Location Of Obstacles Research Articles

Field Obstacle Detection and Location Method Based on Binocular Vision

When uncrewed agricultural machinery performs autonomous operations in the field, it inevitably encounters obstacles such as persons, livestock, poles, and stones. Therefore, accurate recognition of obstacles in the field environment is an essential function. To ensure the safety and enhance the operational efficiency of autonomous farming equipment, this study proposes an improved YOLOv8-based field obstacle detection model, leveraging depth information obtained from binocular cameras for precise obstacle localization. The improved model incorporates the Large Separable Kernel Attention (LSKA) module to enhance the extraction of field obstacle features. Additionally, the use of a Poly Kernel Inception (PKI) Block reduces model size while improving obstacle detection across various scales. An auxiliary detection head is also added to improve accuracy. Combining the improved model with binocular cameras allows for the detection of obstacles and their three-dimensional coordinates. Experimental results demonstrate that the improved model achieves a mean average precision (mAP) of 91.8%, representing a 3.4% improvement over the original model, while reducing floating-point operations to 7.9 G (Giga). The improved model exhibits significant advantages compared to other algorithms. In localization accuracy tests, the maximum average error and relative error in the 2–10 m range for the distance between the camera and five types of obstacles were 0.16 m and 2.26%. These findings confirm that the designed model meets the requirements for obstacle detection and localization in field environments.

Controlling convective heat transfer of shear thinning fluid in a triangular enclosure with different obstacle positions

The free convection of a non-Newtonian fluid in an equilateral triangular cavity containing a triangle obstruction in various positions is investigated numerically in this paper. The research is carried out using the finite element method. The sloped side walls are adiabatic, while the bottom is kept heated. At the obstacle, three positions are examined. The effects of different power law indexes on free convection have been investigated. The temperature field, fluid flow, and heat transfer are all highly influenced by the obstacle's location, Rayleigh number, and power law index. The resulting outcomes are confirmed using existing results in the literature and verified using a grid sensitivity analysis. A comparison of the current results to those found in the literature demonstrates the study's dependability and trustworthiness.

Experimental study on fire extinguishing performance of typical large space fires on ships

ABSTRACT A reliable fire extinguishing system is an effective measure to reduce the risk of ship fire. Based on a typical large space cabin platform, the experiments on the fire extinguishing performance of different fire extinguishing systems (high-expansion foam, aqueous film-forming foam and water spray) against oil pool fire (6 MW) and wood stack fire (0.3 MW) were carried out. The results show that for oil pool fire, the fire extinguishing performance of aqueous film-forming foam system is higher than that of high-expansion foam system. The fire extinguishing performance of high-expansion foam system is significantly affected by the relative location of high-expansion foam generator, fire source and obstacle. For wood stack fire, the fire extinguishing performance of water spray system is the best, and the fire extinguishing time is only 25 s, followed by the aqueous film-forming foam system (54 s) and the high expansion foam system (66 s).

Hierarchical Gradients of Encoded Spatial and Sensory Information in the Neocortex Are Attenuated by Dorsal Hippocampal Lesions.

During navigation, the neocortex actively integrates learned spatial context with current sensory experience to guide behaviors. However, the relative encoding of spatial and sensorimotor information among cortical cells, and whether hippocampal feedback continues to modify these properties after learning, remains poorly understood. Thus, two-photon microscopy of male and female Thy1-GCaMP6s mice was used to longitudinally image neurons spanning superficial retrosplenial cortex and layers II-Va of primary and secondary motor cortices before and after bilateral dorsal hippocampal lesions. During behavior on a familiar cued treadmill, the locations of two obstacles were interchanged to decouple place-tuning from cue-tuning among position-correlated cells with fields at those locations. Subpopulations of place and cue cells each formed interareal gradients such that higher-level cortical regions exhibited higher fractions of place cells, whereas lower-level regions exhibited higher fractions of cue cells. Position-correlated cells in the motor cortex also formed translaminar gradients; more superficial cells were more likely to exhibit fields and were more sparsely and precisely tuned than deeper cells. After dorsal hippocampal lesions, a neural representation of the learned environment persisted, but retrosplenial cortex exhibited significantly increased cue-tuning, and, in motor cortices, both position-correlated cell recruitment and population activity at the unstable obstacle locations became more homogeneously elevated across laminae. Altogether, these results support that the hippocampus continues to modulate cortical responses in familiar environments, and the relative impact of descending feedback obeys hierarchical interareal and interlaminar gradients opposite to the flow of ascending sensory inputs.

