Characterization and calibration of multiple 2D laser scanners

This paper presents the comparative evaluation of multiple compact and lightweight 2D laser scanners for their possible backpack based scanning and mapping applications. These scanners include Hokuyo URG-04LX, Slamtec RPLidar A1-M8 and Hokuyo UTM- 30LX-EW scanners. Since the technical datasheets provide general information and limited working details, this research presents a thorough study on the performance of each scanner related explicitly to indoor mapping operations. A series of scanning experiments have been performed for the characterization of each scanner using statistical analysis. During the testing, all the scanning data has been recorded using Robot Operating System (ROS) and then computed in offline processing. In initial tests, each scanner's drift effect on range measurements has been tested and presented in the relevant section of the paper. In continuation, the effect of various scanning distances on measurement accuracy has been evaluated and discussed. Later the impact of various materials typically found in indoor vicinities and their respective properties of color and smoothness have been tested and provided in the paper. Finally, a Kalman Filtering based mathematical formulation has been utilized to calibrate each scanner and to reduce the measuring uncertainties as observed in various tests for each scanner

Compact rover surveying and laser scanning for BIM development

This paper presents a custom made small rover based surveying, mapping and building information modeling solution. Majority of the commercially available mobile surveying systems are larger in size which restricts their maneuverability in the targeted indoor vicinities. Furthermore their functional cost is unaffordable for low budget projects belonging to developing markets. Keeping in view these challenges, an economical indigenous rover based scanning and mapping system has developed using orthogonal integration of two low cost RPLidar A1 laser scanners. All the instrumentation of the rover has been interfaced with Robot Operating System (ROS) for online processing and recording of all sensorial data. The ROS based pose and map estimations of the rover have performed using Simultaneous Localization and Mapping (SLAM) technique. The perceived class 1 laser scans data belonging to distinct vicinities with variable reflective properties have been successfully tested and validated for required structural modeling. Systematically the recorded scans have been used in offline mode to generate the 3D point cloud map of the surveyed environment. Later the structural planes extraction from the point cloud data has been done using Random Sampling and Consensus (RANSAC) technique. Finally the 2D floor plan and 3D building model have been developed using point cloud processing in appropriate software. Multiple interiors of existing buildings and under construction indoor sites have been scanned, mapped and modelled as presented in this paper. In addition, the validation of the as-built models have been performed by comparing with the actual architecture design of the surveyed buildings. In comparison to available surveying solutions present in the local market, the developed system has been found faster, accurate and user friendly to produce more enhanced structural results with minute details

Slum Terrain Mapping Using Low-Cost 2D Laser Scanners

This paper presents a motorbike-based custom made scanning and mapping system for surveying slums and highly populated urban regions. These vicinities are difficult to reach through standard vehicular scanning systems and require a compact solution as presented in this paper. The system consists of two small range 2D Hokuyo laser scanners mounted in right angle orientations to capture the environment. In addition, the global positioning system, the wheel encoder, the inertial measurement unit, and cameras have been integrated with the system to estimate the pose and visual information. Sensorial information has been used to localise the system using Kalman Filtering. Later, by applying the standard transformations, the 3D point cloud map of the surveyed vicinity has been developed. The scanning system has been tested at various locations including densely populated and slum regions. Precise and detailed 3D mapping results have been obtained, which are further extensively analysed to understand the built structure and the road furniture. The working of the system is found to be quite economical and faster than that of local urban surveying systems

Estimation of Surgical Needle Insertion Force Using Kalman Filter

This paper presents a novel low-cost technique to measure the insertion force of a surgical needle on a testing surface to check needle strength. A combination of a load cell with a current sensor for a linear DC motor has been used to estimate the insertion force based on Kalman Filter (KF). The custom-designed and in-house fabricated system to estimate the insertion force comprises of the motor coupled with a vertically articulated arm. The needle to be tested is mounted at the end of the arm. Movement of the arm has been controlled electronically to produce the insertion force by the needle to a testing surface. The sensory measurement data generated during this process has been collected using Arduino based embedded electronic hardware. The KF based proposed strategy has been validated using the developed system by conducting various tests with different needles. Results in the form of penetration force and friction force have been experimentally observed and are then compared with standard force meters. Comparative analysis witnesses efficiency of the proposed approach

A Comparative Study of Multiple 2D Laser Scanners for Outdoor Measurements

This research work examines the performance of several compact and lightweight 2D laser scanners, including the Hokuyo URG-04LX, RP Lidar and Hokuyo UTM-30LX-EW, for their potential use in scanning and mapping applications. A detailed study was conducted to evaluate the performance of each scanner specifically for outdoor mapping operations. Multiple experiments were performed to characterize each scanner through statistical analysis. The paper discusses the results of testing for the drift effect, the impact of direct sun exposure to different materials and the effect of range measurement in outdoor environments on range and measurement accuracy

Parametric Classification of Furniture From Point Cloud Developed Using Low Cost Trolley Based Laser Scanning System

This paper presents a parametric classification methodology to identify common indoor and outdoor furniture objects present in the 3D Cartesian point cloud of the surveyed environment. For this purpose, a low cost custom made trolley based scanning and surveying system has developed using orthogonal integration of two popular Hokuyo-30LX 2D laser scanners. The developed system has been successfully used to generate 3D point cloud of the environment using Simultaneous Localization and Mapping (SLAM) technique. The instrumentation system of the trolley has been interfaced through Robot Operating System (ROS) for online processing and recording of all sensorial data. While classification of the furniture present in point cloud has been done in offline mode using Random Sampling and Consensus (RANSAC) based parametric segmentation technique. The innovative furniture detection has applied on each scan in order to reduce the region of interest in the developed point cloud. In addition, the validation of the classified furniture objects has been performed using Fuzzy Logic. Multiple indoor and outdoor vicinities have been scanned and modelling results have been found accurate nearer to ground truth. In comparison to available surveying solutions present in the local market, the developed system has been found faster and precise to produce more enhanced structural results with minute details

Effect of Annealing Atmosphere on the Diode Behaviour of ZnO/Si Heterojunction

The effect of thermal annealing atmosphere on the electrical characteristics of Zinc oxide (ZnO) nanorods/p-Silicon (Si) diodes is investigated. ZnO nanorods are grown by low-temperature aqueous solution growth method and annealed in Nitrogen and Oxygen atmosphere. As-grown and annealed nanorods are studied by scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electrical characteristics of ZnO/Si heterojunction diodes are studied by current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. Improvements in rectifying behaviour, ideality factor, carrier concentration, and series resistance are observed after annealing. The ideality factor of 4.4 for as-grown improved to 3.8 and for Nitrogen and Oxygen annealed improved to 3.5 nanorods diodes. The series resistances decreased from 1.6 to 1.8 times after annealing. An overall improved behaviour is observed for oxygen annealed heterojunction diodes. The study suggests that by controlling the ZnO nanorods annealing temperatures and atmospheres the electronic and optoelectronic properties of ZnO devices can be improved.Funding Agencies|Sultan Qaboos Oman IT chair office and Electronic Design Center at the NED University of Engineering and Technology</p