Straight Path Research Articles

Analisis Metode Dakwah Husain Basyaiban di Media Sosial

Da'wah is an activity of inviting and influencing people towards the straight path wisely in accordance with God's commands. This is done for every individual and community to want to improve themselves by doing good deeds and deepening the teachings of the Islamic religion. Da'wah must be carried out by people who are intelligent, civilized and have noble character. Da'wah media continues to evolve by following technology which is becoming more advanced day by day, one of the media used for preaching is social media. You Tube, Instagram, and Tik Tok are examples of social media that are currently widely used by preachers to preach. Husain Basyaiban is one of the young preachers who uses social media as a medium for his preaching. The preaching delivered by Husain had an influence on readers and viewers, because it was packaged well using simple language and strong arguments so that it was easy for his followers to understand. Therefore, researchers are interested in analyzing the preaching methods used by Husain. This research focuses on the da'wah methods and social media used by Husain Basyaiban. This research was carried out using a qualitative approach using the netnographic method where primary sources were obtained from posts and videos uploaded by Husain Basyaiban and secondary data sources were obtained from previous journals and articles. With data collection techniques by means of online documentation and observation. From the results of this research, it was found that Husain used da'wah methods which were categorized into three methods, namely the Al-Hikmah, Mauidzotul Hasanah, and Mujjadi methods. Then there is the development of Husain's social media at this time, with the username kadamsidik for 168 thousand subscribers on You Tube, the username basyasman for 1.9 million followers on Instagram, as well as the username @kadamsidik00 for 6 million followers and also 327.1 million likes on all videos which was uploaded from the beginning of 2020 until now on September 24 2023 on Tik Tok. Researchers hope that this research can be studied and researched more deeply by other researchers, both with other methods and objects.

Analysis and modeling of detours in pedestrian operational navigation

Traditional operational navigation models for pedestrian dynamics demonstrate limitations in reproducing the circle antipode experiment, an artificially designed multi-directional flow scenario. In the experiment, pedestrians take detours to avoid the congestion caused by others taking straight paths. Although the pedestrian detour action is commonly incorporated into the route choice model, it frequently goes unaddressed in the operational navigation model, resulting in a disparity between simulation outcomes and empirical observations. To reveal the mechanism underlying pedestrian detours in the circle antipode experiment, this study employed the K-means clustering method rather than using a threshold approach to categorize the experimental participants into groups taking direct or detour routes. Following this, a heuristic function is formulated to determine the desired direction of agents in a collision-free velocity model, reflecting the trade-off between shorter routes and faster speeds. The parameter of the proposed function is calibrated using the proportion of agents choosing detours, where the route types of agents are identified by a classifier based on the random forest. Compared to two traditional models that do not consider detours, the proposed model can more realistically reproduce the trajectory distributions, the travel time, the route length, and the time series of relevant variables in the circle antipode experiment. The study offers insights into employing machine learning methodologies for analyzing pedestrian flow, validating pedestrian dynamics models, and providing an accurate simulation tool for designing transportation facilities and crowd management at large events.

Role of arm reaching movement kinematics in friction perception at initial contact with smooth surfaces.

