Showing papers by "Mitsubishi Electric published in 2014"

Fast plane extraction in organized point clouds using agglomerative hierarchical clustering

Abstract: Real-time plane extraction in 3D point clouds is crucial to many robotics applications. We present a novel algorithm for reliably detecting multiple planes in real time in organized point clouds obtained from devices such as Kinect sensors. By uniformly dividing such a point cloud into nonoverlapping groups of points in the image space, we first construct a graph whose node and edge represent a group of points and their neighborhood respectively. We then perform an agglomerative hierarchical clustering on this graph to systematically merge nodes belonging to the same plane until the plane fitting mean squared error exceeds a threshold. Finally we refine the extracted planes using pixel-wise region growing. Our experiments demonstrate that the proposed algorithm can reliably detect all major planes in the scene at a frame rate of more than 35Hz for 640×480 point clouds, which to the best of our knowledge is much faster than state-of-the-art algorithms.

Laser radar device

Abstract: Disclosed is a laser radar device having a wide two-dimensional field of view, a large receiving aperture, and responsivity to short pulse light. Specifically disclosed is a laser radar device provided with a laser light source which generates pulse laser light, a scanner which transmits a transmission pulse to a target while two-dimensionally scanning a pencil-shaped transmission beam and outputs scan angle information, a reception lens which receives reception light that has arrived, a long light-receiving element array which converts the reception light to reception signals and outputs the reception signals, a transimpedance amplifier array which amplifies the reception signals, an adder circuit which adds the reception signals from respective elements of the transimpedance amplifier array, a distance detection circuit which measures the light round-trip time to the target of an output signal from the adder circuit, and a signal processing unit which obtains the distances to multiple points on the target on the basis of the light round-trip time and the light speed by causing the scanner to perform a two-dimensional scan operation while associating the two-dimensional scan operation with the scan angle information to thereby measure the three-dimensional shape of the target.

Fast graspability evaluation on single depth maps for bin picking with general grippers

Abstract: We present a method that estimates graspability measures on a single depth map for grasping objects randomly placed in a bin. Our method represents a gripper model by using two mask images, one describing a contact region that should be filled by a target object for stable grasping, and the other describing a collision region that should not be filled by other objects to avoid collisions during grasping. The graspability measure is computed by convolving the mask images with binarized depth maps, which are thresholded differently in each region according to the minimum height of the 3D points in the region and the length of the gripper. Our method does not assume any 3-D model of objects, thus applicable to general objects. Our representation of the gripper model using the two mask images is also applicable to general grippers, such as multi-finger and vacuum grippers. We apply our method to bin picking of piled objects using a robot arm and demonstrate fast pick-and-place operations for various industrial objects.

High-dimensional modulation for coherent optical communications systems.

Abstract: In this paper, we examine the performance of several modulation formats in more than four dimensions for coherent optical communications systems. We compare two high-dimensional modulation design methodologies based on spherical cutting of lattices and block coding of a ‘base constellation’ of binary phase shift keying (BPSK) on each dimension. The performances of modulation formats generated with these methodologies is analyzed in the asymptotic signal-to-noise ratio regime and for an additive white Gaussian noise (AWGN) channel. We then study the application of both types of high-dimensional modulation formats to standard single-mode fiber (SSMF) transmission systems. For modulation with spectral efficiencies comparable to dual-polarization (DP-) BPSK, polarization-switched quaternary phase shift keying (PS-QPSK) and DP-QPSK, we demonstrate SNR gains of up to 3 dB, 0.9 dB and 1 dB respectively, at a BER of 10−3.

