Nonlinear Modeling of a Long Flexible Manipulator and Control by Inertial Devices

We consider the modeling and control of a planar, long, flexible manipulator that is representative of current space-based robotic arms such as the Space Shuttle Remote Manipulator System. The arm is equipped with three actuators: 1) a shoulder motor; 2) a torque wheel at the tip; and 3) a proof-mass actuator at the tip. The goal is to investigate the potential use of inertial devices as control inputs for maneuvering tasks and vibration suppression. The parameters used for the inertial devices at the tip are comparable to those specified for the Mini-Mast facility at the Langley Research Center. A nonlinear distributed parameter model is obtained by the extended Hamilton Principle. The associated eigenvalue/eigenfunction problem is solved and a finite-dimensional state space model is assembled. A preliminary design of a Linear Quadratic Regulator is used and computer simulations illustrate the benefits of using the proposed actuators.