Slewing Maneuvers and Vibration Control of Space Structures by Feedforward/Feedback Moment-Gyro Controls

1995 ◽  
Vol 117 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Li-Farn Yang ◽  
M. M. Mikulas ◽  
K. C. Park ◽  
Renjeng Su
Keyword(s):  
Rigid Body ◽  
Vibration Control ◽  
Vibration Suppression ◽  
Body Motion ◽  
Space Structures ◽  
Rigid Body Dynamic ◽  
Control Approach ◽  
Saturation Constraints ◽  
Two Stages ◽  
The Given

This paper presents a momentgyro control approach to the maneuver and vibration suppression of a flexible truss arm undergoing a constant slewing motion. The overall slewing motion is triggered by a feedforward input, and a companion feedback controller is employed to augment the feedforward input and subsequently to control vibrations. The feedforward input for the given motion requirement is determined from the combined CMG (Control Momentum Gyro) devices and the desired rigid-body motion. The rigid-body dynamic model has enabled us to identify the attendant CMG momentum saturation constraints. The task for vibration control is carried out in two stages; first in the search of a suitable CMG placement along the beam span for various slewing maneuvers, and subsequently in the development of LQ control algorithms for CMG spin-stabilization. Both analytical and numerical results are presented to show the effectiveness of the present approach.

scholarly journals Design of a robust active fuzzy parallel distributed compensation anti-vibration controller for a hand-glove system

2021 ◽  
Vol 7 ◽  
pp. e756
Author(s):  
Leila Rajabpour ◽  
Hazlina Selamat ◽  
Alireza Barzegar ◽  
Mohamad Fadzli Haniff
Keyword(s):  
Vibration Control ◽  
Pid Controller ◽  
Passive Control ◽  
Prolonged Exposure ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Superior Performance ◽  
Control Approach ◽  
Tool Performance ◽  
Active Vibration

Undesirable vibrations resulting from the use of vibrating hand-held tools decrease the tool performance and user productivity. In addition, prolonged exposure to the vibration can cause ergonomic injuries known as the hand-arm vibration syndrome (HVAS). Therefore, it is very important to design a vibration suppression mechanism that can isolate or suppress the vibration transmission to the users’ hands to protect them from HAVS. While viscoelastic materials in anti-vibration gloves are used as the passive control approach, an active vibration control has shown to be more effective but requires the use of sensors, actuators and controllers. In this paper, the design of a controller for an anti-vibration glove is presented. The aim is to keep the level of vibrations transferred from the tool to the hands within a healthy zone. The paper also describes the formulation of the hand-glove system’s mathematical model and the design of a fuzzy parallel distributed compensation (PDC) controller that can cater for different hand masses. The performances of the proposed controller are evaluated through simulations and the results are benchmarked with two other active vibration control techniques-proportional integral derivative (PID) controller and active force controller (AFC). The simulation results show a superior performance of the proposed controller over the benchmark controllers. The designed PDC controller is able to suppress the vibration transferred to the user’s hand 93% and 85% better than the PID controller and the AFC, respectively.

Control of Flexible Payloads Grasped by Actuated Grippers Undergoing Large Rigid-Body Motions: Part I — Dynamics

2002 ◽  
Author(s):  
Edward J. Park ◽  
James K. Mills
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Time Scale ◽  
Normal Modes ◽  
Body Motion ◽  
Actuator Dynamics ◽  
Scale Modeling ◽  
Fixed Interface ◽  
The Given ◽  
System Order

This paper is Part I of a preliminary study to simultaneously control vibration and static shape deformation in flexible payloads. In Part I, the dynamics of a flexible payload grasped by an actuated gripper, which is attached to a rigid link robotic manipulator, is investigated using the component mode synthesis (CMS) method. Robot and actuator dynamics are also added to the system dynamic model to fully define the rigid body motion and elastic motion of the flexible payload. The CMS method is employed to explicitly model the coupling between the payload and actuators, and to reduce the system order. With the addition of fixed-interface quasi-static modes to fixed-interface vibration normal modes and actuator constraint modes an improved component mode representation is defined. Here, it is found that the inclusion of quasi-static modes in the CMS formulation results in increased ac curacy for simulation of dynamic behaviour of flexible payloads subject to both gravity and robot motion induced forces. Numerical examples are presented to demonstrate the effectiveness of the new component mode representation for the given robotics problem. In Part II [9], the two-time scale modeling (TSM) technique is used taking advantage of two-time scale behavior between the quasi-static modes and vibration modes in the dynamic model.

Adaptive boundary iterative learning vibration control using disturbance observers for a rigid–flexible manipulator system with distributed disturbances and input constraints

2021 ◽  
pp. 107754632199015
Author(s):  
Xingyu Zhou ◽  
Haoping Wang ◽  
Yang Tian
Keyword(s):  
Differential Equations ◽  
Vibration Control ◽  
Vibration Suppression ◽  
Virtual Work ◽  
Iterative Learning ◽  
Flexible Manipulator ◽  
Input Constraints ◽  
Control Laws ◽  
Control Approach ◽  
Composite Energy

In this article, an adaptive boundary iterative learning vibration control is developed for a class of the rigid–flexible manipulator system under distributed disturbances and input constraints. With the help of the virtual work principle, the dynamics of the rigid–flexible manipulator are modeled and described by coupled ordinary differential equations and partial differential equations. Based on the original infinite dimension system model, three compounded adaptive boundary iterative learning vibration control laws are constructed with disturbance observers and adaptive vibration laws, aiming to track the desired joint angular positions and achieve vibration suppression simultaneously. Three disturbance observers are proposed to determine the upper bounded approximation of the unknown external disturbances. Hyperbolic tangent and saturation functions are incorporated into adaptive vibration laws to handle input constraints. It is proved by Lyapunov–Krasovskii-like composite energy functions that elastic vibrations and tracking errors can asymptotically converge to zero along the iteration axis. Finally, the efficacy of the developed adaptive boundary iterative learning vibration control approach is illustrated by the simulation results under distributed disturbances and input constraints.

