Warehouse automation has become an essential aspect of modern logistics management. A critical component of warehouse automation is the path finding algorithm, which is responsible for calculating the route for automated guided vehicles to navigate the warehouse. However, conventional single-agent path planning suffers from deadlocks, resulting in a significant reduction in throughput. On the other hand, optimal and complete multi-agent path finding algorithms are slow and computationally expensive, making them unsuitable for warehouses with multiple uncertainties that require constant replanning. In this paper, we propose a novel scheduling technique to avoid deadlocks by introducing nonstop areas based on the dynamics of vehicle intersections. We define critical areas in the warehouse as nonstop areas and prohibit robots from stopping and waiting within these areas. The robot’s reservation length is dynamically extended to ensure that it reserves the entire path through the nonstop area, preventing it from blocking other robots moving through the intersection in other directions. The optimal positions of the nonstop areas were determined in two steps: the placement step to find where the deadlock occurred, and the trimming step to remove the excess nonstop area tiles. Simulation results showed 100% deadlock prevention and significantly improved throughput with the inclusion of the proposed nonstop area. Moreover, the addition of the trimming step further increases the throughput up to 12.27%.

In recent years, the sea ice in the Arctic Ocean has been decreasing due to climate change caused by greenhouse gases. Therefore, the phenomena under the sea ice must be investigated. The existing method of autonomous underwater vehicle (AUV) exploration is limited by its narrow communication and acoustic triangulation range. Therefore, digging a hole through the ice sheet is proposed to secure a communication relay system under the ice sheet. The objective of this study is to develop a robot using peristaltic motion as a system for drilling holes in sea ice. In the previous study, we determined the required specifications for the sea ice drilling robot. In this study, the excavation unit and the propulsion unit of the sea ice drilling robot are developed according to this specification. The basic characteristics of each mechanism were evaluated, and the digging performance of the excavation unit and the gripping performance of the propulsion unit were confirmed.

There is an urgent requirement to solve the problem of global warming. The sea ice beneath the Arctic Ocean strongly affects the global climate. However, it has not been fully explored. The range of Autonomous Underwater Vehicles (AUV) used for under-ice exploration is limited owing to their short communication range. To solve this problem, we propose a communication relay system that uses a sea ice drilling robot. We conducted excavation and gripping experiments on actual sea ice to study the parameters and control methods required to design a sea ice drilling robot. The required specifications of excavation and propulsion units were obtained from the experimental results, and a recovery method was developed to address drilling failure.

Demands for Internet of Things (IoT) platforms are increasing along with the expansion of data-driven sciences, and academic network infrastructure such as national research and education networks (NRENs) are now being encouraged to aggressively support diverse IoT research projects. In Japan, the National Institute of Informatics (NII) operates an NREN called "SINET5," which is an academic backbone network linking more than 900 universities and research institutions. In addition to SINET5's high-speed 100 Gbps backbone network, SINET5 also provides a mobile network called "Mobile SINET" as IoT infrastructure. To provide crucial support to IoT research projects and to facilitate the development and deployment of IoT applications, we present herein our experience with our software library, "SINETStream." In this paper, we provide an overview of SINETStream and discuss lessons learned from examples of application deployment over Mobile SINET. SINETStream provides a common and simple application program interface (API) for various message brokers, security functions, and performance tuning support features. These functions improve the portability of applications and help application developers to remove hindrances to the development of secure and efficient IoT applications. The experimental results provided herein show that application developers can use SINETStream functions within a reasonable overhead. We also show how the combination of SINETStream and Mobile SINET enables users to develop and deploy highly confidential and efficient IoT applications.

This paper presents a precise localization technique for cooperative transportation robots and a work object, e.g., a logistic cart, that utilizes three-dimensional depth data and an optical image obtained by an external depth camera. Both the robots and the work object are simultaneously localized by the camera installed on the ceiling. The projective transformation and shape approximation are accurate enough for the robots to take hold of the work object without being disturbed by fluctuations inherent in the depth data. Evaluations show that the proposed method achieves a sufficiently small localization error of 11mm for the robots and approximately 30mm for the work objects on average. We also demonstrate that a prototype of the proposed cooperative transportation robot system can automate a transportation flow that consists of approaching the work object, holding it, and transporting it.

We propose a payload estimation system for hydraulic excavators. The proposed system achieves the following advantages: (1) it can be externally mounted on existing excavators, (2) it is relatively inexpensive, and (3) it achieves high accuracy. To realize these advantages, we install a depth camera externally on the inside of an excavator’s arm and use a method to determine the depth of the soil in the bucket from a bird’s eye view. Moreover, we utilize kernel ridge regression, which is a machine learning technique, to achieve highly accurate estimation. Furthermore, we enhance the method for small- scale training datasets by combining it with geometrical volume calculation.

