Ken’ichi Koyanagi

Stabilizing output of an electrorheological gel linear actuator

ER gel is a relatively new type of functional material. The surface of ER gel has a shear stress characteristic, which increases according to the applied electric field. Introducing the gel into interface elements of a force transmission system realizes functional clutches and brakes. This study aims to develop a linear actuator that is safe, can operate in reverse, and can generate a large force using such a functional clutch. Applying an ER gel clutch in a force transmission system decreases inertia and the mechanical limits of the maximum speed while not limiting controllability. Such properties contribute to a high level of safety. This article reports, in particular, on stabilizing the output of the linear actuator.

How does the Time Delay of an ER Fluid's Response Affect Control Performance of Servo-systems?

We previously developed a particle type ER (electro-rheological) fluid damper in which viscosity was controlled continuously in real time for fast and precise positioning of a direct-drive motor. However, particle type ER fluids commonly have about 5-mili seconds response times. This delay needs to be taken into account when electric fields to energize ER fluids are controlled in real time. Especially, servo systems with ER fluid devices have a sampling time for the control loop that is about 1-mili second and so is shorter than the response time of ER fluids. Though the delay in this case has a great possibility of affecting on the performance or stability of servo systems, there is little research in this area that has mentioned the problem. In this paper, I investigated how this time delay affected damping performance and stability of this system.

Prototype Development of a Shape Presentation System Using Linear Actuators

We here propose a three-dimensional shape presentation system using linear actuators which can control the displacement of a rod to a precision of 0.1 mm. We assume that this system will be used as a device to present topographical/shape information to people with visual impairments. For this study, we produced a prototype system equipped with precision linear actuators, and conducted experiments to evaluate the capabilities of the system.

Improvement of a Tangible Programming Tool for the Study of the Subroutine Concept

We developed a tangible programming education tool “P-CUBE2” to aim at learning benefits of subroutine such as to create a function once and then reuse it. The target user of this tool are visual impairments and inexperienced persons who are not familiar with PC operation. We introduced the function mat, utterance function blocks and HIRAGANA (Japanese character) blocks so that user can learn subroutine concept. Users can create the function of utterance by combining and placing these blocks which on the function mat. The created function of utterance can be called on the main mat. By these operation, the user can control a robot which outputs sound as a controlled object. In this research, we introduce the system configuration of the P-CUBE2 and report the result of experiment for evaluation of the tool operability.

Effect of surface conditions of one-side patterned electrodes applied to electrorheological gel

The use of a patterned electrode on one side only is expected to be a suitable solution for omitting the wiring to the movable electrode using electrorheological gel. Electrorheological gel is a functional material that changes the force absorbance and frictional force characteristics of its surface in response to the magnitude of an applied electric field. One problem in both the design and the application of electrorheological gels is the wiring of the electrodes that must sandwich the electrorheological gel. Thus, a one-side patterned electrode can be a desirable solution. We investigated the shear stress produced by electrorheological gel applied to such a patterned electrode during rotational and translational motion. Variation of the material of the opposing part reveals that the mechanical and electric characteristics of the electrode meaningfully affect the experienced shear stress.

Interface Design Proposal of Card-Type Programming Tool

We developed a card-type programming tool Pro-Tan as an education tool for beginners in programming. This tool was designed to be usable without any instruction on its operations. In the experiment, we did not tell the users how to use any of the tools. The subjects were instructed to create a program by themselves. We found problems of Pro-Tans design in the experiment. In this paper, we report the system configuration of Pro-Tan and problem of Pro-Tans design.

Direct Perception of Easily Visible Information for Unknown Object Grasping

This paper discusses the estimation of the easily visible information for deciding action of unknown object grasping without all of predefined knowledge in a real situation. To estimate the easily visible information, active perception is an important concept. A conventional active perception method estimates an optimum sensing position to measure the accurate object information. However, a robot has to move all around the object to measure the accurate data beforehand. This is not realistic for a robot operation. On the other hand, a robot wants to know the most easily visible sensing position in the neighborhood of a current position to make a decision as soon as possible from a viewpoint of a robot action. As a first step, we propose an estimation of an easily visible information using a point cloud data of an object which is limited data. Now, we apply the unknown object detection method based on plane detection. And, we propose the graspability and the easily visible information estimation method from the point cloud data of the object. We verify the proposed method in a multiple object environment. The effectiveness of our proposal are discussed for grasping an unknown object.

Multi-layer Situation Map Based on a Spring Model for Robot Interaction

This paper discusses the Multi-Layer Situation Map to estimate the relationship between the objects and the storage places for robot interaction. An interaction robot is required the many rules to take suitable action. But, It is difficult to provide rules based on all situations. Now, we focus on a cleanup service by a robot, and are developing an interaction robot which estimates the storage place where a robot should carry objects. In this system, an interaction robot has to know the relationship of the objects and the storage places in dynamically changing situation. Therefore, we propose the Multi-Layer Situation Map, and express the relationship between the object and the storage place. The multi-layer situation map can move each component using a spring model. To verify the effectivity of the multi-layer situation map, we have performed the simulation experiment. We discuss about the dynamically situation change when the same objects are exist on the table.