Command Shaping Research Articles

Command Shaping in Tracking Control of a Two-Link Flexible Robot

Command Shaping in Tracking Control of a Two-Link Flexible Robot

Positioning Control of a Self-Sensing Micro PVDF Actuator.

Positioning control of a self sensing micro PVDF (Poly Vinylindene Flouride) actuator is presented. A feedback control law of the positioning control of the PVDF actuator is derived by considering the time rate of change of the total energy of the system. In a practical implementation of the self-sensing actuator an electrical bridge circuit is used to measure time rate of tip bending angle of the actuator. The choice feedback gains needs to be addressed. They can be chosen to improve the damping in any subset of critical vibration modes with the knowledge that the controller will not destabilize any part of the system. However, the actuator pole locations of closed-loop system will have to be determined from a rather large symmetric eigenvalue calculation. Overcoming this difficalties, we present a 2 d. o. f (two-degree-of-freedom) control system consists of feedforward and feedback controller. Feedforward controller is designed using inverse system which is one of the input command shaping methods. Numerical simulation and experimental results confirm that faster precise positioning control can be realized with the proposed control system.

Experimental Verification of Vibration Reduction in Flexible Spacecraft Using Input Shaping

The performance of many spacecraft can be improved by using closed-loop control and command-shaping techniques. However, because little information exists about the operation of controlled structures in zero gravity, it is dife cult for designers to anticipate and place cone dence in the on-orbit performance of their ground-based control designs. To address this issue, the middeck active control experiment was conducted aboard the Space Shuttle Endeavor in March of 1995. The results of the command shaping experiments implemented during the mission are presented, and guidelines forusing command shaping to suppress unwanted vibration in e exible space structures are proposed. HE combination of stringent performance specie cations and lightly damped structural modes makes the effective operation of many space systems vulnerable to vibration. To attack this problem, closed-loop control and open-loop command-shaping techniques are often enlisted. However, with only ground-based testing available prior to on-orbit implementation, uncertainty about zerogravity(0-g) behavior can hamper the success of these 0- g control designs. The Massachusetts Institute of Technology (MIT) middeck activecontrolexperiment (MACE)isaSpaceShuttlee ightexperiment designed to expose critical issues associated with the design of controllers and shaped commands for 0 g. As part of this experiment, data were collected from a e exible structure on-orbit, and results illustrated that both the control and command-shaping strategies employed on the test article could effectively reduce problematic vibration. Additionally, as a result of careful ground-based modeling efforts, predictions of 0- g behavior were accurate enough to achieve high-performance control and command shaping without on-orbit redesign. After introducing the MIT MACE project and the MACEcommand-shaping efforts, this paper presents the results from a specie c subset of the mission experiments: the MACE input shaping tests. Based on these results, key points are summarized and conclusions are drawn.

Vibration Reduction in Flexible Space Structures Using Input Shaping on MACE: Mission Results

The performance of many spacecraft can be improved by using closed-loop control and command-shaping techniques. However, since little information exists about the operation of controlled structures in zerogravity, it is difficult for designers to anticipate and place confidence in the on-orbit performance of their ground based control designs. To address this issue, the Middeck Active Control Experiment (MACE) was conducted aboard the Space Shuttle Endeavor in March of 1995. This paper presents the results of the command shaping experiments implemented during the mission and proposes guidelines for using command shaping to suppress unwanted vibration in flexible space structures.

Controlling contact transition

Successful control of contact transitions is an important capability of dextrous robotic manipulators. We examine several methods for controlling the transition from free motion to constrained motion, with an emphasis on minimizing end-effector load oscillations during the transition. A new approach, based on input command shaping, is discussed and compared with several methods developed in prior research. The various techniques were evaluated on a one-axis impact testbed, and we present results from those experiments. The input shaping method was found to be comparable, and in some cases superior, to existing techniques of contact transition control. >

Design of localizer capture and track using classical control techniques

A typical localizer capture and track mode of the automatic landing system control laws provided in new generation commercial airplanes is discussed. The linear control law consists of three separate modules: yaw damper, roll inner-loop, and localizer outer-loop. The yaw damper and roll inner-loop are used in conjunction with other modes of the roll axis control laws of the autopilot and are, therefore, predetermined for the localizer mode. The design includes feedforward, command shaping, and analytic gain schedules.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>