Discriminative NMF and its application to single-channel source separation

Abstract: The objective of single-channel source separation is to accurately recover source signals from mixtures. Non-negative matrix factorization (NMF) is a popular approach for this task, yet previous NMF approaches have not optimized directly this objective, despite some efforts in this direction. Our paper introduces discriminative training of the NMF basis functions such that, given the coefficients obtained on a mixture, a desired source is optimally recovered. We approach this optimization by generalizing the model to have separate analysis and reconstruction basis functions. This generalization frees us to optimize reconstruction objectives that incorporate the filtering step and SNR performance criteria. A novel multiplicative update algorithm is presented for the optimization of the reconstruction basis functions according to the proposed discriminative objective functions. Results on the 2nd CHiME Speech Separation and Recognition Challenge task indicate significant gains in source-to-distortion ratio with respect to sparse NMF, exemplar-based NMF, as well as a previously proposed discriminative NMF criterion.

Development of a 500-kW Modular Multilevel Cascade Converter for Battery Energy Storage Systems

Abstract: Renewable energy sources such as wind turbine and photovoltaic power generators may make the power grid unstable due to their output fluctuations. Battery energy storage systems (BESSs) are being considered as a countermeasure for this issue. A modular multilevel cascade converter (MMCC) is expected as a power conversion circuit for BESSs because each bridge cell can control the state of charge of a battery unit, independent of that of another one, and the harmonic current generated is low enough to eliminate the ac filter, normally installed on conventional two-level converters, from the MMCC. This paper describes the development of a real-scale (500 kW) single-star-bridge-cell-based MMCC for BESSs and reports successful test results obtained from a downscaled grid model and a 6.6-kV real-scale distribution line.

Power conversion device

Abstract: In the case of performing self-sustained operation, when power conversion devices supply power to loads, all DC/AC conversion circuits of the power conversion devices are operated in a voltage control mode, and effective voltage (amplitude) of reference AC voltage as a control target for AC power outputted from each DC/AC conversion circuit under voltage control is adjusted in accordance with the power generation amount of a solar panel as a DC power supply, and the state of charge of a storage battery, thereby the amount of power supplied to the loads is controlled.

4H-SiC Trench MOSFET with Bottom Oxide Protection

Abstract: Ensuring gate oxide reliability and low switching loss is required for a trench gate SiC-MOSFET. We developed a trench gate SiC-MOSFET with a p-type region, named Bottom P-Well (BPW), formed at the bottom of the trench gate for bottom oxide protection. We can see an effective reduction in the maximum bottom oxide electric field (Eox) and a significant improvement in dynamic characteristics with a grounded BPW, whose dV/dt is 76 % larger than that with a floating BPW due to reduction in gate-drain capacitance (Cgd). The grounded BPW is found to be an effective means of both suppressing Eox and reducing switching loss.

Robust Speech Recognition using Long Short-Term Memory Recurrent Neural Networks for Hybrid Acoustic Modelling

Abstract: One method to achieve robust speech recognition in adverse conditions including noise and reverberation is to employ acoustic modelling techniques involving neural networks. Using long short-term memory (LSTM) recurrent neural networks proved to be efficient for this task in a setup for phoneme prediction in a multi-stream GMM-HMM framework. These networks exploit a self-learnt amount of temporal context, which makes them especially suited for a noisy speech recognition task. One shortcoming of this approach is the necessity of a GMM acoustic model in the multi-stream framework. Furthermore, potential modelling power of the network is lost when predicting phonemes, compared to the classical hybrid setup where the network predicts HMM states. In this work, we propose to use LSTM networks in a hybrid HMM setup, in order to overcome these drawbacks. Experiments are performed using the medium-vocabulary recognition track of the 2nd CHiME challenge, containing speech utterances in a reverberant and noisy environment. A comparison of different network topologies for phoneme or state prediction used either in the hybrid or double-stream setup shows that state prediction networks perform better than networks predicting phonemes, leading to stateof-the-art results for this database.

