Laser Range Research Articles

Velocity Estimation and Cost Map Generation for Dynamic Obstacle Avoidance of ROS Based AMR

In the past few years, due to the growth of the open-source community and the popularity of perceptual computing resources, the ROS (Robotic Operating System)Ecosystem has been widely shared and used in academia, industrial applications, and service fields. With the advantages of reusability of algorithms and system modularity, service robot applications are flourishing via the released ROS navigation framework. In the ROS navigation framework, the grid cost maps are majorly designed for path planning and obstacle avoidance with range sensors. However, the robot will often collide with dynamic obstacles since the velocity information is not considered within the navigation framework in time. This study aims to improve the feasibility of high-speed dynamic obstacle avoidance for an ROS-based mobile robot. In order to enable the robot to detect and estimate dynamic obstacles from a first-person perspective, vision tracking and a laser ranger with an Extend Kalman Filter (EKF) have been applied. In addition, an innovative velocity obstacle layer with truncated distance is implemented for the path planner to analyze the performances between the simulated and actual avoidance behavior. Finally, via the velocity obstacle layer, as the robot faces the high-speed obstacle, safe navigation can be achieved.

Electric Field Strength Simulation Using 2D-Environment Map Generated by Tele-Operated Mobile Robot

In this study, we demonstrate the avoidance of the “lost robot” situation when wireless communication is interrupted. In our proposed method, the mobile robot measures the unknown environmental shape using a laser range finder. The sensor data and additional information (thickness and material characteristics) of the real environment are combined into the line segment map. We found that the electric field strength can be simulated using the line segment map. Experimental results verify the effectiveness of our proposed method.

Development of a Real-Time Simulator for a Semi-Autonomous Tele-Robot in an Unknown Narrow Path

This study proposes a teleoperation system for assistive controlling of the movement of a mobile robot in a narrow path. The teleoperation system is created by combining data from real and virtual devices. In CoppeliaSim we applied the Braitenberg algorithm and the open motion planning library module (OMPL). The Braitenberg algorithm is a sensor-based automatic motion designed to aid the robot operator in maneuvering through the narrow path. While the OMPL is used to create a path for the operator to control the robot in narrow paths or intersections within a narrow path, the simulation uses a virtual proximity sensor to fulfill the Braitenberg algorithm requirement. With dynamic simulation a laser rangefinder obtains the environmental data and displays it on the simulation screen. The simulation scene is subjected to the virtual proximity sensor and the Braitenberg algorithm is applied to the simulation scene. Afterward, simulation scripts are written to incorporate the linear and angular velocities into a robot operating system for real-time robot control. The results showed that the system was capable of combining real-time dynamic simulation with the real world. Furthermore, the proposed system could aid the operator in narrow path environments while avoiding collision.

History of military laser technology development in military applications

The aim of this research is to study the development as well as the known cases of military applications of laser technologies – from the first lasers employed in auxiliary systems to modern complex independent laser systems. For better understanding and systematization of knowledge about development of historical applications in the military field, an analysis of publicly known knowledge about their historical applications in the leading world countries was conducted. The study focuses on development that was carried out by the superpowers of the Cold War and the present era, namely the United States, the Soviet Union and the Peoples Republic of China, and were built in metal. Multiple avenues of various applications of laser technology in military applications were studied, namely: military laser rangefinders; ground and aviation target designators; precision ammunition guidance systems; non-lethal anti-personnel systems; systems, designed to disable optoelectronics of military vehicles; as well as strategic and tactical anti-air and missile defense systems. To summarize and compare the results, an analysis of a number of previous works was considered, which considered the historical development, prospects and problems of the laser weaponry development. The issues of ethical use of laser weapons and the risks of their use in armed conflicts, which led to an international consensus in the form of conventions of the United Nations and the International Committee of the Red Cross, were also considered. As a result of the analysis, a systematic approach to the classification of applications of laser technology in military products by three main areas of development was proposed: ancillary applications, non-lethal direct action on the human body and optical devices of military equipment, and anti-aircraft and anti-missile defensive systems. Due to the constant comprehensive modernization of laser technology systems in use, it was decided not to use the periodic classification model, but to indicate important and key events that indicated the main directions of further developmental work. However, it is important to note that the main focus of historical development of laser weapons depended not only on the technological limitations of the time, but also on the military-geopolitical situation in the world.