We propose a method to determine control input on the basis of minimizing the risk-sensitive cost function and show the results of an experiment in which the method was applied to a cooperative transportation robot system that we have developed. In the robot system, two robots hold a work object to transport without an external fixing device. The mechanism yields the force interaction between the robots and the object, which results in unexpected random errors in transportation. We add a stochastic term to the system model to describe such errors and solve the stochastic differential equation numerically to estimate the cost function. Utilizing the risk-sensitive cost function enables us to find the control input that balances efficiency and safety. The experimental results revealed that the chance of a robot colliding with an obstacle during transportation decreased from 90% to 7% compared with the optimal control.

A prototype phase-detection ranging system based on the automotive remote/tele-control narrowband ARIB STDT108 standard and operating in the sub-GHz band is designed, built, and evaluated. The prototype uses a pair of transceivers operating asynchronously. Problems with the frequency offset and initial phase are overcome by using an exchange sequence. The prototype employing 5.6MHz bandwidth achieves a distance error of 0.09 m under ideal environments without multipath and 0.88 m in outdoor conditions within the range of 6.0 m × 6.0 m area.

Although areas devastated by natural disasters must be promptly reconstructed, reconstruction works involving construction machinery are dangerous and bring a significant risk of a second disaster. A remote construction system is thus often used, which enables an operator to conduct reconstruction work from a remote and safe place while viewing on-site videos. However, the remote construction has a major problem: it has much lower work efficiency than manned construction because videos are delayed and impaired in a wireless network environment. In this paper, we present a remote construction system using our proposed adaptive video streaming method that dynamically adjusts the video bitrate on the basis of the predicted communication throughput variation. The experiments show that the proposed remote construction system using adaptive video streaming reduces operation time by 25.5%, which corresponds to a 34.3% improvement in work efficiency.

In the construction industry, remote construction has been introduced in specified cases such as restoration work after natural disasters in order to improve safety. Remote construction can also contribute to allocating limited labor resources efficiently and solving the labor scarcity problem. For this, long-distance remote construction though networks such as a wireless local area network (WLAN) and the Internet must be made possible. However, long-distance networks can have large transmission delays and packet loss, which cause bottlenecks that result in low operability and increased workload. We propose a remote construction system based on adaptive remote control techniques for improving video streaming and operation with considerations made for delays and packet loss. We also conduct an experiment to evaluate how the proposed remote construction system reduces workloads. Our experiment shows that the proposed system reduces the number of manipulations for a certain task by 25%. It also reduces the duration of operations by 16%, which corresponds to a 20% improvement in work efficiency.

Growing shortage of the labor force calls for automation of conveyance operations through the use of autonomous robots. These robots are difficult to implement in complicated facilities such as distribution centers and warehouses because of frequent changes in placements of conveyed goods and dollies. In this paper, we propose a conveyance system using multiple robots and external sensors. Our conveyance system offers adjustability to environmental changes and low cost by linking the robots and the sensors via a wireless network. Moreover, we introduce a prototype system of cooperative conveyance that controls multiple robots based on location information of the robots detected by a stereo camera.

Transmission Control Protocol (TCP) throughput is estimated by using the data size and the transferring time when large data is transferred from a sender to a receiver. However, if divided data is intermittently transferred such as in live video streaming, the estimated TCP throughput has an error because the actual transferring time is unobservable on an application layer. Other methods have been proposed for estimating TCP throughput, such as equation-based estimation that uses network information such as round trip time (RTT) and packet loss rate. Nevertheless, the accuracy of estimation lowers when RTT becomes unexpectedly much longer or when the burst loss occurs. We propose using an ensemble method for estimating TCP throughput on the basis of information that is observable on the application layer. Our proposed method can reduce error of the estimation. An evaluation experiment using actual data obtained on a Wi-Fi network showed that our proposed method estimates TCP throughput more accurately than conventional methods.

