How does the crab-shape design make it better suited to this exploration – what can Crabster do that other designs/crafts cannot?

Some lobsters live in stream and some crabs live in coast where tidal wave exists. They can live there because they constantly control their posture. If they don't control their body like dead crab or lobster, the current will blow them off. CR200 mimics their shape and behavior.

A.     CR200 has advantages over ROVs/AUVs in strong tidal current as follows.

 i.         CR200 can endure in high tidal current environment better than AUVs or ROVs because CR200 walks on boundary layer of seafloor where current speed is relatively less than upper layer.

 ii.         CR200 can keep or adjust its posture stably based on the mechanical contacts between legs and seafloor. CR200 is able to improve its tumble stability by move its footing.

 iii.         CR200 can stabilize its posture by utilizing the hydro forces acting on the body and legs. CR200 can optimize its attitude to reduce the drag force and increase the downward lift force to improve the tumble stability.

B.     CR200 has advantage to overcome high turbid underwater environment

 i.         In the very turbid area, underwater robot has to use sonars such as scanning sonars or acoustic cameras. CR200 provides very stable moving base for the acoustic image equipment.

 ii.         Moreover, moving underwater robots in turbid area may be very dangerous because there may be obstacles around the robot like abandoned fish nets and ropes which entangle the robots. CR200 is safer in those areas due to the stable walking without drift.

C.     It is very dangerous and limited for human divers to go to following area

  i.         deeper than 30m

  ii.         temperature is less than 10 degree C

  iii.         current is more than 1 knot

  iv.         visibility is too short