PREFACE

PREFACE

Use of technical means during an investigative experiment

The article highlights the problems of using technical means during such an investigative (search) activity as an investigative experiment. For this purpose, the practice of pre-trial investigation bodies, expert institutions and scientific literature have been analyzed. Since the purpose of this procedural action is to verify and clarify information important for the pre-trial investigation, it emphasizes the need for mandatory use of a variety of technical means, which will be most appropriate and effective depending on the circumstances of the criminal offence.
 Attention is drawn to cases when an investigative experiment should be conducted in the housing or other property of a person. In this case, a video camera will be a mandatory means of recording, for the normal operation of which during the entire procedural action it is advisable to have several powerbanks and a significant amount (32 GB or more) of data storage device in reserve. To provide direct technical assistance, it is recommended to involve a specialist who has special skills in using technical and other means in conducting an investigative experiment. This will allow the investigator to focus on drawing up a protocol, high-quality organization of the investigative experiment and achieving the purpose of its implementation, and the specialist will ensure its high-quality recording and proper design of applications.
 Recommendations are given for the use during the investigative experiment of not only such standard means of fixation as a camera or video camera, but also a forensic briefcase, various means of lighting, measuring devices (laser range measuring device, measuring tape, sound level meter, speed gun TruCAM), means for reconstructing an event or creating conditions close to it (water sprayers, fans), etc. Taking into account the variety of technical means, it is noted that the investigator must comply with the requirements of Article 104 of the Criminal Procedure Code of Ukraine regarding a detailed description in the protocol of the characteristics of technical means and information carriers using which the investigative experiment is recorded.

Bridge Crack Inspection Efficiency of an Unmanned Aerial Vehicle System with a Laser Ranging Module.

In this study, an unmanned aerial vehicle (UAV) with a camera and laser ranging module was developed to inspect bridge cracks. Four laser ranging units were installed adjacent to the camera to measure the distance from the camera to the object to calculate the object’s projection plane and overcome the limitation of vertical photography. The image processing method was adopted to extract crack information and calculate crack sizes. The developed UAV was used in outdoor bridge crack inspection tests; for images taken at a distance of 2.5 m, we measured the crack length, and the error between the result and the real length was less than 0.8%. The developed UAV has a dual-lens design, where one lens is used for bridge inspections and the other lens is used for flight control. The camera of the developed UAV can be rotated from the horizontal level to the zenith according to user requirements; thus, this UAV achieves high safety and efficiency in bridge inspections.

Particle trajectories, gamma-ray emission, and anomalous radiative trapping effects in magnetic dipole wave.

In studies of interaction of matter with laser fields of extreme intensity there are two limiting cases of a multibeam setup maximizing either the electric field or the magnetic field. In this work attention is paid to the optimal configuration of laser beams in the form of an m-dipole wave, which maximizes the magnetic field. We consider in such highly inhomogeneous fields the advantages and specific features of laser-matter interaction, which stem from individual particle trajectories that are strongly affected by gamma photon emission. It is shown that in this field mode qualitatively different scenarios of particle dynamics take place in comparison with the mode that maximizes the electric field. A detailed map of possible regimes of particle motion (ponderomotive trapping, normal radiative trapping, radial, and axial anomalous radiative trapping), as well as angular and energy distributions of particles and gamma photons, is obtained in a wide range of laser powers up to 300 PW, and it reveals signatures of radiation losses experimentally detectable even with subpetawatt lasers.

Autonavi3at Software Interface to Autonomously Navigate on Urban Roads Using Omnidirectional Vision and a Mobile Robot


 
 
 
 
 
 
 The design of efficient autonomous navigation systems for mobile robots or autonomous vehicles is fundamental to perform the programmed tasks. Basically, two kind of sensors are used in urban road following: LIDAR and cameras. LIDAR sensors are highly accurate but expensive and extra work is needed for human understanding of the point cloud scenes; however, visual content is understood better by human beings, which should be used to develop human-robot interfaces. In this work, a computer vision-based urban road following software tool called AutoNavi3AT for mobile robots and autonomous vehicles is presented. The urban road following scheme proposed in AutoNavi3AT uses vanishing point estimation and tracking on panoramic images to control the mobile robot heading on the urban road. To do that, Gabor filters, region growing, and particle filters were used. In addition, laser range data are also employed for local obstacle avoidance. Quantitative results were achieved using two kind of tests, one uses datasets acquired at the Universidad del Valle campus, and field tests using a Pioneer 3AT mobile robot. As a result, important improvements in the vanishing point estimation of 68.26 % and 61.46 % in average were achieved, which is useful for mobile robots and autonomous vehicles when they are moving on urban roads.
 
