Design and Construction of a "Space Emulator"

A "Space Emulator" by which the motions of a manipulator carried by a small spacecraft can be emulated in lab environment is described. It consists of two Stewart platforms whose velocity and acceleration are controlled by Admittance Controller that acquires the interaction forces between the manipulators\´s base and the space vehicle and between the manipulator and the task from two six degree-of-freedom force/torque sensors, mounted on the platforms. In return, the controller determines the required velocity for each platform so that a free-float motion is emulated. The required platform velocity is fed to platform controller which resolves it to link velocities, using the inverse kinematic solution of the platform, and feed the results to to control modules which regulte the velocity of each link in a closed-loop fasion. The descriptions of the mechanical structure, the force/torque sensors, the controller and the control/interface software are presented.