Tetsuro Yabuta

On the characteristics of the robot manipulator controller using neural networks

Several robot controller schemes using neural networks are proposed. To extract advantages from the neural network controller, it is necessary to clarify the capabilities of the neural networks to express a nonlinear function as well as the robustness of the controller. For this purpose, an inverse kinematics problem and a force control problem are presented. The characteristics of the neural network are compared to adaptive control for the robot controller using the force control problem as an example.<<ETX>>

Three‐dimensional shape recognition method using ultrasonics for manipulator control system

This article describes a three-dimensional shape recognition method that employs an ultrasonic distance sensor mounted on a manipulator, and its application to a manipulator control system. The principle of the method is to reconstruct an object surface numerically using both distance and orientation informations of an object. The method makes it possible to control the manipulator, to set the sensor in any position and orientation employing freedom of the manipulator, and to measure the object. The method is available for manipulator control because it can precisely assess the distance from the manipulator to the object, as well as reconstruct the object shape. Experimental results show that the newly developed method make object shape recognition easy and inexpensive. Application experiment proved that the method is effective for manipulator work due to its provision of distance information.

Dynamics and control of aerial mobile legs

A wire suspended mobile robot for telecommunication cable was proposed, which is equipped with legs by which it walks suspended from cables. A linkage mechanism creates a gait kinematically which causes the robot legs to touch the path at intervals. That is why the robot moves stably and avoid obstacles simultaneously in construction and maintenance work. This paper analyzes the robot kinematics and dynamics, and proposes a control method in minimum driving energy. Fine leg design through kinematic analysis affords the desired motion allowing the robot to walk parallel to the path at approximately constant speed. Inverse kinematics reduces remaining fluctuations of optimum mobile speed. After deducing state equations through dynamic analysis, PID control simulation is performed to evaluate system response and to estimate optimum feedback gain.<<ETX>>

Study on Tensile Strength of Resin Mortar

A new resin mortar has been developed to facilitate a small-diameter shield tunneling method. The breaking elongation, Young’s modulus and tensile strength of the resin mortar are measured and studied. This paper clarifies the relationship between the mechanical properties of the resin mortar and the ones of its constituent materials, using a three-spring model. The mechanical properties of the resin mortar predicted from the model proposed in this paper agree with the measured values.