Many planetary exploration missions which use unmanned mobile robots (Rover) have been planned and carried out. In missions using rovers, attitude determination system is essential for precise guidance to destination and antenna orientation. However, a sensor failure has reported in a recent mission, therefore it is effective to build a redundant system. In this study, we build a new attitude determination system which combines solar panels characteristics and an accelerometer. At first, sun vector can be estimated using current, voltage and temperature of the solar panels because electric power generation of each solar panel is different depending on a position of the sun and geometry of the solar panels. In addition, by using gravity vector obtained by an accelerometer, the attitude of rovers can be estimated through QUEST algorithm. Finally, we confirm the availability of proposal attitude determination system by simulation.

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This paper describes an outdoor localization method by matching skyline. On a surface of the moon, we cannot use either the GNSS (Global Navigation Satellite System), information of artificial landmark or map matching. However a lot of planetary probe's missions need absolute coordinates. Therefore we propose a method that uses DEM (Digital Elevation Model) and panoramic photo image, and compares skylines made by them. Extracting skylines from image uses k-means clustering method with color information. A skyline made by panoramic photo image is determined uniquely by 4 parameters. However the proposed method fixes 2 parameters and uses a rough calculation, assuming that the place to get the photo image is horizontality. As the result of experiments at Oshima Island, it was confirmed that it is possible to estimate location in error by 65 m or 19 m by using the proposed method. One of prospective causes of an error is the assumption of horizontality in the place getting photo images, so we expect to improve accuracy of estimating location if this method is used with attitude sensor.

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It is important technology for an autonomous mobile robot to generate the environmental map and to estimate its position and posture. In recent years, the environmental measurement using LRF is increasing, because measurement by the LRF is a high-speed and its data is very accurate. However, since LRF acquire only 2D data at once, in order to obtain 3D data, it is necessary to rotate a sensor. Shape of the 3D data acquired by rotating LRF becomes slit. When these data are connected by ICP algorithm, an error occurs by the shape-dependence property of it. In this paper, we discovered that the parameter has an error is different in the high area and the low area of the 3D data. Then, we propose a method for improving the accuracy of mapping by integrating the parameters without error, after matching in each of the high area and low area of data. And we show the utility of the method by experiment.

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Mobile robot have to reach at a goal position without collisions against an obstacle. When robot travel in unknown terrain autonomously, it observe geometric information about the surrounding terrain, evaluate a model of the local terrain, search a safety path, and drive. This process is repeated until the goal is reached, a prescribed timeout period expires, or a fault is encountered. However, if generated path which should be followed at once becomes long, gap arises between path and actual environment which are caused by self localization delay, measurement error or wheel slip. This gap will increase a possibility of collision with obstacle. To prevent collision, we have proposed Tele-driving method with Command Data Compensation (CDC), for a long driving. The CDC is a kind of mapping to compensate a distortion of a space, and compensates path to the latest environmental data measured by a rover. In this paper, we discuss combination with proposed Command Data Compensation method and autonomous path planning algorithms.

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This paper proposes a novel lightweight robot arm for astronautical development by using honeycomb structure. In astronautical development, all the launched objects should possess lightweight and compact to save launch cost. Honeycomb structure is one of such lightweight material and already used in astronoutical field mainly for large panels. Besides, Carbon-Fiber Reinforced Plastic (CFRP) is already known to be a lightweight and strong material. In this study, we propose to apply honeycomb structure with CFRP to realize lightweight and compact arm. A prototype using CFRP plates and aluminum honeycomb is produced and its mechanical property is investigated experimentally. The effect of cross-sectional shape and size of honeycomb core onto the mechanical property is also investigated.

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We propose a mobility device using tether for human under the microgravity. This mobility device (TSMD) which makes a user moved by winding the tether, so it does not pollute air in the structure like ISS. It is advantageous to use the tether under the microgravity for its extensibility and easiness of storing. Then we have developed a prototype of TSMD and verified the availability of using the TSMD. In this paper, we improved the prototype to be able to observe its behavior against disturbance that is considering human motion. As a result of experiments to verify the effectiveness of the winding control, it was confirmed that the position control can decrease the rotation of TSMD, and in experiments input disturbance, it is found that human motion has significant influence on position control.