Multi-Band OFDM Transmission at 100 Gbps With Sub-Band Optical Switching

Abstract: In this paper, we present an original work on sub-wavelength optical switching performed over a coherent multi-band orthogonal frequency-division multiplexing (MB-OFDM) super-channel operating at 100 Gbps. After having demonstrated that dual-polarization MB-OFDM (DP-MB-OFDM) is as efficient as single-carrier dual-polarization quaternary phase shift keying (DP-QPSK) technology to transport 100 Gbps data-rate over a 10 × 100-km G.652 fiber-based transmission line, we show that optical add-drop of OFDM sub-bands as narrow as 8 GHz inside a 100 Gbps DP-MB-OFDM signal constituted of four sub-bands is feasible in the middle of this 1000-km transmission line. The flexible optical add-drop multiplexer (FOADM) implemented here is constituted by the association of an ultra-narrow pass-band and stop-band optical filter. The design and realization of such ultra-selective optical filters is presented, while the impact of their physical features over the quality of transmission is discussed. To prove that several add-drop multiplexers can be cascaded, our FOADM is introduced into a G.652 fiber-based recirculating loop and the impact of the cumulated filtering transfer function as well as the crosstalk inside the OADM are investigated. A typical use case for the introduction of such FOADM into long-haul transport networks is given, and the capital expenditure (CAPEX) cost advantage for the multi-layer transport networks is highlighted. By the proof of concept delivered here, combination of super-channel and sub-wavelength optical switching pushes network flexibility far away of what is today proposed by system vendors, opening new horizons for an optimized use of multi-layer transport networks.

Effects of Ions on the OH Stretching Band of Water as Revealed by ATR-IR Spectroscopy

Abstract: The effects of various cations (Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, and Ni2+) and anions (Cl−, Br−, I−, $$ {\text{NO}}_{3}^{ - } $$ , $$ {\text{ClO}}_{4}^{ - } $$ , $$ {\text{HCO}}_{3}^{ - } $$ , and $$ {\text{CO}}_{3}^{2 - } $$ ) on the molar absorptivity of water in the OH stretching band region (2,600–3,800 cm−1) were ascertained from attenuated total reflection infrared spectra of aqueous electrolyte solutions (22 in all). The OH stretching band mainly changes linearly with ion concentrations up to 2 mol·L−1, but several specific combinations of cations and anions (Cs2SO4, Li2SO4, and MgSO4) present different trends. That deviation is attributed to ion pair formation and cooperativity in ion hydration, which indicates that the extent of the ion–water interaction reflected by the OH stretching band of water is beyond the first solvation shell of water molecules directly surrounding the ion. The obtained dataset was then correlated with several quantitative parameters representing structural and dynamic properties of water molecules around ions: ΔG HB, the structural entropy (S str), the viscosity B-coefficient (B η ), and the ionic B-coefficient of NMR relaxation (B NMR). Results show that modification of the OH stretching band of water caused by ions has quasi-linear relations with all of these parameters. Vibrational spectroscopy can be a useful means for evaluating ion–water interaction in aqueous solutions.

Speech search device and speech search method

Abstract: Disclosed is a speech search device including a recognizer 2 that refers to an acoustic model and language models having different learning data and performs voice recognition on an input speech, to acquire a recognized character string for each language model, a character string comparator 6 that compares the recognized character string for each language models with the character strings of search target words stored in a character string dictionary, and calculates a character string matching score showing the degree of matching of the recognized character string with respect to each of the character strings of the search target words, to acquire both a character string having the highest character string matching score and this character string matching score for each recognized character strings, and a search result determinator 8 that refers to the acquired score and outputs one or more search target words in descending order of the scores.

Power conversion device

Abstract: There is provided an inverter (1) to be applied to a dispersed generation system (10) to interconnect with a system bus (7), which measures a system voltage (Vr) of the system bus (7), detects a voltage drop of the system bus (7), based on the measured system voltage (Vr), increases a frequency of a carrier wave when the voltage drop is detected, generates a signal wave to control an output current (Iiv) of the inverter (1), compares the carrier wave with the signal wave, generates a gate signal (Gt), and performs power conversion by PWM control, based on the generated gate signal (Gt).

