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Human collaborative robots (HCRs) are a useful future workforce because they can operate alongside people. Proximity and tactile sensing are important for HCRs to ensure safety. In this study, we propose a combined sensor module for HCRs using time-of-flight (ToF) as well as self-capacitance proximity and tactile sensors. The distance to an object in a noncontact range can be detected by a ToF sensor; however, the detection accuracy and the X-Y measurement range are lower for short ranges, with the Z axis as the measurement plane direction. The self-capacitance proximity and tactile sensors can detect objects and contact conditions in short ranges. For high-sensitivity proximity and contact measurements over a large distance, two of the aforementioned sensors can be combined. Prototypes of the sensor modules were prepared, and sixteen modules were mounted on a robot armto detect the position and distance of an object at 300 mm or less, along with the pressure and position upon contact. In addition, the robot arm was controlled using information obtained from the sensors. The proposed sensor modules can thus be employed for proximity and tactile sensing in HCRs.

Human collaborative robots (HCRs) work in close cooperation with humans. The proximity and tactile sensors placed on the HCR surface ensure the safety of humans working with the robots. However, many of these sensors do not have a collision absorption function. In this paper, we propose a self-capacitance proximity and tactile skin sensor with a shock-absorbing structure for HCRs. We evaluated the shock absorption performance and the proximity and tactile measurements of the prototype sensors using different thicknesses of the soft layer, which acted as a shock absorber. Results confirmed that when the thickness of the soft layer increased, the shock absorption function also increased, but the contact detection sensitivity decreased. In addition, we evaluated the collision between the robot with the sensor and an object when the robot moved. The sensor could absorb the impact of the collision between the robot and the object. Furthermore, multiple sensors placed on the robotic arm could detect an object before and after making contact in real time. We proved that the proposed sensor system with the shock absorber is reliable and can be used as a proximity and tactile skin sensor for HCRs.

In recent years, human cooperative robots (HCRs) have attracted considerable attention. HCRs should be equipped with proximity and contact sensors to ensure human safety. This study combines time-of-flight (ToF) and self-capacitance sensors to obtain proximity and contact sensors for HCRs. ToF sensor can determine the distance between an object and sensor in the proximity range; however, the detection accuracy decreases in a close range. The self-capacitance proximity sensor can detect objects before and during contact; it has high sensitivity in close range. For proximity measurements with high sensitivity and wide range, it is possible to combine the ToF and self-capacitance sensors. We modularized one sensor and connected the other sensor module using a serial bus; the sensor covered the entire HCR surface to ensure human safety. In this sensor, it is possible to obtain efficient measurements for distance ranging 300–0 mm. The prototype 24 pieces of sensor modules were established on the robot arm and these sensor modules detected the object’s position without establishing any contact and detected the human touch. Additionally, the robot arm was controlled in real time based on the sensor information. We believe the proposed sensor system can be employed as a proximity and contact sensor for HCRs.

Human cooperative robots (HCRs) that work in the same spaces as humans have attracted a significant amount of research attention. For safety, it is important to equip such robots with proximity sensors. This paper aims to propose a proximity skin sensor for collaborative robots using time-of-flight (ToF) sensors that are able to detect the distance between the sensors and the objects. These proximity skin sensors can detect object’s position and its approximate shape before contact. The prototype sensors are attached to the surface of the robot and can detect an object at a given proximity range. Therefore, this proximity skin sensor can ensure safety and workability of a robot by preventing unnecessary contact between the robot and the objects, including humans. Therefore, the sensor may be applicable to tactile sensors for HCRs.

The tactile texture of a product is one of many important factors that influences an impression of a product. Numerical evaluation methods for recognizing tactile texture measures, such as roughness, are required because there are indeed individual differences in how users experience tactile textures. In this paper, we propose a tactile sensor to recognize roughness using a convolutional neural network (CNN). Our sensor system consists of a pressure sensor and a six-axis acceleration sensor for detecting time-series data. The sensor measures time-series data, which are the pressure, speed, and posture of the sensor when the sensor is touching an object and is moved by a user. The surface roughness is calculated from these time-series data using a CNN. Here, our system configuration is simple and therefore easy and inexpensive to construct. To evaluate our approach, we constructed a prototype sensor and measured the roughness of six objects. The average correct recognition rate proved to be 71% for the experimental data acquired by one user, which are categorized into learning data and evaluation data. Further, the total average recognition rate for evaluation data by our five users for considering each individual using the sensor system was 42%. While the problem of roughness recognition by each individual user remains, we were able to show the possibility of roughness recognition via our approach. We conclude that our proposed sensor system is useful as a functional and useful device.