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We propose the method to control landing position and speed of an end-effecter in the air by multidirectional tension of wires. The end-effecter is connected with both dummy weights and reel system via the wires. After launching the end-effecter and dummy weights, its trajectory is changed by each tension of the wires when their motion is geometrically constrained. We develop the motion planner which makes the end-effecter reach the target at a suitable speed, and control algorithm for it. The proposed method is applied to the soft landing of the end-effecter. The effectiveness of the proposed method is verified through the experiment.

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The traveling performance of off-the-road vehicles, such as exploration rover and construction machineries, significantly depends on an interaction between the ground and traveling devices since inelastic ground deformation and frictional sliding phenomena are induced by their movement. Furthermore, the tire-soil interaction problem falls within the framework of moving boundary problems; therefore, it is difficult to treat the contact condition. In general, wheels having surfaces with an algorithmic structure called texture are used in a steadily widening range of fields because newer designs and controls require high-performance mechanical systems that utilize the textured surfaces. Needless to say, textured surface causes anisotropic frictional behaviors. To rationally describe anisotropic frictional sliding behavior, we formulate an anisotropic friction model with the orthotropy and rotation of a sliding surface based on the elastoplastic theory and the subloading-surface concept. In this study, we conduct the finite element analysis of anisotropic frictional sliding between tire and ground by using an acceptable frictional model describing the effect of texture.

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The rational treatment of frictional interaction between lunar soil and mechanical system is one of technical issues in lunar operations. This reason is that the evaluation method for frictional interaction in lunar surface environment, for example, heavily over-consolidated soil, soft grand, low gravity and high vacuum condition. In this study, first, we develop a test apparatus to perform the rotational shear test of granular media. Then, we combine a magnetic field device with the friction test apparatus in order to investigate the effect of gravity on frictional interaction. By using the developed test apparatus, we can perform the test under a pseudo low gravity condition. As a result, we can investigate variations of frictional torque with elapsed time between the granular media and various solid surfaces under the pseudo low gravity condition in which the gravity is adjusted at 1.0, 0.95 and 0.9 G.

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Planetary rovers that explore surface of the Moon or Mars easily slip in both longitudinal and lateral directions because it is covered with fine-grained sand. Particularly, when rovers traverse lateral slopes, the side slip occurs significantly. In the worst case, the rovers may deviate significantly on the slopes, and there is a possibility that fails to planetary exploration. To mitigate the slippage problems, we have confirmed in our previous research that the side slip of a rover is able to be reduced by changing the attitude of the rover. In order to study further the traversal behavior of a rover, in this research, we developed a dynamics simulator that includes a wheel-soil interaction model based on terramechanics on slope. To validate the simulator, we conducted numerical simulations for slope-traversing scenarios and compared the results with those of experiments. According to the comparison, the simulation results qualitatively match the tendencies of experimental results in the most cases and thus verify the usefulness of the simulator.

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On the Moon or Mars, common exploration targets for mobile robots (rovers) are covered in loose soil, which can cause slippage. To reduce the risk of wheel slippage, analysis of the mechanics of contact interaction between the soil and wheel is important. Various normal stress distribution models have been proposed until now, but most models assume that the stress distribution is uniform across the width of the wheel that for the sake of ease. This assumption is inaccurate. Therefore, in this research, we measured 2-dimensional normal stress distributions of a wheel traversing over soft soil, with 10 data points across the width of the wheel. In addition, the curved surfaces of each 2-dimensional normal stress distribution have clear relationships to the wheel's center of gravity at each time of measurement. Finally, we intend to use this data to build a 2-dimentional stress distribution model for a wheels on soft sand. In this paper, we report the results of a 2-dimensional stress distribution experiment and the relationship between the stress distributions and wheel's center of gravity.

