Terrain Obstacles Research Articles

Bayesian-optimized deep learning model to segment deterioration patterns underneath bridge decks photographed by unmanned aerial vehicle

In recent years, bridge collapses and fractures have occurred in various countries mostly following a lack of inspection and maintenance. External inspection processes can be very time-consuming and pose labor safety hazards. Terrain obstacles may also prevent the thorough inspection of some structures. The use of artificial intelligence instead of visual inspection by bridge inspectors is state-of-the-art. This study develops a Bayesian-optimized deep learning model for use on an unmanned aerial vehicle (UAV) to identify the deterioration patterns and segment areas of composite decks under bridges by computer vision-based techniques. The proposed module alters traditional labor-intensive methods of visual bridge inspections, reduces labor safety hazards, and increases inspection accuracy. It can be embedded in an artificial intelligence chip, which is then installed in a consumer-grade UAV, making it a dedicated drone for the external inspection of composite bridges.

Cascade Direct Yaw Moment Control for an Independent Eight In-Wheel Motor-Driven Autonomous Vehicle

Unstructured off-road environments with complex terrain obstacles and pavement properties bring obvious challenges for special purpose autonomous vehicle control. A cascade direct yaw moment control strategy (CDYC), which contains a main loop and a servo loop, is proposed to enhance the accuracy and stability of an independent eight in-wheel motor-driven autonomous vehicle with rear-wheel steering (8WD/RWS). In the main loop, double PID controllers are designed to generate the desired drive moment and yaw rate. In the servo loop, the quadratic programming (QP) algorithm with the tire force boundaries optimally allocates the demanded yaw moment to individual wheel torques. The 8WD/RWS prototype is virtually established using TruckSim and serves as the control object for co-simulation. The proposed cascade controller is verified by simulations in customized off-road driving scenarios. The simulation results show that the proposed control architecture can effectively enhance the path-tracking ability and handling stability of the 8WD/RWS, as to ensure the maneuverability and control stability under extreme off-road conditions.

Using Multi-Source Real Landform Data to Predict and Analyze Intercity Remote Interference of 5G Communication with Ducting and Troposcatter Effects

At present, 5G base stations are densely distributed in major cities based on improving user concentrations and the large demand for services in urban hotspot areas. Moreover, 5G communication requires more accurate communication propagation loss (PL) monitoring. Low-build areas, such as suburbs and rural areas, are prone to forming relatively stable tropospheric ducts, which can bend the signal to the surface in the duct-trapping layer for multiple reflections. Due to the random flow of the atmospheric air mass, each reflection of the communication signal is re-scattered in the troposphere through the top of the duct layer, thereby expanding the propagation range of the signal and changing the expected effect of radio wave propagation. If ducting and troposcatter effects happen in the 5G base station antenna layer, co-channel interference (CCI) could occur, affecting the quality of electromagnetic propagation. Urban links in the plain area have no major terrain obstacles, but ground fluctuations and land cover scattering have a greater impact on the signal scattering at the bottom of the duct. On the basis of the forward-propagation theory, this paper adds factors, such as ducting the forecast value using real weather parameters, terrain, and land cover-type distributions to evaluate the CCIs of over-the-horizon communications on the intercity link. Based on 1300 sets of randomly generated terrains and landforms, two deep learning (DL) models were used to predict the PL of over-the-horizon communications between cities in a land-based ducting environment. The accuracy of LSTM prediction could reach 98.4%. The verification of PL prediction using DL in this paper allows for quick and efficient prediction of PL in the land-based ducting of intercity links using land cover characteristics.

Influence of Hydraulic Drivetrain Configuration on Kinematic Discrepancy and Energy Consumption during Obstacle Overcoming in a 6 × 6 All-Wheel Hydraulic Drive Vehicle

One of the problems limiting the off-road mobility of multi-axle-wheeled vehicles is a kinematic discrepancy, which increases the resistance to motion when negotiating obstacles. This paper presents the results of research on the possibility of reducing the kinematic discrepancy in vehicles with a hydrostatic drive for each wheel by the appropriate selection of hydraulic components—hydraulic motors and flow dividers. Four different configurations of the drivetrain were tested. They used slow-running hydraulic orbital motors and multi-piston radial motors, as well as gear and spool flow dividers. The tests were conducted with computer simulations based on tests that had already been performed to identify hydraulic parts. They allowed for the assessment of the influence of the characteristics of the components and the configuration of the drive system on the differentiation of the rotational speeds of individual wheels, slippage between the wheels and the ground, and the developed driving torques while overcoming obstacles. These values directly translate into the kinematic discrepancy of the system, the ability to overcome terrain obstacles, and energy consumption.