When manipulating objects, humans begin adjusting their grip force to friction within 100ms of contact. During motor adaptation, subjects become aware of the slipperiness of touched surfaces. Previously, we have demonstrated that humans cannot perceive frictional differences when surfaces are brought in contact with an immobilised finger, but can do so when there is submillimeter lateral displacement or subjects actively make the contact movement. Similarly, in, we investigated how humans perceive friction in the absence of intentional exploratory sliding or rubbing movements, to mimic object manipulation interactions. We used a two-alternative forced-choice paradigm in which subjects had to reach and touch one surface followed by another, and then indicate which felt more slippery. Subjects correctly identified the more slippery surface in 87±8% of cases (mean±SD; n=12). Biomechanical analysis of finger pad skin displacement patterns revealed the presence of tiny (<1mm) localised slips, known to be sufficient to perceive frictional differences. We tested whether these skin movements arise as a result of natural hand reaching kinematics. The task was repeated with the introduction of a hand support, eliminating the hand reaching movement and minimising fingertip movement deviations from a straight path. As a result, our subjects' performance significantly declined (66±12% correct, mean±SD; n=12), suggesting that unrestricted reaching movement kinematics and factors such as physiological tremor, play a crucial role in enhancing or enabling friction perception upon initial contact. KEY POINTS: More slippery objects require a stronger grip to prevent them from slipping out of hands. Grip force adjustments to friction driven by tactile sensory signals are largely automatic and do not necessitate cognitive involvement; nevertheless, some associated awareness of grip surface slipperiness under such sensory conditions is present and helps to select a safe and appropriate movement plan. When gripping an object, tactile receptors provide frictional information without intentional rubbing or sliding fingers over the surface. However, we have discovered that submillimeter range lateral displacement might be required to enhance or enable friction sensing. The present study provides evidence that such small lateral movements causing localised partial slips arise and are an inherent part of natural reaching movement kinematics.

Impact of the Kuroshio large meander on local atmospheric circulation and precipitation in winter

The Kuroshio, which flows to the south of Japan, typically takes two paths on decadal timescales; the straight path and the large meander path, or the so-called Kuroshio large meander. This phenomenon is characterized by the presence of the cyclonic cold-core eddy located south of Japan, which leads to both negative and positive sea surface temperature (SST) anomalies along the southeastern coast of Japan. To clarify the atmospheric response to these SST anomalies in winter, we conducted a control experiment employing a regional atmospheric model with observed SSTs and two sensitivity experiments in which the SST boundary conditions were substituted with those corresponding to the periods of for the Kuroshio large meander and the straight path. The differences in these two sensitivity experiments showed that the surface wind response to the SST anomalies associated with the Kuroshio large meander was not only characterized by wind divergence over the cyclonic cold-core eddy, as reported previously but also wind convergence along the southeastern coast of Japan. Interestingly, this wind anomaly blew into the positive SST anomaly along the east coast of Japan at around 36°N. Similar wind anomalies along the east coast of Japan were observed in a reanalysis product. The results of the model simulation and the reanalysis product showed that during the Kuroshio large meander period, the number of rainy days increased significantly over the warm SST anomaly, while the precipitation and the number of rainy days decreased over the cyclonic cold-core eddy. Moisture budget analysis revealed that the observed decrease in precipitation was attributed to the disparity between the reduced evaporation and the anomalous horizontal moisture convergence in a region where the surface winds were divergent. This moisture convergence was mainly induced by a decrease in specific humidity, implying this change in specific humidity effectively mitigated the variation in precipitation.

Remote control of fluid motion in a channel by acoustic holography

A new method for manipulating fluid movement using sound waves is presented in this paper. The method relies on acoustic streaming near the free surface of the fluid in a channel with an open top. The sound waves are modulated in phase using acoustic phase holography, which creates a periodic phase pattern from 0 to 2π along a straight path on a target plane. The paper also describes an experimental design to study the main factors influencing the method, such as frequency, number of phase patterns in the path, and sound pressure amplitude. The paper shows that phase pitch and voltage significantly affects fluid speed and that there is a good match between the theoretical and experimental results. Furthermore, the article reports additional experiments with different channel shapes to demonstrate the versatility of the method in controlling fluid motion. The highest fluid speed observed was 0.4 mm/s at a frequency of 1300 kHz and a phase pitch of 5. The paper also investigates the effect of changing the frequency on reversing the flow direction in a U-shaped channel, both experimentally and theoretically. The paper concludes that this method could be a suitable alternative to other acoustic devices for inducing fluid motion because of its simple and flexible design, fabrication, accuracy, and ability to handle complex channels.