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A rubber bush used in an automotive suspension system is an important element for the ride comfort and the driving stability. The relation between the applied force to the rubber bush and its deformation is non-linear and shows a feature of viscoelasticity. In a real-time analysis of a vehicle model with the rubber bush, it becomes a subject of discussion how to express the characteristic of the rubber bush with a simple model. This paper addresses the modeling of the rubber bush using the generalized Maxwell model based on measurement results of the viscoelastic test piece. For this purpose, we developed a testing machine that consists of a small-sized 6-DOF motion platform. The dynamic analysis with the generalized Maxwell models based on the measurement results was conducted for verifying effectiveness of this model.

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In this study, in order to improve the riding comfort and unsprung mass control of a semi-active suspension, we develop a new control system design method introducing unsprung mass control into gain-scheduled H_∞ control that changes the controller gain by the sprung mass vibration frequency. The proposed unsprung mass controller is a modified Ground-hook damper. By including the modified Ground-Hook damper control in the controlled object in the controller design, the gain-scheduled H_∞ control system reducing the vibration of the unsprung mass can be designed, without increasing the dimension of the controller. Thus, because of only the sprung mass vibration reduction, weighting functions can be briefly chosen. Here, the scheduling parameter of gain-scheduled H_∞ controller is included in weighting functions for controller output. Then, the controlled object with the modified Ground-Hook damper is a Linear-Time-Invariant system, The generalized plant including the weighting functions is a Linear-Parameter-Varying system. Furthermore, because of our control performance realization, we develop a design method of Kalman filter which can estimate the vehicle motion with high accuracy. In our study, by considering disturbances for all state values of the observer, we design the Kalman filter which can estimate states accurately. Here, observation signals are sprung mass accelerations and unsprung mass accelerations of semi-active dampers for each wheels. The estimated piston velocity is used to adjust the damping of semi-active suspension. Also, the unsprung mass velocity is used for unsprung mass control. The effectiveness of our control method is verified by carrying out simulations and experiments.

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This paper describes the development of a estimation method of a tire lateral force based on a unscented Kalman filter and a multibody vehicle model. The purpose of this study is to estimate the tire lateral force in running by sensors that can be mounted on general automobiles. We constructed the multibody vehicle model of the experimental vehicle developed in our previous study. In the multibody dynamic analysis, the system Jacobian matrix was linearized in order to decrease the computational cost. Then, we constructed an estimation system by applying the vehicle model to the unscented Kalman filter. The tire lateral force is calculated based on the states estimated by the unscented Kalman filter. Moreover, we performed the estimation actually with the data obtained by a running simulation with the multibody vehicle model.

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In this research, the linkage mechanism of hydraulic excavator which contains the closed loops is modeled based on the Newton-Euler formulation, and the motion equation is derived. Moreover, we apply a soil model for simulation, based on the two dimensional distinct element method (DEM), in order to reproduce reaction force from grounds. These models are integrated and able to analyze detailed interaction between machine and ground. The hydraulics force is analyzed, when an excavator performs digging operations according to the preprogramed digging trajectory. We conduct inverse-dynamics analysis to estimate the influence of digging resistance force on generative cylinder forces. The simulation results show that cylinder generative forces, varying depending on digging reaction force, significantly influence the cylinder force during digging operations.

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To improve railroad safety, many researches about derailment have been tried from several aspects. The researches on derailment are mainly classified into three fields. The first is on derailment mechanism. The second is investigations on safety assessment of derailment. The last is derailment detection. To realize derailment detection systems, measurement systems and detectable algorithms have been developed. Previously, the concept of a flange-climb derailment detection system was explained and its effectiveness was examined by a 1/10-scaled vehicle and an actual bogie experiment. However, the current system has insufficient time to prevent derailment. In this paper, improved derailment detection system with prediction is proposed and its effectiveness is shown.

