scholarly journals Active Controller Design for Microgravity Isolation Systems

2002 ◽  
Vol 9 (6) ◽  
pp. 307-317
Author(s):  
Nan-Chyuan Tsai
Keyword(s):  
Control System ◽  
Transfer Function ◽  
Closed Loop ◽  
Controller Design ◽  
Relative Displacement ◽  
Absolute Acceleration ◽  
Active Isolation ◽  
Space Experiments ◽  
Acceleration Feedback ◽  
Isolation Systems

This paper examines the performance of active isolation systems for microgravity space experiments as a function of desired transmissibilities that are chosen to be either much below or close to what can be tolerated. The control system utilizes two feedback signals: absolute acceleration and relative displacement of the controlled mass. The controller transfer function for acceleration feedback is chosen to avoid marginally stable pole-zero cancellations. The controller transfer function for relative displacement feedback is determined to achieve the desired transmissibility function. The issue of stability and properness of this controller transfer function are discussed. The required input forces and equivalent closed-loop stiffness are examined for various examples of desired transmissibilities.

Effects of Desired Transmissibility Functions on the Performance and Design of Control Systems for Microgravity Isolation Systems

1995 ◽  
Author(s):  
N.-C. Tsai ◽  
A. Sinha
Keyword(s):  
Control System ◽  
Transfer Function ◽  
Control Systems ◽  
Closed Loop ◽  
Relative Displacement ◽  
Absolute Acceleration ◽  
Active Isolation ◽  
Space Experiments ◽  
Acceleration Feedback ◽  
Isolation Systems

Abstract This paper examines the performance of active isolation systems for micrograviry space experiments as a function of desired transmissibilities which are chosen to be either much below or close to what can be tolerated. The control system utilizes two feedback signals: absolute acceleration and relative displacement of the mass. The controller transfer function for acceleration feedback is chosen to avoid marginally stable pole-zero cancellations. The controller transfer function for relative displacement feedback is determined to achieve the desired transmissibility function. The issue of stability and properness of this controller transfer function are addressed. The required input forces and “equivalent” closed-loop stiffness are examined for various examples of desired transmissibilities.

Model Based Simulation of the Active Damping of a Cantilever Plate and Redistribution of Stresses

2000 ◽  
Author(s):  
Sathya V. Hanagud ◽  
Patrick J. Roberts
Keyword(s):  
Control System ◽  
Vibration Control ◽  
Closed Loop ◽  
Active Vibration Control ◽  
High Stress ◽  
Element Simulation ◽  
Control Scheme ◽  
Acceleration Feedback ◽  
Order Of Magnitude ◽  
Active Vibration

Abstract In most structures, fatigue critical areas are associated with regions of high stresses. Sometimes, passive stiffening of structures can displace these high stress regions. Thus, for most applications, active vibration control is preferred. However, the question of whether an active vibration control scheme involving a set of actuators will reduce stresses in the whole structure or create high stress areas in the vicinity of the actuators arises. In previous works, this question has been addressed for cantilever beams which showed that the stresses are reduced by approximately the same order of magnitude as the reduction in vibrations. However, many aerospace structures are constructed of thin walled components whose response to vibration reduction can be very different than that of beams. In this paper, the stresses induced by an active vibration control system, based on the use of an offset piezoceramic stack actuator with acceleration feedback control, are investigated in a plate structure. A 3-D finite element simulation of the closed loop active vibration control system is developed and both the closed loop stresses and vibration amplitude reductions are studied.

Kinematics, Dynamics, and Control of Tendon-Driven Mechanisms Using Signal Flow Graphs

1998 ◽  
Author(s):  
Meng-Sang Chew ◽  
Theeraphong Wongratanaphisan
Keyword(s):  
Control System ◽  
Transfer Function ◽  
Closed Loop ◽  
Transfer Functions ◽  
Signal Flow ◽  
Signal Flow Graphs ◽  
Loop Transfer Function ◽  
Dynamics And Control ◽  
Flow Graphs ◽  
And Control

Abstract This paper presents the analysis of the kinematics, dynamics and controls of tendon-driven mechanism under the framework of signal flow graphs. For decades, the signal flow graphs have been applied in many areas, particularly in controls, for determining the closed-loop transfer function of a control system. The tendon-driven mechanism considered here consists of several subsystems including actuator-controller dynamics, mechanism kinematics and mechanism dynamics. Each subsystem will be derived and represented by signal flow graphs. The representation of the whole system can be carried out by connecting the graphs of subsystems at the corresponding nodes. Transfer functions can then be obtained by using Mason’s rules. A 3-DOF robot finger utilizing tendon-driven mechanism is used as an illustrative example.

