Active Control for the Complete Dynamic Balancing of Linkages

1992 ◽  
Author(s):  
Jorge Angeles ◽  
Meyer A. Nahon ◽  
Thomas Thümmel
Keyword(s):  
Active Control ◽  
Degree Of Freedom ◽  
Dynamic Balancing ◽  
Reaction Forces ◽  
The Masses ◽  
Inertia Forces ◽  
Shaking Moment

Abstract This paper deals with the dynamic balancing of linkages. For one-degree-of-freedom linkages, this task consists of eliminating both the shaking moment and the shaking force exerted by the inertia forces of the moving links on the frame. While the latter can be eliminated by properly deciding on both the location of the mass centers and the ratios of the masses and link lengths involved, the shaking moment due to these forces cannot be eliminated in this way. Indeed, the elimination of the shaking force is attained by having the two transmitted forces cancel each other, although each individual force does not necessarily vanish, thereby still producing a shaking moment. In this paper, we propose the use of redundant motors in order to eliminate the reaction forces transmitted to the base, thereby also eliminating the shaking moment due to these forces. However, the net moment acting on the frame is shown to be unaltered by this technique.

Partial dynamic balancing of a 6-DOF haptic device

2014 ◽  
Vol 228 (14) ◽  
pp. 2632-2641
Author(s):  
Taoran Liu ◽  
Feng Gao ◽  
Chenkun Qi ◽  
Xianchao Zhao
Keyword(s):  
Angular Momentum ◽  
Degree Of Freedom ◽  
Haptic Device ◽  
Centre Of Mass ◽  
Dynamic Balancing ◽  
Reaction Forces ◽  
Rotational Part ◽  
Global Reaction ◽  
Cartesian Coordinate ◽  
Shaking Moment

This article presents the partial dynamic balancing of a 6-DOF (degree of freedom) haptic device. At first, the motion of the 3-DOF rotational part is decoupled with the motion of the 3-DOF translational part, because the former has no effect on the baseplate, so it can be considered as a whole and only discusses the 3-DOF translational part in the process of calculating dynamic balancing. The main feature of this mechanism is that the system is symmetric about the Cartesian coordinate, so the dynamic balancing of the 3-DOF translational part can be simplified to the dynamic balancing of 1-DOF translational part. The conditions of shaking force balancing can be obtained by keeping the linear momentum constant, and the conditions of shaking moment balancing can be get by minimizing the rate of the angular momentum. Finally, simulation examples are given to verify that the centre of mass of the partial dynamically balanced mechanism is fixed, and the global reaction forces on the baseplate are zero, and the global reaction moments on the baseplate decrease about five times at all times and for arbitrary trajectories.

Synthesis, Design, and Prototyping of a Planar Three Degree-of-Freedom Reactionless Parallel Mechanism

2004 ◽  
Vol 126 (6) ◽  
pp. 992-999 ◽  
Author(s):  
Simon Foucault ◽  
Cle´ment M. Gosselin
Keyword(s):  
Parallel Mechanism ◽  
Degree Of Freedom ◽  
Numerical Verification ◽  
Dynamic Balancing ◽  
Synthesis Design ◽  
Reaction Forces ◽  
Three Degree Of Freedom

This paper addresses the dynamic balancing of a planar three-degree-of-freedom parallel mechanism. A mechanism is said to be dynamically balanced if, for any motion of the mechanism, the reaction forces and torques at the base are identically equal to zero, at all times. The proposed mechanism is based on legs consisting of five-bar parallelogram linkages. The balancing equations are first obtained. Then, optimization is used in order to minimize the mass and inertia of the moving links. Finally, a numerical verification of the dynamic balancing is provided and the prototype is presented.

Active Dynamic Balancing Unit for Controlled Shaking Force and Shaking Moment Balancing

2010 ◽  
Author(s):  
Volkert van der Wijk ◽  
Just L. Herder
Keyword(s):  
Conceptual Design ◽  
Control Strategies ◽  
Combined System ◽  
Dynamic Balancing ◽  
Pick And Place ◽  
Reaction Forces ◽  
Computer Controlled ◽  
Shaking Moment

For a mechanism with many elements that needs to be shaking-force and shaking-moment balanced with a low addition of mass, a low addition of inertia, and a low addition of complexity, the use of actively computer-controlled balancing elements is promising. With these actively controlled elements the net reaction forces and the net reaction moments to the base of the mechanism can be balanced directly instead of balancing each mechanism element separately as is common practice for passive balancing. Adaptability of the control also allows balancing of (variable) payload. This paper presents the concept of an active dynamic balancing unit, which is a unit that is mounted on unbalanced mechanisms and is controlled such that the combined system is dynamically balanced. The conceptual design and possible control strategies of such a unit, including pick-and-place motion of variable payloads, is studied. A simulation is presented to give insight in the possibilities and limitations of active dynamic balancing.

