mobility performance evaluation of planetary rover with simi

月球车珍贵资料——来自美国

Mobility Performance Evaluation of Planetary Rover

with Similarity Model Experiment

Yoji KURODA, Teppei TESHIMA, Yoshinori SATO

Department of Mechanical Engineering

Meiji University

1-1-1 Higashimita, Tama-ku, Kawasaki, 214-8571, Japan

{ykuroda | ce33248}@isc.meiji.ac.jp

Abstract - In order to carry out experiments many times on the Earth in consideration of the difference of gravitational acceleration to design the rover properly, we introduce similarity law to design and construct the experimental models. We have produced two experimental models of the planetary rover with 5-wheel suspension system (called "PEGASUS") and 4WD system under for 1G and 1/2G gravity. We have carried out a low-gravity flight experiment in various parameters using the model on the airplane. Assuming that similarity law is true under every gravity environment, we have made relative evaluation on a degree of mobility by the difference of mobility systems. In the result of the flight experiment, it is show that PEGASUS is able to successfully move better than 4WD.

Keywords - Planetary Rover, Similarity law, Experimental models,

Gravitational acceleration.

I. Introduction

Investigation of the Moon or planets is one of the most effective methodologies to know the possibility as humanity's new activity base. As the result of those many missions, e.g. sensing their surfaces with orbiter or lander, had been carried out, we were able to gain wonderful knowledge. Now, it can be said that more detailed investigation should be started to promote the future space development. [1] On the other hand, almost all countries had to cut down the budget for the development of the space off because of their economical problems. As total cost of missions has been reduced, mission concepts have to be changed to "Smaller, Faster, Better" from large-scale projects like Apollo missions [2]. In order to explore in detail in wider area during longer term with low-cost, using a small-unmanned roving vehicle (shown as 'rover' hereafter), which has a high degree of mobility, is one of the fascinating ideas.

By the capacity limitation of a launch vehicle, the rover should have several limitations such as size, weight, amount of energy, etc. However, in order to explore particularly in wider area under limited energy resource, the rover must have a high degree of mobility and low-power-consumption technology to traverse rough terrain. Therefore, we should understand exactly the kinematics properties of the rover on the planet and establish the effective system for the planet. There will be suitable mobility system under different Gravity, e.g. Moon or Mars etc., from the Earth. We have to carry out

Takashi KUBOTA

The Institute of Space and Astronautical Science

Japan Aerospace Exploration Agency

3-1-1 Yoshinodai, Sagamihara, 229-8510, Japan

Kubota@nnl.isas.ac.jp

experiments many times on the Earth in consideration of the difference of gravitational acceleration [3-4].

In this paper, we introduce similarity law to design and construct the experimental models flexibly and quickly. Using many similarity models, which produce, we observe how the models take action by the difference of gravities and systems. Thus, we make relative evaluation on a degree of mobility.

II. Planetary Rover The planetary rover is required to carry out scientific measurement at many points on wide planetary surface during its limited lifetime. In order to achieve above requirements, the rover must have a mobility system which has (1) Mechanism to improve its degree of mobility (2) Low energy consumption (3) High stability

These things listed above show a tendency to exaggerate when a rover becomes smaller, because a small rover has to pass over relatively big rocks within relatively low power. In order to examine micro planetary rover in a total system, we have developed a prototype rover called Micro5 [5] shown in Fig.1. The Micro5 has a new suspension system called ”Pentad Grade Assist SUSpension (PEGASUS)”. PEGASUS has high mobility as well as rocker-bogie suspension [6-10], with very simple mechanism called only-one-joint architecture.

Fig.1 Micro5: the planetary rover

Fig.2 AMSL Minirover: the rover

with PEGASUS

system with 4-wheel drive system

III. Mobility System

The suspension system is the key issue of degree of mobil-ity. And so, we have discussed a variety of mobility systems for cruising rough terrain. In this chapter, we'll see some