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To increase the success rate of space exploration missions by rovers, usually several different types of sensors are mounted. This study, however, discusses the possibility and limitation of autonomous movement of a planetary exploration rover by using only a Laser-Range-Finder (LRF). Terrain recognition by only a LRF implies a possibility for a rover to keep moving, because a mounted computer can handle the LRF outputs in real time without any support from a ground station on Earth. In this paper, as a possibility of a scanning LRF to substitute for an image sensor, recognition of rover's slip and stuck from scanning LRF outputs is examined. As a preliminary study for an experiment using a real LRF, computer simulations are conducted by using virtual LRF outputs for a variety of terrains numerically generated with random numbers. To simply the problem, the LRF outputs are assumed to be obtained by a stationary rover in this paper. The results indicate that travel distance of a rover can be estimated with less than 13 % of error.

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Asteroids have some tips to know the origin of the solar system. In recent years, asteroid exploration by surface explorers has been studied actively. Conventional rovers can move under microgravity, but the rovers have not considered thermal control. In this paper, a new type of rover is proposed to move under microgravity and to control its temperature. The effectiveness of the proposed rover is investigated by simulations.

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When signs of volcanic activity are shown, it becomes difficult to conduct scientific investigation near the volcano for a long term. We developed the rover named "Micro6 Volcano" that can explorer active volcanoes without external battery for a long term, and has autonomous mobile capacity. Our long term investigation which took approximately two weeks was conducted at the middle of Mt.Mihara in Izu Oshima under the assumption that the eruption crisis of the volcanoes looms. During this term, Micro6 Volcano observed meteorological information by remote operation. It has communication device using mobile phone line to send images and observational data such as locational data and so on. We investigated by controlling the rover remotely with consideration for these data at Meiji Univ. in Ikuta, Kawasaki where away from Mt.Mihara about 100 km. This investigation succeeded in moving observation over hundreds of meters and operation through some nights with saving power mode.

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Recently, many studies have been conducted on robot positioning using self-localization method without GPS. One of the efficient methods is called SLAM, Simultaneous Localization And Mapping. This method can estimate robot position with high accuracy by using both internal sensors such as gyro sensor, rotary encoder, and external sensors such as camera sensor to get landmark information. In the SLAM method, robot have to find and detect some landmarks with own camera sensor, but it needs high performance CPU and wide angle camera lens system, and it became an issue for downsizing of robot. To tackle this issue, we propose a novel method called generalized measuring worm algorithm. Fundamental idea of this algorithm is mutual positioning using two robots. We applied a pair of robots for estimating position each other, and made maps using each robot's position as landmarks. Robots equip a two dimension maker that are known size and shape beforehand for distance and direction measuring. Our method assumes a situation of two robots set on line. We call a robot of backward mother robot, while forward child robot. At a first step of measuring, mother robot try to take a photo of child robot's 2D marker, calculates distance, and get direction information by using size and shape of marker. Next step, mother robot sends a command to child robot for correcting child robot direction by using information in mother robot's sight. After child robot correcting, mother robot moves toward child robot nearly. By repeating this operation, two robots can move to any destination. They also can estimate positioning; making maps of any coordinate system based mother robot's coordinate system. To validate effectively of our method, we made an experimental system, and we could show that our method can estimate position and make maps with less than 5% error.

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In 2009, the Selenological and Engineering Explorer (SELENE, nicknamed Kaguya) discovered a vertical hole of 〜60 m diameter and 〜50 m depth in the Marius Hills region on the Moon. After the discovery of the Marius Hills Hole (MHH), two other more gigantic holes were discovered by a global survey executed by the SENENE team. The vertical holes were likely formed by volcanic activities or tectonic processes such as skylight formation on lava tubes, from the terrestrial analogues. The indicative evidence of the existence of subsurface void spaces associating with the holes was indeed acquired by the US LRO later. Similar vertical holes have been discovered on the Mars. Various important knowledge of science on the Moon, the solar system, and extra-terrestrial life will be obtained by direct in-situ explorations into the lunar holes and their associating subsurface void space. However, the exploration of the holes and underlying subsurface voids require a system with the state of art which can overcome difficulties, such as the descent into the floors of the holes studded with boulders and the travel into the dark void spaces hidden from the lunar surface. We have studied on the exploration system by applying space robotics technology. We report the exploration system design, operational scenario in this paper.