Smart Stick Revolutionizes Mobility for the Visually Impaired

Visual impairment significantly hinders daily activities, necessitating innovative solutions. This study develops and tests a smart walking stick using NodeMCU ESP-8266, HCSR-04 ultrasonic sensor, DFPlayer, and GPS, monitored via the Blynk app. Employing a research and development approach, the device demonstrated 100% accuracy in obstacle detection and location tracking, providing real-time feedback through audio notifications and smartphone monitoring. This smart walking stick enhances mobility and safety for visually impaired users, representing a significant advancement in assistive technology. Highlights: Accurate Obstacle Detection: 100% accuracy with HCSR-04 ultrasonic sensor. Real-time Monitoring: GPS tracking via Blynk app. Enhanced Mobility: Increases safety and independence for visually impaired users. Keywords: Visual impairment, Smart walking stick, Ultrasonic sensor, GPS tracking, IoT

Smart Gloves for Blind Person using Ultrasonic Sensor & Arduino Nano

This paper presents the design and development of smart gloves aimed at enhancing the mobility and independence of blind individuals. The proposed system integrates an Arduino Nano microcontroller with an ultrasonic sensor to detect obstacles in the user's path. The ultrasonic sensor continuously scans the surroundings and provides real-time feedback to the wearer through haptic feedback mechanisms incorporated into the gloves. The system employs vibration patterns to convey the proximity and location of obstacles, allowing the user to navigate safely and confidently in various environments. Additionally, the compact and lightweight nature of the Arduino Nano ensures portability and ease of use. The effectiveness of the smart gloves was evaluated through user testing, demonstrating promising results in improving the mobility and autonomy of visually impaired individuals. This innovative solution has the potential to significantly enhance the quality of life for blind individuals by providing them with greater freedom of movement and increased safety in their daily activities. Keywords: Ultrasonic Sensors Arduino Nano, Vibrator motor, Speaker, Connecting wires, JQ6500 voice module.

An Infrared Obstacle Avoidance Car Based on STM32

With the rapid development and wide application of artificial intelligence technology, the function of intelligent obstacle avoidance vehicle is becoming increasingly prominent. This article presents a design and realization method of infrared obstacle avoidance intelligent car based on STM32 MCU. The design is driven by two DC motors as main power sources. The motor drive circuit adopts L298N driver chip to control the DC motor to achieve the purpose of controlling the trolley. The infrared obstacle-avoidance sensor is used to judge obstacles and road conditions, and the distance between the car and obstacles is monitored in real time. The error caused by external physical condition can be eliminated by the calibration and optimization of the infrared obstacle avoidance module and the program of the single-chip microcomputer, so as to achieve the goal of accurate location of obstacles.

Toward the Enhancement of Rail Sustainability: Demonstration of a Holistic Approach to Obstacle Detection in Operational Railway Environments

Rail transport plays a crucial role in promoting sustainability and reducing the environmental impact of transport. Ongoing efforts to improve the sustainability of rail transport through technological advancements and operational improvements are further enhancing its reputation as a sustainable mode of transport. Autonomous obstacle detection in railways is a critical aspect of railway safety and operation. While the widespread deployment of autonomous obstacle detection systems is still under consideration, the ongoing advancements in technology and infrastructure are paving the way for their full implementation. The SMART2 project developed a holistic obstacle detection (OD) system consisting of three sub-systems: long-range on-board, trackside (TS), and Unmanned Aerial Vehicle (UAV)-based OD sub-systems. All three sub-systems are integrated into a holistic OD system via interfaces to a central Decision Support System (DSS) that analyzes the inputs of all three sub-systems and makes decision about locations of possible hazardous obstacles with respect to trains. A holistic approach to autonomous obstacle detection for railways increases the detection area, including areas behind a curve, a slope, tunnels, and other elements blocking the train’s view on the rail tracks, in addition to providing long-range straight rail track OD. This paper presents a demonstration of the SMART2 holistic OD performed during the operational cargo haul with in-service trains. This paper defines the demonstration setup and scenario and shows the performance of the developed holistic OD system in a real environment.

