Indoor Applications Research Articles

Unsupervised Stereo Matching with Surface Normal Assistance for Indoor Depth Estimation.

To obtain more accurate depth information with stereo cameras, various learning-based stereo-matching algorithms have been developed recently. These algorithms, however, are significantly affected by textureless regions in indoor applications. To address this problem, we propose a new deep-neural-network-based data-driven stereo-matching scheme that utilizes the surface normal. The proposed scheme includes a neural network and a two-stage training strategy. The neural network involves a feature-extraction module, a normal-estimation branch, and a disparity-estimation branch. The training processes of the feature-extraction module and the normal-estimation branch are supervised while the training of the disparity-estimation branch is performed unsupervised. Experimental results indicate that the proposed scheme is capable of estimating the surface normal accurately in textureless regions, leading to improvement in the disparity-estimation accuracy and stereo-matching quality in indoor applications involving such textureless regions.

EVALUATION OF INTEL REALSENSE D455 CAMERA DEPTH ESTIMATION FOR INDOOR SLAM APPLICATIONS

Abstract. The aim of this study is to propose evaluation methodology for the quality assessment of depth cameras for indoor mapping applications. Specifically, we evaluate the RGBD sensor Intel Realsense D455 w.r.t. measurement accuracy and noise while investigating their dependence on two central parameters characterizing the measurement scenario simultaneously: measurement distance and inclination of observed surfaces. The evaluation results are presented two-dimensionally as a function of both parameters. To this aim, two evaluation studies are conducted. First, a checkerboard pattern is used as reference object in a controlled setting. Secondly, actual indoor mapping data resulting from the deployment of the evaluated sensor in the context of an RGBD-SLAM application is used to conduct a similar evaluation in representative conditions for the intended usage scenario of indoor mapping. In this case, a TLS scan of the respective indoor environment is used as reference for evaluation.

Indoor light energy harvesting technique to energize a heat sensor using polycrystalline solar panel

This paper presents the effect of using different illumination types between the polycrystalline solar panel and the light sources on energy harvesting performance for indoor low-power applications such as heat sensors. The main advantage of indoor energy harvesting is it makes good use of ambient energy from the environment and converts it directly to electricity for small power devices. In this paper, the maximum power of polycrystalline solar panels for four different light illuminations has been investigated under different distances of light sources from the polycrystalline solar panel. Implementation and test results of the effect of varying the distance and the power produced for different light illuminations are presented which highlights the practical issues and limitations of the system.

Self-Powering Sensory Device with Multi-Spectrum Image Realization for Smart Indoor Environments.

The development of organic-based optoelectronic technologies for the indoor Internet of Things market, which relies on ambient energy sources, has increased, with organic photovoltaics (OPVs) and photodetectors (OPDs) considered promising candidates for sustainable indoor electronic devices. However, the manufacturing processes of standalone OPVs and OPDs can be complex and costly, resulting in high production costs and limited scalability, thus limiting their use in a wide range of indoor applications. This study uses a multi-component photoactive structure to develop a self-powering dual-functional sensory device with effective energy harvesting and sensing capabilities. The optimized device demonstrates improved free-charge generation yield by quantifying charge carrier dynamics, with a high output power density of over 81 and 76 µW cm-2 for rigid and flexible OPVs under indoor conditions (LED 1000lx (5200 K)). Furthermore, a single-pixel image sensor is demonstrated as a feasible prototype for practical indoor operating in commercial settings by leveraging the excellent OPD performance with a linear dynamic range of over 130dB in photovoltaic mode (no external bias). This apparatus with high-performance OPV-OPD characteristics provides a roadmap for further exploration of the potential, which can lead to synergistic effects for practical multifunctional applications in the real world by their mutual relevance.

Optimal audio beam pattern synthesis for an enhanced parametric array loudspeaker

A parametric array loudspeaker (PAL) generates highly directional audible sound in air with a small aperture size compared to a conventional loudspeaker. But in indoor applications, the long propagation distance of a PAL causes reflections, which disturbs the reproduction of narrow audio beams. Moreover, sound distortion appears along the off-axis direction due to the frequency dependence of the beam width. This study proposed an optimal audio beam pattern synthesis for a PAL-based convex optimization, which can design the audio beam of a PAL with an optimal solution. The proposed method overcame the mentioned limitations by applying it to a length-limited PAL for audio spot control and a multichannel PAL array for a constant beam width audio beam. In a length-limited PAL, the proposed method restricts the audio spot to a smaller region and weakens the sound leakage along the off-axis direction. Whereas in a multichannel PAL array, the proposed method also achieves a constant beam width near the radiator axis. Simulations and experiments verify the effectiveness of the proposed method, which will enhance the performance of a PAL in scenarios where control of the audio beam is required.