In recent years, human collaborative robots (HCRs) working in a same place with people has become more attractive. We have proposed a self-capacitance proximity and tactile skin sensor for HCRs. The structure of the sensor is simple and consists of two electrodes (E 1 and E 2 ) and an elastic body. The measurement system is also simple because only the self-capacitance measurement is used to detect objects both before and after contact. In this paper, we developed a ten-sensor system covering a whole robot surface. This sensor can detect objects before contact, and can detect pressure and positions after contact. In addition, we propose an operating method using the sensor for the safety and workability of HCRs. The proposed operating method including the sensor may be a useful system for HCRs.

Touch screens are useful human interfaces on smartphones. Most touch screens only detect contact position. We propose a proximity and pressure touch-screen method to increase usability. The proposed touch screen consists of plane separated-type and parallel-type electrodes using mutual capacitance measurement. The proposed sensor detects an object and its position using the plane separated-type electrodes within the proximity range. It also detects the pressure and precise center position using the parallel-type electrodes (capacitance pressure sensor) on contact. We believe that the proposed proximity and pressure touch screen will become a functional and useful interface.

Touch screens are widely used in smartphones, tablet PCs, and other electronics. Most touch screens detect contact position only. We propose a proximity touch screen method using separation-type electrodes with mutual capacitance measurement to improve functionality. In the experiments described in this paper, the proposed proximity touch screen detects an object and its position before contact (within the proximity range). In addition, we compare the proposed proximity measurement with conventional measurement. We expect that the proposed proximity touch screen will be a functional and useful interface.

Unmanned aerial vehicles including drones are attracting attention in recent years. A drone is required to approach an object and obstacles when the drone uses for inspection and an indoor space. However, the collision risk is increased when the drone is close to the object. In this paper, we propose the omni-directional proximity sensor for a drone to avoid a collision. The sensor system consists of 30 units of time-of-flight (ToF) sensors that are able to detect the distance between the sensors and objects. The sensor system attaches the propeller guard and the drone, and detects the object at non-contact area. Thus, this sensor system can avoid unnecessary contact between the drone and objects. Therefore, the sensor system may be useful for drones.

Touch screens have become one of the most common human interfaces in recent year. Most touch screens detect contact position only. We proposed the proximity and pressure touch screen method. This touch screen method consists of plane separation-type electrodes and parallel-type electrodes with mutual capacitance measurement. In this paper, we describe a proposed sensor using indium tin oxide (ITO) electrodes which are transparent on the LCD monitor. In addition, we consider the precise X-Y-Z position measurement by the proposed touch screen using the correction processing. The prototype sensor using this technique detects an object and its position on the LCD monitor before and after contact. We think that the proposed touch screen will be a functional and useful interface.

When people decide on preferences of personal belongings, they consider not only the appearance of the object but also the its tactile texture. The design of tactile texture is an important factor in the development of commercial products. To measure a feeling of an object, a numerical evaluation method for tactile texture is required. The measurement is performed using a large-scale apparatus, generally. In this paper, we propose a novel recognition method for tactile texture using long short-term memory recurrent neural network. In proposed framework, the tactile texture information is obtained by analyzing a time-series data of a pressure sensor and 6-axis acceleration sensor. Thus, the system configuration is simple, and it is possible to construct the system inexpensively.

In this paper, we develop a tactile and proximity sensor using self-capacitance measurement on the curved surface for human collaboration robot (HCRs). The proposed sensor consists of two measurement electrodes and an elastic body. We produced the prototype sensor using the flexible circuit board. Thus, the sensor can curve in the curved surface. The sensor using self-capacitance measurement can detect the object before contact, and detect the pressure and discriminate the material on contact. Therefore, the sensor will assure the safety and workability of the robot because the robot will avoid unnecessary contact with objects including humans.

Tactile texture is an important factor to determine to impression of an object. To measure a feeling of an object, a numerical evaluation method for tactile texture is required. In this paper, we propose a novel recognition method for tactile texture using deep convolutional neural networks. In proposed framework, the tactile texture information is obtained by analyzing a time-series data of a pressure sensor and 6-axis acceleration sensor. Thus, the system configuration is simple, and it is possible to construct the system inexpensively.

In this paper, we develop a layered 3D touch screen using capacitance measurement to detect an object both before and after contact for operation of a 3D image on the display. The proposed 3D touch screen employs layered parallel and plane-type capacitance sensors. The 3D touch screen can detect indentations and the precise position of an object and can identify the material in contact with it. In addition, it can detect the object and its position during noncontact (proximity range). Thus, the proposed 3D touch screen detects objects in the 3D range. In this paper, the proposed 3D touch screen is set on a display and detects objects and their positions before and after contact. The proposed 3D touch screen has the potential to be used as functional and useful interface.