Supplemental vibrissal extensions as an alternative to improve the tactile sensitivity of blind dogs - a preliminary approach investigation.

This preliminary study suggests a way to artificially extend vibrissae of blind dogs to assist ambulation and avoiding facial contact with obstacles. Fourteen irreversibly blind dogs had 5-6 mystacial vibrissae on each side of the face supplementally extended by attaching carefully chosen adult pig hairs to them and were subjected to a maze test before and after the procedure. In three of these dogs the test was repeated one more time after all the extensions had fallen off. Collision counts and course times with and without extensions were analyzed and compared. A p-value > 0.05 was considered significant. Median number of collisions was significantly higher post-extensions (5 IQR 2.25) and after extensions had fallen off (4 IQR 7.50) compared to pre-extensions (1 IQR 1), p = 0.021. Median times were significantly higher pre-extension (25.6 IQR 8.98) and after the extensions had fallen off, compared to the post-extension performance (22.8 IQR 8.55), p = 0.04. Vibrissae play an important role in the tactile perception of blind dogs, and our preliminary results suggest that extending this sensory organ possibly improves obstacle location and their quality of life.

Effects of exit obstacles on the evacuation dynamics of blind people

The modeling of blind people’s behavior is an important topic in pedestrian evacuation dynamics. In order to study movement characteristics of blind people in evacuation process and the effect of indoor obstacles on the evacuation efficiency of blind people, an extended cellular automata model is proposed to simulate blind people evacuation by considering the influence of obstacles. The control variable method is adopted to study the effect of indoor obstacles on the blind evacuation efficiency rule. The numerical simulation is applied to analyze the evacuation process of blind people under different setting (e.g. the location, size and other factors) of obstacles and different evacuation scenarios. The shunt effect of obstacles is discussed and the layout strategy of obstacles is optimized. The results show that the longitudinal obstacles in front of the exit can effectively play the diversion role of obstacles when the obstacle is at a certain distance from the exit, which will improve the evacuation efficiency of the blind. Furthermore, a horizontal obstacle of appropriate length can constrain the trajectory of the blind people and improve the efficiency of evacuation, but when the horizontal obstacle is too long, it will induce extra jam on both sides of the obstacle and hinder the evacuation of the blind. The finding can provide the theoretical basis for the blind people’s organization, management and the optimization of evacuation strategies during an emergency.

Acoustic propagation simulation of closed cavity with obstacles based on finite volume method

The propagation characteristics of sound in different cavities and cavity tube combinations are different. With reasonable design, sound will be dissipated in it to achieve noise elimination effect.Therefore, it is beneficial to optimize the structure design distribution to explore the sound field distribution inside the mechanical structure, so as to minimize the transmitted sound through the wall.Therefore, this paper mainly discusses the sound field distribution in closed cavity and the influence of obstacles on it, providing theoretical guidance for sound insulation design. Firstly, the advantages and disadvantages of different numerical simulation methods are discussed, and the feasibility of finite volume method in acoustic numerical simulation is expounded by comparing the methods used in commercial software. Secondly, based on the FVM, the influence of the location and number of obstacles in the closed cavity on the sound field distribution is emphatically analyzed. The simulation results show that acoustic waves are easy to overlap near obstacles with reflection boundaries. When the number of obstacles increases, the higher-order natural frequency increases. Therefore, in the internal design of the equipment, different sound absorbing materials can be laid on the internal obstruction to reduce the sound wave reflection.

Practical Charger Placement Scheme for Wireless Rechargeable Sensor Networks with Obstacles

Benefitting from the maturation of Wireless Power Transfer technology, Wireless Rechargeable Sensor Networks have become a promising solution for prolonging network lifetime. In practical charging scenarios, obstacles are ubiquitous. However, most prior arts have failed to consider the combined impacts of the material, size, and location of obstacles on the charging performance, making these schemes unsuitable for real applications. In this article, we study a fundamental issue of W ireless ch A rger placement w I th obs T acles (WAIT), that is, how to place wireless chargers by comprehensively considering these parameters of obstacles, such that the overall charging utility is maximized. To tackle the WAIT problem, we first build a practical charging model with obstacles by introducing shadow fading, and conduct experiments to verify its correctness. Then, we design a piecewise constant function to approximate the nonlinear charging power. Afterwards, we develop a Dominating Coverage Set extraction algorithm to reduce the continuous solution space to a limited number. Finally, we prove the WAIT problem is a maximizing monotone submodular function problem, and propose a 1-1/e-ε approximation algorithm to address it. Extensive simulations and field experiments show that our scheme outperforms comparison algorithms by at least 20.6% in charging utility improvement.