Headlight module and headlight device

Abstract: Provided is a vehicle headlight module (100) that forms and projects a light distribution pattern, said headlight module (100) having a first light source (1) and an optical element (3). The first light source (1) emits a first light. The optical element (3) includes a reflecting surface (32), which reflects the first light, and a light-guiding part (3a) that guides the first light reflected by the reflecting surface (32). A light distribution pattern including a high-luminosity region formed where the first light reflected by the reflecting surface (32) and the first light not reflected by the reflecting surface (32) overlap is projected in the direction corresponding to the vertical direction of the vehicle. The first light reflected by the light-guiding part (3a) is emitted in the direction corresponding to the horizontal direction of the vehicle.

New aspects of UHF PD diagnostics on gas-insulated systems

Abstract: Gas insulated switchgears (GIS) have been increasingly introduced as main substation equipment since the late 1960s thanks to their high reliability, safety, and compactness. The UHF method to diagnose partial discharge (PD) is broadly employed in the field as an advanced insulation diagnostic technology. There are three primary factors related to the PD signal detection characteristics using this UHF method; namely the frequency spectrum of the PD signal itself inside GIS, the propagation characteristics of the PD signal inside the GIS tank, and the detection characteristics of the sensor measuring the PD signal. Accordingly, to further improvement of the diagnostic technique based on the UHF method, the PD phenomenon itself and its propagation characteristics should be clarified and the measurement system refined. From these perspectives, the present study reviewed the recent and latest findings concerning the PD phenomenon and its propagation characteristics inside GIS as well as the PD measurement system verification methods and diagnostic technologies, and summarized typical examples. Firstly, with regard to the PD phenomenon, measurement up to the high frequency band exceeding 10 GHz (even 30 GHz) clarified that the rise time of the PD current waveform is several tens of picoseconds, shorter than previously known. In the case of PD in micro-defects inside the epoxy insulator, however, the rise time is relatively long, in the order of nanoseconds, and a crack is the most critical defect. Subsequently, with regard to UHF PD diagnostics/monitoring technology, a novel technique using PD current waveform characteristics has been developed, and a more advanced PD diagnostic algorithm has been established by clarifying the influence of the shape and GIS internal structures on the electromagnetic wave propagation characteristics. Less uncertain and simplified calibration and verification technologies are also proposed both for a single UHF sensor and the entire UHF measurement system. These new technologies and further advanced studies in future are expected to make the UHF method more convenient and sophisticated.

Device and method for understanding user intent

Abstract: A voice recognition unit (3) generates a plurality of voice recognition results from a single voice input (2). An intent understanding unit (7) estimates an intent for each voice recognition result and outputs one or more intent understanding results and scores. A weight calculation unit (11) calculates a standby weight using setting information (9) for a device to be controlled. An intent understanding correction unit (12) calculates a final score by correcting the score of an intent understanding result candidate using the standby weight and selects an intent understanding result (13) from among intent understanding result candidates on the basis of the final score.

Power conversion system

Abstract: In a power conversion system in which one or more converter cells are connected in series to form an arm for each phase, a control device includes a voltage command generating unit for generating a positive arm voltage command and a negative arm voltage command for each phase The voltage command generating unit includes an AC current control unit, a circulating current control unit, and a command distributing unit On the basis of inputted voltage commands, the command distributing unit subtracts voltage drop portions due to inductance values in the arms from respective voltages assigned as outputs of the positive arm and the negative arm, to distribute voltage components, thereby determining the positive arm voltage command and the negative arm voltage command

The MERL/MELCO/TUM system for the REVERB Challenge using Deep Recurrent Neural Network Feature Enhancement

Abstract: This paper describes our joint submission to the REVERB Challenge, which calls for automatic speech recognition systems which are robust against varying room acoustics. Our approach uses deep recurrent neural network (DRNN) based feature enhancement in the log spectral domain as a single-channel front-end. The system is generalized to multi-channel audio by performing single-channel feature enhancement on the output of a sum-and-delay beamformer with direction of arrival estimation. On the back-end side, we employ a state-of-the-art speech recognizer using feature transformations, utterance based adaptation, and discriminative training. Results on the REVERB data indicate that the proposed front-end provides acceptable results already with a simple clean trained recognizer while being complementary to the improved back-end. The proposed ASR system with eight-channel input and feature enhancement achieves average word error rates (WERs) of 7.75 % and 20.09 % on the simulated and real evaluation sets, which is a drastic improvement over the Challenge baseline (25.26 and 49.16 %). Further improvements can be obtained by system combination with a DRNN tandem recognizer, reaching 7.02 % and 19.61 % WER.