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Moon holes were first discovered in the world by JAXA in 2009. It is believed that moon hole is helpful to know the formation of the moon because bedding plane is exposed. In addition, because inner hole is sealed from solar wind, it is also important as a candidate site for base camp in the future. However, exploration of the moon hole is difficult with the conventional robots. A new robot is required for going down and explore moon hole. In this study, a system to throw a small robot into a moon hole with wire is proposed. The author describes modeling and attitude control in a state where the robot is hanging by a wire, and evaluates the effectiveness of the system.

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Touchdown technology on target planet is important for detailed space exploration. Due to the limitation of mission time, safe landing in the vicinity of area of interest is essential even if the area is unsafe with slope or stepped surface. Conventional 4-leg landing gear has disadvantages for landing on slope because of tradeoff problem between shock absorption and attitude maintenance. In this paper, a novel landing gear is proposed for shock absorption and landing stability. Computer simulations of proposed landing gear in presence of horizontal velocity have demonstrated satisfactory performance.

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The development of highly accurate landing technology is required for the next generation lunar-planetary exploration lander to touch down on rough but interesting area. For the safe landing, the development of landing leg is required to prevent overturning and reduce landing impact of the lander in the final phase of landing sequence. However, it is difficult to design a landing leg which is applicable to a wide variety of terrain. The active landing leg is proposed as a solution of solving this problem. This paper presents the simulation of the lander with active landing leg and development of experimental system using Magneto-Rheological damper, and examines the landing shock response and penetration of the lander leg to the sand terrain.

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This paper presents a technique for driving a wheel to control the sinkage of a planetary rover on loose soil. Dynamic sinkage of the wheels of the rover always occurs when it travels on loose soil in the planetary surface; sinkage is then caused by the soil deformation due to a compressive force generated by the wheel and the soil conveyance due to slippage in the wheel. When the wheel is driven in an acceleration profile with a trapezoidal shape, it is experimentally confirmed that the depth of sinkage changes during both acceleration and deceleration. Further, it is also confirmed that the terminal sinkage is proportional to the magnitude of the maximum rotational acceleration and deceleration of the wheel; consequently, we propose the method of controlling the sinkage by adjusting their magnitude. The proposed control is verified through the experiments using the single wheel test bed and the full body rover with 4 wheels; thus, it is confirmed that twofold increase of sinkage is caused and the terminal sinkage is controlled, especially suppressed.

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Simulation technology for lunar/planetary rover locomotion plays an important role in the R&D phase for mechanical design optimization and performance analysis of the rovers as well as the exploration phase for real-time path planning and navigation support, etc. In this paper, we first briefly describe the general work flow of a rover simulation technique with the use of multibody dynamics(MBD), we then reconsider the validity of Bekker and Wong & Reece models which form the basis of the MBD simulation. These are the long-established models, but they are still implemented in up-to-date rover simulation packages. The outline of the theories and its limitations when being implemented in MBD simulations are discussed. Moreover, reviews and discussions of the state-of-the-art simulation techniques were given for three benchmarking approaches attempted to improve the accuracy.

