Abstract: The balance problem of athree-arm space robot has been discussed during its manipulation. The first arm of the space robot is used to keep connection with the spacecraft (shuttle orspace station), the second arm to balances the whole system, and the third arm to manipulate a job. The linear momentum and angular momentum equations and an optimization function have been advanced. An optimization solution of the angles and the angular velocities of those joints of the second arm (the balance arm) according to conservation of the linear momentum and angle momentum of all systemhave been gotten respectively. One example of a simple three-arm space robot onan air-bearing table has been simulated and the results simulated have been given out with two pictures.

Key words: robots, three-arm space robot, balances, manipulation