Precise Positioning Capabilities Research Articles

An Integrated Algorithm Fusing UWB Ranging Positioning and Visual–Inertial Information for Unmanned Vehicles

During the execution of autonomous tasks within sheltered space environments, unmanned vehicles demand highly precise and seamless continuous positioning capabilities. While the existing visual–inertial-based positioning methods can provide accurate poses over short distances, they are prone to error accumulation. Conversely, radio-based positioning techniques could offer absolute position information, yet they encountered difficulties in sheltered space scenarios. Usually, three or more base stations were required for localization. To address these issues, a binocular vision/inertia/ultra-wideband (UWB) combined positioning method based on factor graph optimization was proposed. This approach incorporated UWB ranging and positioning information into the visual–inertia system. Based on a sliding window, the joint nonlinear optimization of multi-source data, including IMU measurements, visual features, as well as UWB ranging and positioning information, was accomplished. Relying on visual inertial odometry, this methodology enabled autonomous positioning without the prerequisite for prior scene knowledge. When UWB base stations were available in the environment, their distance measurements or positioning information could be employed to institute global pose constraints in combination with visual–inertial odometry data. Through the joint optimization of UWB distance or positioning measurements and visual–inertial odometry data, the proposed method precisely ascertained the vehicle’s position and effectively mitigated accumulated errors. The experimental results indicated that the positioning error of the proposed method was reduced by 51.4% compared to the traditional method, thereby fulfilling the requirements for the precise autonomous navigation of unmanned vehicles in sheltered space.

Design and Modeling of a Long Range Motion Compliant Nanopositioning Stage Driven by a Normal Stressed Electromagnetic Actuator

Compliant nanopositioning stages with built-in ultra-precision actuators are frequently integrated into production and analysis instruments comprising ultra-high precision motion generation systems. These stages are essential nanotechnology and advanced material analysis components, providing precise positioning capabilities for various applications. However, in the practical engineering field, there is a lack of compliant nanopositioning stages that can achieve a long-range motion while maintaining accuracy, reliability, and compact size, which is the inspiration for this research. This paper investigates the design, modeling, and experimental testing of a long-range motion-compliant nanopositioning stage driven by a normal stressed electromagnetic actuator (NSEA). The nanopositioning stage components’ structural framework and working principle, including NSEA, bridge type distributed compliant (BTDC) mechanism, and the guiding mechanism, are fully examined to derive an analytical model. The analytical model is utilized in the sections that follow. Factors affecting the stroke and natural frequency of the nanopositioning stage are also illustrated. The optimization process of the nanopositioning stage is conducted in pursuit of a high-precision stage by specifically looking into the electromagnetic, BTDC mechanism, and guiding mechanism parameters. This optimization procedure also takes into account various design constraints, including stiffness, saturation flux density, and stress. Furthermore, the finite element analysis is used to verify the analytical model, and the results are discussed. The prototype is fabricated with reference to the analytical and finite element analysis results, and the experimental tests are conducted, including motion and natural frequency tests. In addition, a control system, which adopts both a proportional-integral-derivative controller and a damping controller, is designed to create a closed-loop system. Finally, the tracking performance of the stage was investigated, and a very minimal tracking error was observed. Overall, the comprehensive models and experimental tests proved the stage to be a good model which achieved the objective of the research.

Design of a logistics warehouse robot positioning and recognition model based on improved EKF and calibration algorithm

Automatic guided vehicles for logistics warehousing are a key link in the construction of intelligent logistics. To improve the positioning accuracy of warehouse robots, we designed an advanced extended Kalman filter method integrating multiple synchronous positioning techniques and map construction methods, and completed the calibration and detection of pallets based on color image information. The results revealed that the proposed multi-innovation enhanced model achieved minimum relative rotation and absolute trajectory errors of 0.13 and 0.09, outperforming existing models. It showcased excellent mapping fidelity and integrity (above 0.9) across various datasets, with a high loop detection success rate (0.91) enhancing map precision. The tray fusion detection algorithm's AUC (area under the curve) reached 0.92, reflecting a balanced accuracy-recall tradeoff. This research offers robust positioning and mapping capabilities in logistics warehousing environments, effectively identifying errors and ensuring pallet accuracy. The detection error and accuracy of this method are better than the other three models, with the lowest average absolute error of 0.32 and the lowest root-mean-square error of 0.27, and the overall error in the detection of pallets is small. The findings provide strong theoretical backing and technical support for advancing intelligent logistics warehousing technology. Precise positioning and identification capabilities enable logistics and warehousing robots to accurately and quickly complete tasks such as access, handling and sorting of goods, greatly improving the efficiency of warehousing operations, promoting the digital transformation and intelligent development of the logistics and warehousing industry, and improving the competitiveness of the industry and the level of service.

