A Systematic Method for Optimal Integration of Smart Materials Into the Structure of High Speed Mechanisms

1999 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar
Keyword(s):  
Smart Materials ◽  
High Speed ◽  
Closed Loop ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Primary Source ◽  
Linkage Mechanism ◽  
Constant Input ◽  
Systematic Method

Abstract A systematic method is presented for the integration of smart (active) materials based actuators into the structure of mechanical systems in general and mechanisms with closed-loop chains in particular for the purpose of modifying the output motion of the system. In the resent study, the method is applied to a four-bar linkage mechanism with a constant input velocity for the purpose of eliminating the high harmonic component of the output link motion. By eliminating the high harmonic component of the output motion of a mechanism, the potential vibrational excitation that the mechanism can impart on the overall system and its own structure is greatly reduced. The resulting system should therefore be capable of operating at higher speeds with increased precision. For mechanisms with rigid links, the primary source of high harmonic motions is the nonlinearity of the kinematics of the closed-loop chain. The usually less prominent high harmonic motions due to joint and/or structural flexibility may be eliminated in a similar manner and will be addressed in future publications.

A New Approach for the Reduction of Vibrational Excitation in Kinematics Synthesis of High Speed Linkages

2000 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar
Keyword(s):  
High Speed ◽  
Closed Loop ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Primary Source ◽  
Linkage Mechanism ◽  
New Approach ◽  
Function Generation ◽  
Four Bar Linkage

Abstract A new method is presented for the modification of the output motion of linkage mechanisms with closed-loop chains using cams positioned at one or more of its joints. In particular, the method is applied to a four-bar linkage mechanism that is synthesized for function generation for the purpose of eliminating the high harmonic component of the output link motion. By eliminating the high harmonic component of the output motion of a mechanism, the potential vibrational excitation that the mechanism can impart on the overall system, including its own structure, is greatly reduced. The resulting system should therefore be capable of operating at higher speeds with increased precision. For mechanisms with rigid links, the primary source of high harmonic motions is the nonlinearity of the kinematics of closed-loop chains. With the present method, the higher harmonic motions generated due to such nonlinearities are eliminated by the integration of appropriately designed cams that are used to vary the effective link lengths. A numerical example is provided together with a discussion of the related topics of interest.

Linkage Mechanisms With Cam Integrated Joints for Controlled Harmonic Content of the Output Motion: Theory and Application

2004 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar
Keyword(s):  
Closed Loop ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Primary Source ◽  
Linkage Mechanism ◽  
Output Link ◽  
Mechanism Synthesis ◽  
Constant Input ◽  
Cam Mechanism

In a recent study, the authors presented a systematic method for the modification of the output motion of linkage mechanisms with closed-loop chains using cams positioned at one or more of the mechanism joints. In this paper, the method is applied to the design of a linkage mechanism with an integrated cam mechanism for the purpose of eliminating the high harmonic component of the output link motion. The mechanism may be synthesized using well-developed linkage mechanism synthesis techniques for the intended application. Based on this method, a cam mechanism is synthesized for a prescribed output link motion while limiting the output motion to a simple harmonic motion with the frequency of its constant input velocity. The mechanism is constructed and tested. In mechanisms with relatively rigid links, the primary source of high harmonics in the output motion is the nonlinearity of the kinematics of their closed-loop chains. With the present method, a selected range or ranges of high harmonic motions generated due to such nonlinearities may be eliminated by integrating appropriately designed cams. By eliminating the high harmonic component of the output motion of a mechanism, the potential vibrational excitation that the mechanism can impart on the overall system, including its own structure, is greatly reduced. The resulting system should therefore be capable of operating at higher speeds and with increased precision.

A Systematic Method for Kinematics Synthesis of High-Speed Mechanisms With Optimally Integrated Smart Materials

2000 ◽  
Author(s):  
J. Rastegar ◽  
L. Yuan
Keyword(s):  
Smart Materials ◽  
High Speed ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Linkage Mechanism ◽  
Output Link ◽  
Mechanism Synthesis ◽  
Systematic Method ◽  
Four Bar Linkage

Abstract A systematic method is presented for kinematics synthesis of high-speed mechanisms with optimally integrated smart materials based actuators for the purpose of modifying the output link motion. As an example, the method is applied to a four-bar linkage mechanism that is synthesized for function generation to eliminate the high harmonic component of the output link motion. For mechanisms with rigid links, the high harmonic motions are generated due to the nonlinearity of the kinematics of their closed-loop chains. By eliminating the high harmonic component of the output motion, the potential vibrational excitation that the mechanism can impart on the overall system and its own structure is greatly reduced. The resulting system should therefore be capable of operating at higher speeds with increased precision. A numerical example is provided together with a discussion of the application of the method to other mechanism synthesis problems and some related topics of interest.

