Abstract

Reconfigurable robots provide an attractive option for cleaning tasks, thanks to their better area coverage and adaptability to changing environment. However, the ability to change morphology creates drastic changes in the reconfigurable robot dynamics, and existing control design techniques do not take this into account. Neglecting configuration changes can lead to performance degradation and, in the worst scenarios, instability. This paper proposes to embed the changes arising from reconfiguration in the control design, via a switched uncertain Euler-Lagrangian model. Accordingly, a novel switched adaptive design is proposed for trajectory tracking. Closed-loop stability is assured using the multiple Lyapunov function framework, and the design is implemented and validated on a self-reconfigurable pavement cleaning mobile robot (PANTHERA). Note to Practitioners —Self-reconfigurable mobile cleaning robots, which can change their configurations as per the application requirements, are now predominantly used for cleaning and maintenance operations because of their better area coverage, less manpower requirement and consistent performance. However, the state-of-the-art control strategies for conventional robots cannot always ensure stability and performance under the simultaneous effects of configuration changes and uncertainties. The switched Euler-Lagrange model formulated in this work can capture the configuration changes of the robot and the proposed switched adaptive controller can tackle uncertainties of each configurations of the robot. The simulation and experimental results clearly show the potential issues of the state-of-the-art methods and the remarkable benefits of the proposed approach.

Abstract

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Abstract

Recently, there has been a major shift in advanced driver assistance systems (ADAS) from the camera and LiDAR-oriented systems to mmWave radar-based systems. Such high-frequency band radars currently using frequency modulated continuous wave (FMCW) technique require programmable dividers with large divide ratios and fine frequency resolution to obtain high-frequency chirps with sufficiently large bandwidth. This paper presents a low-power multi-modulus programmable frequency divider for a frequency synthesizer operating in the 19.25-20.25 GHz frequency band from a reference frequency of 40 MHz. The divider consumes 14 mW of power and is capable of producing divide ratios in the range of 481.25-506.25 with a fine resolution of 1 MHz. The divider has a phase noise of −146 dBc/Hz at an offset of 2 kHz.

Abstract

Recent developments in advanced driver assistance systems (ADAS) have raised the demands of mmWave radars in 24 GHz and 77 GHz band. For higher accuracy and precision, frequency modulated continuous wave (FMCW) technique has become very popular for mmWave radars, which requires low phase noise and high bandwidth chirp frequency synthesizers. In this work, we present analysis and design of a low phase noise, transformer tank based mmWave voltage controlled oscillator (VCO) near 20 GHz for multiplier based 77 GHz FMCW chirp synthesizer. The proposed VCO design is implemented in 65 nm CMOS technology. Post layout simulations show that the proposed VCO exhibits a figure-of-merit is 192 dBc/Hz and phase noise of -117.98 dBc/Hz at 1 MHz offset while operating at 18.94 GHz and achieves a tuning range of 1.42 GHz (18.94-20.36 GHz), while consuming a power of 13.78 mW from 1.1 V supply.

Abstract

The used sodium from experimental studies is un-economical to purify or reuse from fast breeder reactors and is to be discarded safely. This disposal is done by converting the sodium into sodium hydroxide(NaOH) and hydrogen gas as a by product. The molarity of the sodium hydroxide aqueous solution thus obtained ranges from 12M to 16M, which needs real-time monitoring. This paper describes the feasibility study to develop a simple, innovative sensor to measure such high concentrations of NaOH surrounded by hydrogen gas in the light of no COTS sensor available in the market to meet the requirements

Abstract

Digital multimedia tools are becoming increasingly important as the world slowly shifts to an online mode. In this work, we present a low-cost, flexible writing pad that uses a 16×16 pressure sensing matrix based on the piezoresistive thin film of velostat. The writing area is 5 cm×5 cm with an effective pixel area of 0.06 mm2. A read out circuit is designed to detect the change in resistance of the velostat pixel using a voltage divider. A microprocessor raster scans through the sensor pixel matrix to obtain a data frame of 256 integers. This data is processed using techniques like squaring and normalising (S&N), Gaussian blurring, and adaptive thresholding to generate a more readable output. The writing pad is able to resolve characters larger than 2 cm in length. The flexible writing pad produces legible output while flexed at bending radius of upto 4 cm. Such flexibility promises to enhance the usability and portability of the writing pad significantly.