Real-time cloud computing of GNSS measurements from smartphones and mobile devices for enhanced positioning and navigation

In recent years, Global Navigation Satellite Systems (GNSSs) have become integral to our daily lives because of their precise positioning and navigation capabilities. Widespread use of smartphones equipped with GNSS receivers results in the generation of a huge amount of positioning data. Therefore, real-time cloud computing has emerged as a promising approach to effectively leverage this wealth of location information. In this study, we developed an Android app that captures raw GNSS data from smartphones, leverages cloud computing resources, calculates the position of the device, and returns the computed solution to the user. Integration of cloud-based processing not only conserves the device resources but also enables real-time position calculation, paving the way for enhanced location-based applications and services.

In situ detection of dopamine in single living cells by molecularly imprinted polymer-functionalized nanoelectrodes

In situ detection of dopamine (DA) at single-cell level is critical for exploring neurotransmitter-related biological processes and diseases. However, the low content of DA and a variety of distractors with similar oxidation potentials as DA in cells brought great challenges. Here, a sensitive and specific electrochemical nanosensor was proposed for in situ detection of DA in single living cells based on nanodiamond (ND) and molecularly imprinted polymer (MIP)-functionalized carbon fiber nanoelectrode (ND/MIP/CFNE). Due to its excellent electrocatalytic property, ND was modified to the surface of CFNE based on amide bonding. Compared with bare CFNE, ND-modified CFNE can enhance oxidation currents of DA by about 4-fold, improving signal-to-noise ratio and detection sensitivity. MIP was further electropolymerized on the surface of nanoelectrodes to achieve specific capture and recognition of DA, which could avoid the interference of complex matrix and analogs in cells. Taking advantage of the precise positioning capability of a single-cell analyzer and micromanipulator, ND/MIP/CFNE could be precisely inserted into different locations of single cells and monitor oxidation signal of DA. The concentration of DA in the cytoplasm of single pheochromocytoma (PC12) cell was measured to be about 0.4 μM, providing a sensitive and powerful method for single-cell detection. Furthermore, the nanoelectrodes can monitor the fluctuation of intracellular DA under drug stimulation, providing new ideas and methods for new drug development and efficacy evaluation.

Research on the Pattern of Pet Fostering Based on Internet Technology

In the post pandemic era, people's social and travel needs have gradually increased, and the concept of pet care has gradually become popular. The demand for pet foster care is also increasing day by day. In this environment, we carry out innovative reforms based on customer needs, supported by big data cloud computing technology and artificial intelligence technology. The core innovation of the "Mingchongwu" project lies in utilizing internet technology to achieve precise integration of resources and needs. By serving both supply and demand simultaneously, utilizing the precise positioning capabilities, powerful information processing capabilities, and data analysis capabilities of internet technology, we can find the most suitable foster care point for the foster care provider and seek additional business cooperation for the service provider, achieving a win-win situation for both parties.

Visible CCD Camera-Guided Photoacoustic Imaging System for Precise Navigation during Functional Rat Brain Imaging

In photoacoustic (PA) imaging, tissue absorbs specific wavelengths of light. The absorbed energy results in thermal expansion that generates ultrasound waves that are reconstructed into images. Existing commercial PA imaging systems for preclinical brain imaging are limited by imprecise positioning capabilities and inflexible user interfaces. We introduce a new visible charge-coupled device (CCD) camera-guided photoacoustic imaging (ViCPAI) system that integrates an ultrasound (US) transducer and a data acquisition platform with a CCD camera for positioning. The CCD camera accurately positions the US probe at the measurement location. The programmable MATLAB-based platform has an intuitive user interface. In vitro carbon fiber and in vivo animal experiments were performed to investigate the precise positioning and imaging capabilities of the ViCPAI system. We demonstrated real-time capturing of bilateral cerebral hemodynamic changes during (1) forelimb electrical stimulation under normal conditions, (2) forelimb stimulation after right brain focal photothrombotic ischemia (PTI) stroke, and (3) progression of KCl-induced cortical spreading depression (CSD). The ViCPAI system accurately located target areas and achieved reproducible positioning, which is crucial in animal and clinical experiments. In animal experiments, the ViCPAI system was used to investigate bilateral cerebral cortex responses to left forelimb electrical stimulation before and after stroke, showing that the CBV and SO2 in the right primary somatosensory cortex of the forelimb (S1FL) region were significantly changed by left forelimb electrical stimulation before stroke. No CBV or SO2 changes were observed in the bilateral cortex in the S1FL area in response to left forelimb electrical stimulation after stroke. While monitoring CSD progression, the ViCPAI system accurately locates the S1FL area and returns to the same position after the probe moves, demonstrating reproducible positioning and reducing positioning errors. The ViCPAI system utilizes the real-time precise positioning capability of CCD cameras to overcome various challenges in preclinical and clinical studies.