What do we head for while exiting a room? a novel parametric distance map for pedestrian dynamic simulations

Identifying effective strategies describing crowd dynamics is crucial to enhance simulations of pedestrians for crowded event planning and management. Various modelling solutions have been proposed to describe how people try to exit from a built environment in normal and emergency. Several of these solutions rely on the use of distance maps or floor fields to account for the positions of existing goals and the location of obstacles to avoid. To date, distance maps are assumed to be static (they do not vary over time) and that pedestrians aim at the actual central coordinate of a door.In this work, we challenge the static goal assumption by proposing a novel parametric distance map which is variable depending on the polar coordinates defining the position of a pedestrian having the centre of an exit as the origin (i.e., the distance of the pedestrian and an angle between its direction and the perpendicular to the exit). In this work, we investigate what pedestrians head for while trying to reach an exit. Different parametric solutions are proposed and calibrated using likelihood-based optimisation methods with over 9000 trajectories of individual pedestrians who navigated through an indoor university atrium building to reach several exits. The results highlight good performance for this modelling approach: pedestrians head for targets in front of an exit when they are away from it, and their targets shift behind the exit as they get closer to it, (i.e., distance impact) while their angle does not have impact on this process. The proposed dynamic goal-based distance map can be applied for future pedestrian simulations for crowded event planning and management.

A Head-Mounted Assistive Device for Visually Impaired People with Warning System from Object Detection and Depth Estimation

People with visual impairment use white cane as their traditional method for perceiving the surroundings. However, the utilization of a cane is limited by its length and orientation. In Thailand, the obstacles on paveway in daily life are not located only on the floor but also above knee level which sometimes could be harmful to pedestrians, especially blind people. A head-mounted assistive device is developed to be an enhancement used with a cane for the visually impaired to comprehend their environment both lower and higher the knee level. The assistive device is designed to be compact and light-weight. It could also send the tactile feedback as a warning from vibration motors mounted on the device. To generate a warning signal, YOLOv4 is used to detect the location of obstacles and depth map from the stereo camera is used to estimate the distance mapping into 4 defined ranges: dangerous, very close, close and fine. The results indicate that the head-mounted assistive device has the ability to perceive obstacles locating farther than 0.9 m. The prediction returned 9.23%, 14.63% and 7.86% error when estimating the depth of obstacles at 1.3 m., 2.8 m. and 4.2 m. respectively. The average execution time for the device to return the command controlling vibration motors is 0.13 second and the maximum estimated time for the motor to send the haptic feedback is 1.05 second.

A Novel VL-Based Positioning Model for Obstacle Location Sensing and 3-D Shape Detection in Crowded Indoor Networks

A Novel VL-Based Positioning Model for Obstacle Location Sensing and 3-D Shape Detection in Crowded Indoor Networks

Study on the effect of obstacles on smoke diffusion and airflow structure in subway stations

Although obstacles exist in every subway station, the impact of obstacles on smoke diffusion characteristics is always overlooked. This work investigates the effect of rectangular obstacles on the ceiling temperature distribution, vertical temperature distribution, and airflow field structure in a subway station fire scenario. Small-scale experiments and numerical simulations are conducted considering varied fire location, heat release rate, blockage ratio, and obstacle location. A dimensionless temperature rise ratio is proposed to quantify the obstacle influence. The key results include (1) Obstacles would cause a proportional decrease in the ceiling temperature rise behind. And the proportion is positively correlated with the blockage ratio but not related to heat release rate, fire location, and obstacle location. (2) The influence of obstacles on vertical temperature rise presents hierarchical characteristics. The same proportional decrease is observed in the smoke layer at the top. As the height decreases in the mixture layer, the temperature rise ratio would also decrease gradually. The air layer at the bottom is kept at a small temperature rise ratio. (3) The wake area behind the obstacle is composed of a recirculation area and a wake recovery area. There is less smoke and slower airflow velocity in the wake area, which means the acquired temperature rise rule is not applicable in this area. A calculation method of the length of the wake area based on the airflow velocity characteristics is presented. This work aims at arousing attention on the influence of obstacles in the fire smoke studies in subway stations.