Travelers on the Straight Path: Truth Seekers

This article analyzes the concepts of al-ṣirāṭ al-mustaqīm (the Straight Path) and istiqāma (steadfastness) and how they guide one to the Qur’ānic roadmap to success in this world and in the hereafter. Al-ṣirāṭ al-mustaqīm is a methodology to define, verify, correct, and establish our concepts, principles, and relationships. I apply the hermeneutic of reading the divine text as a structural unity (al-waḥda al-binā’iyya li-l-Qur’ān). After defining al-ṣirāṭ al-mustaqīm, I suggest that a holistic reading of the Qur’ān can help believers rebuild istiqāma from within it, a specific methodological approach. I present al-ṣirāṭ al-mustaqīm as a roadmap that envisions the characteristics of upright and righteous truth seekers and true believers following Prophet Abraham’s religion and carried on by Prophet Muhammad and his umma to arrive at the Straight Path (Qur’ān 3:68). I close by stressing that it is imperative to become upright by remaining steadfast on the Straight Path. It is by remaining steadfast that individuals can restore balance in their relationships, uniting together as one family.

High-order kinematics of uniform flexures

In the last decades, many efforts have been made to analyze and model small and large deflections of flexures, considering complex load cases and different solution techniques. However, few investigations focused on the kinematic aspects related to the deflection analysis of the flexible elements, and limited the study to the second-order kinematics. In this paper, an analytical formulation based on the instantaneous geometric invariants is developed to give deep kinematic insight, up to the fourth order, into the motion generated by the deflections. The problem is addressed from a geometrical point of view, defining the fundamental geometric entities that characterize the motion, that are inflection circle, cubic of stationary curvature and its derivative, Ball’s point, and Burmester’s points. Thanks to these special points on the plane, straight and circular paths can be approximated to the third and to the fourth order, respectively. The proposed formulation defines the geometric characteristics of flexures with different curvatures. An application regarding the definition of pseudo-rigid body models is discussed. Finite element simulations are performed to validate the results.

‘Following the Straight Path’: Egypt Political Regime’s Quest for Political Legitimacy

The study aims to investigate the sources of the Egyptian regime’s legitimacy after the removal of Mohammed Morsi from office in 2013. The ruling elite, in particular President alSisi, has recently shown a growing inclination towards adopting Islam in the political discourse. As a result, there is a need to examine the factors that have contributed to this trend. The central hypothesis of the research is that the government, lacking institutional legitimacy, is compelled to reinforce the Islamic values in political communication to overcome internal political divisions and establish a sense of social connection between the authorities and citizens. To test this hypothesis, the study employs a qualitative content analysis of speeches made by President alSisi to the nation between 2014 and 2023. The analysis identifies four techniques for legitimation (mobilization, national identity consolidation, construction of a common past, and construction of a common future) and examines the functional role of Islam in each of them. The findings of the study suggest that Islamic norms and values are most actively appealed to in segments of texts devoted to national identity consolidation and constructing a common future. Both approaches involve a similar strategy of invoking Islam by associating and transferring attributes within pairs of words (religious context - secular context): nation - the Ummah; state - Islamic world; citizen - a Muslim. By using this rhetorical strategy, the government is shaping a narrative that places the contemporary Egyptian state within a religious and historical framework, as depicted in the Qur’an. This approach is aimed at establishing a set of values that can unite the nation and foster loyalty among citizens towards the government’s vision for Egypt’s future. However, there are almost no semantic sections dedicated to mobilizing citizens in the texts. This can be attributed to a pragmatic effort to steer clear of politicizing the electorate.

Motor imagery ability scores are related to cortical activation during gait imagery

Motor imagery (MI) is the mental execution of actions without overt movements that depends on the ability to imagine. We explored whether this ability could be related to the cortical activity of the brain areas involved in the MI network. To this goal, brain activity was recorded using high-density electroencephalography in nineteen healthy adults while visually imagining walking on a straight path. We extracted Event-Related Desynchronizations (ERDs) in the θ, α, and β band, and we measured MI ability via (i) the Kinesthetic and Visual Imagery Questionnaire (KVIQ), (ii) the Vividness of Movement Imagery Questionnaire-2 (VMIQ), and (iii) the Imagery Ability (IA) score. We then used Pearson’s and Spearman’s coefficients to correlate MI ability scores and average ERD power (avgERD). Positive correlations were identified between VMIQ and avgERD of the middle cingulum in the β band and with avgERD of the left insula, right precentral area, and right middle occipital region in the θ band. Stronger activation of the MI network was related to better scores of MI ability evaluations, supporting the importance of testing MI ability during MI protocols. This result will help to understand MI mechanisms and develop personalized MI treatments for patients with neurological dysfunctions.

