This paper describes a position identification method to precisely estimate the relative movement onboard of an autonomous explorer in such natural terrain as Moon or Mars. This paper proposes a new map matching scheme that registers the visual information of consecutive robot positions and expresses the robot displacement in a common coordinate system. Local elevation maps of the environment are therefore retrieved from the 3D perception of a stereo camera. The proposed scheme consists of three main steps: feature point extraction from map data, matching of features points using triangle configurations and a voting procedure, and direct calculation of the robot displacement in six degrees of freedom using quaternions. The effectiveness of the proposed method is confirmed by computer simulations with synthetic terrain and experiments with stereo perception.

Planetary exploration requires rovers to perform a variety of challenging tasks autonomously. In order to complete relevant scientific mission, these rovers need to overcome difficulty for rough terrain traversing by "online methods". This paper discusses an idea that utilizes a rover mobile center of mass in order to aid in traversing rough terrain. According to vehicle pitch angle and contact angles, the rover recalculates the optimal position for the center of mass to minimize the indicator defined by two factors : the wheel driving force over the wheel normal force (adhesion coefficient) and tip-over stability angle (stability coefficient). Two innovative approaches are developed in this paper. The first one is that the authors defines easily comprehensible two factors, adhesion and stability coefficients for traversability indicator and proposes a method to calculate optimal center of mass position. The second one is that in the case of four-wheels drive, the relation between the front wheel and the rear wheel adhesion coefficient is easily solved and the best case for giving the driving forces can be solved as force making the front and the rear wheel adhesion coefficient equal. The authors call this "optimal force distribution method". Finally, this paper shows some simulation results for traversing rough terrain that compute the optimal center of mass while traversing the terrain.

This paper presents a mobile robotic system designed to perform deep soil sampling for lunar subsurface exploration in the near future. Drilling robots have to carry the excavated regolith backward because of its high density. Therefore a new scheme is proposed, to move forward under the soil by making use of reactive force caused by pushing the discharged regolith. Simple experiments demonstrate the effectiveness of the proposed method.

Hopping is effective mobility for exploration robot on small body. To explore small bodies, a mobile robot is required to move to target points. In case of exploration of microgravity environment by a hopping locomotion, hopping trajectories cannot be controlled after a robot hops. To move to target points, hopping direction and velocity should be controlled at takeoff. The authors proposed a, hopping robot, which consists of three masses, two linear actuators and a spring. This paper discusses how to control a hopping direction of the proposed robot in microgravity environment. When the robot hops, the friction force between the robot and the ground becomes larger. The simulation results show the controllability of a hopping direction even if there is a slip on a ground. The controllability is also confirmed by the free fall experiments.

This paper proposes a hopping robot that can move in a microgravity environment. The robot consists of three masses, which are connected by a spring and linear actuators. Using the spring and the linear actuators, the robot can obtain the vertical velocity and the horizontal velocity. Therefore, the robot can hop with the horizontal velocity from the stationary state. Furthermore, the robot can land without bounding and the slipping by transforming the kinetic energy to the elastic energy. Using this approach for controlling hopping and landing, the robot can move to a target in a microgravity environment. The simulation studies and the microgravity experiments shows the effectiveness of the proposed mobility.

This paper proposes a new mobility system for planetary rover using springs and linear actuators. In the microgravity environment, hopping mobility is a possible choice for enhancing a new mobility of the robot. One method to hop is to press one's own to the ground. The proposed robot consists of two masses, and can press one's own to the ground using springs. So the rover can hop from the stationary state by transforming the elastic energy to the kinetic energy using the springs and linear actuators. Furthermore the robot can land without bounding by transforming the kinetic energy to the elastic energy. The simulation studies and the ground experiments shows that the proposed rover could hop and land.

This paper proposes a four-wheel-type robot with the springs and linear actuators mechanism. In the microgravity environment, hopping mobility is a possible choice for enhancing a new mobility of the robot. The proposed robot can hop and land without bounding in the microgravity environment using the spring mechanism. Furthermore, at the moment of hopping, the wheels are pressed to the ground, so the rover can obtain the horizontal velocity by rotating the wheels. The wheels are also used for the attitude control in the air. The simulation of hopping with horizontal velocity is performed and the equation of kinematics of the rover is developed.

Under the micro-gravity environment such as on the surface of small planetary bodies (asteroids or comets), traditional wheeled rovers are not expected to move effectively due to the low friction and inevitable detachment from the surface. Therefore, the authors propose a hopping rover suitable for exploration on the surface of small bodies. This paper describes the micro-gravity experiments of a proposed hopping rover which is driven by an internal DC motor torque. The proposed rover could hop under a micro-gravity environment. Experimental results are compared with the computational simulations.

Under the micro gravity environment, such as on the surface of small planetary bodies (asteroids or comets), traditional wheeled rovers are not expected to move effectively due to the low friction and the inevitable detachment from the surface. This paper discusses the friction-based mobility around the surface of small bodies and proposes a new mobility mechanism that drives the rover by hopping. The hop angle and the velocity are analyzed by numerical simulations, which show the effectiveness of the new mobility system.

This paper describes a practical method for autonomous capture of a target satellite in space using an on-board manipulator. In retrieving a satellite, a reference trajectory for control of the manipulator is generated with time delay due to the processing time of the target motion estimator and the manipulator controller. Consequently, the control system shows a poor performance and the end-effector sometimes fails to capture the target satellite. To solve this problem, a control system is proposed, which utilizes predictive trajectory based on the target satellite dynamics. The validity and the usefulness of the proposed control method are shown by computer simulations and experiments using a 3D hardware simulator with 9 degrees of freedom.

In autonomous retrieval of a free-flying object, tumbling motion makes it difficult to grapple the objects with an on-board manipulator. This paper presents a new control scheme to capture a tumbling satellite based on a simple dynamical model. The target motion is estimated based on visual information using Kalman filtering technique. The capture planning based on the proposed model becomes simple because the motion of a grapple fixture on a target satellite nearly stops relative to the end-effector of a manipulator. The validity and the usefulness of the proposed method are shown by computer simulations and experiments using a 3-D hardware simulator with 9 degrees of freedom.