Mitsuharu Matsumoto

Robotic Tactile Sensor System and Applications

This paper presents a tactile sensor system for a robot manipulator and an active-sensing technique to realize 3-D object recognitions concerning object shape, object surface normal, and object edge tracing with experimental results. The proposed tactile sensor units implemented on the robot hand consist of three thin sheets of force-sensitive resistors arranged triangularly with the peripheral circuits. One potential application of the proposed techniques is to realize an effective human-robot cooperation to move an object together by utilizing the control of a hand pose to keep the direction of the hand normal to the object surface in three dimensions, which is often necessary when pushing an object. Another is a 3-D object edge tracing. The proposed techniques can be employed in industrial processes such as welding and inspection to eliminate manual teaching procedures for searching the object edge automatically before doing the welding process. In these applications, information about the object shape or orientation is not required in advance.

Haptic Sensing Foot System for Humanoid Robot and Ground Recognition With One-Leg Balance

This paper presents a haptic sensing foot system for humanoid robot. The two different kinds of implementations are investigated: One is an active tactile sensing technique to recognize a contacting ground slope. The other is to balance the robot body with one leg for human-robot interaction. The proposed sensors are implemented on two robotic feet. Each sensing unit on each foot consists of three thin sheets of force sensitive resistors arranged triangularly with the peripheral circuits. The research objective is to produce an artifact which can be operated in a natural and intuitive manner by utilizing the control of a foot pose to keep the direction of the foot normal to the ground surface. Throughout these works, we aim to realize the tactile sensing foot to detect the ground slope for natural foot posture control in order to assist the biped walking robot to balance its body on various types of ground surfaces. In these applications, the information about the ground floor or orientation is not required in advance.

A miniaturized adaptive microphone array under directional constraint utilizing aggregated microphones.

This paper introduces a miniaturized microphone array using the Directionally Constrained Minimization of Power (DCMP) method, which utilizes the transfer functions of microphones located at the same place, namely aggregated microphones. The phased microphone array realizes a noise reduction and direction of arrival (DOA) estimation system according to differences in the arrival time, phase shift, and/or the level of the sound wave for each microphone. Hence it is difficult to miniaturize the microphone array. The objective of our research is to miniaturize the system size using aggregated microphones. In this paper, we first show that the phased microphone array system and the proposed aggregated microphone system can be described within the same framework. We then apply a microphone array under directional constraint to the aggregated microphones and compare the proposed method with the microphone array. We show the directional pattern of the aggregated microphones. We also show the experimental results regarding DOA estimation.

Multiple Signal Classification by Aggregated Microphones

This paper introduces the multiple signal classification (MUSIC) method that utilizes the transfer characteristics of microphones located at the same place, namely aggregated microphones. The conventional microphone array realizes a sound localization system according to the differences in the arrival time, phase shift, and the level of the sound wave among each microphone. Therefore, it is difficult to miniaturize the microphone array. The objective of our research is to build a reliable miniaturized sound localization system using aggregated microphones. In this paper, we describe a sound system with N microphones. We then show that the microphone array system and the proposed aggregated microphone system can be described in the same framework. We apply the multiple signal classification to the method that utilizes the transfer characteristics of the microphones placed at a same location and compare the proposed method with the microphone array. In the proposed method, all microphones are placed at the same place. Hence, it is easy to miniaturize the system. This feature is considered to be useful for practical applications. The experimental results obtained in an ordinary room are shown to verify the validity of the measurement.

A simple tactile sensor system for robot manipulator and object edge shape recognition

This paper proposes a simple tactile sensing and control method for robot to realize an active object surface recognition. The tactile sensor implemented on the robot hand consists of three force sensitive resistors with the peripheral circuits. The robot arm equipped with the sensor can perform active object recognition. Our research goal is to realize an effective robot controller for the 3D object handling. An additional final aim is to produce artifacts that is a kind of artificial creature, which enables to cooperate works between human and machine (robot) in a natural and intuitive manner. Throughout these works, we aim to realize a harmonized human-machine environment. The two examples of applications of the proposed tactile sensor are also introduced. First is a hand pose control to keep the moving direction normal to the object, which is often required in pushing an object for positioning. This application can be used for human-machine interaction tasks. Next is a hand pose and motion control for 3D-object edge tracing, which is required for industrial use such as welding machines and welding inspection. In these applications, we need no information about object shape or orientation in advance. We also show three experimental results using the proposed sensor unit. The system and results of experiments are presented.