A novel 3D topological metamaterial for controllability of polarization-dependent multilayer elastic waves

The achievement of high-quality wave manipulation and energy concentration has always been considered as state-of-the-art technologies, especially for integrated photonics, acoustics, and mechanics. The exploration of the topological phase of matter provides abundant design tools for robust waveguiding that is immune to backscattering at small defects and sharp bends. Recent research has extended the elastic wave manipulation from 2D edge waveguiding to 3D planar waveguiding. However, most of them are limited to single-mode and single-frequency wave propagation along the designed plane. This paper introduces a novel 3D topological metamaterial structure whose geometrical parameters are specifically configured to obtain dual-mode topological states at distinct frequencies. Parametric studies are presented to demonstrate the controllability of bandgaps and to provide a design principle for preventing the effects of unwanted modes. Topological interface modes with either high group velocity or near-zero group velocity along the z direction are found. Full-scale finite element simulations are presented to uncover the elastic wave propagation behavior. The interesting layer-locked and layer-unlocked waveguiding based on excitation polarization and frequency for both straight path and zig-zag path are demonstrated. The outcomes of this work suggest abundant potential applications related to elastic wave control such as wave filters, energy harvesters, mechanical computers, and the like. This work may also help inspire future research on more complex and sophisticated multi-mode waveguiding in 3D spaces.

ANALISIS SURAH AL-HUJURAT DAN PEMAKNAAN MENUJU AKTUALITAS PENGAMALAN

Manners include the main part discussed in surah Al-Hujurat, how to get along with Allah, the Messenger and fellow human beings. Interaction with humans has its own difficulties, it also causes many problems. So that Allah guides people through His Messenger to organize a good and prosperous life. Through a good relationship with Allah and His Messenger we get instructions towards a happy life. Surah Al-Hujurat verses 6-8 discusses Tabayyun checking news to prove its validity, obedience to the apostle, love for faith and hatred for its opponents and obstacles, and gifts given to those who are on the straight path and achieve true love of faith. Meanwhile, Tabayyun is a solution that the Qur'an offers in an increasingly sophisticated era of information and technology.

Модель проходження повороту автомобілем

The car turning model is considered, in particular at an X-shaped intersection with an arbitrary intersection angle of the tracks. The conditions and restrictions that are imposed when the car enters a turn are analyzed. It is shown that, when the car moves from straight to curved sections, angular accelerations acting relative to its vertical axis have a significant influence on the redistribution of the forces of interaction between the wheels and the road surface and, accordingly, on the stability and controllability of the car. The analysis of motion trajectories, which consist of conjugate rectilinear and curvilinear sections and are described by the equations of a circle, a parabola, and a hyperbolic cosine, is provided. It is shown that choosing a trajectory according to the law of parabola and hyperbolic cosine slightly reduces the turning radius of the car, but significantly reduces the curvature gradient in the conjugation zone and, accordingly, reduces angular accelerations and increases the resistance of the car to rotation relative to the vertical axis. For a smooth transition from a straight path to a curved one, a special logistic dependency was used to connect (stitch) different sections of the route. This made it possible to describe the trajectory of the car by a smooth function, the first and second derivatives of which are also smooth functions. For the selection of the trajectory of passing turns with a slight curvature of the route, a dependence in the form of a fourth-degree polynomial, the curvature of which at the point of conjugation is equal to zero, is proposed, which ensures a smooth transition from a straight to a curved section and ensures passing a turn with minimal dynamic loads. &#x0D; The developed model allows you to design the trajectory of turning for various types of intersections in real time and can be used to build dynamic models of car movement along given trajectories, as well as to build simulators for unmanned vehicles.

Enhanced trajectory tracking for quadrotors: disturbance observer state feedback control.

