electric vehicles with dedicated hybrid transmission based on robust model predictive control

Car-following and lane-changing are extremely important for vehicles. The traditional adaptive cruise control (ACC) strategy has various drawbacks due to the complicated driving conditions. A new control strategy of robust model predictive control (RMPC) for car-following and lane-changing is proposed based on a new type of hybrid electric vehicle (HEV) with dedicated hybrid transmission (DHT-HEV). The control model includes a vehicle model, a following and lane-changing model and an RMPC controller. The vehicle model integrates the DHT-HEV and dynamic models with a longitudinal dynamic model, seven degrees of freedom (DOF) vehicle dynamic model and three DOF control model. The following and lane-changing model is described as car-following and lane-changing models of two-quintic function. The RMPC controller is used to balance the control of vehicle longitudinal and lateral dynamics with the lateral acceleration disturbance. Simulation results demonstrate that the RMPC controller can track the reference trajectory during two lane-changing process when the test scenarios of different accelerations are set compared with the conventional ACC control. Different Np (predictive horizon) and Nc (control horizon) are also analysed to improve the solving performance of RMPC. Results indicate that the solving performance of the system is optimal when Np = 30 and Nc = 1. Furthermore, different weight coefficient matrixes ( Q and R) are taken into the consideration by coordinating the car-following performance and lateral stability. Accordingly, the controllers of RMPC-LC, RMPC-ACC and RMPC-LA are set, demonstrating that the control of RMPC-LA best balances two aspects and is always within a safe car-following distance. Meanwhile, the hardware in the loop (HIL) is utilised to verify the effectiveness of the proposed RMPC control strategy, which comprises model compilation, the establishment connection between the D2P ECU and the simulator and control input.

Robust Path Tracking Control of Distributed Driving Six-Wheel Steering Commercial Vehicle Based on Coupled Active Disturbance Rejection

With the advancement of chassis technology, a distributed driving six-wheel steering commercial vehicle chassis (DD-6WS CVC) became useful for enhancing traffic efficiency and facilitating rapid emergency rescue. In the face of harsh, complex working conditions and multiple unknown disturbances, the difficulty of research is determining how to comprehensively integrate the benefits of various subsystems to improve the stability of dynamics. Based on the dynamic model of the DD-6WS CVC, a coupled active disturbance rejection controller (ADRC) is designed to improve the robustness of path tracking in emergency obstacle avoidance. First, the preview path information is optimized by the tracking differentiator (TD), and then the six-wheel steering control quantity is computed using model predictive control (MPC). Using the extended state observer (ESO), the total lateral disturbance is estimated and compensated. Second, the heading state quantity and disturbance estimation value are incorporated into the nonsingular fast terminal sliding mode control (NFT-SMC) so that the direct yaw moment control (DYC) can achieve yaw stability in real time. Finally, the optimal distribution of six-wheel drive torque is completed. Experiments validate the algorithm's effectiveness and high robustness under multiple coupling disturbance. The results demonstrate that, in comparison to MPC and the linear quadratic regulator (LQR), the proposed algorithm has superior control characteristics and effectively enhances the robustness of the DD-6WS CVC in-phase steering path tracking.

Lateral stress and its transmission law caused by operation of a double-wing subsoiler in sandy loam soil

Sandy loam soils are widespread and important for agricultural soil use. The lateral stress caused by the loosening shovel of a subsoiler produces lateral disturbances in sandy loam soil, reducing compaction and improving soil structure. To explore the variation and transmission of lateral stress due to the operation of a double-wing subsoiler in sandy loam soil, a lattice of point-type soil sensors was arranged in a soil bin, and the lateral stress generated by subsoiling was measured in the shallow, medium, and deep soil layers. The experimental results show that when the lateral stress generated by the double-wing subsoiler is transferred to the lateral position of different distances.The lateral stress shows a sinusoidal fluctuation law with time, the sine wave frequency range is: shallow (0.366–0.549); middle (0.306–0.494); and deep (0.088–0.501). There were greater fluctuation amplitudes in the transfer process for the shallow and deep soil layers than for the middle layer. Shallow soil had the largest final stable lateral stress (0.1617 N), and middle soil the smallest (0.0733 N). Thus, lateral stress from deep loosening has the greatest effect on shallow soil and the least effect on middle soil. These results indicate that the fluctuating lateral stresses generated by double-wing-subsoiler operation drive a fluctuating soil disturbance that can improve soil structure, and that they are greater for shallow and deep soils than for middle soils.

Lateral Disturbance Compensation of a Gondola-Embedded Façade Cleaning Robot via Compliant Planar Arm Structure

Façade cleaning is a dangerous task for human workers. If a façade cleaning robot is equipped with a gondola, it can perform façade cleaning with a simple planar manipulator via the vertical movement of the gondola. To clean a façade using a gondola-embedded robot successfully, the disturbance in the lateral direction of the gondola movement should be measured and compensated. In this study, we propose a compliant parallel structure-based position sensing device to measure the lateral directional disturbances. The compliant structure keeps contacts on the edge of the glass frame during the operation of the gondola and obtains disturbance information from forward kinematics of the joint mechanism. The prototype was produced, and experiments were performed on a test bench designed with a similar façade geometry as that of the target building. The disturbance compensation feature of the proposed mechanism was verified by experimental analysis.

Motion Control of Autonomous Vehicles Based on Offset Free Model Predictive Control Methods

Abstract Model predictive control (MPC) is the mainstream method in the motion control of autonomous vehicles. However, due to the complex and changeable driving environment, the perturbation of vehicle parameters will cause the steady-state error problem, which will lead to the degradation of controller performance. In this paper, the offset-free MPC control method is proposed to solve the steady-state error problem systematically. The core idea of this method is to model the model mismatch, control input offset, and external disturbances as disturbance terms, then use filters to observe these disturbances and finally eliminate the influence of these disturbances on the steady-state error in the MPC solution stage. This paper uses the Kalman filter as an observer, which is integrated into our latest designed MPC solver. Based on state-of-the-art sparse quadratic programming (QP) solver operator splitting solver for quadratic programs (OSQP), an offset free model predictive control (OF-MPC) framework based on disturbance observation and MPC is formed. The proposed OF-MPC solver can efficiently deal with common model mismatch problems such as tire stiffness mismatch, steering angle offset, lateral slope disturbance, and so on. This framework is very efficient and completes all calculations in less than 7 ms when the horizon length is 50. The efficiency and robustness of the algorithm are verified on our newly designed robot operating system (ROS)-Unreal4-carsim real-time cosimulation platform and real vehicle experiments.