The users' perceived quality of web page browsing, so-called “Web QoE”, is becoming an important consideration for mobile network operators. The means by which operators can increase their customer base is shifting from ensuring high network quality of service (QoS) in terms of throughput to improving the quality of experience (QoE) of their users of their networks. They hence need to estimate the Web QoE from a vast number of logs stored on their network equipment, e.g., HTTP proxy servers. Generally, HTTP proxy servers record connection logs not on a per web access basis but rather on a per HTTP connection basis. Moreover, a single web access typically consists of multiple HTTP connections. Because of that, mobile network operators need to estimate web sessions from a lot of HTTP connection logs in a HTTP proxy server. To estimate web sessions, earlier studies took the following three approaches: (1) content type based, (2) time based, and (3) mixed. These approaches, however, inaccurately estimate (misestimate) web sessions in some cases. When a user accesses multiple web pages in a short time, these approaches may not distinguish which HTTP sessions compose a single web page and thus they may aggregate multiple web sessions as a single session. As a result, the estimation accuracy of web sessions decreases, and the estimation accuracy of Web QoE correspondingly decreases. In this paper, to more accurately estimate web sessions, we focus on the number of HTTP sessions in misestimated web sessions and propose a method for detecting erroneous estimations of web sessions that is based on statistical hypothesis testing. An experiment conducted on an operational LTE network showed that our method can decrease the mean absolute error of web session estimation by 0.09 point from that of the conventional method. Moreover, our method can get within 0.03 point of the estimation accuracy limit.

To achieve high-quality video streaming on a best-effort network, adaptive video streaming methods for controlling video bitrate in accordance with fluctuation in network throughput have been developed. These methods change the video bitrate in 1-10-second intervals. However, delay of the video increases if the throughput deteriorates drastically, and delay requirements cannot be satisfied when the requirement is short. To resolve this issue, adaptive video-streaming methods using scalable video coding (SVC) have been proposed. By using SVC, the bitrate can be controlled more frequently, and the delay can be reduced. However, the quality of SVC video worsens compared to that of the same bitrate non-SVC video due to coding overhead. The overhead increases as the number of layers increases. This paper proposes a method for adaptively controlling the bitrates of SVC layers. With this method, wide fluctuations in network throughput can be covered by a few layers, and the coding overhead can be reduced. Simulation results indicate that the method improves the video-quality score, which is the bitrate removing the effect of the coding overhead of SVC, by up to 38%.

Recently, the number of industrial robots connected to the Internet as Internet of Things (IoT) applications has increased. These machines mainly use wireless Internet connections rather than wired connections so that they have more mobility. To improve the responsiveness of a robot remote control system, it is important to select the control cycle that minimizes both control cycle and communication delay simultaneously. This minimization is difficult in general because the communication frequency affects the communication delay. In the present paper, we measure the communication delay when transmitting small packets with high frequency. We then present a novel method to minimize the summation of the control cycle and the communication delay and evaluate the results by simulation of remote control of a mobile robot. The simulation shows that the moving time and the precision improved by up to 70.2 % with the proposed method.

A method has been developed to predict the probability density function of the round-trip time (RTT) of a mobile/wireless network in an online manner by using data obtained from probe packets. In the present paper, we show the measurement results for the RTT by using LTE and Wi-Fi. On the basis of the results, we have built a two-state model. The states of the model correspond to a connected state, where the RTT is given by the shifted gamma distribution, and a disconnected state, where the packet is queued. The proposed method predicts the future probability density of the RTT by estimating the model parameters. A comparison with conventional methods revealed the proposed method can predict the probability density function more precisely with better stability.

Sub-seafloor exploration is an important area of biological and geological research, and often requires samples of seafloor mud to be recovered. The minerals and marine sediments trapped in this mud are also potentially valuable resources. However, seabed exploration has been limited by the complexity and cost of the traditional equipment used. Wide area exploration can be made possible by deploying multiple robots to autonomously search beneath the ocean floor. In this study, we prototyped a sub-seafloor excavation robot for use in seabed exploration. The key system comprised a propulsion unit and an excavation unit that allow the robot to move freely within the seabed. We experimentally demonstrated the ability of the excavation robot to produce curved boreholes with a diameter of 160 mm, a turning radius of 1.67 m, and a depth of 613 mm. Our experimental results confirm that nonlinear excavation is possible using the excavation robot developed.

Voice over IP (VoIP) services are now offered on many mobile networks. However, delay spikes, which are sudden large increases in packet delay, affect the quality of VoIP on mobile networks. This paper proposes a quality of experience (QoE) indicator considering delay spikes. The QoE indicator combines a voice quality indicator such as ITU-T P.862 and the delay part of ITU-T G.107, which is a quality indicator for VoIP. This paper also proposes a transmission control method that selects the codec type and the sending interval of voice packets so as to maximize the QoE indicator. The method improves the mean opinion score (MOS), which indicates QoE as a value between 1 and 5, by up to 0.4.