 
 
 
 
 

Next-generation Laser Ranging at Lunar Geophysical Network and Commercial Lander Payload Service Sites

Five retroreflector arrays currently on the Moon reflect short laser pulses back to Earth, allowing range to be measured. Each array has multiple small corner cubes. Due to variable lunar optical librations of the direction to Earth, the tilted arrays spread return times of single photons in the returned laser pulse, degrading the synthesized multiphoton normal point range accuracy. The Next Generation Lunar Retroreflectors (NGLRs) and MoonLIGHT reflectors currently being fabricated are larger 10 cm single corner cubes that do not spread the pulse. The Lunar Geophysical Network (LGN) mission will place NGLRs at three separated sites on the lunar nearside. The Commercial Lander Payload Service (CLPS) and early Artemis missions will precede the LGN mission. Solutions that include 6 yr of simulated Lunar Laser Ranging (LLR) data to two sites in the north and two in the south show improvement in the uncertainties of many science parameters. Lunar solution parameters include displacement Love numbers h 2 and l 2, tidal dissipation at several frequencies, fluid-core/solid-mantle boundary (CMB) dissipation, and moment of inertia combinations (C–A)/B and (B–A)/C, with principal moments of inertia A < B < C. Submeter-accuracy coordinates of the new reflectors will result from the first month of well-distributed data. There are benefits other than lunar science: gravitational physics includes the equivalence principle; Earth science includes terrestrial tidal dissipation and ranging station positions and motions; and astronomical constants with GM(Earth+Moon) for the gravitational constant times the mass of the Earth–Moon system. Improvements are illustrated for h 2, l 2, (C–A)/B, (B–A)/C, equivalence principle, and GM(Earth+Moon).

A global, continuous calibration curvature strategy for bending sensors of soft fingers

PurposeThe aim of the paper is to propose a global, automated and continuous curvature calibration strategy for bending sensors, which is used for the angle feedback control of soft fingers.Design/methodology/approachIn this work, the proposed curvature calibration strategy for bending sensors is based on the constant curvature bending properties of soft fingers. The strategy is to install the bending sensor on the soft finger and use the laser distance sensor to assist calibration, then calculate the relationship between the curvature and the voltage of the bending sensor through geometric conversion. In addition, this work also develops a full set of standard calibration systems and collection procedures for the bending sensor curvature calibration and uses machine learning algorithms to fit the collected data.FindingsFirst, compared with the traditional calibration methods, the proposed curvature calibration strategy can achieve constant curvature measurement with the advantages of better continuity. Second, using the sensor data obtained by the proposed calibration method as the feedback signal for the soft finger bending angle control, the control effect is better than that of the traditional method.Originality/valueThis work proposes and verifies a global, automated and continuous curvature calibration strategy for bending sensors and is used for the angle feedback control of soft fingers. In addition, this work also develops a full set of standard calibration systems and collection procedures, which can be applied to a variety of flexible bending sensors with a good adaptability.

Evaluation of strategies for the ultra-rapid orbit prediction of BDS GEO satellites

ABSTRACT The quality of BeiDou Navigation Satellite System (BDS) Geostationary Earth Orbit (GEO) ultra-rapid products is unsatisfactory because GEO satellites are nearly stationary relative to ground stations. To optimize the quality of these ultra-rapid orbit products, we investigated the effects of the fitting arc length, an a priori Solar-Radiation Pressure (SRP) model, and the along-track empirical acceleration on the prediction of BDS GEO satellite orbits. The predicted orbit arcs of 24-h were evaluated through comparisons with the corresponding observed orbit arc and Satellite Laser Ranging (SLR) observations. In both eclipse and non-eclipse seasons, accuracy of the orbit predictions obtained using a 48-h fitting arc length were better than those obtained using 24-h and 72-h fitting arc lengths. Although the overlapping precision of predicted orbits exhibited no obvious improvement when an a priori SRP model was employed, the systematic bias in the SLR residuals was significantly reduced. Specifically, the mean value of SLR residuals decreased from −0.248 m to −0.024 m during non-eclipse seasons and from −0.333 m to −0.041 m during eclipse seasons, respectively. In addition, when an empirical acceleration in the along-track direction was introduced, the three-Dimensional Root-Mean-Square (3D RMS) of overlapping orbits during eclipse seasons decreased from 2.964 to 1.080 m, which is comparable to that during non-eclipse seasons. Furthermore, the Standard Deviation (STD) of SLR residuals decreased from 0.419 to 0.221 m during eclipse seasons. The analysis of SRP estimates shows that the stability of SRP parameters was significantly enhanced after the introduction of along-track empirical acceleration in eclipse seasons. The optimal BDS GEO ultra-rapid orbit prediction products were yielded by using a 48-h fitting arc length, an a priori SRP model and an along-track empirical acceleration.