High speed 60 Gbps RGB laser based-FSOC link by incorporating hybrid PDM-MIMO scheme for indoor applications

Abstract Visible Light Communication (VLC) systems enhanced by red, green and blue (RGB) lasers are at the forefront of indoor technology, offering dynamic lighting, high-speed data transfer, and energy efficiency. This innovative combination not only revolutionizes connectivity and illumination but also ensures privacy and security, making it a game-changer for smart homes, offices, and various indoor applications. In our research, we introduce a polarization division multiplexing and Multiple Input Multiple Output based (PDM-MIMO) system that carries 60 Gbps of data over a transmission range of 500 m in free space Channels. The utilization of the cost-effective on-off key (OOK) modulation format is attributed to its affordability in our transmission scheme. For parallel data transmission, three laser diodes in RGB were utilized. To enhance both the transmission range and reduce the Bit Error Rate (BER), MIMO scheme is employed. Our study presents simulation outcomes, conducted using OptiSystemTM software, that focus on evaluating the bit error rates for the proposed PDM-MIMO link. Our findings demonstrate successful 60 Gbps data transmission over 350 m in FSO with an acceptable BER, reinforced by clear eye diagrams. Introducing MIMO expands the range to 500 m while improving BER, paving the way for real-time experimentation and research advancement.

GNSS/UWB/INS indoor and outdoor seamless positioning algorithm based on federal filtering

An integrated navigation system plays an important role in the application of indoor and outdoor seamless positioning. Essentially, it is a flexible fusion positioning of multiple sensors with different combinations. The Global Navigation Satellite System (GNSS) can provide high-precision positioning and navigation in an outdoor environment with good observation conditions. Ultra-wide Band (UWB) has the characteristics of great bandwidth and anti-multipath, which can be applied to provide high-precision positioning and navigation indoors. Inertial Navigation System (INS) has independent navigation capabilities that can be tightly combined with GNSS and UWB to enhance positioning robustness. In response to the problem of a single sensor struggling to provide reliable location information for indoor and outdoor seamless positioning, this study applies federal filtering to integrate and construct the GNSS/UWB/INS integrated positioning algorithm based on Horizontal Dilation of Precision (HDOP) of UWB and carrier-to-noise ratio of GNSS weighting. The gross errors are first detected during the data preprocess, and an adaptive weighting approach to reduce the influence of the anomalous observations is constructed. The tight combination of GNSS/INS and UWB/INS is implemented in the subfilter of the federal filtering. In the main filter, the weights of the two subfilters are adjusted based on HDOP and carrier-to-noise ratio weighting, and the information is allocated and fused to reduce the impact of potential poor UWB geometric configuration on the positioning solutions. It is proven that the error in the horizontal direction in the indoor and outdoor seam area is less than 10 cm. Compared with conventional federal filtering and Huber-based Kalman filtering, the algorithm in this study improves the accuracy of the reference point in indoor and outdoor seam area by 46.1% and 15.4%, respectively, which is beneficial for applications in indoor and outdoor seamless activities.

Optimizing CBTSSe solar cells for indoor applications through numerical simulation

Optimizing CBTSSe solar cells for indoor applications through numerical simulation

BER analysis of a full-duplex relay-assisted BPSK-SIM based VLC system for indoor applications.

This paper contemplates a relay-assisted visible light communication (VLC) system, where the light source (table lamp) acts as a relay node and cooperates with the main light source. Following the IEEE 802.15.7r1 VLC reference channel model, we assume that there are two different light sources present in an office room. The first one is the source terminal present on the ceiling and another one is the desk lamp that serves as the relay station, which works in a full-duplex method. Because of the loop interference channel, we model the VLC relay terminal using ray tracing simulations. We have analyzed the bit error rate (BER) performance of the relay-assisted VLC system using a binary phase shift keying-subcarrier intensity modulation (BPSK-SIM) technique. The proposed method outperforms existing phase shift keying (PSK) and square M-quadrature amplitude modulation (M-QAM) techniques. The proposed VLC system using the BPSK-SIM technique achieves a BER performance of 10-12 for an SNR of 20dB. The results of the proposed full-duplex and half-duplex relayed VLC systems are evaluated using equal power allocation (EPA) and optimum power allocation (OPA) techniques over three different modulation schemes, which are 2-PSK, square M-QAM, and BPSK-SIM.