Abstract

The ever-increasing problem of forest fire risks has intrigued researchers globally to find a mechanism that can provide an early warning of forest fire incidents as well as assess the extent of spatial-temporal damage caused by them. Further information and data on its impacts would help in mitigating the disaster through advanced planning and management. The effects of forest fire have been known for a long time, but due to limited data, mitigation measures were always hampered. With the advancement of technology in the recent past with respect to high-resolution satellite data, a programming interface, and the development of mobile applications to a certain extent, it is now possible to predict forest fires and to study the impacts at local, regional, and global levels. Several open satellite data sets available from NASA, NOAA, and COPERNICUS have facilitated the quantification of various variables in near real time. Further the easy access to open-source data facilitated in the development of user-friendly web interfaces and APPS to continuously monitor the spatio-temporal changes caused as a result of forest fires on the ecosystem and on climate.

Abstract

Plantar pressure or foot pressure analysis is a predominant tool for biomedical assessment of posture, gait, and other activities. The distribution and magnitude of pressure can provide fruitful information to diagnose or predict any risk of foot disorders or impairments. This paper presents the design and fabrication of a low-cost, flexible pressure sensor (FLEPS) mat for assessing plantar pressure variations. We have designed a 32× 32 velostat-based piezoresistive pressure sensor array with dimensions of 330 mm × 330 mm and an active sensing area of 284 mm × 284 mm. Each sensor pixel is of size 5 mm × 5 mm with a pitch of 4 mm. To enhance the resolution and the visual quality of the heat map obtained, we have used different interpolation techniques like the nearest neighbor, bilinear, and bicubic for the received data and transformed the 32× 32 array to a 100× 100-pixel array. It was observed that the bicubic interpolation technique gives a better image quality but takes more computation time than the other two interpolation techniques.

Abstract

Table olives are becoming well recognized as a source of probiotic bacteria that might be used to create a health-promoting fermented food product by traditional procedures based on the activities of indigenous microbial consortia present in local environments. Methodology. In the present study, the characterization of probiotic bacteria isolated from mince, chunks, and brine of fermented green and black olives (Olea europaea) was done based on morphological, biochemical, and physiological characteristics. Results: Bacterial isolates demonstrated excellent survival abilities at 25, 37, and 45°C and at a variable range of pH. However, the optimum temperature is 37 and the optimum pH is 7 for all three isolates. An antimicrobial susceptibility pattern was found among these isolates through the disc diffusion method. Most of the isolates were susceptible to streptomycin, imipenem, and chloramphenicol, whereas, amoxicillin showed resistance to these isolates, and variable results were recorded for the rest of the antibiotics tested. The growth of the isolates was optimum with the supplementation of 3% NaCl and 0.3% bile salt. The isolated bacteria were able to ferment skimmed milk into yogurt, hence making it capable of producing organic acid. Conclusion: Isolates of Lactobacillus crispatus MB417, Lactococcus lactis MB418 from black olives, and Carnobacterium divergens MB421 from green olives were characterized as potential candidates for use as starter cultures to induce fermentation of other probiotic food products.

Abstract

The current study presents the findings of a laboratory investigation on the geotechnical behavior of quarry waste and the outcomes of numerical investigation supporting the application of quarry waste in the earthen dam. In addition, the chemical and morphological characteristics of quarry waste have also been studied. Quarry waste which would traditionally be disposed of as waste in landfills has been concluded as a high-strength material from the laboratory investigation. A high friction angle of about 38.4° has been recorded for the quarry waste, and the permeability was recorded in the fine sand range. These geotechnical properties of the quarry waste make it a satisfactory earthen dam shell material. The seismic performance of an earthen dam with quarry waste in the shell portion has been investigated using the finite