Abstract This paper describes mechanism and control  of  leg-wheel hybrid mobile robot.  Legged locomotion has high adaptability for  rough  terrain, and wheeled locomotion posses  speed  and  eficiency.  A  new locomotion mechanism that  combines legs  and  wheels is proposed,and a prototype mobile robot  that adopts  the mechanism 10796
is introduced.  The  robot  has four  legs,  and  a wheel  is
attached  at the end of  each leg.  The  front  leg has three
joints  and  a passive  wheel.  The  rear  leg has one joint
and  an  active  wheel.  In  order  to make the  best  of  the
mechanism,  three locomotion modes, wheel mode, hybrid
mode, and step mode, are developed.  In  the wheel mode,
four  wheels  are  used on  flat  terrain.  On the rough
terrain,  the  hybrid mode  is select, and  two legs  and  two
active  wheels  are  used  for  locomotion. To  climb  or
descend a large step, the step mode is used.
1.  Introduction
Recently, works in manufacturing industry have been
automated. In the case of outdoor works, mechanization
such  as  construction machines  has  been  done only  on
relatively flat  terrain.  Japan  is  a mountainous country,
and seventy percent of  the land  is mountain area.  Most
of works in the mountain sites depends on human labors.
For  the  future,  the  works in such  area  will  become
important from  the  point  of  view  of  the  prevention  of
natural calamities  or  the  environmental  problems,.  To
automate such works, development  of  the  locomotion
system that can move in mountainous environment  is
essential.  The  mountain environment includes steps,
inclined  terrain, and  easily deformed and collapsed
terrain.
Many mobile robots  for  outdoor environment  are
equipped  with  wheels  or  crawlers.  However,  they
cannot move  on  discontinuous terrain  like  steps.
Although legged robots have great adaptability  for
complicated environment, they  have  some difficulties
also. Generally, legged robots require  large number  of
actuators and complicated mechanism. Moreover, their
walking speed is slow even on flat terrain. Considering
these facts, authors propose a new locomotion
mechanism that combines  legs and wheels.
Up  to  the present, several leg-wheel hybrid type
mobile robots have  been  developed. Hitachi, Ltd.
developed a five-legged robot, whose leg has  two joints
and an active wheel at  its tip  [l].  It has fifteen degrees
of  freedom. A  robot  that has  four legs  and  six wheels
was developed by Mitsubishi Heavy Industries, Ltd.  [2].
The robot body was equipped with  two active wheel and
four legs that has two  joints and an active wheel at  their
end.  It  has fourteen actuators.  Kobe  Steel, Ltd.
constructed a six-leg-wheel type robot in  the  Japanese
national project named Advanced Robot Technology [3].
This robot has six two-degrees of  freedom legs, and each
leg has a two-degrees of  freedom (steerage and traction)
wheel. Totally, it  has twenty-four degrees  of  freedom. 轮足复合式移动机器人英文文献和中文翻译:http://www.youerw.com/fanyi/lunwen_9943.html