Ahstract- In this study, we propose a development and formation control of a passive mobile robot equipped only with servo brakes and no motors. The developed passive mobile robot can move forward by utilizing an external pulling force, and steers itself by controlling the servo brakes attached to each wheel. Systems composed of multiple mobile robots are very effective at exploring vast areas. However the coordination and simultaneous control of several robots utilizing simple information is a difficult task. Therefore we propose a leader follower architecture composed of multiple passive follower robots tethered to one active leader. In this paper, we first introduce the developed passive mobile robot. Then, we analyze the fundamental control method of this passive mobile robot from the perspective of the feasible braking control region, which considers the slip of the passive robot and the limitation of the external pulling force from the active leader. Lastly, a control law for the servo brakes attached to each wheel is proposed, followed by a feasibility study to determine whether the passive followers can stay in formation by controlling the servo brakes with the proposed control law.

In an asteroid exploration and sample return mission, accurate estimation of the shape and motion of the target asteroid is essential for selecting a touchdown site and navigating a spacecraft during touchdown operation. In this work, we present an automatic estimation method for the shape and motion of an asteroid, which is planned to be tested in future exploration missions including Japanese Hayabusa-2 [1]. Our task is to estimate the shape and rotation axis of the asteroid, as well as positions of the spacecraft from optical images. The proposed method is based on the expectation conditional-maximization (ECM) framework that consists of an auxiliary particle filter and nonlinear optimization techniques. One of our technical contributions is the estimation of the direction of rotation axis of the asteroid from monocular camera images, which are taken by the moving spacecraft. We conducted two experiments with synthetic data and an asteroid mock-up to show the validity of the proposed method and to present the numerical accuracy.

We propose a new framework and novel visual control system for motile cells in three-dimensional (3-D) space. Our goal is to utilize microorganisms as micro-robots in various applications by exploiting galvanotaxis (locomotor response to electrical stimulus) to actuate them. This requires automated motion control of swimming cells in 3-D space; in contrast, our previous work has been limited to 1-D or 2-D motion control on the focal plane. The system is capable of 3-D tracking and control of swimming cells by utilizing a high-speed vision system. A combination of "lock-on" tracking within the focal plane and automated focusing using a Depth-From-Diffraction method executed at 1-kHz frame rate ensures both detailed measurement and a large working space. Experimental results for closed-loop 3-D motion control of Paramecium cells trapped within a small 3-D region demonstrate the possibility of using microorganisms as micromachines.

We propose a novel method to control a lot of microorganisms by using visual feedback for micro-robotic application. Our goal is to control a cluster of microorganisms as microscale smart robots for various applications, since microorganisms have efficient actuators and accurate sensors. Compared with single-cell level actuation methods proposed before, this method has the following advantages: (1) a cluster of microorganisms can cancel stochastic perturbations of behavior by taking the average; (2) a cluster of microorganisms can be more powerful than a single microorganism, and thus it can perform a variety of tasks. A visual feedback system is constructed to control cells using galvanotaxis (response to the electric field). Experimental results show the feasibility of visual feedback control of a paramecium cell cluster. In addition, micro-manipulation of small objects by the cell cluster is also demonstrated

We propose a dynamics model of galvanotaxis (locomotor response to electrical stimulus) of the protozoan Paramecium. Our purpose is to utilize microorganisms as micro-robots by using galvanotaxis. For precise and advanced actuation, it is necessary to describe the dynamics of galvanotaxis in a mathematical and quantitative manner in the framework of robotics. However, until now the explanation of Paramecium galvanotaxis in previous works has remained only qualitative. In this paper, we construct a novel model of galvanotaxis as a minimal step to utilizing Paramecium cells as micro-robots. Numerical experiments for our model demonstrate realistic behaviors, such as U-turn motions, like those of real cells.

We propose a visual control system for motile cells. Our goal is to control microorganisms as microscale smart robots for various applications. As a first step, we have developed a visual feedback control system for Paramecium caudatum cells. In order to ensure both detailed measurements and a large working space, "lock-on" tracking of a free-swimming cell with a high frame rate is essential. In our system, high-speed (1-kHz frame rate) tracking hardware and software are used for the continuous observation of moving cells with high magnification. Cells swim in a chamber, and their positions and other properties are measured and computed in real time. The chamber position is visually controlled automatically to track a specific cell. The cell motion is controlled electrically by utilizing the galvanotaxis (intrinsic reaction to electrical stimulus) of microorganisms. Experimental results for open-loop control (periodic zigzag motion) and closed-loop control (trapping within a small region that is 1 mm wide) demonstrate the possibility of using microorganisms as micromachines.

We propose a control system of motile cells. Our goal is to construct a large-scale Organized Bio-Modules (OBM) in which microorganisms are controlled as micro-size smart robots in an organized way. For the first step, we have developed a visual feedback control system of Paramecium caudatum cells. Tracking method is used for observation of moving cells with high magnification. Cells swim in a chamber and their positions are measured by high-speed vision. The chamber position is visually controlled to track a specific cell. The cell motion is controlled electrically by utilizing the galvanotaxis (intrinsic reaction to electrical stimulus) of microorganisms. Experimental results of region-trapping demonstrate the possibility of the OBM system.

We present an autostereoscopic display named TWISTER I (Telexistence Wide-view-angle Immersive STEReoscope, Model I), which is designed for a face-to-face telecommunication system called "mutual telexistence". By rotating display units that consist of LED arrays and a barrier around a viewer, TWISTER I can display panoramic stereoscopic images that can be observed without the use of special eyewear. This "glassless" feature is essential for applying this apparatus to mutual telexistence because eye contact is important in non-verbal communication.