Flexible Motion Framework of the Six Wheel-Legged Robot: Experimental Results

In complex real-world scenarios, wheel-legged robots with maneuverability, stability, and reliability have addressed growing research attention, especially in material transportation, emergency rescue, as well as the exploration of unknown environments. How to achieve stable high-level movement with payload delivery simultaneously is the main challenge for the wheel-legged robot. In this article, a novel hierarchical framework for the flexible motion of the six wheel-legged robot is considered in experimental results. First, for the wheeled motion, the speed consensus algorithm is implemented to the six-wheeled cooperative control; for the legged motion, three gait sequences, and foot-end trajectory based on the Bezier function are designed. Furthermore, a whole-body control architecture includes the attitude controller, impedance controller, and center height controller is developed for obstacle avoidance, which can ensure the horizontal stability of the body of the robot when it passes through obstacles in different terrain. Finally, extensive experimental demonstrations using the six wheel-legged robot (BIT-6NAZA) are dedicated to the effectiveness and robustness of the developed framework, indicating that it is a superior case of a selectable flexible motion with satisfactory stable performance under the field world environment.

Study on the Positioning Accuracy of the GNSS/INS System Supported by the RTK Receiver for Railway Measurements

Currently, the primary method for determining the object coordinates is positioning using Global Navigation Satellite Systems (GNSS) supported by Inertial Navigation Systems (INS). The main goal of this solution is to ensure high positioning availability, particularly when access to satellite signals is limited (in tunnels, areas with densely concentrated buildings and in forest areas). The aim of this article is to determine whether the GNSS/INS system supported by the RTK receiver is suitable for the implementation of selected geodetic and construction tasks in railway engineering, such as determining the place and extent of rail track deformations (1 cm (p = 0.95)), the process of a rapid stocktaking of existing rail tracks (3 cm (p = 0.95)) and for design and construction works (10 cm (p = 0.95)), as well as what the impact of various terrain obstacles have on the obtained positioning accuracy of the tested system. During the research, one INS was used, the Ekinox2-U by the SBG Systems, which was supported by the Real-Time Kinematic (RTK) receiver. GNSS/INS measurements were conducted on three representative sections varying in terms of terrain obstacles that limit the access to satellite signals during mobile railway measurements in Tricity (Poland). The acquired data allowed us to calculate the basic position accuracy measures that are commonly used in navigation and transport applications. On this basis, it was concluded that the Ekinox2-U system can satisfy the positioning accuracy requirements for rapid stocktaking of existing rail tracks (3 cm (p = 0.95)), as well as for design and construction works (10 cm (p = 0.95)). On the other hand, the system cannot be used to determine the place and extent of rail track deformations (1 cm (p = 0.95)).

CLUTTER HEIGHT PRODUCTION TECHNOLOGY WITH ARCGIS FOR THE PURPOSES OF LTE AND 5G RADIO NETWORK PROPAGATION AND OPTIMIZATION

The geospatial data accuracy and specification requirements for LTE and 5G radio propagation and optimization are much higher than those used in planning 2G and 3G networks. The recommended geospatial data resolution of 1–2 meters allows the display of the smallest parts of geospatial objects. In the article, we describe the technology and its practical implementation to produce an accurate clutter height (raster canopy height model) for the purposes of LTE and 5G radio network propagation and optimization. This technology, which is based on aerial images, may be adapted to use LiDAR data. The technology includes the data integration between the different software. The processing of digital terrain models, obstacles (buildings and vegetation) and DSM cloud points is performed in geographic information systems, such as ArcGIS. The technology was proven by the practical implementation and calculation in multi-technology wireless network design and optimization platform Atoll.

