Yasuhiro Masutani

Sensory feedback control for space manipulators

The positioning control problem of the end tips of space manipulators which have no fixed bases is investigated. According to the momentum-conservation law, the system is represented by a nonholonomic model. Thus, the conventional control method for industrial robots, based on a local feedback at each joint, is not applicable when the end tip must be positioned at a floating target. For this problem, the sensory feedback control scheme is based on the artificial potential defined in the sensor coordinate frame. The generalized Jacobian plays an important role in determining the control torque of each joint from the data of the external sensors. This scheme is simple, and the stability of the system is strictly assured. The approximate Jacobian, which needs less computation and less parameter identification, is shown to work well.<<ETX>>

Flyaround maneuvers on a satellite orbit by impulsive thrust control

Close circumnavigation is an important function indispensable for servicing satellites. We discuss the bielliptic flyaround maneuver by impulsive thrust control for a small and low cost servicing satellite flying around a target satellite. An optimal feedback control scheme for the thrust is proposed to maintain this trajectory in the presence of disturbances. The extended Kalman filter is employed to estimate state variables which are not available for measurement. Simulation results that verify the trajectory keeping capability of the proposed thrust control are presented.

Motion estimation of unknown rigid body under no external forces and moments

This paper presents a method to estimate and to predict general three-dimensional motions of an unknown rigid body under no external forces and moments using visual information, which is applicable to autonomous space robotic missions. Four parameters of dynamics and a reference coordinate frame to describe the motion are computed based on the Eulers equation of motion from a sequence of angular velocity vectors extracted from difference of images. Through computer simulations for various kinds of motions the effectiveness and limitation of this method are discussed.<<ETX>>

Vision-based motion control for a hitting task-Hanetsuki

We describe our approach to the robotic Hanetsuki task (Japanese badminton), that is, to return the incoming shuttlecock to the humans side with a racket. A learning method using a novel database is proposed to compensate for the insufficiency in a model-based approach. Experimental results obtained with the developed Hanetsuki robot are presented.<<ETX>>

High-Speed Obstacle Avoidance and Self-Localization for Mobile Robots Based on Omni-directional Imaging of Floor Region

In this paper, we propose a method of obstacle avoidance and a method of self-localization based on floor region provided by omni-directional imaging. With our methods, omni-directional imaging is used not for recognition of the three-dimensional environment but for detecting obstacles and landmarks in a wide area at high speed. Several experiments with a real robot according to the rules of the RoboCup Small-Size League was demonstrated, and proved the effectiveness of these methods.

Safe Navigation in Unknown Dynamic Environments with Voronoi Based StRRT

For a robot to move autonomously in an unknown dynamic environment, a real-time motion generation is necessary. Especially, safety motion generations are important. There are a lot of methods for making safe motion. For example, it is popular to check only around the robot with additional sensors and avoid obstacles detected by the sensors, though, the coordination problem between global trajectory making and local obstacle avoidance should be accrued in this way. It is also popular to estimate the size of obstacles to be large, though adequate width of the dilatation is different by environment. Another approach would be to determine candidates of the safe trajectory from the layout of obstacles as a generalized Voronoi diagram and then randomly search for an appropriate trajectory. This approach can acutualize the global trajectory making and local obstacle avoidance at the same time. However, it may be sufficient if a local generalized Voronoi diagram is available for limiting the sampling area. Based on this idea, this paper explains Voronoi-based StRRT composed of an StRRT subjected to biasing extraction of sample points toward the border of a generalized Voronoi diagram and proposes the efficient method of applying StRRT to the omnidirectional mobile robots. Finally, it shows the possibilities of this method for practical situations.

Development of a standard robotic dummy for the purpose of evaluating rescue equipment and skill

Concepts and necessity of a dummy (human model) which can simulate a disaster victim for the purpose of evaluating rescue equipments including robots and rescue skills of human and robots are proposed. By contrast of conventional dummies in various fields, the concrete requirements are made clear. The plan of research and development project based on the concept is described. In the latter part of this paper, the 1st prototype under development is introduced. It is based on a human model (doll) for training of bathing assistance, and is equipped with 8-channel telemetric sensors, a wireless camera, a voice recorder, a heater vest, and a carbon dioxide gas tank.

Estimation of general three-dimensional motion of an unknown rigid body under no external forces and moments

This paper presents a method, which is applicable to autonomous space robotic missions, to estimate and to predict the general three-dimensional motion of an unknown rigid body under no external forces and moments using visual information. The authors assume that both geometric and inertial parameters of the rigid body are completely unknown to consider a general situation. Thus it is difficult to identify the absolute orientation of an object due to lack of knowledge. However, it is possible to estimate the angular velocity from two successive images. Therefore the problem is how to get the description of orientation as a function of time from a sequence of angular velocities based on Eulers equation of motion. Although the solution of Eulers equation is complicated and expressed with the elliptic functions, it can be also interpreted geometrically with Poinsots ellipsoid, which is useful to understand this problem. The solution is classified into four cases: asymmetric, non-periodic, axially symmetric and single axial. Four parameters of dynamics and a reference frame are essential to describe the motion. Since the solution is expressed in terms of the body frame, it cannot be directly used for the estimation of the parameters from the angular velocity vector in terms of the camera frame. To avoid this problem, focusing on the magnitude of angular velocity and the herpolhode, four models corresponding to the four cases are employed. Moreover, an integrated strategy to make proper use of these models is proposed. The effectiveness and limitation of this method are discussed, through computer simulations for various kinds of motion.

The Team Description of the Team OMNI

The Team OMNI has developed a robot system with omni-directional vision and omni-directional mobility according to the rule of the RoboCup Small Size League. This paper describes the hardware configuration, software configuration, and simulator of this robot system.

Motion estimation of an unknown rigid body rotating freely in zero gravity based on complex spectrum of position of a point on the body

In order for a robotic system autonomously to capture an unknown rigid body rotating freely in zero gravity, it is necessary for it to detect the objects motion. This paper presents a method for estimating object motion based on position information concerning a point located on the objects surface. We assume that the objects motion is described by the superposition of the rotations with constant angular velocities. When position sensors, etc., can obtain three dimensional position information about a point on the object, we can estimate parameters describing its motion. In other words, using this method we can calculate each frequency and direction of the axes of rotation by applying a Fourier transform to a time sequence of the points three dimensional position.