Reversing Stealthy Dopant-Level Circuits

Abstract: A successful detection of the stealthy dopant-level circuit trojan, proposed by Becker et al. at CHES 2013 [1], is reported. Contrary to an assumption made by Becker et al., dopant types in active region are visible with either scanning electron microscopy SEM or focused ion beam FIB imaging. The successful measurement is explained by an LSI failure analysis technique called the passive voltage contrast [2]. The experiments are conducted by measuring a dedicated chip. The chip uses the diffusion programmable device [3]: an anti-reverse-engineering technique by the same principle as the stealthy dopant-level trojan. The chip is delayered down to the contact layer, and images are taken with 1 an optical microscope, 2 SEM, and 3 FIB. As a result, the four possible dopant-well combinations, namely i p+/n-well, ii p+/p-well, iii n+/n-well and iv n+/p-well are distinguishable in the SEM images. Partial but sufficient detection is also achieved with FIB. Although the stealthy dopant-level circuits are visible, however, they potentially make a detection harder. That is because the contact layer should be measured. We show that imaging the contact layer is at most 16-times expensive than that of a metal layer in terms of the number of images.

Planar light source device and display apparatus incorporating same

Abstract: A planar light source device with highly uniform intensity and high light utilization efficiency, and a display apparatus incorporating the same, are provided. A light guide plate, configured by a material such as plate-shaped and transparent acryl resin, polycarbonate resin, or glass, causes incident light to propagate within the light guide plate and then to exit the light through an exit surface as a surface emitting light. A first recess is formed substantially in the center of the exit surface. The first recess is cylinder-shaped, and on a bottom thereof is provided a lens that refracts incident light from a light source, in a direction away from the center of a circle on the bottom.

Silicon carbide semiconductor device and method for manufacturing same

Abstract: Provided is a silicon carbide semiconductor device wherein an electric field in a protection diffusion layer formed at a trench lower portion can be attenuated. A silicon carbide semiconductor device (100) is provided with: a first conductivity-type drift layer (2a); a first conductivity-type source region (4), which is formed at an upper portion in a semiconductor layer (2); an active trench (5a), which is formed by penetrating the source region (4) and a base region (3); a terminal trench (5b), which is formed around the active trench (5a); a gate insulating film (6), which is formed on the bottom surface and the side surfaces of the active trench (5a); a gate electrode (7), which is formed by being embedded in the active trench (5a) via the gate insulating film (6); a second conductivity-type protection diffusion layer (13), which is formed at a lower portion of the active trench (5a), and which has a first impurity concentration as a second conductivity-type impurity concentration; and a second conductivity-type terminal diffusion layer (16), which is formed at a lower portion of a terminal trench (5b), and which has a second impurity concentration as a second conductivity-type impurity concentration, said second impurity concentration being lower than the first impurity concentration.

Design and control of a three-fingered tendon-driven robotic hand with active and passive tendons

Abstract: This paper presents a design of a three-fingered robotic hand driven by active and passive tendons and proposes control methods for this hand. The tendon-driven robotic hand consists of the thumb, the index and the middle fingers. The robotic thumb can move all the joints independently. In contrast, the index and the middle robotic fingers are under-actuated using the combination of active and passive tendons, and move the terminal two joints synchronously, which is one of the important features of the human digits. We present passivity-based impedance and force controllers for tendon-driven robotic fingers and discuss how to combine them for fast and secure grasps. We experimentally validate that the robotic hand moves fast and manipulates an object and demonstrate that the robotic hand grasps objects in diverse ways.