A critical perspective for emerging ultra-thin solar cells with ultra-high power-per-weight outputs

Ultrathin, solution-processed emerging solar cells with high power-per-weight (PPW) outputs demonstrate unique potential for applications where low weight, high power output, and flexibility are indispensable. The following perspective explores the literature of emerging PVs and highlights the maximum reported PPW values of perovskite solar cells (PSCs) 29.4 W/g, organic solar cells (OSCs) 32.07 W/g, and quantum dot solar cells 15.02 W/g, respectively. The record PPW values of OSCs and PSCs are approximately one order of magnitude higher compared to their inorganic ultrathin solar cells counterparts (approximately 3.2 W/g for CIGS and a-Si). This consists emerging PVs, very attractive for a variety of applications where the PPW is the key parameter. In particular, both OSCs and PSCs can be implemented in different scenarios of applications (indoor and biocompatible applications for OSCs and outdoor and high-energy radiation conversion conditions for the PSCs) due to their unique optoelectronic and physiochemical properties. Finally, our theoretical optical and electrical simulation and optimization study for the most promising and well-suited PV technologies showed an impressive maximum realistic theoretical PPW limit of 74.3 and 93.7 W/g for PSCs and OSCs, respectively. Our finding in the theoretical section shows that the experimental results achieved in the literature of PSCs and OSCs toward high PPW outputs is not quite close to the theoretical maximum (35% and 40% of the theoretical maximum for OSCs and PSCs, respectively), and thus, more work needs to be done to further increase the experimental PPW output of these promising PV technologies.

Experiment on the formaldehyde removal performance of TiO2 coating agent for finishing materials

As the frequency of indoor habitation escalates and advancements in building technology optimize airtightness, the importance of maintaining high-quality indoor air has grown increasingly critical. This urgency is further amplified by the proliferation of chemical building materials, necessitating more effective strategies for air pollutant abatement. To address this need, the current study explored the utility of titanium dioxide photocatalysts, which possess chemical decomposition capabilities, as a means of improving air quality within indoor environments. To verify the effectiveness of this approach, the research focused on the removal of formaldehyde—a quintessential indoor air pollutant—by incorporating a titanium dioxide photocatalyst into a coating agent commonly employed in construction materials. Notably, ultraviolet (UV) light, essential for activating the photocatalytic process, is generally absent in indoor settings. To mitigate this limitation, a consistent source of UV radiation was provided through the use of an UV lamp. Adhering to protocols outlined by the International Organization for Standardization, we employed a photoreactor to evaluate the photocatalytic efficiency of the composite material under varying intensities of UV radiation and reactor volumes. The results unequivocally confirmed that variations in UV radiation intensity and reactor volume significantly influenced the photocatalytic effectiveness of the material, resulting in a demonstrable reduction in pollutant concentrations. These findings suggest the feasibility of utilizing titanium dioxide photocatalysts for mitigating outdoor air pollutants, where natural UV radiation is more readily available. However, for indoor applications, the absence of naturally occurring UV radiation presents a considerable challenge. Overcoming this constraint could facilitate the indoor application of photocatalytic coatings, as informed by the optimal conditions of low pollutant reactivity and robust UV radiation revealed in this study, thereby substantially enhancing indoor air quality.

Synthesis and Mechanical Performances of Polyurethane Bio-Based Adhesives Resulted from the Depolymerization of Lignocellulose Biomass.

The purpose of this study is to valorize biomass waste into products with added value for indoor applications. Thus, broadleaf sawdust was chemically processed by the solvolysis reaction in acid catalysis in the presence of diethylene glycol at 160 °C for 4 h. After filtration and removal of the unreacted biomass, the glycolysis product was used in 6 different polyurethane adhesive formulations for wood bonding. The adhesive films were characterized by FT-IR, TGA, and DMA, while the mechanical performances were investigated by tensile and three-point bending tests. An innovative method for the determination of the working time was proposed. After the displacement of the wood substrates by the tensile test, the bonded area was investigated by SEM analysis. To confirm a correlation between the mechanical performances of the adhesives and their structure/formulation, two-dimensional (2D) simulations were performed based on the tensile tests.