Human-machine interaction through object using robot arm with tactile sensors

This paper presents a tactile interaction system for human-machine interaction and an active sensing technique to realize object surface sensing for human-machine interaction tasks. The tactile sensor unit implemented on the robot hand consists of three force-sensitive resistors arranged triangularly. The unit not only can detect the reactive force from the object but also determine the orientation of the object surface. Our research goal is to realize an effective robot controller for the 3D object handling. As a possible application, we also introduce an effective human-robot cooperation to move an object together. This application is realized by a control of a hand pose to keep the direction of the hand normal to the object surface in 3-D, which is often necessary when pushing an object. We also show the experimental results using the proposed sensor unit.

Noise Reduction and Edge Enhancement Based on Band-Pass Epsilon-filter

Band-pass bilateral filter is an improved bilateral filter which does not have low-pass characteristics but has band-pass characteristics to enhance image contrast around edges. However, the computation time is relatively large due to Gaussian calculation in all pixels. To reduce the calculation cost, we look to a nonlinear filter called epsilon-filter and propose an advanced epsilon-filter which does not have low-pass charactersitics but has band-pass characteristics to enhance the image contrast around edge, namely band-pass epsilon-filter. Due to its simple design, the calculation cost is relatively small the same as epsilon-filter. To show the effectiveness of the proposed method, we also report the results of some comparative experiments concerning the filter characteristics and computational cost.

An acoustical array combining microphones and piezoelectric devices.

This paper describes an acoustical array combining microphones and piezoelectric devices. Conventional microphone arrays have been widely utilized to realize noise reduction, sound separation and direction of arrival estimation system. However, when a conventional microphone array is mounted on a real system, such as a machine, vehicle or robot, the microphones are set extremely close to the systems actual body. In such cases, the noise from the system itself, such as motors, gears, and engines, namely internal noise, often becomes a troublesome problem. It is difficult to reduce internal noise utilizing a conventional microphone array because internal noise sources are extremely close to the microphones. As internal noise is not always stationary, statistically independent or sparse, most useful blind source separation approaches, such as independent component analysis and the sparseness approach, cannot be employed. Our aim is to reduce internal noise utilizing microphones and piezoelectric devices attached to the internal noise source. In this paper, a general description of the acoustical array is formulated and the characteristic features of microphones and piezoelectric devices in an acoustical array are given. An acoustical array combining microphones and piezoelectric devices is also described with some experimental results.

A Simple Robotic Tactile Sensor for Object Surface Sensing

This paper presents a new tactile sensor system and an active sensing technique to realize active object surface sensing. Experimental results are also presented. The tactile sensor unit implemented on the robot hand consists of three force-sensitive resistors arranged triangularly. The unit can detect not only the reactive force from the object, but also determine the orientation of the object surface. Three possible applications are introduced. The first application is three-dimensional (3-D) object edge tracing, which can be employed in industrial processes such as welding and inspection to eliminate manual teaching procedures. The second application is the control of a hand pose to keep the direction of the hand normal to the object surface in 3-D, which is often necessary when pushing an object. Third is the realization of effective human–robot cooperation to move an object together.

Passive Self-Replication of Millimeter-Scale Parts

Self replication is a kind of self-assembly in which a desired structure is obtained automatically from simple parts. We propose self-replication not by controlling the parts directly, but by controlling their environment, namely passive self-replication, which makes self-replicating structures by imitating the semi-conservative replication of DNA. The proposed self-replication strategy is available for multiple types of parts by introducing selective surface structures on parts and two different bonding forces.