A regressor-free adaptive controller for robot manipulators without Slotine and Li's modification

Robotica ◽  
2013 ◽  
Vol 31 (7) ◽  
pp. 1051-1058 ◽  
Author(s):  
Chen-Yu Kai ◽  
An-Chyau Huang
Keyword(s):  
Function Approximation ◽  
Closed Loop ◽  
Controller Design ◽  
Robot Manipulators ◽  
Adaptive Controller ◽  
Approximation Technique ◽  
Simple Method ◽  
Acceleration Vector ◽  
Acceleration Feedback ◽  
Joint Acceleration

SUMMARYSimilar to the traditional adaptive strategies for robot manipulators, the regressor-free adaptive controller design also requires applying Slotine and Li's modification to avoid the feedback of joint accelerations. In this paper, a simple method is proposed to construct a regressor-free adaptive controller for robot manipulators without Slotine and Li's modification. In the new design, the joint acceleration vector is lumped into an unknown time-varying function and the function approximation technique is utilized to cover its effect; therefore, its implementation is free from joint acceleration feedback. The closed-loop stability and boundedness of internal signals are justified by the Lyapunov-like technique. Both simulation and experimental results for a two-link robot are presented to show the effectiveness of the proposed design.

scholarly journals Multiloop and Prediction Based Controller Design for Sugarcane Crushing Mill Process

2015 ◽  
Vol 4 (4) ◽  
pp. 135
Author(s):  
Sandeep Kumar Sunori ◽  
Pradeep Kumar Juneja ◽  
Anamika Bhatia Jain
Keyword(s):  
Control System ◽  
Linear Model ◽  
Predictive Control ◽  
Closed Loop ◽  
Controller Design ◽  
Mimo System ◽  
Pi Controller ◽  
Open Loop ◽  
Turbine Speed ◽  
Mill Process

In the present work a sugarcane crushing mill is presented as a MIMO system with high multivariable interaction.A linear model of the plant is taken with flap position and turbine speed as manipulated variables and mill torque and buffer chute height as controlled variables.The multiloop PI controller has been designed for this plant by first investigating the RGA and the value of Niederlinski index of this plant.The decoupling of this system is done and the respective open loop and closed loop step responses are observed and compared with those of the composite MIMO system. Also the performance of multiloop controller is compared with controller designed using model predictive control system strategy for this plant.

Active Damping by Acceleration Feedback Control and Redistribution of Stresses in the Structure

1999 ◽  
Author(s):  
Maxime P. Bayon de Noyer ◽  
Patrick J. Roberts ◽  
Sathya V. Hanagud
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Vibration Control ◽  
Closed Loop ◽  
Driving Forces ◽  
Active Vibration Control ◽  
High Stress ◽  
Low Frequency ◽  
Acceleration Feedback ◽  
Active Vibration

Abstract In most structures, fatigue critical areas are associated with regions of high stresses. Passive stiffening of structures usually displaces these high stress regions. Thus, for most applications, active vibration control is preferred. However, the question of whether an active vibration control scheme involving a set of actuators will reduce stresses in the whole structure or create high stress areas in the vicinity of the actuators arises. In this paper, the stresses induced by an active vibration control system based on the use of an offset piezoceramic stack actuator with acceleration feedback control are investigated. Using a modal analysis of the actuator acting on a cantilever beam, a low frequency approximation of the actuator is developed in the form of a spring and two driving forces. Based on this approximation, a 3-D finite element simulation of the closed loop active vibration control system is developed and the closed loop stresses are studied.

Digital Control Algorithms for Microgravity Isolation Systems

1991 ◽  
Author(s):  
A. Sinha ◽  
Y.-P. Wang
Keyword(s):  
Digital Control ◽  
Controller Design ◽  
Relative Displacement ◽  
Control Algorithms ◽  
Isolation System ◽  
Single Degree Of Freedom ◽  
Numerical Studies ◽  
Maximum Current ◽  
Isolation Systems ◽  
New Algorithms

Abstract New digital control algorithms have been developed to achieve the desired transmissibility function for a microgravity isolation system. Two approaches have been presented for the controller design in the context of a single degree of freedom system for which an electromagnet is used as the actuator. The relative displacement and the absolute acceleration of the mass have been used as feedback signals. The results from numerical studies are presented. It has been found that the resulting transmissibility is quite close to the desired function. Also, the maximum coil currents required by new algorithms are smaller than the maximum current demanded by the previously proposed phase lead/lag method.

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