In this paper, we propose a 3D tactile sensor using self-capacitance measurement for robot. The proposed sensor consists of the two electrodes (E1 and E2) and elastic body. The capacitance between E1 or E2 and GND is measured by switching between E1 and E2. The capacitance between E1 and GND is used to detect the object before contact (proximity range) and to discriminate the material on contact. The capacitance between E2 and GND (E1) is used to detect the indentation on contact. The sensor is attached to the robot surface, and can detect object both before and after contact (3D range). This technique may be applicable to proximity and tactile sensor for robot.

This paper proposes simple power line communication (PLC) method among DC-DC converters in DC distribution network system. In this method, current ripples in the converters' inputs are used as signal carrier whose frequency is modified as a function of information data. The modulator is easily realized by just adding a transistor and a resister to conventional PWM control circuit. Demodulator is also realized by simple analog circuit. With proposed method, the converters are capable of bidirectional data transmissions among all converters in the system. Circuit simulation results show the effectiveness of proposed method.

This paper proposes a simple circuit model to estimate output voltage fluctuation in paralleled converter system with optimized on-off control. The optimized on-off control method changes the number of active converter modules to minimize power losses in paralleled system according to load current. However, it causes voltage fluctuation in transient response. Output voltage fluctuation due to the on-off control is estimated with proposed simple circuit model. The estimation is verified by accurate circuit simulation. Simple guideline for circuit components is also given to meet a specific output voltage tolerance.

We proposed a proximity and tactile sensor using self-capacitance measurement for robot hand. The proposed sensor consists of the two electrodes (E 1 and E 2 ), GND and elastic body. The capacitance between E 1 or E 2 and GND is measured by switching between E 1 and E 2 . The capacitance between E 1 and GND is used to detect the object before contact (proximity range) and to discriminate the material on contact. In addition, the capacitance between E 2 and GND is used to detect the indentation on contact. In this paper, we propose the array system of this proposed sensor. In the experiment, detection of the object before and after contact, and identification of materials on contact were demonstrated. In addition, the prototype sensor array measured the shape of the object. The proposed sensor array may be useful as a tactile and proximity sensor on robot hand.

A simple method for interleaving operation suitable for paralleled converter system is proposed. This method automatically detects the number of converters and adjusts phases between converter modules equally for any number of modules in the system. The method is realized by simple analog circuit which is easily implemented as conventional PWM controller IC. Principle of multiphase controlling circuit is introduced, and the influence of non-ideal circuit parameters on interleaving operation are discussed. A compensator for reducing phase error is also proposed to achieve wide-use application. Experimental and analytical results confirm the effectiveness of the proposed method.

Paralleled converter system with synchronous rectifiers (SRs) causes several problems such as surge voltage, inhalation current and circulating current. Generally, the system stops operation of the SRs in light load to avoid these problems. However, simultaneously, large voltage fluctuations in the output of the modules are occurred due to forward voltage drop of diode. The fluctuations cause serious faults to the semiconductor devices working in very low voltage such as CPU and VLSI. Moreover, the voltage fluctuations generate unstable current fluctuations in the paralleled converter system with current-sharing control. This paper proposes new switching control methods for rectifiers to reduce the voltage and current fluctuations. The effectiveness of the proposed methods is confirmed bv computer simulation and experimental results.

Analysis and experiment are carried out for the current balancing characteristics of the parallel dc–dc converter system with averaged current-balancing controllers. The suppression effect of the current unbalance caused by the difference in the module parameters in the static and dynamic characteristics is quantitatively determined. With regard to the instability inside the parallel system caused by the current-balancing control with a phase delay, the phenomena are presented and the stable operating region is derived. © 2001 Scripta Technica, Electron Comm Jpn Pt 1, 84(5): 67–75, 2001

This paper proposes estimation method of optimized switching points for on-off module control to improve overall power conversion efficiency of paralleled converter system. On-off module control changes the number of active modules according to load current. The main concern of the control is to determine the on-off points of converter modules. Optimized switching points for on-off control are estimated by simple manner. Experimental results show the effectiveness of proposed estimating method to improve the efficiency.

This paper proposes nonlinear power source booster which amplifies voltage and current in small size of nonlinear power source such as photovoltaic (PV) cell and wind power generator. The booster simulates large size of nonlinear power source by using a small nonlinear power source, a flyback converter, and a control circuit including variable current source. Principle of proposed booster is described at first. Prototype of the booster suitable for PV cell is built and tested to confirm the effectiveness of the booster.