This paper uses a fluid mechanics approach to perform swarming aggregation on a quadrotor unmanned aerial vehicle (QUAV) swarm platform. This is done by adapting the Smoothed Particle Hydrodynamics (SPH) technique. An algorithm benchmarking is conducted to see how well SPH performs. Simulations of varying set-ups are experimented to compare different algorithms with SPH. The position error of SPH is 30% less than the benchmark algorithm when a target enclosure is introduce. SPH is implemented using Crazyflie quadrotor swarm. The aggregation behavior exhibited successfully in the said platform.
This paper presents the implementation of the physicomimetics framework in governing the behavior of a swarm of quadrotors. Each quadrotor uses only local information about itself and the neighboring quadrotors to determine its own movement by applying the principles of physicomimetics. Through these localized and relatively simple interactions, the swarm of quadrotors was able to organize itself into various structures and exhibit different swarm behaviors such as aggregation, obstacle avoidance, lattice formation, and dispersion.
One of the novel approaches in multiple quadrotor control is swarm robotics. It aims to mimic social behaviors of animals and insects. This paper presents the physical implementation of the swarm social foraging behavior in unmanned aerial vehicle quadrotors. To achieve this, it first explores the basic behavior of aggregation. It is implemented over a quadrotor swarm test-bed that makes use of external motion capture cameras. The completed algorithm makes use of the artificial potential function model combined with the environment resource profile model. Results show successful demonstration of the social foraging algorithm with minimal error in position. Also, the proposed algorithm’s performance presents an increase in aggregation speed and time as the number of swarm member increases.
This paper presents a fuzzy logic system for audio event detection using mel frequency cepstral coefficients (MFCC). Twelve MFCC of audio samples were analyzed. The range of values of MFCC were obtained including its histogram. These values were normalized so that its minimum and maximum values lie between 0 and 1. Rules were formulated based on the histogram to classify audio samples as normal, gunshot, or crowd panic. Five MFCC were chosen as input to the fuzzy logic system. The membership functions and rules of the fuzzy logic system are defined based on the normalized histograms of MFCC. The system was tested with a total of 150 minutes of normal sounds from different buses and 72 seconds audio clips abnormal sounds. The designed fuzzy logic system was able to classify audio events with an average accuracy of 99.4%.
A new engineering methodology is proposed to improve the automation process in monitoring the water quality in a small scale aquaculture system. Behavioural Response Analysis using Vision Engineering Network or BRAVENet is proposed, as a support system to a traditional sensor-based system, to monitor critical water quality parameters such as temperature, pH, salinity and dissolved oxygen. BRAVENet is based on the reactions or behavioural responses of tiger prawns to different water conditions. The performance of both the sensor-based system and BRAVENet are analysed and discussed. It is shown that the BRAVENet can identify unsafe levels of water parameters and is a good monitoring and prediction tool for water conditions especially those instances when industry grade sensors fail or become erroneous. Promising results show that BRAVENet can be used as a support system, if not as a replacement, in continuously monitoring the status of the critical water quality parameters of aquaculture systems.
Battlefield decision-making is an important part of modern information warfare. It can analyze and integrate battlefield information, reduce operators’ work and assist them to make decisions quickly in complex battlefield environment. The paper presents a dynamic battlefield decision-making method based on Markov Decision Processes (MDP). By this method, operators can get decision support quickly in the case of incomplete information. In order to improve the credibility of decisions, dynamic adaptability and intelligence, softmax regression and random forest are introduced to improve the MDP model. Simulations show that the method is intuitive and practical, and has remarkable advantages in solving the dynamic decision problems under incomplete information.