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A wheeled mobile robot traversing on sandy terrain should be aware of its mobility hazard such as wheel slip that will be a trigger of immobilizing wheel stuck in loose sand. A wheel having large diameter/width generally possesses high traversability on sandy terrain because its large contact area can moderate steep stress concentration between wheel-terrain interactions, resulting less deformation of sand. However, such large wheel is relatively heavy and needs large envelope to be stowed, and also it requires large input power for its rotation. Therefore, a well-defined guideline for wheel design, namely how to determine an appropriate wheel size, is of an important issue. This paper presents a method providing the most appropriate wheel parameters (wheel radius and wheel width) which maximizes wheel traction performance on sandy terrain. The proposed method consists of the following four steps. First, a wheel parameter set is assumed as uncertain parameter, and defined by a statistical distribution form (i.e. Gaussian, Uniform). Then, a wheel-terrain contact model is employed to define an evaluation metric for the wheel traction performance. Subsequently, a stochastic method for uncertainty analysis called SRSM (stochastic response surface method) is to obtain an equivalent system model which is expressed as a polynomial function composed of the wheel parameters. Finally, the most appropriate set of wheel parameters which maximizes the evaluation metric is then numerically obtained by solving an optimization problem of the equivalent system model. In this paper, each step of the proposed method is introduced and then a simulative study of the wheel parameter evaluation is described.

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Autonomous mobility robots are required a high performance to traverse rough terrain like loose soil with steeps. Our proposed robot, "LOROPII" has high mobility performance, especially, it can traverse loose soil with steep slopes. LOROPII can support on surface of loose soil with steep slope because of it has "piles" which are inserted into the soil. In this study, we research the optimal piles, for instance, the optimal diameter and the optimal penetrated length. We will furthermore carry out running experiments using slope actually, 20, 25, 30deg. From these results, we discuss the optimal pile and problems.

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This study proposes a new Variable Speed Control Moment Gyros (VSCMG) steering law, which aims to achieve both agile attitude maneuvering and shortening of settling time for a control of a spacecraft. In the proposed steering law, an actuator acts like a typical Single Gimbal Control Moment Gyros (SGCMG) during agile maneuvering using an existing singularity avoidance steering law. And then an actuator acts like a VSCMG or Reaction Wheel (RW) during terminal attitude, which is required high accuracy attitude control in order to suppress torque error due to singularity avoidance and inner disturbance due to gimbal motion. This algorism results in shortening of settling time of a spacecraft. From the result of the numerical simulation, it is confirmed that the proposed steering law realizes high accuracy pointing control and shortening of settling time during a terminal attitude by compared with a typical and classical SGCMG singularity avoidance steering law.

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In recent years, it has been required accurate and agile attitude control of satellites. For this purpose, the necessity of Control Moment Gyros (CMGs) has been increasing, which can generate much higher torque than reaction wheels which are used as conventional spacecraft actuators. Furthermore, it is important for the attitude control systems to have function of fault tolerant. In a conventional 4 CMG system, the CMGs are placed in a pyramid mounting arrangement with skew angle set to 54.74 degrees. The maximum angular momentum of the CMG system is changed according to the skew angle. The suitable skew angle should be designed considering normal and failure situations. Moreover, the suitable parameters of the satellite attitude and CMG control system are changed according to the skew angle. Therefore, this paper proposes a design method of the fault-tolerant attitude control system. In the proposed method, the skew angle and the parameters of the control system are tuned simultaneously by genetic algorithm. To verify the fault-tolerant of the proposed method, numerical simulations in case that the one CMG is failed are carried out.

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Musculoskeletal system degenerates due to microgravity environment in ISS. Crews are obligated to exercise using the instrument apparatus for countermeasure. These apparatus are a large size and it takes much time for exercise. In order to overcome these problems, our research group proposed a hybrid training (HYBT) using electrical stimulation. In this paper, we evaluated the following influence caused by the HYBT of upper and lower limbs in the microgravity: rotational motions of human body floating in ISS; acceleration of Japanese Experiment Module (JEM). The simulated results showed that the supposed HYBT on crews did not disturb the microgravity environment.

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Mars airplane is one of the candidate payloads of JAXA's next Mars exploration programs. Airborne observation of Mars is expected to fill the "gap" between rovers, which provides a detailed observation but a limited area of coverage, and orbiters, which can cover a wide range of area but with a limited resolution. Two key challenges to realize a Mars airplane are 1) unavailability of GPS for localization and 2) limited computing power due to tight restriction on the mass of on-board instrument. We address these issues by developing a computationally tractable vision-based navigation and guidance algorithm. Our approach is based on an efficient feature detector and descriptor, Oriented FAST and Rotated BRIEF (ORB), combined with the information from an inertial measurement unit (IMU) using the extended Kalman filter (EKE) method. In this paper, we demonstrate the proposed ORB/EKF-based localization method by simulations using image data from Mars Reconnaissance Orbiter.