A Systematic Method for Kinematics Synthesis of High-Speed Mechanisms With Optimally Integrated Smart Materials

2000 ◽  
Vol 124 (1) ◽  
pp. 14-20 ◽  
Author(s):  
J. Rastegar ◽  
L. Yuan
Keyword(s):  
Smart Materials ◽  
High Speed ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Linkage Mechanism ◽  
Output Link ◽  
Mechanism Synthesis ◽  
Systematic Method ◽  
Four Bar Linkage

A systematic method is presented for kinematics synthesis of high-speed mechanisms with optimally integrated smart materials based actuators for the purpose of modifying the output link motion. As an example, the method is applied to a four-bar linkage mechanism that is synthesized for function generation to eliminate the high harmonic component of the output link motion. For mechanisms with rigid links, the high harmonic motions are generated due to the nonlinearity of the kinematics of their closed-loop chains. By eliminating the high harmonic component of the output motion, the potential vibrational excitation that the mechanism can impart on the overall system and its own structure is greatly reduced. The resulting system should therefore be capable of operating at higher speeds and with greater precision. A numerical example is provided together with a discussion of the application of the method to other mechanism synthesis problems and some related topics of interest.

Kinematics Synthesis of Linkage Mechanisms With Cam Integrated Joints for Controlled Harmonic Content of the Output Motion

2004 ◽  
Vol 126 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Lifang Yuan ◽  
Jahangir S. Rastegar
Keyword(s):  
Closed Loop ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Primary Source ◽  
Effective Length ◽  
Linkage Mechanism ◽  
Function Generation ◽  
Harmonic Content ◽  
Four Bar Linkage

A new method is presented for the modification of the output motion of linkage mechanisms with closed-loop chains using cams positioned at one or more of its joints. As an example and to present the basic concept, the method is applied to a four-bar linkage mechanism that is synthesized for function generation for the purpose of eliminating the high harmonic component of the output link motion. By eliminating the high harmonic component of the output motion of a mechanism, the potential vibrational excitation that the mechanism can impart on the overall system, including its own structure, is greatly reduced. The resulting system should therefore be capable of operating at higher speeds and with increased precision. For mechanisms with rigid links, the primary source of high harmonics in the output motion is the nonlinearity of the kinematics of their closed-loop chains. With the present method, a selected range or ranges of high harmonic motions generated due to such nonlinearities may be eliminated by integrating appropriately designed cams that are used to vary the effective length of one or more of the links during the motion. A numerical example is provided together with a discussion of the related topics of interest.

Linkage Mechanisms With Cam-Integrated Joints for Controlled Harmonic Content of the Output Motion: Theory and Application

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar ◽  
J. Zhang
Keyword(s):  
Closed Loop ◽  
Vibrational Excitation ◽  
High Harmonic ◽  
Harmonic Component ◽  
Linkage Mechanism ◽  
Mechanism Synthesis ◽  
Cam Mechanism ◽  
Harmonic Content ◽  
Harmonic Components ◽  
Four Bar Linkage

In a recent study, the authors presented a systematic method for the modification of the output motion of linkage mechanisms with closed-loop chains using cams positioned at one or more joints of the mechanism. In this paper, the method is applied to the design of a linkage mechanism with an integrated cam mechanism to eliminate high harmonic component of the output motion. The mechanism may be synthesized using any existing linkage mechanism synthesis technique. In the present study, a cam mechanism is synthesized to eliminate all high harmonic components of the output link motion of a four-bar linkage mechanism to illustrate the potentials of the present approach. The mechanism is then constructed and successfully tested. With the present method, selected ranges of high harmonic motions generated due to the mechanisms kinematics nonlinearity can be eliminated by integrating appropriately designed cams, thereby significantly reducing the potential vibrational excitation that the mechanism can impart on the overall system, including its own structure. Such systems should therefore be capable of operating at higher speeds and with increased precision.

On the Relationship Between the Harmonic Amplitudes of the Output Motion of Closed-Loop Linkage Mechanisms

2008 ◽  
Author(s):  
Jahangir Rastegar ◽  
Dake Feng ◽  
Lin Hua
Keyword(s):  
Closed Loop ◽  
High Harmonic ◽  
Constant Input ◽  
Vibration Excitation ◽  
Basic Characteristics ◽  
Harmonic Components ◽  
Input Motion ◽  
Four Bar Linkage ◽  
The Relationship

It is well known that due to the nonlinearity of the kinematics of linkage mechanisms, their output motion contains harmonics of the input motion. In most mechanisms, the generated high harmonic components in the output motion are the main source of vibration excitation that the mechanism imparts on the overall system, including its own structure. For simple linkage mechanisms such as slider-cranks and four-bar linkage mechanisms, the amplitudes of the harmonics of the output motion for constant input rotation have been derived. In the present study, it is shown that certain relationships exist between the amplitudes of the harmonic of the output motions. In particular, odd and even harmonic amplitudes are shown to be related through an inequality relationship. These relationships are due to the basic characteristics of the linkage mechanisms motions, which are significantly simplified for certain linkage geometries. The relationships between the amplitudes of the output velocity harmonics are derived for slider-crank and four-bar linkage mechanisms.