The initial iterative control signal is often adopted a zero or a certain value in the conventional iterative learning control (ILC) system, and an ILC process needs to renew again as long as the desired trajectory is changed. In this paper, the NURBS (Non-Uniform Rational B-Splines) model is used for describing all trajectory primitives and the desired trajectory. It is studied that the problem of the initial iterative control signal is extracted in ILC, which presents a method of extracting the initial iterative control signal based on the trajectory primitive optimal matching and combining algorithm. Firstly, the definition of the similarity index between the two different spacial trajectories is introduced. Secondly, an optimal matching and combining algorithm is designed under a certain similarity index, which is used to find two or more combined primitive sequences with space patterns similar to the desired trajectory. Thirdly, the initial iterative control signals of the desired trajectory are extracted by using the control information of the combined primitive sequences. Finally, the simulation is carried out to demonstrate the effectiveness of the present method.
Population growth has made the probability of incidents at large-scale crowd events higher than ever. In the past decades, automated crowd scene analysis done by computer vision has attracted attention. However, severe occlusions and complex crowd behaviors make such analysis a challenge. As a key aspect of crowd scene analysis, a number of works dealing with dense crowd anomaly detection based on computer vision have been presented. This work is a survey of computer vision techniques for analyzing dense crowd scenes. It covers two aspects: crowd density estimation and abnormal event detection. Some problems and perspectives are discussed at the end.
In gesture recognition systems, segmenting gestures from complex background is the hardest and the most critical part. Gesture segmentation is the prerequisite of following image processing, and the result of segmentation has a direct influence on the result of gesture recognition. This paper proposed an algorithm of adaptive threshold gesture segmentation based on skin color. First of all, the image should be transformed from RGB color space to YCbCr color space. After eliminating luminance component Y, similarity graph of skin color will be obtained from the Gaussian model. Then Otsu adaptive threshold algorithm is used to carry out binary processing for the similarity graph of skin color. After the segmentation of skin color regions, the morphology method is used to process binary image for determining the location of hands. Experimental results show that the detailed segmentation of skin color using the dynamic-adaptive threshold can improve noise resistance and can produce better results.
In this paper, the decentralized stabilization of networked interconnected systems is investigated. The switched system approach is used to deal with the network-induced time-varying delays, and a discrete-time switched systems model is proposed to describe the networked interconnected systems. Furthermore, a sufficient condition is derived for the closed-loop systems to be exponentially stable by introducing the average dwell time, and a procedure for the design of decentralized state feedback controllers is presented by solving a convex optimization problem. A numerical example is given to illustrate the effectiveness of the proposed results.
Heavy-haul trains must be energy-efficient and safe during their operations. Owing to the multidimensional high-order nonlinear characteristic of heavy-haul trains, which include numerous cars, this paper proposes a uniform pseudospectral real-time closed-loop optimal control framework to minimize the energy consumption with control inputs and state constraints based on the Radau Pseudospectral Method (RPM). In the framework, in order to ensure safe running of the heavy-haul train, the desired in-train force and speed limit requirements are formulated as constraints of optimal control. Simultaneously, a constrained closed-loop optimal control is constructed by using the receding horizon control principle and pseudospectral observer, in which RPM is leveraged to obtain real-time optimal solutions. The effectiveness of the proposed approach is verified from simulation results.
This study proposes model predictive control (MPC) for onboard ultracapacitors for light rail vehicles using a maximum current constraint. In this study, a Kalman filter is used to estimate the system states. Compared to the PID controller, the MPC-based charging control strategy can solve the maximum current limit problem because it converts the charging problem to an optimization one. Simulation and experiments are carried out to demonstrate the effectiveness of the method.
The crossiterative proportion, integration, and differentiation (PID) Neural Networks control algorithm presented here enhances position synchronization control in machine tools driven by two ball screws. An electromechanical coupling dynamics model reflecting typical system characteristics is established and then, based on dynamic analysis, a coordination control between two motor forces is investigated by separating machine tool translational and rotational dynamics. Based on state feedback, we adopt a crossiterative PID Neural Networks control algorithm using the Lyapunov function to guarantee controller stability to achieve coordination between two motor forces. Computer simulation and experimental results indicate that the algorithm follows reference input well and shows good control performance in reducing synchronization errors. The proposed algorithm also has good control performance on a biaxial synchronous machine system regardless of whether interference effects are large or small.