Active Balancing of a Flexible Linkage With Redundant Drives

2003 ◽  
Vol 125 (1) ◽  
pp. 119-123 ◽  
Author(s):  
Yue-Qing Yu ◽  
Jing Lin
Keyword(s):  
Active Control ◽  
Dynamic Equations ◽  
Dynamic Balancing ◽  
Active Balancing ◽  
Redundant Actuators ◽  
First Time ◽  
Flexible Mechanisms ◽  
Flexible Linkage ◽  
Shaking Moment

The dynamic balancing of flexible linkages, which is a challenging topic in the dynamics of mechanisms, is accomplished by active control with redundant drives for the first time in the present study. The mathematical modal and dynamic equations of flexible mechanisms with redundant actuators are derived. The optimum shaking force and shaking moment balancing of a flexible linkage have been obtained through an active way of additional actuators. The effectiveness and advantage of redundant drives on the dynamic balancing of flexible mechanisms is fully demonstrated by an example of four-bar linkages.

Dynamic Absorption by Passive and Active Control1

2000 ◽  
Vol 122 (4) ◽  
pp. 429-433 ◽  
Author(s):  
Kumar Vikram Singh ◽  
Yitshak M. Ram
Keyword(s):  
Steady State ◽  
Active Control ◽  
Conservative System ◽  
Degree Of Freedom ◽  
Loss Of Stability ◽  
Steady State Motion ◽  
Damped System ◽  
Single Sensor ◽  
Dynamic Absorber

The motion of a particular degree-of-freedom in a harmonically excited conservative system can be vanished by attaching an appropriate dynamic absorber to it. It is shown here that under certain conditions, which are characterized in the paper, the steady state motion of a damped system may be completely absorbed, without loss of stability, by active control implementing a single sensor and an actuator. The results are established theoretically and they are demonstrated by means of analytical examples. [S0739-3717(00)02104-8]

Reactionless Two-Degree-of-Freedom Planar Parallel Mechanism With Variable Payload

2009 ◽  
Author(s):  
Alexandre Lecours ◽  
Cle´ment Gosselin
Keyword(s):  
Dynamic Simulation ◽  
Parallel Mechanism ◽  
Reaction Force ◽  
Simulation Software ◽  
Degree Of Freedom ◽  
Dynamic Balancing ◽  
End Effector ◽  
Planar Mechanism ◽  
Two Degree Of Freedom ◽  
Arbitrary Trajectory

A reactionless mechanism is one which does not exert any reaction force or moment on its base at all times, for any arbitrary trajectory of the mechanism. This paper addresses the static and dynamic balancing of a two-degree-of-freedom parallel planar mechanism (five-bar mechanism). A simple and effective adaptive balancing method is presented that allows the mechanism to maintain the reactionless condition for a range of payloads. Important proofs concerning the balancing of five-bar mechanisms are also presented. The design of a real mechanism where parallelogram linkages are used to produce pure translations at the end-effector is also presented. Finally, using dynamic simulation software, it is shown that the mechanism is reactionless for arbitrarily chosen trajectories and for a variety of payloads.

Experimental Forced Response Analysis of Two-Degree-of-Freedom Piecewise-Linear Systems With a Gap

2020 ◽  
Author(s):  
Akira Saito ◽  
Junta Umemoto ◽  
Kohei Noguchi ◽  
Meng-Hsuan Tien ◽  
Kiran D’Souza
Keyword(s):  
Piecewise Linear ◽  
Excitation Frequency ◽  
Forced Response ◽  
Degree Of Freedom ◽  
Linear Oscillator ◽  
Phase Portraits ◽  
Response Analysis ◽  
Experimental Setup ◽  
The Masses ◽  
Two Degree Of Freedom

Abstract In this paper, an experimental forced response analysis for a two degree of freedom piecewise-linear oscillator is discussed. First, a mathematical model of the piecewise linear oscillator is presented. Second, the experimental setup developed for the forced response study is presented. The experimental setup is capable of investigating a two degree of freedom piecewise linear oscillator model. The piecewise linearity is achieved by attaching mechanical stops between two masses that move along common shafts. Forced response tests have been conducted, and the results are presented. Discussion of characteristics of the oscillators are provided based on frequency response, spectrogram, time histories, phase portraits, and Poincaré sections. Period doubling bifurcation has been observed when the excitation frequency changes from a frequency with multiple contacts between the masses to a frequency with single contact between the masses occurs.

Active control for multi-degree-of-freedom wave energy converters with load limiting

2020 ◽  
Vol 159 ◽  
pp. 1177-1187 ◽  
Author(s):  
A.J. Hillis ◽  
C. Whitlam ◽  
A. Brask ◽  
J. Chapman ◽  
A.R. Plummer
Keyword(s):  
Active Control ◽  
Wave Energy ◽  
Degree Of Freedom ◽  
Wave Energy Converters ◽  
Energy Converters

The Active Control of Forced Vibration Produced by Arbitrary Disturbances

1985 ◽  
Vol 107 (1) ◽  
pp. 33-37 ◽  
Author(s):  
J. S. Burdess ◽  
A. V. Metcalfe
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Forced Vibration ◽  
Disturbance Observer ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Impact Forces ◽  
Mass Spring

This paper considers the vibration control of a single degree of freedom mass-spring-damper system when subjected to an arbitrary, unmeasurable disturbance. The idea of a disturbance observer is introduced and it is shown how an estimate of the excitation can be derived and used to generate a control, which reduces the vibration. This control is shown to be robust with respect to the parameters describing the behavior of the system. Experimental results are presented which show the efficacy of the method when the system is excited by periodic, random, and impact forces. Comments are made on the application of the method.

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