Live streaming services over HTTP used on smart devices via a mobile network have become very popular. However, playback interruption often occurs during a live streaming. This is because TCP throughput fluctuates due to radio strength variation and cross-traffic, and the playback buffer on the client side is small. To solve the playback interruption problem, adaptive rate control techniques are helpful. However, using a smart device with insufficient CPU power leads to control delays, which cause the rate to be controlled improperly. This paper proposes a novel rate control method that uses plural codecs and detection of throughput degradation, and shows that the proposed method reduces playback interruptions on smart devices. We evaluate our proposed method with a live streaming for 100 seconds as an experiment in conditions in which the TCP throughput is fluctuated by a network emulator. Playback interruption occurred three times and lasted 1.8 seconds in total with the conventional method, but did not occur with the proposed method. We also evaluate the method from the viewpoint of QoE defined in ITU-T Rec.P.1201/Amd.2. The proposed method is able to improve QoE(MOS) to 3.5 from 2.6 of conventional method.

Sub-seafloor explorations are important for biological and geological research. Sampling mud is one of the major sub-seafloor exploration procedures. The mud-including mineral resources and marine sediments are potentially valuable resources for future studies. Therefore, we propose a peristaltic-crawling-based sub-seafloor excavation robot for deep sea exploration. This robot consists of three units (propulsion, excavation and extraction units), enabling it to move freely through mud. The excavation and propulsion units are fitted with an earth auger and artificial muscles, respectively. In this paper, we verify the propulsion actuator as the first stage of robot development. First, we evaluate the performance of an oil hydraulic artificial muscle under water pressure. Next, we develop an excavation robot by incorporating a pneumatic artificial muscle into a robot and then experimentally evaluate propulsion and excavation of the robot. We confirmed that the artificial muscle appropriately performs as an actuator for the excavation robot.

End-to-end TCP throughput on best-effort networks fluctuates widely depending on cross traffic and radio interference, which degrades the quality of public cloud services. However, if throughput variation is predictable on the application layer, service providers can be proactive in solving the problem of quality deterioration. We argue that TCP throughput fluctuation occurs in two states, stationary and non-stationary, and developed a method for characterizing these states. We also constructed a stochastic model of TCP throughput, which is a mixture of a stationary process model and a non-stationary one based on stationarity analysis. An evaluation experiment showed that our proposed model could predict the next 200 seconds of TCP throughput fluctuation through the Internet on three types of access networks (HSDPA/LTE/Wi-Fi) with an average accuracy of about 90%.

An incredible amount of movies are released every year in Japan, and movies that match the viewers' social needs are the ones that become the big hits. All movies share a common trait in that they all include various “concepts”. For example, the American film “The Matrix” includes the concepts “virtual space”, “artificial intelligence”, “domination”, and others. We have developed a system for predicting hit movie concepts that uses a case base comprised of an immense amount of “ Cause → Consequence” pairs derived from past movies. We consider past hit movies a “consequence” and a news item that has a strong relationship with such movies as a “cause”. When we input new social needs into the system, we can predict hit movies by referring to the case base. Experimental results showed that the proposed system could successfully predict certain parts of what made up a hit movie.

Many of the video streaming services on the Internet and mobile networks use HTTP/TCP for video transport. Video streaming clients are generally designed to download a sufficient amount of data to avoid playback interruption caused by the lower TCP throughput. Storing more video data than necessary may generate a large amount of wasted traffic when users quit playing video before all of the downloaded video data are played. To prevent downloading unnecessary video data, HTTP downloading with just-in-time delivery features, called video pacing, is focused on. However, video pacing may cause playback discontinuity, resulting from a decrease in the playout buffer size. This is because conventional video pacing methods control the playout buffer size without considering the TCP throughput fluctuation. In this paper, we propose an adaptive video pacing method that enables both reducing unnecessary video traffic and maintaining user-perceived quality. The proposed method has two unique video-pacing functionalities, namely, predicting the stochastic diffusion of TCP throughput and controlling the playout buffer size by taking into account the future throughput. Experimental results from simulating mobile networks show that the proposed method can decrease the average playout buffer size in stable environments by up to 42.62% compared with the conventional methods. Moreover, the frequency of the playback discontinuity of the proposed method is shown to be up to 34.1% less than that of the conventional methods in unstable environments.

Network throughput of the best-effort networks as typified by the Internet and wireless networks is often insufficient for multimedia communication, and it spoils the quality of communication. Therefore, it is important to analyze a dynamic characteristics of the throughput when multimedia traffic is injected. We point out that the dynamics of the throughput has the viscosity and the elasticity because of an interaction among traffic passing through the network. We also introduce a viscoelastic material model to analyze the throughput. A total of 120 simulations were performed with an ns-2 simulation model. The results of simulations showed that the dynamics of the throughput does indeed have the viscoelasticity. Furthermore, we found that our proposed model can be used to analyze the throughput dynamics with a fit rate of about 90% on a wired network, and about 80% on a wireless one. This fact proved that there was an analogous relationship between variation of throughput and deformation of the viscoelastic material. We believe that we have developed a novel science field of Network Rheology.