This paper investigates a genetic model with delay. The stability, direction, and bifurcation periodic solution is derived by using the center manifold theorem and normal form theory. Numerical simulations illustrate the theoretical results.
Multi-objective optimization problems involve two or more conflicting objectives, and they have a set of Pareto optimal solutions instead of a single optimal solution. In order to support the decision maker (DM) to find his/her most preferred solution, we propose an interactive multi-objective optimization method based on the DM’s preferences in the form of indifference tradeoffs. The method combines evolutionary algorithms with the gradient-based interactive step tradeoff (GRIST) method. An evolutionary algorithm is used to generate an approximate Pareto optimal solution at each iteration. The DM is asked to provide indifference tradeoffs whose projection onto the tangent hyperplane of the Pareto front provides a tradeoff direction. An approach for approximating the normal vector of the tangent hyperplane is proposed which is used to calculate the projection. A water quality management problem is used to demonstrate the interaction process of the interactive method. In addition, three benchmark problems are used to test the accuracy of the normal vector approximation approach and compare the proposed method with GRIST.
The goal of this study is to evaluate the swallowing functions of people with dysphagia using an acoustic microphone sensor. As a basic investigation towards this end, we measured the swallowing sounds using an acoustic emissions microphone sensor (AE sensor), then analyzed the frequency range of the measured signals, and we examined the method for obtaining the necessary information to evaluate the swallowing functions. For the measurement, two types of sensors, i.e., a condenser throat microphone and an AE sensor, were employed to measure the swallowing sounds. The acoustic signals obtained were subjected to spectral analysis using the wavelet transformation, and a comparison was performed between the measurable ranges of the acoustic signals obtained by the AE and the acoustic sensors. The results from the wavelet transformation of the acoustic signals obtained by the AE sensor indicated that acoustic signals generated during swallowing contained frequency information of 3 kHz and higher, which were not measurable with the acoustic sensor used in the experiment. In addition, we proposed a method of evaluating swallowing sounds using a novel approach based on the probability distribution. From the analysis results, it was found that the distance between the theoretical values and the measured values has a high correlation with the sample viscosity. Furthermore, it was found that the data measured with the AE sensor more sensitively reflected the difference in the sample viscosity. We were thus able to demonstrate the possibility of evaluating the swallowing function via the proposed method.
The Research Institute of the National Rehabilitation Center for Persons with Disabilities has been developing an assistive application for mouse operations for use by persons suffering from neuromuscular disease with muscular depression. When persons with neuromuscular disease have trouble using a standard type of mouse to operate personal computers, we try on them commercially available track ball, slide pad or mouse operation device for disabled persons just to find that such devices do not fit them so well because their upper limb’s movable range is so small and less dexterous. To cope with such difficulties and to assist users’ operations to move the mouse cursor, we have developed an application that is tuned with the motions of the upper limbs and fingers. In particular, the developed application has an additional function to compensate user’s mouse cursor’s large movement operations so that it can just fit in the cases where persons with muscular depression cannot lift up the mouse or let the fingers off the slide pad.
For ensuring information accessibility for hearing impaired, speech-to-text interpretation captioning is used. Usually, a text interpreter at the site interprets the speech of a speaker and enters a text into a PC. The text is then displayed through a projector or other devices to the users. For Japanese typing, in 1998, a method was developed for a pair of interpreters to collaboratively enter a sentence in which they used dedicated software to convert speech to text and present the resulting text. In the recent years, remote speech-to-text interpretation using the internet has been studied to overcome place and time restrictions of interpreters and users. However, conventional remote speech-to-text systems necessitated ensuring the availability of a network and preparing and operating devices for the system establishment and, hence, could be operated only by a limited number of organizations and groups. To overcome these limitations, we developed a system called captiOnline through which one can perform remote speech-to-text interpretation by simply accessing it through a web browser. In this paper, we explain how to implement captiOnline, evaluate its use in actual situations, and compare it with conventional systems. In addition, we show that captiOnline can realize remote speech-to-text interpretation in a simple configuration requiring less preparatory works.