This study investigates the dynamics and trajectory tracking of quadcopters by utilizing the Disturbance Observer-based Control (DOBC) algorithm. The quadcopter's dynamic model, which consists of six degrees of freedom, includes both disturbances and uncertainties in the model. The DOBC approach incorporates the disturbance model into the system by introducing it at the input variables. It then compensates for disturbances to achieve accurate tracking of different reference trajectories. The simulated trajectories span a range of motion, varying from simple straight paths to complex spiral paths. In order to verify and evaluate the efficacy of the suggested control technique, simulations are performed using MATLAB. The simulations conclusively show that the disturbance observer-based method effectively achieves the tracking of specified reference trajectories in three-dimensional space. The study highlights the effectiveness of the DOBC algorithm in reducing the effects of disturbances and uncertainties, thereby improving the quadcopter's capacity to accurately track various trajectories.

Seismic behaviour of the non-straight steel beams in the structural plans

Purpose This research study focuses on investigating the seismic performance of non-straight beams in steel structures and exploring the mechanism by which plastic hinges are formed within these beams. The findings contribute to the understanding of their behaviour under seismic loads and offer insights into their potential for enhancing the lateral resistance of the structure. The abstract of the study highlights the significance of corners in structural plans, where non-coaxial columns, diagonal elements or beams deviating from a straight path are commonly observed. Typically, these non-straight beams are connected to the columns using pinned connections, despite their unknown seismic behaviour. Recognizing the importance of generating plastic hinges in special moment resisting frames and the lack of previous research on the involvement of these non-straight beams, this study aims to address this knowledge gap.Design/methodology/approachThis study examines the seismic behaviour and plastic hinge formation of non-straight beams in steel structures. Non-straight beams are beams that connect non-coaxial columns and diagonal elements, or deviate from a linear path. They are usually pinned to the columns, and their seismic contribution is unknown. A critical case with a 12-m non-straight beam is analysed using Abaqus software. Different models are created with varying cross-section shapes and connection types between the non-straight beams. The models are subjected to lateral monotonic and cyclic loads in one direction. The results show that non-straight beams increase the lateral stiffness, strength and energy dissipation of the models compared to disconnected beams that act as two cantilevers.FindingsThe analysis results reveal several key findings. The inclusion of non-straight beams in the models leads to increased lateral stiffness, strength and energy dissipation compared to the scenario where the beams are disconnected and act as two cantilever beams. Plastic hinges are formed at both ends of the non-straight beam when a 3% drift is reached, contributing to energy damping and introducing plasticity into the structure. These results strongly suggest that non-straight beams play a significant role in enhancing the lateral resistance of the system. Based on the seismic analysis results, this study recommends the utilization of non-straight beams in special moment frames due to the formation of plastic hinges within these beams and their effective participation in resisting lateral seismic loads. This research fills a critical gap in understanding the behaviour of non-straight beams and provides valuable insights for structural engineers involved in the design and analysis of steel structures.Originality/valueThe authors believe that this research will greatly contribute to the knowledge and understanding of the seismic performance of non-straight beams in steel structures.

A comparative analysis of the performance of various GNSS positioning concepts dedicated to precision agriculture

Abstract Automated guidance systems for precision agriculture rely on Global Navigation Satellite Systems (GNSS) and correction services for high accuracy and precision in field operations. This study evaluates the performance of selected GNSS positioning services for precision agriculture in a field experiment. We use three correction services: SF1, SF3, and RTK, which apply varying positioning concepts, i.e., Wide Area Differential GNSS, Precise Point Positioning, and Real-Time Kinematics, respectively. The tractor is autonomously steered along multiple predefined paths located in open-sky areas as well as near the heavy tree cover. The reference route of the vehicle is determined by classical surveying. Tractor trajectories, a SF1 and SF3 corrections, are shifted from predefined straight paths, unlike in the case for RTK. Offsets of up to several decimeters are service- and area-specific, indicating an issue with the stability of the reference frame. Additionally, the varying performance of the correction services implies that environmental conditions limit the precision and accuracy of GNSS positioning in precision agriculture. The pass-to-pass analysis reveals that SF1 improves the declared accuracy, while SF3 is less reliable in obstructed areas. RTK remains a stable source for determining position. Under favorable conditions, the pass-to-pass accuracy at 95% confidence level is better than 11.5 cm, 8.5 cm, and 4.5 cm for SF1, SF3, and RTK, respectively. In the worst-case scenario, the corresponding accuracies are: 25.5 cm, 65.5 cm, and 22.5 cm.

