Active gravity compensation test bed for a six-DOF free-flying robot
A novel active gravity compensation concept is proposed to simulate space on-orbit microgravity environments for free-flying robots on ground. Here, robots are suspended by active-controlled motion path tracking mechanisms through wires to compensate for gravitational forces. Based on the concept, an experimental test bed was designed and fabricated in laboratory to study on-ground kinematic and dynamic behaviors of a free-flying robot. The experimental fabrication contains an active horizontal motion tracking mechanism composed of primary and secondary active rotating arms. An multi-objective optimization method calculating the tension of the wires to minimize torques on robot joints is approved. The tension of the suspension wires is obtained through passive counterweights using pulley mechanisms. The kinematics and dynamics of a 6-DOF free-flying manipulator were calculated in MATLAB and simulated in MSC Adams under three working conditions: zero-gravity, gravity compensation and gravity. The lowest ratio of the torque compensation reached 80%. Agreements between numerical analyses and simulation results confirm the ability of this gravity compensation concept to simulate the kinematic and dynamic behaviors of free-flying manipulator in space.
Micro-G emulation system using constant-tension suspension for a space manipulator
A hardware system for emulating microgravity for an on-the-ground space manipulator is described. The manipulator is suspended by wires, kept vertical by the suspension arms controlled to follow the manipulator's motion. The manipulator base is supported by a six-degree-of-freedom mechanism, with which free floating is emulated based on the numerical integration of the dynamic and kinematic equations for the manipulator. The gravitational force acting on the manipulator is thus canceled by the combination of the contact force on the base and the upward tensile forces through the wires. Optimizing the manipulator's suspension keeps the values of individual tensions acting on it constant, whatever the manipulator's attitude. Experiments show that the suspension system is sensitive enough to emulate the vertical free-floating motion of a suspended object, and can be tuned to initiate a microgravity environment of at least 0.01 g under restricted conditions.<<ETX>>
Body sculpturing.
Significant improvements in body contour can be accomplished by surgical procedures having reliable, predictable results. Similar to the modern sculptor of inanimate art forms, plastic surgeons have utilized new materials and devised new techniques to achieve aesthetic improvement of the face, trunk, and extremities. The goals of the surgical sculptor are perhaps more challenging than those of the pure artistic sculptor, not only because they must result in improved appearance but also because the surgeon is limited at all times by considerations of regional anatomy, the availability of viable tissue materials, and the safety of his patient.