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This paper presents the development and preliminary experiments of dynamic buoyancy adjusting device with an assist spring. The proposed buoyancy adjusting device is actuated by an electric motor with a passive spring that provides some assistance to the motor. The device can achieve better energy efficiency and higher speed for dynamic control because the assist spring support actuator torque and allows low gear. In this paper, we have designed and developed a dynamic buoyancy adjusting device as a prototype. We have tested the performance of the developed device in a water tank with a depth of 1 meter.

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Ocean, the familiar environment for us, is one of attractive environments because of abundant mineral resources, energy, marine lives, and the research and development related with underwater environment are growing up rapidly during recent decades. Underwater robots are expected and developed as efficient tools for the operation in place of human beings. The autonomy and intelligence of underwater robots are one of the most important research topics, and highly automated underwater robots, Autonomous Underwater Vehicles (AUVs), are expected as one of new tools for underwater operations. The required missions of AUVs are getting more and more complicated, and underwater manipulators of AUVs are needed to accomplish complex tasks. In this research, the concept of an underwater robot hand to capture marine creatures are proposed and evaluated by experiments.

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The sea transportation by ships covers most of trade volume, and the technologies for fuel efficiency and reductions of carbon-dioxide emissions should be developed. One of the technical issues to improve fuel efficiency of ships is how to prevent the marine biofouling to the ship hulls and remove organisms from ships. In general, the cleaning of ship hull is carried out on the ship inspection in dock yard or by divers in harbor. Frequent cleaning of ship walls is desirable to keep good fuel efficiency, however, the ship inspection on dock is done once a year and the cleaning by divers is high-cost and involve high risk. One of the solutions to the problem is the introduction of underwater robots to clean ship surfaces. In this paper, the absorbing force to ship-hull and cleaning ability of cleaning robot are described.

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As the water depth of offshore oil/gas development becomes deeper, cost reduction of installing various subsea facilities becomes more important. Using an existing installation vessel, a new method which is applicable to more precise installation of subsea modules should be developed. As for future resource development in the Japanese EEZ, the cost reduction of the development systems and their installation is essential. In this paper, I examine a possibility of a method which uses active control of a structure. The structure is suspended from an installation vessel and a thruster is attached to control the horizontal position relative to the vessel. The control force is LQR feedback based on the modeling of the linearized equations of motion. Several simulation results showed if the descending speed of the structure is higher the horizontal displacement becomes larger, which means there is a trade-off relation in saving time with accurate positioning. From the simulation, active control method has possibility to solve this trade-off issue and seems effective for precise installation to the deep sea and may reduce the total installation cost.

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A kind of an air cushion vehicle (ACV) is known as a hovercraft which carries out a cruise by blowing off the air from the bottom of the body. The ACV has many advantages, such as amphibian vehicle, large payload, and so on. However, the ACV has drawbacks such as its drivability is bad. An improvement of the drivability is effective for the control of the ACV and the disturbance rejection performance of the controller is very significant. In this research, the position of the ACV is estimated using a marker by a turning camera. When the ACV runs on the straight and arc, the ACV is kept on the path by the designed controller. It compares with the control run performed by fixing a camera. The usefulness of the designed controller and followed marker is confirmed through an experiment.

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This study examines driver's following characteristics with the past two vehicles immediately ahead, i.e. a preceding vehicle and a pre-preceding vehicle. Driving simulator experiments are examined with five participants who are required to follow the preceding vehicle with/without the pre-preceding vehicle which the driver can observe directly. The multiple regression analysis is applied to identify which information the driver uses to follow the vehicles. Experimental results show that the participants follow the preceding vehicle with information not only on the following vehicle but also on the pre-preceding vehicle, and the pre-preceding vehicle information suppresses unnecessary acceleration.