Ipsilateral lower limb motor performance and its association with gait after stroke.

Motor deficits of the ipsilateral lower limb could occur after stroke and may be associated with walking performance. This study aimed to determine whether the accuracy and movement path of targeted movement in the ipsilateral lower limb would be impaired in the chronic stage of stroke and whether this impairment would contribution to gait. Twenty adults with chronic stroke and 20 age-matched controls went through Mini Mental Status Examination (MMSE), and a series of sensorimotor tests. The targeted movement tasks were to place the big toe ipsilateral to the lesion at an external visual target (EXT) or a proprioceptive target (PRO, contralateral big toe) with eyes open (EO) or closed (EC) in a seated position. A motion analysis system was used to obtain the data for the calculation of error distance, deviation from a straight path, and peak toe-height during the targeted movement tasks and gait velocity, step length, step width and step length symmetry of the lower limb ipsilateral to the brain lesion during walking. The stroke group had significantly lower MMSE and poorer visual acuity on the ipsilateral side, but did not differ in age or other sensorimotor functions when compared to the controls. For the targeted movement performance, only the deviation in PRO-EC showed significant between-group differences (p = 0.02). Toe-height in both EXT-EO and in PRO-EO was a significant predictor of step length (R2 = 0.294, p = 0.026) and step length symmetry (R2 = 0.359, p = 0.014), respectively. The performance of ipsilateral lower limb targeted movement could be impaired after stroke and was associated with step length and its symmetry. The training of ipsilateral targeted movement with unseen proprioceptive target may be considered in stroke rehabilitation.

Cultural Influence on Architectural Evolution in Nigeria: A Case Study of Igala Indigenous Homestead

Architecture and culture are two concepts that represent the identification of any society. Architecture is the manifestation and expression of culture. So, Architecture and Culture are interdependent and inseparable. Research has identified culture as the main factor in the evolution of the architecture of a people and it plays an important role in the environmental and social development and sustainability of a place. The culture of any society is based on their beliefs, history, civilization, climate and customs, whilst architecture symbolizes a society’s culture that has evolved. This research explores the intricate relationship between culture and architecture in the evolution of traditional architecture in Nigeria, with a specific focus on the evolution of the indigenous homestead of the Igala people of North Central Nigeria. Employing a narrative approach, the study utilized historical research, field surveys, and interviews to explore how cultural beliefs, norms, practices, and socio-cultural factors have profoundly influenced the design and planning of Igala traditional dwellings. By investigating the interplay between indigenous knowledge systems, community practices, and material availability, the research uncovers the unique architectural features that have emerged from the rich tapestry of Igala culture to include the long straight entrance path (ojikpologu), the circular curvilinear homestead and buildings, courtyard (anuku/okolo), reception house (atakpa), and food storage barn (aka). Others include shrine (achękwu), grinding hut (ǫdǫ-okuta), animals’ pen (unyi-amęñwu-ǫrę), and security fence (ϙgba), all deeply rooted in Igala culture. This research provides valuable insights into the adaptability of traditional architecture to culture. It further offers essential knowledge for architects, preservationists, and policymakers, guiding their efforts in heritage preservation, sustainable architectural design, and urban planning within multicultural contexts.

