： ln future iunar〆 planetary exploration missions ， wheeled rovers wi11 be promising robots to perfbrm wide − area explorations ． Wheeled robots ， howeve夙 are prone to s ］ ip in so 負 terrain ： therefbre． securing mobility wil ［be a criticahssue ， This paper first describes a soi レwheel 孟 nteraction model which is simply found from Coulomb ' s friction law． The model enables slip − ratioestimation frem a combination of wheeUoad and traction ． Second 、 a silnple control me1hodology ， wheel load distributjon controL f ( ＞ r rna 重 ntaining vehicle mobil 註 y is d至 scussed ． Moreover ． a six − wheeled robot which 癜 plements 重 he Gontrol system was deveioped ． The robot has six wheels and six vertical suspenslons 、 「 ith built −in linear ac 加 ators ， Load ceUs are installed between cach wheel and suspension Io moni 璽 or the wheeUoad

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