We have developed a polymer actuator that has rapid displacement response under the applied voltage. The differences in size and velocity between cations and anions play a major role in the bending mechanism of the actuator. We have predicted the dynamic behavior of an ion-conductive polymer film actuator that uses carbon electrodes. We have also clarified the bending mechanism of an ion-conductive polymer actuator that uses carbon electrodes and includes a bending back motion.
Compared with the fixed morphological robots, the self-reconfigurable robots (SR) are very flexible as they can adapt to a wide range of task requirements. However, the current efforts on SR mainly focus on the locomotion issues, while the manipulation capabilities of existing systems are still quite limited. In this paper, a new kind of mobility reconfigurable robotic structures (MRRS) with self-reconfiguration ability is presented. The reconfigurable topology and variable mobility characteristics of the MRRS are realized by integrating the cooperative kinematic mechanism (CKM) and the separable parallel kinematic mechanism (SPKM) into one robotic system, which makes the robot capable of reconfiguring its mechanical assembly to adapt to the multiple motion task requirements. Based on Lie group of displacements, the commonly used robotic tasks are first classified into three categories: positioning motion, tooling motion and grasping motion, possible motion types of these tasks are enumerated, then how to deal with the multiple tasks by using the MRRS is synthesized systematically. Finally, a multi-task working process is employed as an example to illustrate the advantages of this reconfigurable robotic structure.
In design of logistics networks, it is inevitable to consider various forward factors that will often change from their reference values. With this point of view, this study formulates a global logistics network design problem under uncertainties and present a solution method in terms of the stochastic programming known as recourse model. To reduce the effort to solve the resulting problem, a scenario-base approach is adopted instead of considering infinite realizations of uncertain parameters and sample average approximation. Furthermore, we present a method to support decision-making on robust design under noisy environment in terms of the knowledge from multi-objective optimization. Numerical experiments revealed validity of the proposed method through comparison with the reference results.
In this paper, a frictional damper is proposed for suppression of chatter in slender endmill tool. This damper is made up of a core and a multi fingered hollow cylinder. The core is press fitted into the hollow cylinder, and they both are press fitted into an axial hole inside the tool. This combination produces a resisting frictional stress against bending vibration. An analytical model including accurate modeling of friction in sliding and pre-sliding regions is developed for this damper. Based on the simulation of the analytical model a parameter study is done to achieve optimum parameters of damper that increases the stability limit as much as possible. Finally, the optimal damped tool with damper inside is fabricated and experimentally tested in compare with traditional tool. The results show a considerable improvement in tool performance. An acceptable agreement between analytical and experimental results is obtained which show the effectiveness of damped tool in improvement of tool performance.
In high aspect ratio micro deep drilling, to shorten the machining time while maintaining the tool life, the addition of ultrasonic vibrations to increase the step feed was examined. First, machining experiments with L/D=10 were conducted, and an increase in the step feed upon the addition of ultrasonic vibrations was confirmed by evaluation of the cutting force and tool wear. Furthermore, micro deep drilling with a high aspect ratio of L/D=20 was examined. Our results reveal that reducing the cutting speed and adding ultrasonic vibrations shorten the machining time by increasing the step feed while maintaining a long tool life. Moreover, we confirmed that the developed technique is effective for the micro deep drilling of holes with a small diameter of 0.1 mm and L/D=15.
Titanium alloy has been applied to elements and structures in aerospace engineering, bioengineering, marine engineering, etc. because of its superior properties. However, machining of this alloy is likely to accelerate tool wear, shorten tool life and deteriorate the surface integrity. Therefore, high-speed machining of this alloy has been studied for many years. In this study, finish-turning of Ti-6Al-4V was conducted at higher cutting speeds using a new lubrication method called air jet assisted (AJA) machining, in which not only the cutting fluid but also the jet of compressed air was applied to the cutting zone to extend tool life. The results of cutting experiments using an uncoated cemented carbide tool showed that the air jet toward the tool tip applied to the conventional wet machining was effective to extend the tool life. Finally, cooling mechanism in AJA machining was discussed from a viewpoint of enhancement of the heat transfer coefficient from the cutting tool to the cutting fluid.