A Unified Theory of Structure, Synthesis and Analysis of Multibody Mechanical Systems with Geometrical, Flexible and Dynamic Connections. Part 1. Basic Structural Equations and Universal Structure Tables

2020 ◽  
pp. 24-43 ◽  
Author(s):  
V.I. Pozhbelko
Keyword(s):  
Mechanical Systems ◽  
Kinematic Chain ◽  
Variable Structure ◽  
Structural Equations ◽  
Contact Friction ◽  
Unified Theory ◽  
Direct Drive ◽  
Variable Structure Systems ◽  
Kinematic Chains ◽  
Structure Synthesis

Multibody mechanical systems (mechanisms and machine drives) are widely used in different fields of modern engineering due to their reliability and simple design. They can be found in robots, manipulators, technological and construction equipment, automatic lines, etc. This paper presents a unified theory of structure, synthesis and analysis of mechanisms and machines with geometrical (single and multiple kinematic pairs), flexible contact (friction or belt) and dynamic contactless (inertial, gravitational, etc.) connections. The theory can be used to construct planar and spatial single- and multi-loop kinematic chains of machines with a given number of closed loops and driving motors. Areas of possible existence of multibody mechanical systems with open, closed and mixed kinematic chain are determined. Based on these findings, various planar and spatial gear and linkage patentable mechanisms are developed that can be used in vibrational drives, variable structure systems requiring precise stoppage during the cycle, lever actuators of multi-axle locomotives, spatial mixers with several mixing tanks, tribometers for measuring the limiting pulling capacity of flexible belts of belt-and-pulley drives, and direct-drive devices for horizontal motion of a suspended load with a low set velocity.

A Unified Theory of Structure, Synthesis and Analysis of Multibody Mechanical Systems with Geometrical, Flexible and Dynamic Connections. Part 2. Limiting Theorems and Existence Areas

2020 ◽  
pp. 36-52
Author(s):  
V.I. Pozhbelko
Keyword(s):  
Mechanical Systems ◽  
Optimal Structure ◽  
Unified Theory ◽  
Redundant Constraints ◽  
Structure Synthesis

This paper examines a family of limiting structural and topological theorems complemented by two well-known Gruebler theorems that can be used for determining the limiting areas of existence of possible multibody mechanisms. All the multiloop linkage, cam and gear mechanisms synthesized using the proposed unified theory have the optimal structure without redundant constraints and uncontrolled movements.

Modeling mechanical systems of variable structure

1989 ◽  
Vol 25 (6) ◽  
pp. 603-610
Author(s):  
E. Ya. Antonyuk ◽  
S. V. Zubarev
Keyword(s):  
Mechanical Systems ◽  
Variable Structure

Structure Based Grading of Kinematic Chains

2014 ◽  
Vol 575 ◽  
pp. 501-506 ◽  
Author(s):  
Shubhashis Sanyal ◽  
G.S. Bedi
Keyword(s):  
Structural Properties ◽  
Structural Property ