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Lunar or planetary exploration rovers are expected to have the ability to move across an area as wide as possible in an unknown environment during a limited mission period. Hence, they need an efficient navigation method. Most of the surface of the moon or planets consists of flat ground, sand, and scattered rocks. In a simple flat sandy terrain with some rocks, rough route planning is sufficient for a lunar or planetary rover to avoid obstacles and reach an assigned point. This paper proposes an efficient vision-based planning scheme for exploration rovers on a flat surface with scattered obstacles. In the proposed scheme, dangerous areas are robustly extracted by processing image data, and the degree of danger is defined. A rough routing plan and sensing plan are simultaneously constructed based on the dangerous-area extraction results. The effectiveness of the proposed scheme is discussed based on the results of some simulations and simple experiments.

Rovers are one of the most important vehicles used for conducting planetary exploration missions. This paper focuses on a small, lightweight rover that can be used for lunar exploration. It should be noted that, with a small rover, it is difficult to traverse loose soil such as that on the lunar surface. The rocks that cover the lunar surface, moreover, hinder the traversal of a small, lightweight rover. We develop a small, lightweight rover having 2 configurations to solve these tasks. One configuration involves the installation of elastic wheels whose 2 form changes depending on the surface that the rover traverses. The other configuration involves passive suspension using differential gears. We perform running experiments on rovers with these configurations. Experimental results prove that elastic wheels are more efficient than rigid wheels for traversing loose soil. We also found, moreover, that the proposed rover shows good climbing performance. We thus have shown the efficiency of the proposed small, lightweight rover in this study.

Investigation of small planetary bodies is now attracted and some missions on asteroids and comets have been realized. Such bodies are full of geographical features that next demand would be direct surface investigation by a rover. In order to navigate the rover to the specific points, the localization of the rover is required. However, conventional localization method is not adequate on small bodies whose size is less than 1[km]. One of the conventional methods, localization by camera images obtained on the rover needs a map made by a mother spacecraft. The resolution of the map is not enough for the rover's local view. Another method, localization by observing the movements of stars and the sun has little accuracy. Global positioning system (GPS) is not practical for small planetary bodies because it needs several orbiters. In this paper, we propose a reasonable method which localizes the rover on a small body with reasonable accuracy, with reasonable time and with reasonable resource. This method measures two way range between a rover and a mother spacecraft repeatedly. Even this method uses only one orbiter, the localization accuracy is estimated about 1[m] assuming ITOKAWA-size asteroidwhoseradiusisatmost600[m].

This paper proposes an efficient scheme to make a routing and sensing plan simultaneously for lunar or planetary exploration rovers. In the proposed scheme, the environment is widely recognized by using a vision system. The proposed algorithm can detect obstacles based on gray-level image. And a rough route is produced by judging whether the area is safe or dangerous. Firstly, the shade average and the variance at each pixel are calculated from the obtained image, and the environment recognition is performed. According to the recognition results, a rough path and a sensing strategy are planned. A rover senses locally based on the proposed behaviour and moves to the destination. The validity of the proposed method is shown by some computer simulations.

Because a hopping robot moves long distances at minimum energy and can observe its surrounding from high points when it jumps, it is expected to explore microgravity environments effectively. Despite the importance of attitude control in such exploratory robots, few attitude control mechanisms have been proposed. This paper proposes a four-wheeled hopping robot that hops horizontally and lands without bouncing. Its wheels are applied to attitude control in the air. A simulation study and free-fall experiments verified the feasibility of the proposed mobility and the applicability of the robot.

Accepted: 2004-07-06, 資料番号: SA1001686000

This paper proposes a new mobility system for planetary exploration robot using springs and linear actuators. In microgravity environment, it is difficult to obtain the horizontal velocity, because the friction force between a robot and the ground is very small. By pushing the ground, however, the robot can not only hop, but also obtain the horizontal velocity. The proposed hopping robot consists of two masses, and can push the ground by using springs. The robot can hop from the stationary state by transforming the elastic energy to the kinetic energy using the sprigs 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 show the effectiveness of the proposed mobility system.

This paper describes a newly developed rover with small size, lightweight, low power consumption. Unmanned mobile robots for surface exploration of the moon or planets have been extensively studied and developed. A lunar or planetary rover is required to travel safely over a long distance for many days in unfamiliar terrain. This paper presents exploration mission, scientific signification, requirements, and technology of a lunar rover. This paper proposes a new mobility system, which has four wheels and one supported wheel. This novel suspension system is a simple and light mechanism like a four-wheeled rover and provides a high degree of mobility like a six-wheeled rover. Multiple rovers exploration by buddy system is also discussed. The performance of the developed rover is shown by some experiments.

Exploration missions for small planetary bodies such as asteroids and comets have received significant attentions in recent years. In upcoming missions, it is very important for planetary science to make science-equipped robots hang around the surface of small bodies. In order to provide an exploration robot on the surface of small bodies whose gravity is very small, the authors have researched the mobility under the micro-gravity and have developed a small robot which is specialized in the micro-gravity environment. This paper describes the mobility and the system design of the developed robot and is accompanied with explanation of the strategy how to explore and navigate along the small body surface.

For future exploration missions to small planetary bodies, in-situ surface observation by robots would be a promising method to investigate the target body whose surface gravity is very small. The authors have researched the mobility system under the microgravity environment and proposed a new mobile system which drives a robot by hopping. Due to the uncertainty of the escape velocity from the target small body, the hop velocity of the robot has to be controlled on-board. This paper proposes a velocity control method of the hopping mechanism, which was evaluated by microgravity experiments and compared with numerical simulation analyses.

This paper proposes a new mobility system for planetary rover using springs and linear actuators. In the microgravity environment, hopping is a possible choice for enhancing a new mobility of the rover. The proposed rover can hop from stationary state by transforming the elastic energy to kinetic energy using the sprigs and linear actuators. Furthermore the rover can land at the aimed point by transforming kinetic energy to elastic energy. The simulation for the motion of the rover when the rover hops and lands are performed.

In recent years, many researchers have extensively studied and developed unmanned mobile robots for surface exploration of the moon or planets. A planetary rover is required to travel safely over a long distance for many days in unfamiliar terrain and to collect samples such as sands, stones, rocks, etc. This paper describes a telescience method by a rover-equipped manipulator for lunar or planetary rover missions. The investigated telescience strategy of capturing scientific samples is to control the on-board manipulator as automatically as possible. An experimental rover system has been developed to demonstrate the strategy, which derives the required autonomous functions in unknown natural environments and the desirable man-machine interface.

In recent years, missions for exploring small bodies such as asteroids, comets, and meteorites have received a significant attention all over the world. The rovers which hang around the surface of such small planetary bodies can provide in-situ surface observations on the various points of the target body. So the research and development of exploration rovers for small planetary bodies are very important.Under the micro gravity environment such as on the surface of small planetary bodies, 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.

An in-situ observation of small planetary bodies (asteroids or comets) has been of great interest for planetary science. The authors have proposed a small rover for MUSES-C asteroid exploration mission of the Institute of Space and Astronautical Science. The proposed rover adopts a novel and innovative mobility that drives a rover by hopping, which has a lot of advantages under the micro-gravity environment on the surface of small planetary bodies. A test model of the proposed rover was developed and the micro-gravity experiments were conducted. This paper describes the experimental results, which are compared with the simulation analysis.

Accepted: 1994-07-18, 資料番号: SA1003273000

PLANET-B is the Japanese Mars project and the launch is scheduled for August,1998 with the funding started in 1992. The primary science mission of PLANET-B is to study Martian upper atmosphere and its interaction with the solar wind. The total spacecraft weight is 536kg with the propellant 278kg. The dry weight excluding the propellant hardware is 186kg, and we are trying to fulfill major scientific achievements taking advantage of the state of the art in advanced technologies. This paper presents the overall feature of the Planet-B project with an emphasis on the engineering aspect.

A new generation of M-series launch vehicle, M-V, is currently being developed at Institute of Space and Astronautical Science and the first flight is scheduled for 1996. We will carry out several planetary missions using M-V which can launch a spacecraft of a few hundred kilograms into a trans-planet orbit. Lunar penetorator mission “LUNAR-A” and Mars orbiter mission “PLANET-B” have been approved and the launch is scheduled for 1997 and 1998, respectively. Our follow-on planetary missions will be more advanced and complex because of the increasingly demanding scientific requirements. One of them is the asteroid sample return mission. In order to realize advanced planetary missions, it is absolutely necessary to establish highly advanced and light-weight spacecraft design under the constraint of launch capability. In this paper, we will describe our advanced spacecraft design concept for the asteroid sample return mission with M-V vehicle as an example.