The facilities and performance of TianQin laser ranging station

The TianQin Project is aiming at gravitational wave (GW) detection in space. TianQin GW observatory comprises three satellites orbiting on 1 × 105 km Earth orbits to form an equilateral-triangle constellation. In order to minimize the variations in arm lengths and breathing angles, the satellites must be launched and adjusted precisely into an optimized orbit. Therefore, satellite laser ranging must be used to enhance the precision of satellite orbit determination. To develop the capability of satellite laser ranging for TianQin’s orbit, the TianQin Laser Ranging Station has been designed and constructed to perform high-precision laser ranging for TianQin satellites and lunar laser ranging as well. Applying a 1064 nm Nd: YAG laser with 100 Hz repetition frequency, 80 pico-second pulse duration, and 2 × 2 array of superconducting nanowire single-photon detectors, we have obtained the laser echo signals from the five lunar retro-reflector arrays, and the measurement data have been packaged into 234 normal points (NPs), including a few data measured during the full-moon lunar phase. Each NP is calculated from continuous measurement for about ten minutes and the statistical error of the NPs is about 7 mm (1σ).

An Accurate and Stable Extrinsic Calibration for a Camera and a 1D Laser Range Finder

Due to low cost and ease of manufacture, the combined sensor consisted of a camera and a 1D laser range finder is commonly used in many engineering applications. Especially in aerospace field, this type of combined sensor is important to earth observation and deep space exploration. This article proposes a novel extrinsic calibration method to get the accurate and stable calibration results of camera-1D laser range finder combined sensor. Firstly, an accuracy criterion named with directional comprehensive criterion is proposed to solve the less constraint in traditional calibration methods, which can evaluate the inconsistencies in the 1D laser ranging direction and the mean reprojection error in the 2D image plane direction fully. Then, according to the proposed directional comprehensive criterion, a novel robust extrinsic calibration framework is presented, which removes the observation data with large errors automatically and utilizes a stability criterion as the termination condition. The simulation experiments and real data experiments reveal that the proposed method is effective, which is superior to the existing methods.

Map-based localization for intelligent vehicles from bi-sensor data fusion

Accurate localization is a challenging task for intelligent vehicles (IVs). Map-based localization methods are promising as they have no cumulative errors and high accuracy. Most methods are based on a single sensor, such as a camera or laser rangefinder (LRF). However, these sensors have disadvantages. Thus, this study proposes a map-based localization method from bi-sensor data fusion. We proposed a method using a camera, LRF, differential Global Positioning System, Inertial Navigation System to generate a multi-scale map. The multi-map consists of scenario nodes, and each node encodes scenario features, road 3D structure, and trajectories. Based on the multi-scale map, we propose an accurate localization method that includes coarse, node-level, and metric localizations. A bitopological localization model is set up for coarse localization. In this model, we use previous feature matching results to predict the current position. The features include image and light detection and ranging (LIDAR) data, and each of them set up one topological model. The two models make up a bitopological localization model. In node-level localization, we extract the LIDAR and image features and match them with the multi-scale map. The closest node is found by K-nearest neighbors from multiple feature spaces. In this step, we keep the image feature extraction in mind and propose a novel LIDAR feature extraction method called the LIDAR-image feature. In metric localization, we solve the perspective n-points problem between the current position and the closest node to compute the pose of IVs. In the experiments, our method has been tested on open road and campus. Each route covers different times and weather conditions. The proposed method can achieve less than 0.20 m mean localization errors. Compared with existing map-based methods, our method utilizes bi-sensors to improve localization performance.

Contribution of Etalon Observation to Earth Rotation Parameters under a New Observation Scenario

The standard products of the International Laser Ranging Service (ILRS) are mainly based on the two laser geodynamics satellites (LAGEOS) due to the sparse observations of the Etalon satellites. With improvements in the ability to track high-altitude satellites, ILRS conducted a 3-month Etalon tracking campaign. In this paper, we study the contribution of more Etalon observations in the new observation scenario to weekly ILRS products, such as station coordinates, Earth rotation parameters (ERPs) and satellite orbit. We compare the ILRS products estimated from LAGEOS-only solutions and LAGEOS+Etalon solutions. In the new observation scenario of 2019, the numbers of observations of Etalon satellites are 1.4 and 1.7 times larger than those in 2018. It is shown that the quality of station coordinates, and the satellite orbit of LAGESOS satellites are only slightly affected by the increase in Etalon observations of the campaign. However, for station 1868, which is dedicated to high-altitude satellites, the root mean square (RMS) values of the residuals in the N, E, and U components are improved by 3.1 cm, 2.1 cm and 2.3 cm, respectively. The internal precision of orbit for Etalon-1/2 satellites in tangle and normal directions are improved by 1.5 cm and 2.9 cm, respectively. Most remarkably, the standard deviations for Xp, Yp and LOD can be improved by 6.9%, 14.3% and 5.1%, respectively, compared with the International Earth Rotation System (IERS)-14-C04 series. With our research, the ILRS could increase efforts on Etalon satellite tracking without affecting the routine observations of LAGEOS satellites.