Neural-Adaptive Constrained Flight Control for Air–Ground Recovery Under Terrain Obstacles

This article contrives a neural-adaptive constrained controller of the cable towed air–ground recovery system subject to terrain obstacles, unmeasurable cable tensions, trailing vortex, wind gust, and actuator saturation. In air–ground recovery system modeling, the towed vehicle's nominal 6 DOF affine nonlinear dynamics and the cable system's finite links-joints dynamics are formulated. To achieve accurate air–ground recovery under terrain obstacles, an asymmetric barrier Lyapunov function-based flight controller of the towed vehicle is proposed, by transforming the terrain obstacles into time-varying constraints on the vehicle's trajectory. Then, to approximate the towed vehicle's lumped unknown dynamics caused by the unmeasurable cable tensions and airflows, several echo state network (ESN) approximators are established for velocity and attitude subsystems. By using the state approximation errors-based neural weights learning strategy and minimal learning parameter technique, these ESNs possess better transient behaviors and lower online computational burden. Furthermore, the actuator saturation is automatically monitored and released, by incorporating a specially designed auxiliary compensating system into the angular rate control law for compensation. The stability of the closed-loop system is analyzed. Finally, numerical simulations under two air–ground recovery scenarios are performed to demonstrate the performance of the proposed controller.

Improvement in algorithms for quality control of weather radar data (RADVOL-QC system)

Abstract. Data from weather radars are commonly used in meteorology and hydrology, but they are burdened with serious disturbances, especially due to the appearance of numerous non-meteorological echoes. For this reason, these data are subject to advanced quality control algorithms. The paper presents a significant improvement of the RADVOL-QC system made necessary by the appearance of an increasing number of various disturbances. New algorithms are mainly addressed to the occurrence of clutter caused by wind turbines (DP.TURBINE algorithm) and other terrain obstacles (DP.NMET algorithm) as well as various forms of echoes caused by the interaction of a radar beam with RLAN signals (set of SPIKE algorithms). The individual algorithms are based on the employment of polarimetric data as well as on the geometric analysis of echo patterns. In the paper the algorithms are described along with examples of their performance and an assessment of their effectiveness, and finally examples of the performance of the whole system are discussed.

Drone-based electromagnetic survey system for geophysical applications

Geophysical electromagnetic (EM) methods are used in geological mapping, mineral exploration, groundwater studies and geotechnical investigations. Airborne EM methods have the benefit of avoiding terrain obstacles such as lakes, rivers, swamps, and ravines. Compared to manned aircrafts, drones or unmanned aerial vehicles (UAVs) have benefits of their own. Drone-based surveys are versatile, fast to deploy, economical and ecologically more friendly. Presently, magnetic surveying is the only geophysical method that is routinely conducted with drones. The modest maximum payload limit of drones imposes severe restrictions on the applicability of other methods including EM and radiometric methods, for example. Finnish company, Radai Ltd has been developing Louhi, a novel drone-based frequency-domain EM survey system, in an EU funded Horizon 2020 project NEXT – New Exploration Technologies. The EM system has two operation options – the first uses a large loop on the ground as an EM source and the other uses a small portable EM transmitter loop. Both systems utilize a stand-alone and light-weight three-component EM receiver that can be towed by a drone. This article presents the theoretical background of the EM methods, the solution developed by Radai Ltd, the current version of the EM device, and results from field and flight tests that demonstrate the applicability of the drone-based EM system under development.

Development of a Caterpillar-Type Walker for the Elderly People

A walker assists elderly people with age-related reduced walking ability and helps to improve stability and balance ability. However, if the general-type walker (GTW) is used on an uneven, obstacle, or sloped terrain, it may cause excessive muscle use and falls. Therefore, in this study, we developed a caterpillar-type walker (CTW) that elderly people can safely use in various terrains. Twelve elderly who were able to walk normally participated in the study. The activity of upper and lower extremity muscles, the number of obstacles overcome, and walking speed was compared and analyzed when using two types of walkers in uneven terrain, obstacle terrain, and sloped terrain. In addition, satisfaction with the use of these walkers was evaluated. When CTW was used, the activity of the muscles of the upper and lower extremities was significantly reduced compared to the use of GTW on all terrains. The walker developed in this study overcame obstacles of all heights, but the GTW failed to overcome obstacles starting from the 2 cm section. In terms of walking speed, when the CTW was used, the walking speed was higher than that of the GTW in uneven terrain and obstacle terrain. In satisfaction, there were significant differences in safety, durability, simplicity of use, comfort, and effectiveness. Through these results, it was confirmed that the CTW can efficiently and safely assist the elderly in walking on uneven terrain, obstacle terrain, and inclined terrain.