Research on Sensor Optimization Technology of Driverless Vehicle

Driverless cars in operation, the perception of the surrounding environment demand is very rich, it is a kind of automatic detection of road information, detection of obstacles, calculation of obstacle location, speed and other functions, but due to the limitations of technology and detection means, the perception data of self-driving cars is not accurate enough, prone to safety accidents. Therefore, the optimization of various sensors can greatly improve the safety performance of unmanned vehicles, thereby greatly promoting the development of unmanned technology. Environmental perception technology is one of the core technologies of unmanned cars, environmental perception information comprehensiveness and accuracy is the guarantee of safe driving of unmanned cars, this paper elaborates on image recognition, sensor layout, sensor perception range and accuracy, sensor anti-interference ability and rapid processing of sensor massive data in environmental perception technology.

Recovering source location, polarization, and shape of obstacle from elastic scattering data

We consider an inverse elastic scattering problem of simultaneously reconstructing a rigid obstacle and the excitation sources using near-field measurements. Specifically, we are concerned with the inverse elastic scattering of a bounded obstacle embedded in an unbounded, homogeneous, and isotropic medium. The obstacle is illuminated by the time-harmonic incident field generated by each point source with a single given frequency, and the time-harmonic measurements are the total field along an entire circular curve enclosing the obstacle. A two-phase numerical method is proposed to achieve the co-inversion of multiple targets. In the first phase, we develop several indicator functionals to determine the source locations and the polarizations from the total field data, and then we manage to obtain the approximate scattered field. In this phase, only the inner products of the total field with the fundamental solutions are involved in the computation, and thus it is direct and computationally efficient. In the second phase, we propose an iteration method of Newton's type to reconstruct the shape of the obstacle from the approximate scattered field. Using the layer potential representations on an auxiliary curve inside the obstacle, the scattered field together with its derivative on each iteration surface can be easily derived. Theoretically, we establish the uniqueness of the co-inversion problem and analyze the indicating behavior of the sampling-type scheme. An explicit derivative is provided for the Newton-type method. Numerical results are presented to corroborate the effectiveness and efficiency of the proposed method.

Numerical Investigation of Fluid Flow and Heat Transfer Characteristics over Double Backward-Facing Step with Obstacles

Many engineering device, including nuclear reactors, heat exchangers, and electronic circuit boards, exhibit flow separation and reattachment. To reduce thermal stress impacts, the components of these devices, which resemble stepped channel designs and are susceptible to high heat flux, must be properly cooled. The present work numerically investigates the fluid flow and heat transfer characteristics through a double backward-facing step with elliptic obstacles located after each step. For this purpose, equations governing fluid flow and heat transfer are solved in a Cartesian framework using an in-house code based on streamline upwind/Petrov-Galerkin finite element method. The effect of various parameters (axis ratios (0.25, 0.5, 0.75, 1), vertical location of obstacles (0.38, 0.577, 0.769), Reynolds number (300, 500, 800, 1000)) on fluid flow and heat transfer characteristics in the channel with and without obstacles are compared and quantified. The recirculation region length of the double backward-facing stepped channel with obstacles decreases after the first and second steps when compared with no obstacles. The local Nusselt number distribution along the corner regions of the stepped wall is enhanced due to obstacles. The axis ratio of obstacles has less influence on the convective heat transfer enhancement than the vertical location of the obstacles.

Effect of obstacle parameters on explosion resistance performance of hydrogen crimped-ribbon flame arrester

The effect of the obstacle location L, the distance D, the number N and blockage rate BR on the explosion resistance performance of hydrogen crimped-ribbon flame arrester was investigated. The experimental data including the flame velocity Vf, the explosion pressure Pf and flame temperature Tf entering the flame arrester, and the corresponding flame resistance result Rs were obtained. The results indicated that the Vf, Pf and Tf showed a trend of first increasing and then decreasing with the increase of L, D and BR, while the probability of flame resistance success showed an opposite change trend. The explosion intensity was the highest as L = 650 mm. The Vf, Pf and Tf showed an increase trend with the increase of N, and the rising degree was continuously increased. The hydrogen explosion inhibition by the crimped-ribbon flame arrester was mainly attributed to the combination of endothermic effect and wall effect.