Analysis of veering during gait in blind individuals

BackgroundVeering occurs during blind walking, which causes individuals to deviate from crosswalks or fall off platforms. Despite being linked to static postural control, the relationship between veering and gait function (gait variability and plantar pressure), which is presumed to be related to dynamic postural control, has yet to be fully understood. Research questionHow do gait variability and plantar pressure affect veering? MethodsThis experiment involved a walking task in which 11 blind adults were instructed to walk along a straight path using a white cane. We measured the veering values and analyzed the relationship between gait variability and plantar pressure. ResultsOne participant with a particularly severe veering tendency was excluded from the analysis. Based on the veering characteristics of the participants, the walking trajectories were classified as veering to the left (14 trials) or the right (14 trials) sides. Correlation analysis showed no significant correlation between the veering value and gait variability (vertical, lateral, and anterior-posterior). Plantar pressure (the ball of the fifth toe and the total) was significantly negatively correlate with the veering value. In contrast, the plantar pressure results for the participant who was excluded showed a different characteristic. SignificanceWe hypothesized that blind individuals would exhibit dynamic postural control to stay on a straight path by increasing the plantar pressure on the ball of the fifth toe and the total pressure on the opposite foot when veering occurs. However, this adaptation was not observed in a blind individual with severe veering tendencies.

Adaptive Basis Function Method for the Detection of an Undersurface Magnetic Anomaly Target

The orthogonal basis functions (OBFs) method is a prevailing choice for the detection of undersurface magnetic anomaly targets. However, it requires the detecting platform or target to move uniformly along a straight path. To circumvent the restrictions, a new adaptive basis functions (ABFs) approach is proposed in this article. It permits the detection platform to search for a possible target at different speeds along any course. The ABFs are constructed using the real-time data of the onboard triaxial fluxgate, GPS module, and attitude gyro. Based on the pseudo-energy of an apparent target signal, the constant false alarm rate (CFAR) method is employed to judge whether a target is present. Moreover, by defining the pixel as a relative possibility for a target at a geographic location, a magnetic anomaly target imaging scheme is introduced by displaying the pixels onto the searching area. On-site experimental data are utilized to demonstrate the proposed approach. Compared with the traditional OBFs method, the present ABFs approach can substantially improve the detection possibility and reduce false alarms.

TargetTree-RRT*: Continuous-Curvature Path Planning Algorithm for Autonomous Parking in Complex Environments

Rapidly-exploring random tree (RRT) has been studied for autonomous parking as it quickly finds an initial path and is easily scalable in complex environments. However, the planning time increases by searching for the path in narrow parking spots. To reduce the planning time, the target tree algorithm, which substitutes a parking goal in RRT with a set (target tree) of backward parking paths, was proposed. However, as it consists of circular and straight paths, it deteriorates parking accuracy because of curvature-discontinuity. Moreover, the planning time increases in complex environments; backward paths can be blocked by obstacles. Therefore, this paper introduces the TargetTree-RRT* algorithm for complex environments. First, a target tree is designed using clothoid paths to address such curvature-discontinuity. Second, to reduce the planning time further, a cost function is defined to initialize a proper target tree that considers obstacles. By integrating with optimal-variant RRT and searching for the shortest path, the proposed TargetTree-RRT* algorithm obtains a near-optimal path as the sampling time increases. Experiment results in real environments showed that the vehicle parked more accurately, and continuous-curvature paths were obtained more quickly and with higher success rates than those acquired using other sampling-based and other types of planning algorithms. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This work was motivated by the need to develop a fast and practical path planning algorithm for autonomous parking, not only in simple environments but also in complex environments. Sampling-based planning algorithms have been studied in this area, with the advantages of rapid planning of an initial path and easily reflecting vehicle’s constraints. Nevertheless, in cluttered environments, it needs considerable time to obtain a path for the autonomous vehicle easy for tracking and precise parking. To address the aforementioned issue, this article presents the TargetTree-RRT* algorithm. It finds a path by replacing a parking goal with a set of pre-defined continuous-curvature paths considering cluttered environments. TargetTree-RRT* achieves better performance for real parking scenarios and rapidly obtains a near-optimal parking path, compared to other parking path planners. The proposed algorithm is not limited to autonomous vehicles. It can be applied to other unmanned vehicles or robots, such as autonomous underwater vehicles (AUVs). In any application where the goal of path planning can be replaced with predefined standardized paths, the proposed algorithm can be extended.