Analysis of the usability of rolling resistance measurement methods to study the mechanisms of some wheelchairs

Reducing the driving force when propelling a wheelchair, e.g. through mechanical gears, is beneficial for people using wheelchairs. This makes it possible to overcome terrain obstacles that would be otherwise impassable with a classic drive system. However, the disadvantage of additional mechanisms supporting the propulsion of the wheelchair is usually the additional mass, ultimately increasing the rolling resistance. The article presents methods of measuring the rolling resistance – widely developed in the automotive industry – in terms of measuring the rolling resistance of wheelchairs. Innovative methods have been demonstrated to measure the rolling resistance on various surfaces and with the use of various drive mechanisms. The developed methods also enable the determination of the rolling resistance coefficient. The methods used are innovative and are subject to patent protection prepared by the authors in recent years. The results of the respondents allow to compare the measurement accuracy of the developed methods and show that the second method (being a simplification of the first method) is characterized by better accuracy.

Development of Medical Drone for Blood Product Delivery: A Technical Assessment

Drone is the well-known technology in military and amateur application. Recently, the drone was used to deliver goods and parcels. There is an increasing need for urgent delivery of medical supplies in low resource setting due to traffic congestion and terrain obstacles. The delivery of blood in emergency cases such as postpartum hemorrhaging is challenging and can be delayed due to geographical condition in underserved area. Postpartum hemorrhaging needs an immediate blood transfusion with proper blood product to save the life of mother and baby. To address to this need, a drone that can deliver blood supply to the desired location may be a good option. Therefore, research has been conducted to identify the baseline of drone specifications for blood delivery. A Hexacopter with the ArduPilot firmware and a Lithium-Polymer battery of 16,000 mAh were used to study the applicability of blood products delivery using drone. Using several tests to assess drone limitations, experimental data was obtained and analyzed using distinctive methods. The results indicated that the thrust-to-weight ratio of the drone play a paramount role for the drone performance and flight time. The GPS guidance performance showed a reliable and stable flight with only a slight deviation of ±6 meters during the tests. Finally, a test flight was conducted to simulate the actual test location from Queen Elizabeth Hospital and Hospital Wanita dan Kanak-Kanak, Likas, Sabah. The developed drone reached a flight time of 25 minutes covering 8.38 km with 4.3 kg take-off weight.

Methodology of Using Terrain Passability Maps for Planning the Movement of Troops and Navigation of Unmanned Ground Vehicles.

The determination of the route of movement is a key factor which enables navigation. In this article, the authors present the methodology of using different resolution terrain passability maps to generate graphs, which allow for the determination of the optimal route between two points. The routes are generated with the use of two commonly used pathfinding algorithms: Dijkstra’s and A-star. The proposed methodology allows for the determination of routes in various variants—A more secure route that avoids all terrain obstacles with a wide curve, or a shorter route, which is, however, more difficult to pass. In order to achieve that, two functions that modify the value of the index of passability (IOP), which is assigned to the primary fields that the passability map consists of, have been used. These functions have a β parameter that augments or reduces the impact of the applied function on IOP values. The paper also shows the possibilities of implementation of the methodology for the movement of single vehicles or unmanned ground vehicles (UGVs) by using detailed maps as well as for determining routes for large military operational units moving in a 1 km wide corridor. The obtained results show that the change in β value causes the change of a course of the route as expected and that Dijkstra’s algorithm is more stable and slightly faster than A-star. The area of application of the presented methodology is very wide because, except for planning the movement of unmanned ground vehicles or military units of different sizes, it can be used in crisis management, where the possibility of reaching the area outside the road network can be of key importance for the success of the salvage operation.

Study on Blasting Construction Technology of Tunnel Engineering in Soil-rock Interlaced Strata at Soft and Hard Rock Boundary

With the development of transportation construction and the acceleration of urbanization in China, the construction of urban highway tunnel engineering has also entered a new climax. In order to overcome obstacles in terrain and elevation such as railway construction, blasting technology for railway tunnel construction is widely used. However, due to the unhealthy and complex geological conditions of railway tunnels, and the unreasonable application of blasting technology, blasting safety accidents occur. Blasting technology in railway tunnel construction, but blasting construction is easily interfered by various external interference factors. In the tunnel face blasting construction under the condition of soil-rock crisscross composite stratum, not only the physical and mechanical properties of the lower surrounding rock should be considered, but also the engineering characteristics of the upper surrounding rock or surface rock mass have great influence on the construction blasting. Taking the actual project as an example, this paper expounds the tunnel engineering and geological conditions, and studies the blasting construction technology of the tunnel engineering in the soft and hard rock boundary soil-rock crisscross strata to ensure the safety of blasting construction.