Heat pump device

Abstract: Provided is a heat pump apparatus(200), including: a two-cylinder compressor (100) including: an electric motor (8); and two compression units (10, 20) to be driven by the electric motor (8), the two-cylinder compressor (200) being structured to switch between two operation modes including single operation in which one of the compression units (10, 20) is brought into a non-compression state, and parallel operation in which both the compression units (10, 20) are brought into a compression state; an inverter drive control device (150) for supplying drive power to the electric motor (8) of the two-cylinder compressor (100); an operation mode detecting-determining unit (145) for determining a current operation mode based on an electric signal acquired from the inverter drive control device (150); and a capacity control device (160) for determining a rotating frequency of the electric motor (8) so that a temperature of a target object is brought close to a set value, to thereby control the inverter drive control device (150) based on a result of determination of the operation mode detecting-determining unit (145).

Expressive Attribute-Based Encryption with Constant-Size Ciphertexts from the Decisional Linear Assumption

Abstract: We propose a key-policy attribute-based encryption (KP-ABE) scheme with constant-size ciphertexts, whose selective security is proven under the decisional linear (DLIN) assumption in the standard model. The proposed scheme also has semi-adaptively security, which is a recently proposed notion of security. The access structure is expressive, that is given by non-monotone span programs. It also has fast decryption, i.e., a decryption includes only a constant number of pairing operations. As an application of our KP-ABE construction, we also propose a fully secure attribute-based signatures with constant-size secret (signing) keys from the DLIN. For achieving the above results, we employ a hierarchical reduction technique on dual pairing vector spaces and a modified form of pairwise independence lemma specific to our proposed schemes.

Synchronous machine controller

Abstract: A synchronous machine controller includes a position detecting unit that detects a position of a rotor, a current detecting unit that detects an armature current, a current command generating unit that generates first and second current commands, a voltage command generating unit that generates a voltage command on the basis of the current commands, the position of the rotor, and the armature current, a power converting unit that outputs a voltage to the synchronous machine on the basis of the voltage command, a magnetic flux estimating unit that estimates an armature interlinkage flux on the basis of a rotational velocity calculated from a variation of the position of the rotor, the voltage command, and the armature current, and a magnet state estimating unit that estimates a magnetic flux or a temperature of the permanent magnet from the position of the rotor, the armature current, and the armature interlinkage flux.

A regularized Newton method without line search for unconstrained optimization

Abstract: In this paper, we propose a regularized Newton method without line search. The proposed method controls a regularization parameter instead of a step size in order to guarantee the global convergence. We show that the proposed algorithm has the following convergence properties. (a) The proposed algorithm has global convergence under appropriate conditions. (b) It has superlinear rate of convergence under the local error bound condition. (c) An upper bound of the number of iterations required to obtain an approximate solution $$x$$x satisfying $$\Vert abla f(x) \Vert \le \varepsilon $$??f(x)?≤? is $$O(\varepsilon ^{-2})$$O(?-2), where $$f$$f is the objective function and $$\varepsilon $$? is a given positive constant.

Integrated Spatial Optical System for Compact 28-Gb/s \(\times \) 4-lane Transmitter Optical Subassemblies

Abstract: A compact 28 Gb/s \(\times 4\) -lane transmitter optical subassembly is developed for 100Gb/s Ethernet (100 GbE)/OTU4 applications with a hybrid integrated spatial multiplexer optical system. The system simply comprises three bandpass filters and a mirror, despite the narrow guardband specification. Moreover, by an intensively improved precise lens manipulation technique acting in an upward direction in addition to horizontally and downward, high-coupled power into the single-mode output fiber can be achieved, with resolving the previously reported issue that the controllable direction was limited. Finally, we show that eye diagrams with adequate mask margins (≥15%) and high extinction ratio (≥8 dB) are obtained at 28 Gb/s with a low modulating voltage (≤1.6 V \(_{\mathrm {\mathbf {pp}}}\) ).