Kazunori Tsushima

Effect of Vertical Displacement of Coiling Pin on Dimension of Helical Compression Springs Formed by Two Coiling Pin System.

In this paper, it is the purpose to clarify the effect of a vertical displacement of the coiling pin as the influencing factors on the dimension of helical compression springs, and moreover to obtain the instruction to set up a vertical displacement of the coiling pin for forming them with highly dimensional accuracy. First, the effects of a vertical displacement of the coiling pin on the dimension of helical compression springs and on the initial tension of solid coil springs are analyzed by the differential geometry. Next, the experiments of forming springs are carried out in order to confirm the analyzed results. As the results, it is confirmed that the experimental results qualitatively agree with the analytical ones. Moreover, it is obtained the instruction to set up a vertical displacement of the coiling pin for forming helical compression springs with highly dimensional accuracy. Namely, helical compression springs can be formed with highly dimensional accuracy by setting up a vertical displacement of the coiling pin in the constant range of the initial tension of solid coil springs.

Effect of Torsion of Wire generated by Feed Rollers on Free Height of Helical Compression Springs.

The purpose of this paper is to improve the accuracy of free height of helical compression springs. A pair of feed rollers generate torsion of wire at feeding of wire. Torsion of wire makes the accuracy of free height of helical compression springs lower at the continuous production. And then, the mechanism that a pair of feed rollers getaerate torsion of wire is analyzed with a geometric approach in order to estimate torsional angle of wire. Moreover, the relationship between torsional angle of wire generated by a pair of feed rollers and free height of helical compression springs is analyzed with a geometric approach. And it is shown experimentally that these analyses are available. As the results of the analysis and the experiments, it is important that the upper roller and the lower one should be set on the position not to generate torsion of wire. Namely, the effect of torsion of wire generated by a pair of feed rollers can be removed on the accuracy of free height of helical compression springs.

Trajectory Control of Robot with Flexible Joints Using Torque Feedback Control and Feed-Forward Control. Improvement of Trajectory Tracking Accuracy on SCARA Robot Driven by Stepping Motor.

Robot arms vibrate during trajectory control because of the flexible joints. We have already proposed the method of torque feedback control of a robot with flexible joints in order to suppress the vibration of robot arms. This method only takes into consideration the torsional angle caused by vibration, but not the torsional angle to transmit torque to links. Thus it does not realize improvement of the trajectory tracking accuracy. Therefore we attempt to compensate this torsional angle to transmit torque by means of feed-forward control. We propose a method of trajectory tracking control which includes both torque feedback control and feed-forward control in order to improve the trajectory tracking accuracy. In experiments, we use the trial SCARA robot which has flexible joints and is driven by stepping motors. It is shown that the proposed method is effective in improving the trajectory tracking accuracy.

A Study on Path Tracking Control of an Autonomous Wheel Robot. The Relationship of Each Feedback Gain of Software-Servo for Straight Path Tracking Control with 2DW1C-Type Tri-car Mobile Robot to System's Stability and Positioning Characteristics.

The present research is about designing straight path control for a 2DW1C-Type tri-car mobile robot. At the beginning of a position feedback control system is designed with the actual position surveyed by external sensor. The purpose of this paper is to clarify the relationship of each feedback gain corresponding to each position error to the systems stability and positioning characteristics. As a result of step resonance and running simulation on real road conditions, the analysis confirms the systems stability. Results of this research can be adapted any optional path by dotting desired path.

Coiling Loads in Two-Finger Systems

The loads on tools for coiling close coils are analyzed in a two-finger coiling system. The experimental results are compared with the theoretical results. The main results are as follows: (1) The loads on working tools are inversely proportional to the spring indices of coils. (2) The mean diameters of coils are related to the load on the 2nd finger. The load is in proportion to the square of the wire diameter and to the yield stress of wires. (3) Within the range of this experimental condition, the dynamical friction coefficient seems to be a value between 0.3 and 0.6.