Development of a Vision-Based Recognition and Position Measurement System for Cooperative Missions of Multiple Heterogeneous Unmanned Vehicles

Research on cooperation missions of multiple unmanned vehicles (UVs) is growing to overcome the limitations of conventional missions and to increase the variety of missions. In this study, a vision-based recognition and position measurement system was developed to cooperate with an unmanned aerial vehicle (UAV) in case an unmanned ground vehicle (UGV) is unable to drive due to terrain obstacles. Phase, mode, and requirements were derived to develop the vision system. After installing the developed vision system on UAV, several flight tests were conducted, which proved that the system satisfies all requirements. The vision system showed an average measurement error within 1 m for 80 measurements. It is expected that the vision-based system developed in this study can be applied for the cooperative mission of UAVs and UGVs.

Selection and Study of Functional Modules for Amphibious Unmanned Search Vehicles

In recent years, since the 18th National Congress first proposed the strategy of a strong country of the sea, China has begun a series of measures to improve the ability to develop marine resources, develop the marine economy, protect the marine ecological environment, and build a strong country of the sea in all aspects. Although China’s maritime search and rescue work at the policy level has made some progress, but the overall search and rescue system, the mechanical equipment process of propulsion is not yet mature, and the combination of existing search and rescue technology is not perfect, need more new thinking to. While the application of air search and rescue system has certain limitations, but the two search and rescue technology has gone through a long development, if it is applied to the marine level, it can better avoid terrain obstacles, so as to get better results.

Verification Protocols for the Lightning Protection of a Large Scale Scientific Instrument in Harsh Environments: A Case Study

This paper is devoted to the study of the most suitable protocols needed to verify the lightning protection and ground resistance quality in a large-scale scientific facility located on a site with high risk of lightning strikes. We illustrate this work by reviewing a case study: the largest telescopes of the Northern Hemisphere Cherenkov Telescope Array, CTA-N. This array hosts sensitive and high-speed optoelectronics instrumentation and sits on a clear, free from obstacle terrain at around 2400 m above sea level. The site offers a top-quality sky but also features challenging conditions for a lightning protection system: the terrain is volcanic and has electrical resistivities well above 1 kOhm·m. In addition, the environment often exhibits humidities well below 5%, and strong winds pose challenging conditions. On the other hand, the high complexity of a Cherenkov telescope structure does not allow a straightforward application of lightning protection standards. We describe here how the risk assessment of direct strike impacts was made and how contact voltages and ground system were both tested. Finite Element Simulation (COMSOL Multiphysics) has been used to estimate the current flowing through the parts of the earthing system designed for the telescopes in the case of a direct strike impact. This work is intended to provide assistance to scientists and managers involved in the construction of scientific installations, particularly those in charge of defining verifiable reliability and safety requirements for lightning protection.

A hybrid tactile sensor-based obstacle overcoming method for hexapod walking robots

Walking robots are considered as a promising solution for locomotion across irregular or rough terrain. While wheeled or tracked robots require flat surface like roads or driveways, walking robots can adapt to almost any terrain type. However, overcoming diverse terrain obstacles still remains a challenging task even for multi-legged robots with a high number of degrees of freedom. Here, we present a novel method for obstacle overcoming for walking robots based on the use of tactile sensors and generative recurrent neural network for positional error prediction. By using tactile sensors positioned on the front side of the legs, we demonstrate that a robot is able to successfully overcome obstacles close to robots height in the terrains of different complexity. The proposed method can be used by any type of a legged machine and can be considered as a step toward more advanced walking robot locomotion in unstructured terrain and uncertain environment.

IoD swarms collision avoidance via improved particle swarm optimization

Abstract Drones flights have been investigated widely. In the presence of high density and complex missions, collision avoidance among swarm of drones and with environment obstacles becomes a challenging task and indispensable. This paper aims to enhance the optimality and rapidity of three dimensional IoD path generation by improving the particle swarm optimization (PSO) algorithm. The improvements include using chaos map logic to initialize the population of PSO. Also, adaptive mutation is utilized to balance local and global search. Then, the inactive particles are replaced by new fresh particles to push the solution toward global optimal. Furthermore, Monte Carlo simulation is carried out and the results are compared with slandered PSO and with recent work CIPSO. The results exhibit significant improvement in convergence speed as well as optimal solution which prove the ability of proposed method to generate safety path for IoD formation without collision with terrain obstacle and among drones.