Method of Slewing the Spacecraft to Minimize Settling Time

Abstract

The low-frequency flexible modes of solar arrays on spacecraft are excited by the minimum-time bang-bang control during a slew maneuver. These flexible modes limit the control bandwidth and degrade the pointing error at the end of slew maneuver, resulting in a longer settling time. The objective of this investigation is to develop and verify methods to shape the torque profile of reaction wheels for the slew maneuver such that, at the end of slew, vibration are minimized and the settling time is reduced. Effectiveness of the smooth versine input profiles, torque feedforward, and input shaping are accessed. Both numerical simulation results and ground simulated experimental results are presented in this paper.

Flattening the Curve of Flexible Space Robotics

“…Piezo-electric materials may be used to control flexible robot arms. [45] (a) piezo bimorph bender; a kind of piezo-electric material used as both sensors and as actuators; [46,47] (b) utilization of piezo-electric sensor and actuators utilized on the free-floating flexible space robot simulator in figure 8b [48] simulating hardware such as the Robotic Refueling Mission-3. [49] Subfigure b is taken from [47] a publication that is a work of the U.S. Government as defined in Title 17, United States Code, Section 101.…”

Single-Axis, Spin-to-Spin Slew Maneuvers Under a Finite Jerk Constraint

“…The angular positions corresponding to the angular velocities in Eqs. (17)(18)(19)(20)(21)(22)(23) are calculated by subproblem P and θ f ; ω f , and the following seven pairs of angular position and velocity are defined.…”

“…The implementation of time-optimal control input designed under a rigid-body model for a flexible-body model results in excitation of a flexible mode; hence, alternative methods, such as input shaping methods and methods for designing smoothed control inputs, have been proposed [1,2,[13][14][15][16][17]. Furthermore, the effectiveness of smoothed control inputs has been demonstrated through numerical and experimental studies [18][19][20].…”

“…In Refs. [12,13,[18][19][20], ramp, versine, and polynomial functions were considered in the profiles of the smoothed control inputs. In Ref.…”

Experiments on Jerk-Limited Slew Maneuvers of a Flexible Spacecraft

“…For a complete cancellation of the vibration, the input shaping technique 3 has been successfully adopted and tested with the experimental testbed for rest-to-rest maneuvers. 6 Input shaping can be used in conjunction with any reference input. When time-optimal bang-bang control is used as a reference control input, the resulting control will completely eliminate the targeted frequency vibration mode.…”