An artificial intelligence based 3-dimensional markerless motion capture system for indoor and outdoor sport applications

An artificial intelligence based 3-dimensional markerless motion capture system for indoor and outdoor sport applications

Object Fetching UAV using Autonomous Flight and Object Detection Algorithms

Abstract: Autonomous UAVs (Unmanned Aerial Vehicles) are being used in various applications around the world like surveillance and aerial security, construction, agriculture, delivery, etc. These applications require heavy duty UAVs with high payload capacity and long battery life. The aim of this project is to use the principles of autonomous flight and object detection for indoor autonomous flight with the target to fetch and deliver lightweight objects with minimum energy and time consumption to create a viable prototype for indoor applications like delivering objects to bedridden patients, smart home applications, warehouse management and more.

Non-line-of-sight optical camera communications based on CPWM and a convolutional neural network.

Non-line-of-sight (NLOS) optical camera communications (OCC) exhibit greater link availability and mobility than line-of-sight links, which are more susceptible to blocking and shadowing. In this work, we propose an NLOS OCC system, where the data signal is mapped into color pulse width modulation (CPWM) symbols prior to transmission using a red-, green-, and blue light-emitting diode. A convolutional-neural-network-based receiver is used to demodulate the CPWM signal. Based on experimental results, the proposed scheme effectively mitigates the effects of diffuse reflection induced intersymbol interference, resulting in an increased data transmission rate to 7.2kbps over a link span of more than 2m, which is typical for indoor applications.

Bifacial and Semitransparent Sb2 (S,Se)3 Solar Cells for Single-Junction and Tandem Photovoltaic Applications.

Thin-film solar cells are expected to play a significant role in the space industry, building integrated photovoltaic (BIPV), indoor applications, and tandem solar cells, where bifaciality and semitransparency are highly desired. Sb2 (S,Se)3 has emerged as a promising new photovoltaic (PV) material for its high absorption coefficient, tunable bandgap, and nontoxic and earth-abundant constituents. However, high-efficiency Sb2 (S,Se)3 solar cells exclusively employ monofacial architectures, leaving a considerable gap toward large-scale application in aforementioned fields. Here, a bifacial and semitransparent Sb2 (S,Se)3 solar cell and its extended application in tandem solar cells are reported. The transparent conductive oxides (TCOs) and the ultrathin inner n-i-p structure provide high long-wavelength transmittance. Despite the MnS/ITO Schottky junction, power conversion efficiencies (PCEs) of 7.41% and 6.36% are achieved with front and rear illumination, respectively, contributing to a great bifaciality of 0.86. Consequently, the reported device gains great enhancement in PV performance by exploiting albedo of surroundings and shows exceptional capability in absorbing tilt incident light. Moreover, anSb2 (S,Se)3 /Si tandem solar cell with a PCE of 11.66% is achieved in preliminary trials. These exciting findings imply that bifacial and semitransparent Sb2 (S,Se)3 solar cells possess tremendous potential in practical applications based on their unique characteristics.

Dual emitting carbon nanoparticles for tunable white light emission

Eco-friendly, biomass derived single component luminescent materials with dual emission bands hold immense potential in white light emitting devices (WLED). Compared to WLED fabricated from different color emitting carbon nanoparticles, self-reabsorption and degradation will be negligible in single system white light emitting materials which guarantees stability in long run. Herein, we report a facile, inexpensive and sustainable direct thermal decomposition method to synthesize carbon nanoparticles with dual emission bands. Addition of PVP could efficiently enhance the red emission band of carbon nanoparticles. The excitation dependent broad blue-green emission and excitation independent narrow red emission helps to obtain white light emitting carbon nanoparticles. Upon change in excitation wavelength from 410 nm to 370 nm, white light emissions are obtained with tunable CCT value from 2648 K to 8980 K respectively. By virtue of this tunable warm to cool white light emission, single system WLED can be designed suitable for both indoor and outdoor applications.