Step-length measurement as a spatial gait parameter is useful for the physician and physical therapist for determining the patient’s gait condition. We hypothesized that this could be determined using ultrasonic sensors mounted on a shoe-type measurement device. For that purpose, we have developed a shoe-type measurement device to measure gait parameters. Our system was found to effectively measure step-length and pressure distribution. However, we found that the presence of shoes leads to perishable and fragile conditions for the sensors. Therefore, we redesigned the number, angle, and range of the ultrasonic sensors mounted on the shoes in order to clarify and improve the step-length prediction. This paper discusses the improvement of a shoe-type measurement device from the implementation with real shoes and the step-length prediction using an artificial neural network (ANN). The results of the experiment show that the number, angle, and positioning of ultrasonic sensors affect their ability to capture the human step region, that is, 50×70 cm under the experimental condition of foot progression angle up to 30 degrees. The results of the predictive performance of step-length using the proposed ANN architecture demonstrate an improvement.
Because the number of elderly people is rapidly growing, using information and communication technology (ICT) for services to watch single-elder-person households has been attracting attention. Most of these services are aimed at detecting elders’ abnormalities. They could become more effective, from the preventive-medicine point of view, if additional functions were added to watch for any decline in the elders’ cognitive functions. In this paper, we describe a method for detecting minor declines in elders’ cognitive functions, which they may not be aware of, by measuring and analyzing their spiral-tracing ability using a tablet device. We developed such a measurement/analysis system and applied it to three groups of test participants: young, non-frail elders, and frail elders. This paper first describes the method for analyzing the numbers of out-of-orbit tracing attempts, the numbers of uncompleted attempts, the required time, and the angular velocities, and then refers to these tasks to reveal the elders’ characteristics from the analytic results.
Sit-to-stand (STS) activity from a chair is an important motion in daily life. Some commercial products assist with STS activity in toilet use. These products control seat orientation by changing three parameters, i.e., seat height, tilt, and shift in a forward-backward direction. The reason for selection of these three parameters for seat orientation control has not been reported. Moreover, there are no reports on the best combination of these parameters. Therefore, in this study, we investigated the relationship between ease of STS activity and seat orientation during STS activity. We found that seat tilting provided good support for STS activity when the seat was in a high position (0.55 m), and shifting the seat forward provided good support for STS activity when the seat was higher than 0.45–0.55 m.
Improving the texture of foods provided during nursing care is necessary to improve the appetite of elderly individuals. We developed a system to vary perceived food texture using pseudo-chewing sounds generated from electromyogram (EMG) signals. However, this previous system could not provide chewing sounds that were sufficiently congruous with foods. Because food/sound combinations that seem unnatural cause individuals to feel uncomfortable with pseudo-chewing sounds, food/sound congruity is important. This research aims to improve the derivation and presentation of pseudo-chewing sounds so as to be able to provide various kinds of chewing sounds. The developed system adjusts the volume of pseudo-chewing sounds that are stored in a digital audio player based on the amplitude of the EMG signal envelope. Using this system, food/sound congruity was examined with two kinds of softened Japanese pickles. Six kinds of pseudo-chewing sounds were tested (noisy chewing sound, EMG chewing sound, and four kinds of actual chewing sounds: rice cracker, cookie, and two kinds of Japanese pickles). Participants reported that food/sound combinations were unnatural with the noisy and EMG chewing sounds, whereas the combinations felt more natural with the pseudo-chewing sounds of Japanese pickles. We concluded that the newly developed system could effectively reduce the unnatural feeling of food/sound incongruity.