As IT systems grow bigger and complex, they are comprised of many resources supplied by various vendors. Also, the Internet accelerates inter-enterprise business transactions and IT systems are connected each other. Consequently enterprise application systems are becoming a kind of large business process across multiple vendors. This transformation will also bring new type of complexity and difficulties to enterprise IT system management. Having awareness of these issues, IBM and Fujitsu have been collaborating on standardization effort for various areas of autonomic computing technologies. Autonomic computing and open standard interface are an effective approach to deal with these challenges. The initial areas of collaboration are common event format and interface for action to manage IT resources. hi this presentation, we show how an autonomic manager can solve these issues with using an open standard, WSDM (Web Service Distributed Management). We demonstrate the autonomic manager that behaves based on defined policy, continuously monitors systems, handles events and takes actions through WSDM interface in Multi-vendor IT Systems.

In direct conversion receivers, which down-convert RF signal to baseband directly, DC offset in the baseband signal significantly degrades receiver performance and thus the DC offset cancellation is one of the most important issues regarding the achievement of high receiving performance. This paper proposes a fast-settling DC offset canceller that eliminates DC offset using stored DC data estimated in advance so as to cancel residual DC offset by a feedback loop. Experimental results and computer simulation results show that the DC offset canceller can eliminate a DC offset within 5 [musec], although it does not remove the desired signal component so as not to degrade BER (bit error rate) performance, because cut-off frequency in the HPF (high-pass filter) characteristic due to DC offset cancellation can remain low.

We have developed a wireless LAN PC card for 2.4 GHz and 5 GHz dual-band operation using printed planar antennas, and evaluated its throughput performance. The planar antennas, which combine an inverted-F antenna with an inverted-L antenna, can realize a dual-band at low cost in a limited integrated area on the PC card. The radio propagation performance was evaluated in a shielded room which is modeled after an office. In the 2.4 GHz band, operation is stable and independent of the deployed position and the direction of a laptop PC with the PC card. On the other hand, in the 5 GHz band, although the performance is affected by surrounding objects and antenna directivity, the PC card with the printed antennas can realize as high a throughput as one with external omnidirectional antennas.

An antenna-selective transmit diversity (ASTD) technique, applied to a PC card for an orthogonal frequency division multiplexing (OFDM)-based wireless local area network (WLAN) system, is presented. The PC card, which is based on IEEE 802.11 a/g, is equipped with dual-band printed antennas. The ASTD processing is implemented in the developed WLAN system, which has two antennas for transmit and receive modes. The effects of the ASTD technique on the TCP (transmission control protocol) throughput performance are experimentally evaluated. Measurement results with the PC card in an imitated office show that the TCP throughput is improved on both the 2.4 and 5.2 GHz bands under the conditions of an indoor radio propagation channel due to the ASTD technique. In particular, application of the ASTD technique to an access point (AP) achieves four times the average TCP throughput on the 5.2 GHz band.

The paper describes the design and implementation of library module components for WBT systems conforming to the WBT standards such as AICC CMI specification or ADL SCORM specification. These components provide high level APIs for a WBT application program to handle WBT content data models defined in the specifications.

A software defined radio with the analog stage using the direct conversion principle and the digital stage using a DSP demodulator has been developed. The developed receiver realizes a multi-band characteristic of the 1.5 GHz and 1.9 GHz bands and a broadband characteristic up to 10 MHz together with a demodulation function of /spl pi//4-QPSK and GMSK, and the overall receiver performance was confirmed.

This paper presents a method to remove the DC offset which degrades the performance of a direct conversion receiver for burst mode QPSK signals. A canceller constructed from analog and digital signal processing circuits is proposed. Computer simulation results show that the canceller has a remarkable function of reducing the degradation in BER (bit error rate) performance by only 0.4 dB. The results show that the proposed offset canceller is suitable for the reception of burst mode QPSK signals such as those employed in NADC (North American Digital Cellular) and PHS (Personal Handy-phone System).

The paper presents a multi-layer structure for personal communications services (PCS). An evaluation is shown for low and high mobility of PCS in terms of cost economy, capacity and spectrum usage. It is supposed that the service area with 30 km radius is covered by a multiple micro cells in the low mobility plane, while the high-mobility plane employs macro cells. Two type of traffic shape are assumed; uniform and exponentially tapered traffic. It is shown that each plane has the optimum cell radius for the prescribed subscriber numbers. Therefore it is desirable to integrate the two systems for the support of full mobility.>