Single-Epoch, Single-Frequency Multi-GNSS L5 RTK under High-Elevation Masking.

The Japanese Quasi-Zenith Satellite System (QZSS) satellite system has placed in orbit four satellites by October 2017. The Indian Regional Navigation Satellite System (IRNSS) system has launched the new satellite IRNNSS-11 in April 2018, completing seven operational satellites. Together with the GPS block IIF satellites and the Galileo satellites, four different global navigation satellite systems (GNSSs) are providing precise L5 signals on the frequency of 1176.45 MHz. In this contribution, we challenge the strength of the multi-GNSS model by analysing its single-frequency (L5), single-epoch (instantaneous) precise positioning capabilities under high-elevation masking (up to 40 degrees). With more satellites available, multi-GNSS real time kinematic (RTK) positioning is possible using L5-only signals with a high customary elevation mask. This helps to enable positioning in areas with constrained measurement geometry, and could significantly reduce the multipath effects in difficult measurement environments like urban canyons and mountainous areas. In this study, benefiting from the location of the Asia–Australia area, instantaneous multi-GNSS L5 RTK analysis is performed with respect to the ambiguity resolution and positioning performance. Formal results are shown and discussed for baselines located in different grids covering Australia, part of the Pacific Ocean, Indian Ocean and Asia, and empirical analysis is given for two baselines in Perth, Australia. Compared to the stand-alone cases, for baselines in Perth, it is shown that combining L5 signals from GPS/Galileo/QZSS/IRNSS significantly improves both the ambiguity success rates (ASR) and the positioning performance under high elevation mask. While the average single-system ASR is under 50% even with a low elevation mask of 10 degrees, combining all the four systems increases the ASR to above 95% under an elevation cut-off angles of 40 degrees. With an elevation mask of 40 degrees, using satellites from one system does not allow for meaningful positioning solutions of more than 8 h within the test day, while mm-to-cm level ambiguity-fixed standard deviations could be obtained based on the positioning results of almost the entire day when combining all the four systems. In addition to that, simulation was also performed for receivers with larger signal standard deviations, i.e., for low-cost receivers or receivers located in environments with larger multipath.

Australia-first high-precision positioning results with new Japanese QZSS regional satellite system

The Japanese Quasi-Zenith Satellite System (QZSS) has recently (October 2017) reached its first 4-satellite constellation. In this contribution, the standalone performance of this 4-satellite QZSS constellation is assessed by means of its triple-frequency (L1 + L2 + L5) real-time kinematic (RTK) integer ambiguity resolution and precise positioning capabilities. Our analyses are carried out for data collected in Perth, Australia, and include a study of the noise characteristics of the QZSS code and phase data, particularly concerning their precision, time correlation and multipath. Our results show that while the phase observations on different frequencies are of similar precision, the code observations on different frequencies show considerably different precisions and can be ordered, from high to low, as L5, L2 and L1. As to positioning and ambiguity resolution, we demonstrate that the Position Dilution Of Precision (PDOP) and the Ambiguity Dilution Of Precision (ADOP) exhibit complementary characteristics, both of which are important for predicting precise positioning capabilities. We show that despite the large PDOPs, the ADOPs are sufficiently small to indicate (almost) instantaneous successful ambiguity resolution. This is confirmed by our empirical data analyses, demonstrating that instantaneous ambiguity resolution is feasible, despite the relatively poor 4-satellite receiver-to-satellite positioning geometry over Australia, thus showing that already now centimeter-level stand-alone QZSS positioning is possible with the current 4-satellite constellation (February–March 2018).

Performance Analysis of Hyperbolic Multilateration Using Circular Error Probability

Precise positioning and tracking capability of any object or radio source has now become a necessity for many industries and a number of sectors like automation, medicine, defence, transport etc. Hyperbolic Multilateration or Time Difference of Arrival (TDOA) positioning is one of the many techniques widely used to achieve this end. However, a few problems that concern any designer include the choice of number of sensors and reference sensor, the geometry of sensors, effect of source position on position error accuracy etc Accuracy measures like Circular Error Probable (CEP) provide a solution to this dilemma. CEP may be used to obtain the entire position accuracy profile of an area for any chosen geometry of sensors. This paper explains the significance of CEP and also illustrates the CEP profile for two chosen sensor geometries deployed in unknown source location using TDOA method.

A new generation of scanning probe technology

Scanning probe microscopy (SPM) analysis of materials is reliant upon direct physical interaction between a scanning probe and a sample surface. This physical interaction provides a range of analysis and surface modification techniques that are unique in microscopy and offers particular advantages and limitations. Precise computer-controlled positioning capabilities of SPM instrumentation continues to improve and is being combined with new nanoengineered probe types to achieve long-sought nanotechnology goals and minimize some of the traditional limitations of scanning probe technology.