Autonomous Movement Control of Coaxial Mobile Robot based on Aspect Ratio of Human Face for Public Relation Activity Using Stereo Thermal Camera

In recent years, robots that recognize people around them and provide guidance, information, and monitoring have been attracting attention. The mainstream of conventional human recognition technology is the method using a camera or laser range finder. However, it is difficult to recognize with a camera due to fluctuations in lighting 1), and it is often affected by the recognition environment such as misrecognition 2) with a person's leg and a chair's leg with a laser range finder. Therefore, we propose a human recognition method using a thermal camera that can visualize human heat. This study aims to realize human-following autonomous movement based on human recognition. In addition, the distance from the robot to the person is measured with a stereo thermal camera that uses two thermal cameras. A coaxial two-wheeled robot that is compact and capable of super-credit turning is used as a mobile robot. Finally, we conduct an autonomous movement experiment of a coaxial mobile robot based on human recognition by combining these. We performed human-following experiments on a coaxial two-wheeled robot based on human recognition using a stereo thermal camera and confirmed that it moves appropriately to the location where the recognized person is in multiple use cases (scenarios). However, the accuracy of distance measurement by stereo vision is inferior to that of laser measurement. It is necessary to improve it in the case of movement that requires more accuracy.

A Low-Cost and Portable Indoor 3D Mapping Approach Using Biaxial Line Laser Scanners and a One-Dimension Laser Range Finder Integrated with Microelectromechanical Systems

Existing indoor 3D mapping solutions suffer from high cost and poor portability. In this article, a low-cost and portable indoor 3D mapping approach using biaxial line laser scanners and a one-dimension laser range finder integrated with microelectromechanical systems is proposed. A multiple-sensor calibration approach is presented to perform the extrinsic calibration of the integrated 3D mapping system. The 2D point cloud acquired by the horizontal laser scanner and the orientation information obtained by the microelectromechanical systems are used as inputs for a simultaneous localization and mapping framework to estimate the 2D poses. The height information acquired by the laser range finder is then fused to obtain the 3D pose, which is applied to restore the actual position and orientation of the 2D point cloud generated by the tilted laser scanner to reconstruct the 3D point cloud of the indoor environment. The experimental results—three typical indoor scenes—demonstrate that the proposed approach can achieve accuracies of 3 cm and 2°. Therefore, the proposed approach is a low-cost, portable, and accurate solution for indoor 3D mapping.

A new fast estimating floor region based on image segmentation for smart rovers

In this paper, a new algorithm that hardware acceleration has enabled to estimate floor regions in a single image for unmanned ground vehicle (UGV) robots is presented. In general, the cluttered indoor surroundings patterned floors, shadows, and reflections make it extremely difficult to identify floor regions. The proposed algorithm combines extracting surface texture characteristics with specific geometric areas to determine object boundaries and then uses SVM classification to distinguish between the floor and non-floor regions. To achieve real-time performance, the implementation of the proposed algorithm on an SoC FPGA embedded platform gives a heterogeneous hardware acceleration methodology. In experimental results, a public MIT scene dataset and indoor database were used to verify detection accuracy. Compared to other research, the proposed algorithm accuracy can reach up to 94.72% on average without the assistance of any other physical sensors, such as RGB-D or laser ranger sensors.

Wavelength tuning for random lasing of mist-CVD-grown Zn1−x Mg x O crystals with nanostructures on a-plane sapphire substrates

Zn1−x Mg x O crystals with nanostructures were grown on a-plane sapphire substrates by mist chemical vapor deposition (mist-CVD). The grown Zn1−x Mg x O crystals had a wurtzite crystalline, and their room-temperature photoluminescence peaks of them varied from approximately 355.5 to 377.9 nm depending on the composition of magnesium. Under high excitation conditions using a Nd:YAG pulse laser, random lasing behaviors were obtained from Zn1−x Mg x O crystals, and the tuning in the wavelength range of these random lasing was demonstrated. These results suggest that the mist-CVD crystal growth on a-plane sapphire substrates is useful for the growth of Zn1−x Mg x O crystals exhibiting random lasing.