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The longitudinal flying qualities of airplanes is going to worse in lower airspeed region, as shown in the criteria for short-period mode in MIL-F-8785C. However, Background Information and User Guide for MIL-F-8785B does not give the detailed explanation on this degradation. Our study pays attention to the deviation in lower airspeed region from short-period mode approximation, which is valid in higher airspeed region. The main parameter of this deviation is Phugoid-mode natural angular frequency ω_<n ph>, which cannot be neglected in lower airspeed region because its oscillation period is going to be shorter in that region. Also, we investigated the relations between short-period mode natural angular frequency ω_<n ph>, and ω_<n ph>. The results of flight simulator experiment show that the flying qualities evaluation based on Short-period mode approximation is improper in lower airspeed region and then upper limit of ω_<n ph> should be added into the criteria for longitudinal flying qualities.

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Many types of driving assistance systems have been developed in recent years. To achieve using continuous support for the drivers, haptic feedback has been proposed for more accurate driving, and it has some advantage compared to visual or auditory assists. This paper deals with an experiment of velocity adaptive haptic guidance steering system and effectiveness of proposed system is discussed by comparing with normal driving and constant gain haptic guidance. The driving experiment under 3 conditions is carried out: Normal, constant gain haptic guidance (Haptic C), and velocity adaptive haptic guidance. As a result, driving with Haptic A showed less lateral deviation in 80% of subjects.

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Series magnetic suspension is applied to force measurement. In a double series magnetic suspension system, two floators are suspended with a single electromagnet. When PID control is applied to the lower (second) floator and force acts on the lower floator, the upper (first) floator displaces whereas the lower floator is maintained at the original position. Therefore, the force can be estimated for the displacement of the upper floator. When the parameters are set appropriately, small force leads to large displacement so that the proposed measurement method is suitable for noncontact measurement of micro force. In this work, an apparatus for tri-axis force measurement was fabricated. Force measurements were carried out with the apparatus. The results show that three-dimensional forces were measured with a high resolution by the developed apparatus.

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Parallel magnetic suspension has been proposed where multiple floators are controlled with a single power amplifier. The feasibility of voltage-controlled double parallel magnetic suspension with parallel connected coils has been already demonstrated in the previous work. This study focuses on the zero-power control in a voltage-controlled double parallel suspension system with parallel connected coils. In this system, there are three methods of achieving zero-power control: feeding back the control voltage, either or the sum of the coil currents. This paper shows the conditions for the system with each zero-power controller to be controllable, and compares their performances.

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This paper presents a new modeling method and a control system design procedure for a flexible rotor with many flexible modes using active magnetic bearings. The purpose of our research is to let the rotor rotate passing over the 1st and the 2nd critical speeds caused by flexible modes. To achieve this, it is necessary to control motion and vibration of the flexible rotor simultaneously. The new modeling method named as Extended Reduced Order Physical Model is presented to express its motion and vibration uniformly. By using transfer function of flexible rotor-active magnetic bearings system, we designed a local jerk feedback control system and conducted stability discrimination with root locus. In order to evaluate this modeling and control method, levitation experimentation is carried out. An armature is installed in the rotor in order to make a revolution, and a safety cover is designed.

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Recently, it is necessary for rotors of centrifugal compressors, industrial rolls and so on to be high speed rotation, long span and light weight, because of increase in productivity. However, such rotor is easy to have high order mode at the same rotational speed, and it may become unstable. In order to solve this problem, active magnetic bearings are used to support the flexible rotor. However, since a general active magnetic bearing uses bias current to control bearing force, it consumes large electricity. In this paper, a hybrid active magnetic bearing which consists of electromagnets and permanent magnets is used to reduce the power consumption. The hybrid active magnetic bearing has negative stiffness not only in radial direction but in tilt direction. Experimental results show that the hybrid active magnetic bearings can support the flexible rotor stably.

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