Firm standing of legged mobile manipulator

In order for a legged mobile manipulator to work, it is essential to change its posture for stable standing in response to the force at the end effector. We define 'firm standing' as keeping a stable posture in working without moving the positions of the point of contact of legs and end effector. We analyze firm standing and show required degree of freedom for it. We also experiment on it by using redundant d.o.f. in 2-D space.