Active Vibration Control of Flexible Space Structures by Using Piezoelectric Sensors and Actuators

1993 ◽  
Author(s):  
Brij N. Agrawal ◽  
Hyochoong Bang
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Space Structures ◽  
Sensors And Actuators ◽  
Flexible Space Structures ◽  
Flexible Arm ◽  
Active Vibration ◽  
Structural Mode

Abstract The application of piezoelectric actuators and sensors in the vibration suppression of flexible structures is demonstrated experimentally. Navy Type II piezoceramic wafers were bonded at the base of a flexible arm to increase damping of its first structural mode at at 0.138 Hz. A Positive Position Feedback (PPF) analog compensator was used for active vibration control. The damping of the first mode was increased from 0.3% to 1.5 % by using the active control.

scholarly journals Rigid-Body Dynamic Analysis of Multi-Stage Planetary Roller Screw Mechanism

2020 ◽  
Vol 38 (5) ◽  
pp. 1001-1009
Author(s):  
Xin Li ◽  
Geng Liu ◽  
Chunyu Song ◽  
Xiaojun Fu ◽  
Shangjun Ma ◽  
...  
Keyword(s):  
Rigid Body ◽  
Structural Characteristics ◽  
Great Influence ◽  
Body Motion ◽  
Motion Equations ◽  
Rigid Body Dynamic ◽  
Multi Stage ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Body Dynamic

Based on the structural characteristics of the multi-stage Planetary Roller Screw Mechanism (PRSM), the motion and force among the different stages are analyzed. In terms of the Newton's second law, the rigid-body motion equations of the multi-stage PRSM without considering the manufacturing and assembly errors are derived. Then, the method for solving the motion equations is given. The forces acting on the parts in the multi-stage PRSM and the motion of the mechanism can be obtained from the present rigid-body dynamic model. The influence of the friction coefficients among the different stages on the dynamic characteristics of the multi-stage PRSM is discussed. The results show that the forces acting on the first-stage PRSM are larger than that acting on the second-stage PRSM, although the nominal radius of the screw in the first-stage PRSM is smaller. The friction coefficient between the nut and the screw in the different stages has the great influence on the efficiency of multi-stages PRSM with small helix angles, while that among the screws in the different stages has the slight effect on the efficiency.

Operation Experiences with Biological Phosphorus Removal at the Sewage Treatment Plants of Berlin (West)

1991 ◽  
Vol 24 (7) ◽  
pp. 133-148 ◽  
Author(s):  
A. Peter ◽  
F. Sarfert
Keyword(s):  
Phosphorus Removal ◽  
Sewage Treatment ◽  
Chemical Precipitation ◽  
Biological Phosphorus Removal ◽  
Treatment Results ◽  
Sewage Treatment Plants ◽  
Research Activities ◽  
Two Stages ◽  
The Given ◽  
Biological Phosphorus

In investigations concerning sludge bulking in Berlin enhanced biological phosphorus removal was first observed unexpectedly. Because since 1986 an officially preset limit of 2 mg TP/l must be kept in all Berlin wastewater discharges it was decided to explore the capabilities of the observed mechanism under the specific circumstances of the exciting two large treatment plants in Ruhleben (240,000 m3/d) and Marienfelde (100,000 m3/d). For this purpose some of the existing units at both plants were equipped with anaerobic zones which were generated mainly by process modifications. Additionally stage one of the Ruhleben plant was altered completely in order to investigate the combination of biological phosphorus and nitrogen removal as a special pilot study in three parallel trains. The research activities and treatment results gained in each of the two stages of the Ruhleben and in the Marienfelde plant are reported in detail. For example BOD-related phosphorus removal rates were obtained ranging from 2.3-4.5 mg TP per 100 mg BOD removed. It must be stressed that all examinations were performed on full-scale conditions. At present the given limit of 2 mg TP/l in the Ruhleben plant is met without any chemical precipitation at least on average. From the beginning biological phosphorus removal will be integrated into further projected extensions.

scholarly journals Viscous Flow Around a Rigid Body Performing a Time-periodic Motion

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Thomas Eiter ◽  
Mads Kyed
Keyword(s):  
Rigid Body ◽  
Sobolev Spaces ◽  
Periodic Motion ◽  
Viscous Incompressible Fluid ◽  
Body Motion ◽  
Translational Velocity ◽  
Ill Posed ◽  
Homogeneous Sobolev Spaces ◽  
The Mean ◽  
Time Periodic

AbstractThe equations governing the flow of a viscous incompressible fluid around a rigid body that performs a prescribed time-periodic motion with constant axes of translation and rotation are investigated. Under the assumption that the period and the angular velocity of the prescribed rigid-body motion are compatible, and that the mean translational velocity is non-zero, existence of a time-periodic solution is established. The proof is based on an appropriate linearization, which is examined within a setting of absolutely convergent Fourier series. Since the corresponding resolvent problem is ill-posed in classical Sobolev spaces, a linear theory is developed in a framework of homogeneous Sobolev spaces.

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