Masaharu Takano

Classification Of Objects' Surface By Acoustic Transfer Function

Objects surfaces are classified by cal- culating the acoustic transfer function between an echo from a reference plane and that from an object to be tested. A method to obtain this transfer function is presented. Experiment on simple shape classification show that phase characteristic in the transfer function is useful. Future possibili- ties of ultrasonic sensing in robotics is also dis- cussed.

Study On Mobile Robot Navigation Control By Internal And External Sensor Data With Ultrasonic Sensor

A new method to combine internal and external sensor information for stable navigation of an autonomous land vehicle is presented. Usually, vehicles relative position to its environment is available only at some time interval, because of low sampling rate of the sensor such as vision or ultrasonic sen- sor. Also, summation of wheel rotation is not reliable for position estimation due to wheel slippage. The presented method is an iterative method to minimize the estimation error by using both internal and external sensor information. Mechanical parameters of the vehicle such as tread, effective wheel diameter and slip ratio are also estimated together with position and orientation. This paper deals with a vehicle equipped with an ultrasonic range sen- sor as an external sensor. First, a. general principle of navigation using internal and extemal sensor is described. Secondly, simula- tion and experimental results are presented and evaluated. Both results show that the presented method is useful for guiding an autonomous land vehicle along a desired trajectory.

Type selection of robot manipulators using fuzzy reasoning in robot design system

A method for the selection of a suitable type of robot manipulator for a given task using fuzzy reasoning is proposed. Various types of robot have different characteristics of the performances such as the shape and size of the workspace, the accuracy, the speed, and the weight capacity. Therefore, it is necessary to select the robot type with suitable performances for the given task in the design of the robot. The proposed method selects the most suitable robot type for the task, in the same way as a design expert. This method consists of the following steps; (1) The design experts knowledge of the characteristics of the performances of each robot type is expressed as a fuzzy fact in the database. (2) The operator analyzes the task and obtains the performances required for it, pressed as fuzzy rules. (3) The degree of suitability for the task of each robot type is obtained from the knowledge concerning the performances of the robot type and the performances required for the task by fuzzy reasoning.

Measurement of 3-D position and orientation of a robot using ultrasonic waves

A system for measuring the 3-D position and orientation of a robot hand using ultrasonic waves is proposed. The principle is a triangulation using distances between transmitters attached to a robot and receivers placed around the robots work space. An electric spark discharge which works as a nondirectional point source of ultrasound is used as a transmitter. This system is simple and economical compared with that using laser beams or light-emitting diodes. The accuracy is good because it measures distances directly from the transit time of an ultrasonic pulse. The relationship between the accuracy and the number of receivers is discussed, and the possibilities of automatic tracking of a moving transmitter are examined.<<ETX>>

Positioning System for Indoor Mobile Robot Using Active Ultrasonic Beacons

Abstract A reliable, safe and inexpensive positioning system for an indoor mobile robot is proposed. It utilizes active ultrasonic beacons mounted on the ceiling and the emission of the ultrasonic pulse is controlled from the robot by sending the ID code to them by radio link. The 2 receivers on the robot measures the time-of-flight of the ultrasonic pulses from the 2 beacons at known locations to determine the robots 2D position and orientation. The developed system enabled the robot to obtain its position with an accuracy of ±40[mm] and ±10(deg] in about 4[m] square respectively.

Development of Invisible Mark and Its Application to a Home Robot

To develop a practical multipurpose robot, the authors have previously proposed the RECS (Robot-Environment Compromise System) concept, which means the technology to compromise a robot and its environment in order to increase the robot’s performance. As the modification in the environment side, the author gave a mark made from a commercial retro-reflective sheet to the tableware: however, this mark was slightly visible to a human. Moreover this mark was not resistant to the dishwashing. To overcome the abovementioned problem of the previous mark, the present paper reports the development of a completely invisible mark.

METHOD FOR SOLVING INVERSE KINEMATICS OF REDUNDANT ROBOT UNDER RESTRAINT BY OBSTACLES

ABSTRACT For the purpose of collision avoidance, a new efficient method for solving inverse kinematics of a redundant robot (all joints are rotational) is proposed. This method is divided into three procedures, which are position synthesis by 3 joints, orientation synthesis by 3 wrist joints, and collision avoidance by other remaining joints. Each of these three procedures can be calculated analytically. After series of three procedures, the positioning error is occurred, since they are not independent from each other. Therefore, the calculation is carried out iteratively until sufficient convergence is obtained. A simulator based on this method is developed. A robot of 14 DOF can successfully pass through two cylindrical holes in two thick walls, while realizing high positioning and orientating accuracy of its end effector.

Study on Air Damping Force Exerted on an Oscillating Micro Cantilever

Air damping force exerted on an oscillating micro cantilever is studied in this paper. The contents consist of two parts. In the first part, force exerted on a cantilever is simulated by using FEM software. From simulation results, it is proved that the approximation of the damping coefficient to 3μ (μ: air viscosity) holds true only when the Reynolds number is very small (less than 0.1). In the second part, the relationship between the damping ratio of the cantilever and the ambient air pressure is investigated. A micro cantilever is set to a specially developed vacuum chamber, and the out-of-plane vibration of it is observed by a laser Doppler vibrometer. It is proved that the damping ratio decreases steeply below 1000Pa, whereas it does not decrease so much over this pressure. This trend can be explained theoretically by the transition from viscous flow to molecular flow.Copyright

DEVELOPMENT OF A WELFARE ROBOT BASED ON RECS CONCEPT - TASK OF SETTING A MEAL ON THE TABLE -

ABSTRACT In this paper, a home robot is developed based on RECS (Robot Environment Compromise System) concept. This concept aims to share the technical difficulties with robot and environment. In other words, RECS modifies the environment in order that the robot task would be possible or easy. Among the various domestic tasks, setting a meal on the table is focused. This task comprises preparing a meal and loading tableware with meals to a tray at a kitchen, transporting this tray to the table, putting the tableware on the table, and pouring bottled drinks to cups on demand.

Tapping Motion Analysis of a Cantilever based on Elastic Vibration Theory under the Condition that Impulsive Force and Moment are given on Its Tip. Analysis Method in the case that Modal Functions are not Orthogonal.

A new method of analyzing the tapping motion of a cantilever, on the tip of which impulsive force and moment are given, is proposed based on elastic vibration theory. In this method the contact object is assumed to be a spring of which stiffness is hard enough. The force which is given by the spring is regarded as the impulsive force. The product of this force by the gap length between the surface of cantilever and that of the contact object is regarded as the impulsive moment. Contact damping and air damping are also considered. It is newly proved that the modal functions, which satisfy the boundary condition, are not orthogonal in the state that the tip is contact with the object. Taking account of that, the method which solves the initial value problem by using a matrix operation is proposed. By joining the solution in the free state and that in the contact state so as to satisfy the initial conditions at every beginning and ending time of the contact successively, the behavior of the tapping vibration of the cantilever can be analyzed. A micro cantilever, which is assumed to be used for a probe memory head, is adopted as a numerical example, and the motion of it is analyzed by the proposed method. FEM analysis and experiments using a macro scale model are also carried out, and the validity and the merit of saving the calculating time of the proposed method are proved.