Smart Actuator Positioning and Displacement Transmissibility in Serial and Parallel Robot Manipulators for Performance Enhancement

2004 ◽  
Vol 127 (4) ◽  
pp. 589-595 ◽  
Author(s):  
J. Rastegar ◽  
L. Yuan ◽  
J. Zhang
Keyword(s):  
Smart Materials ◽  
Performance Enhancement ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
High Harmonic ◽  
Harmonic Component ◽  
Operating Speed ◽  
End Effector ◽  
High Harmonics ◽  
Joint Motions

A method is presented for the evaluation of the transmissibility of displacement from smart (active) actuators integrated in the structure of robot manipulators to the manipulator joint and end-effector displacements. The method is based on studying the characteristics of the Jacobian of the mapping function between the two displacements for a given position of the robot manipulator. The developed method provides a tool for the determination of the positioning of smart actuators to provide maximum effectiveness in eliminating high harmonics of the joint or the end-effector motion. In robots with serial and parallel kinematics chains containing nonprismatic joints, due to the associated kinematics nonlinearity, if the joint motions were synthesized with low harmonic trajectories, the end-effector trajectory would still contain high harmonics of the joint motions. Alternatively, if the end-effector motion were synthesized with low harmonic components, due to the inverse kinematics nonlinearity, the actuated joint trajectories would contain a significant high harmonic component. As a result, the operating speed and tracking precision are degraded. By integrating smart materials based actuators in the structure of robot manipulators to provide small amplitude and high frequency motions, the high harmonic component of the actuated joint and/or the end-effector motions can be significantly reduced, thereby making it possible to achieve higher operating speed and tracking precision.

scholarly journals Redesigned Sensor Holder for an Atomic Force Microscope with an Adjustable Probe Direction

2021 ◽  
Author(s):  
Janik Schaude ◽  
Maxim Fimushkin ◽  
Tino Hausotte
Keyword(s):  
Atomic Force Microscope ◽  
Piezoelectric Actuator ◽  
High Speed ◽  
Closed Loop ◽  
Coefficient Of Thermal Expansion ◽  
Measuring System ◽  
Contact Mode ◽  
Loop Control ◽  
Atomic Force ◽  
Measuring Machine

AbstractThe article presents a redesigned sensor holder for an atomic force microscope (AFM) with an adjustable probe direction, which is integrated into a nano measuring machine (NMM-1). The AFM, consisting of a commercial piezoresistive cantilever operated in closed-loop intermitted contact-mode, is based on two rotational axes, which enable the adjustment of the probe direction to cover a complete hemisphere. The axes greatly enlarge the metrology frame of the measuring system by materials with a comparatively high coefficient of thermal expansion. The AFM is therefore operated within a thermostating housing with a long-term temperature stability of 17 mK. The sensor holder, connecting the rotational axes and the cantilever, inserted one adhesive bond, a soldered connection and a geometrically undefined clamping into the metrology circle, which might also be a source of measurement error. It has therefore been redesigned to a clamped senor holder, which is presented, evaluated and compared to the previous glued sensor holder within this paper. As will be shown, there are no significant differences between the two sensor holders. This leads to the conclusion, that the three aforementioned connections do not deteriorate the measurement precision, significantly. As only a minor portion of the positioning range of the piezoelectric actuator is needed to stimulate the cantilever near its resonance frequency, a high-speed closed-loop control that keeps the cantilever within its operating range using this piezoelectric actuator further on as actuator was implemented and is presented within this article.

High-Performance Motion Control With Slosh: A Constrained Sliding Mode Approach

2008 ◽  
Author(s):  
Hanz Richter ◽  
Kedar B. Karnik
Keyword(s):  
High Speed ◽  
High Performance ◽  
Design Methodology ◽  
Closed Loop ◽  
Sliding Mode ◽  
Initial Conditions ◽  
Rectilinear Motion ◽  
Industrial Setting ◽  
Open Container ◽  
Nominal Performance

The problem of controlling the rectilinear motion of an open container without exceeding a prescribed liquid level and other constraints is considered using a recently-developed constrained sliding mode control design methodology based on invariant cylinders. A conventional sliding mode regulator is designed first to address nominal performance in the sliding mode. Then an robustly-invariant cylinder is constructed and used to describe the set of safe initial conditions from which the closed-loop controller can be operated without constraint violation. Simulations of a typical transfer illustrate the usefulness of the method in an industrial setting. Experimental results corresponding to a high-speed transfer validate the theory.

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