Design of a microcontroller-based quadcopter prototype module Fly Sky XL163RX take off and landing

This research paper presents the design and development of a microcontroller-based quadcopter prototype module, named Fly Sky XL163RX, with the capability of take off and landing. The objective of this study is to design a reliable and efficient quadcopter module that can be utilized for various applications, such as aerial photography, surveillance, and delivery services. The proposed quadcopter module is equipped with the Fly Sky XL163RX microcontroller, which serves as the control unit for managing the flight operations. The design process involves several key steps, including the selection of appropriate components, integration of sensors and actuators, and the development of control algorithms. The quadcopter module utilizes a combination of sensors, including gyroscopes, accelerometers, and altimeters, to gather real-time data and stabilize the flight. The control algorithm employs a proportional-integral-derivative (PID) controller to adjust the motor speeds and maintain stability during take off and landing. The Fly Sky XL163RX microcontroller offers a user-friendly interface and supports various communication protocols, allowing for easy customization and control of the quadcopter module. Additionally, the module incorporates safety features, such as emergency landing capabilities and collision avoidance systems, to enhance flight security and prevent potential accidents. The performance of the Fly Sky XL163RX quadcopter module was evaluated through extensive flight testing. The results demonstrate the module's capability to achieve stable take off and landing operations, as well as its responsiveness to user commands. The module's compact size and lightweight design make it suitable for indoor and outdoor applications. In conclusion, this research presents the design and development of the Fly Sky XL163RX microcontroller-based quadcopter module, which exhibits reliable and efficient take off and landing operations. The module's integration of sensors, control algorithms, and safety features contribute to its overall performance and usability. Future work may focus on enhancing the module's capabilities, such as implementing autonomous flight modes and improving battery efficiency.Quadcopter, Microcontroller, FlySky XL163RX, Take Off, Landing, Control Algorithm, Sensors, Actuators, PID Controller, Flight Testing, Aerial Applications.

The hybrid pulse amplitude width modulation scheme: high efficiency technique for dimmable VLC systems

Abstract Visible-light communications (VLC) is an environmentally friendly optical wireless communication (OWC) technology that operates in the 400–800 THz frequency band. It is currently a critical technology for 5G and 6G wireless indoor applications due to its high data rates, low latency, and superior reliability. Intensity modulated direct detection (IM/DD) is widely used in VLC systems. A channel modulation scheme is designed using L-level pulse modulation techniques such as on–off keying (OOK), amplitude modulation (PAM), position modulation (PPM), and the width modulation (PWM). We introduce a novel hybrid modulation scheme n-M-PAWM based on both PAM and PWM schemes to improve throughput and significantly increase power and spectrum efficiency in VLC communication systems. The performance of our proposed hybrid n-M-PAWM scheme is studied in several aspects, including the number of transmitted bits per symbol, average BER, information rate ratio (IRR), PAPR, bandwidth, and power requirement. In an extremely noisy VLC system, the proposed 2-M-PAWM modulation outperforms both PPWM and PAPM modulation schemes due to its better BER performances. Additionally, we examine the performance of the VLC system in terms of spectral efficiency (SE) using our proposed PAWM-based dimming control system by varying the number of pulses transmitted during one symbol period. We demonstrate through simulation results that our PAWM-based dimming control system performs significantly better compared to the other pulse modulation schemes. All results of this research show that our proposed hybrid PAWM modulation scheme has high potential for VLC technology in indoor and noisy environments.

Construction of Multifunctional Hierarchical Biofilms for Highly Sensitive and Weather-Resistant Fire Warning.

Multifunctional biofilms with early fire-warning capabilities are highly necessary for various indoor and outdoor applications, but a rational design of intelligent fire alarm films with strong weather resistance remains a major challenge. Herein, a multiscale hierarchical biofilm based on lignocellulose nanofibrils (LCNFs), carbon nanotubes (CNTs) and TiO2 was developed through a vacuum-assisted alternate self-assembly and dipping method. Then, an early fire-warning system that changes from an insulating state to a conductive one was designed, relying on the rapid carbonization of LCNFs together with the unique electronic excitation characteristics of TiO2. Typically, the L-CNT-TiO2 film exhibited an ultrasensitive fire-response signal of ~0.30 s and a long-term warning time of ~1238 s when a fire disaster was about to occur, demonstrating a reliable fire-alarm performance and promising flame-resistance ability. More importantly, the L-CNT-TiO2 biofilm also possessed a water contact angle (WCA) of 166 ± 1° and an ultraviolet protection factor (UPF) as high as 2000, resulting in excellent superhydrophobicity, antifouling, self-cleaning as well as incredible anti-ultraviolet (UV) capabilities. This work offers an innovative strategy for developing advanced intelligent films for fire safety and prevention applications, which holds great promise for the field of building materials.