scholarly journals Shaping the response of multi-degree-of-freedom mechanical systems

2013 ◽  
Author(s):  
Vyacheslav Ryaboy
Keyword(s):  
Mechanical Systems ◽  
Degree Of Freedom

A Method for Identifying Parameters of Mechanical Joints

1990 ◽  
Vol 57 (2) ◽  
pp. 337-342 ◽  
Author(s):  
J. Wang ◽  
P. Sas
Keyword(s):  
Physical Parameter ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Modal Testing ◽  
Physical Parameters ◽  
Mechanical Joints ◽  
Joint Parameters

A method for identifying the physical parameters of joints in mechanical systems is presented. In the method, a multi-d.o.f. (degree-of-freedom) system is transformed into several single d.o.f. systems using selected eigenvectors. With the result from modal testing, each single d.o.f. system is used to solve for a pair of unknown physical parameters. For complicated cases where the exact eigenvector cannot be obtained, it will be proven that a particular physical parameter has a stationary value in the neighborhood of an eigenvector. Therefore, a good approximation for a joint physical parameter can be obtained by using an approximate eigenvector and the exact value for the joint parameters can be reached by carrying out this process in an iterative way.

Modal Control of Underactuated Systems

2010 ◽  
Author(s):  
D. Dane Quinn ◽  
Vineel Mallela
Keyword(s):  
Control System ◽  
Mechanical System ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Feedback Gain ◽  
Underactuated Systems ◽  
Modal Control ◽  
Underactuated Mechanical Systems ◽  
Sensors And Actuators ◽  
Sensor Actuator

This work addresses the modal control of underactuated mechanical systems, whereby the number of actuators is less than the degree-of-freedom of the underlying mechanical system. The performance of the control system depends on the structure of the feedback gain matrix, that is, the coupling between sensors and actuators. This coupling is often not arbitrary, but the topology of the sensor-actuator network can be a fixed constraint of the control system. This work examines the influence of this structure on the performance of the overlying control system.

Technical Note: A two-degree-of-freedom ambulance stretcher suspension: Part 3: Laboratory and road test performance

1998 ◽  
Vol 212 (5) ◽  
pp. 401-407 ◽  
Author(s):  
R. J. Henderson ◽  
J. K. Raine
Keyword(s):  
Test Performance ◽  
Natural Frequencies ◽  
Low Cost ◽  
Mechanical Systems ◽  
Technical Note ◽  
Suspension System ◽  
Degree Of Freedom ◽  
Road Test ◽  
Pneumatic Suspension ◽  
Two Degree Of Freedom

Parts 1 and 2 of this paper gave a design overview and described the dynamics of a prototype two-degree-of-freedom pneumatic suspension for an ambulance stretcher. This concluding part briefly reviews laboratory shaker table and ambulance road test performance of the suspension with passive pneumatic damping. The suspension system is found to offer compact low-cost isolation with lower natural frequencies than achieved in earlier mechanical systems.

Inertia Matrix Singularity of Series-Chain Spatial Manipulators With Point Masses

1993 ◽  
Vol 115 (4) ◽  
pp. 723-725 ◽  
Author(s):  
Sunil K. Agrawal
Keyword(s):  
Computer Simulation ◽  
Dynamic Behavior ◽  
Mechanical Systems ◽  
Positive Definite ◽  
Degree Of Freedom ◽  
Numerical Errors ◽  
Singular Configurations ◽  
Spatial Series ◽  
Inertia Matrix ◽  
Incomplete Models

Often, the dynamic behavior of multi-degree-of-freedom mechanical systems such as robots and manipulators is studied by computer simulation. An important step in this simulation is the inversion of inertia matrix of the system. In singular configurations of the inertia matrix, the simulation is prone to large numerical errors. Usually, it is believed that an inertia matrix is always positive definite. In this paper, it is shown that for spatial series-chain manipulators, when the links are modeled as point masses, a multitude of configurations exists when the inertia matrix becomes singular. These singularities arise because point masses lead to incomplete models of the system.

scholarly journals Advances in Polynomial Continuation for Solving Problems in Kinematics

2004 ◽  
Vol 126 (2) ◽  
pp. 262-268 ◽  
Author(s):  
Andrew J. Sommese ◽  
Jan Verschelde ◽  
Charles W. Wampler
Keyword(s):  
Mechanical Systems ◽  
Robotic Manipulators ◽  
Degree Of Freedom ◽  
Polynomial Equations ◽  
Dimensional Solution ◽  
Solution Sets ◽  
The Past ◽  
Higher Dimensional ◽  
Isolated Roots ◽  
System Of Polynomial Equations

For many mechanical systems, including nearly all robotic manipulators, the set of possible configurations that the links may assume can be described by a system of polynomial equations. Thus, solving such systems is central to many problems in analyzing the motion of a mechanism or in designing a mechanism to achieve a desired motion. This paper describes techniques, based on polynomial continuation, for numerically solving such systems. Whereas in the past, these techniques were focused on finding isolated roots, we now address the treatment of systems having higher-dimensional solution sets. Special attention is given to cases of exceptional mechanisms, which have a higher degree of freedom of motion than predicted by their mobility. In fact, such mechanisms often have several disjoint assembly modes, and the degree of freedom of motion is not necessarily the same in each mode. Our algorithms identify all such assembly modes, determine their dimension and degree, and give sample points on each.

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