In recent times, the use of subtitles and audio descriptions in movies for individuals with either hearing or visual impairment and the need to develop systems to provide these have been realized. However, even the need and possibility for deaf-blind individuals to enjoy movies have not been discussed yet. This study created an environment for deaf-blind individuals to “watch” a film, and conducted a screening of feature-length films with subtitles and audio descriptions. Interviews of 26 deaf-blind individuals indicated that 56% had watched films in a theater after becoming deaf-blind and before the screening session. When watching the films, 26.9% of participants used individual monitoring devices, headphones, or other conventional video or audio equipment. Furthermore, 50% were able to use either subtitles or audio descriptions. Regardless of their impairment conditions, participants responded positively towards watching the film in the screening session. Among the deaf-blind, 42.1% of the partially sighted and deaf, blind and hard of hearing, and partially sighted and hard of hearing individuals appreciated a special aspect of the theater, i.e., “sharing an opportunity and communication with others.”
In this study, a web application of kikimimi, a game for visually-impaired persons, was created. The game rules were simplified to allow the visually-impaired to easily play it. This was verified in an experiment in which visually-impaired persons actually enjoyed the web application game. Moreover, it was confirmed that even the simplified version of the game was sufficiently entertaining.
Assisting the elderly to or from a toilet for excretion is a heavy burden, and staff at nursing homes and families at home have problems such as backache and tiredness. There are several previous studies on standing up from a chair, bed, or toilet seat but almost no studies on the series of actions required for excretion (i.e., from a bed to a transfer apparatus and from the transfer apparatus to the toilet seat). The difference in the physical burden (muscular strength) for helpers when using the Norisukesan II, a transfer-type wheelchair developed in collaboration with the authors, and an ordinary wheelchair when transferring a patient to or from a toilet for excretion was studied by biometrics with surface electromyogram (EMG) patterns. We chose a total of 11 healthy adult examinees, 10 males and one female, with an average age of 47.7±9.7. Muscle activity was measured at eight positions: right and left biceps brachii muscles, right and left quadriceps femoris muscles, upper right and left trapezius muscles, and right and left waist muscles. The results showed that if the transfer-type wheelchair was used, the muscle activity of the helpers’ biceps brachii muscles decreased by 70%, that of the quadriceps femoris muscles decreased by 60%, that of the trapezius muscles decreased by 70%, and that of the waist muscles decreased by 40%, when compared to using the ordinary wheelchair. It was therefore quantitatively clarified that assisting patients with the transfer-type wheelchair could reduce the assisting burden significantly, as the helpers did not have to tightly hold or turn the patients.
Communication has such a vital function as the foundation of human social life that speech disabilities can drastically deteriorate people’s quality of life. The author has developed a voice output communication aid (VOCA) to enable children/persons with speech disabilities to communicate with other people according to conversation situations with iOS devices with global positioning system (GPS), positional information acquiring technology (iBeacon), and a clock function installed. The developed technology is an application compatible with iOS (hereinafter, app) that displays a list of messages (hereinafter, VOCA interface) if any of them correspond to the information on the user’s location and time of use as acquired by users with a portable information device with a GPS function, iBeacon function, and clock function installed. Users can communicate by selecting the icons of required messages from VOCA interfaces to reproduce registered voice data instead of their own voices. We have named the developed technology “Friendly VOCA” because its intentions are that: (1) users can communicate with other people with as few operations involved as possible; (2) it should be easy for users to learn and to operate. This paper reports the development processes of the Friendly VOCA and defines the ratios of preregistered VOCA interfaces displayed (hereinafter, correct answer rates) in acquiring positional information with GPS and with iBeacon. In Research Task 1, we have conducted experiments to verify the correct answer rates of the GPS system in outdoor use of the Friendly VOCA and in Research Task 2 we have conducted experiments to verify the correct answer rates of the iBeacon system in indoor use of the Friendly VOCA. The research results show that both the GPS system and iBeacon system can specify user’s spatial information and display appropriate lists of messages. However, the experiments found that iBeacon signal transmitters can transmit signals over a distance of 50 m or more: to improve the correct answer rates of the iBeacon system, we may need to increase the distance between iBeacon signal transmitters or select devices with a shorter range of transmission.