Engineered large area fabrication of ordered InGaAs-GaAs nanotube arrays

ABSTRACTStrain induced self-rolling semiconductor micro and nanotubes and related structures represent a new class of building blocks of nanotechnology. They are formed when strained planar bilayers are released from the substrate by selectively removing the sacrificial layer. Compared to other nanotechnology building blocks, one of the main advantages is the precise positioning capability due to top down fabrication approach. In this article, we demonstrate the fabrication of perfectly aligned arrays of InGaAs/GaAs nanotubes and the dispersion of freestanding semiconductor nanotubes into solution and onto foreign substrates. In addition, we systematically investigate the crystal orientation dependence of the rolling direction by using a wheel configuration. Other aspects of formation process are also discussed.

Teaching Old Microscopes New Tricks

Abstract There are many transmission electron microscopes (TEMs) that have provided years of reliable service and good images, but they lack the positioning systems that are standard on the newest microscopes. A precise digital positioning capability is essential for many quantitative stereological studies and relocating specific features on a grid. For many of the older TEMs, retrofitting them with a digital positioning system is not an option, or at least a very expensive upgrade. Now Martin Hohmann-Marriott, William Sharp, Robert Roberson, and Robert Blankenship have described the hardware and software that offer a second life to these older microscopes.

Design and performance analysis of a space-time block coding scheme for single band UWB

Ultra wide-band (UWB) systems have recently attracted much research interest owing to their appealing features in short-range mobile communications. These features include high data rates, low power consumption, multiple access communications, and precise positioning capabilities. Space-time coding techniques, such as the block coding scheme or the trellis coding scheme, are known to be simple and practical ways to increase both the spectral efficiency and the capacity in wireless communications. So far, few contributions have looked over multiple-inputs-multiple-outputs UWB systems. In the paper, a method to adapt the space-time block coding technique to single band UWB signalling is proposed. A space-time block codec, based on orthogonal pulses to achieve spatial diversity and collect the multipath diversity is developed. A theoretical analysis is conducted to enlighten the performance enhancements provided by the proposed scheme compared to the classic single link scheme. Simulations support analysis, for various numbers of transmit and receive antennas, several types of channel scenarios, and different detection techniques. In a typical studied UWB environment, the results revealed that the proposed scheme improves the bit error rate performances compared to those of a single link scheme and it provides a strong immunity against timing jitter.

Modeling and Control of the Mitsubishi PA-10 Robot Arm Harmonic Drive System

The purpose of this paper is to present our results in developing a dynamic model of the Mitsubishi PA-10 robot arm for the purpose of low-velocity trajectory tracking using low-feedback gains. The PA-10 is ideal for precise manipulation tasks because of the backdrivability, precise positioning capabilities, and zero backlash afforded by its harmonic drive transmission (HDT). However, the compliance and oscillations inherent in harmonic drive systems, and the lack of any technical information on the internal dynamics of the transmission, make the development of an accurate dynamic model of the robot extremely challenging. The novelty of this research is therefore the development of a systematic algorithm to extract the model parameters of a harmonic drive transmission in the robot arm to facilitate model-based control. We have modeled all seven joints of the Mitsubishi PA-10, and we have done several experiments to identify the various parameters of the harmonic drive system. We conclude with a sample trajectory-tracking task that demonstrates our model-based controller for the Mitsubishi PA-10 robot arm.

摩擦駆動式マイクロ圧電リニアアクチュエータの研究 グリップ式圧電リニアアクチュエータの推力特性

This paper reports study on a very small linear actuator which can have big force, long stroke and precise positioning capability. Although the actuator is driven by multilayer piezoelectric devices in cyclic way, small displacement is continuously transmitted to a slider through friction drive method. The spring plates which are fixed on both sides of the slider press the actuator grip points and the pressing force generates friction drive force. The maximum pressing force under which the actuator can work normally is calculated by FEM analysis. As a result, the actuator with an appropriate structure is designed, fabricated and experimentally evaluated. The factors which give effects to thrust force characteristics are studied.

Direct Electrochemical Measurements Inside a 2000 Angstrom Thick Polymer Film by Scanning Electrochemical Microscopy

An extremely small, conically shaped Pt microelectrode tip (with a radius of 30 nanometers) and the precise positioning capabilities of the scanning electrochemical microscope were used to penetrate a thin (200 nanometers) polymer film and obtain directly the standard potential and kinetic parameters of an electrode reaction within the film. The thickness of the film was determined while it was immersed in and swollen by an electrolyte solution. The film studied was the perfluorosulfonate Nafion containing Os(bpy)(3)(2+) (bpy, 2,2'-bipyridine) cast on an indium tin oxide surface. The steady-state response at the ultramicroelectrode allowed direct determination of the rate constant for heterogeneous electron transfer K(o) and the diffusion coefficient D without complications caused by transport in the liquid phase, charge exchange at the liquid-polymer interface, and resistive drop.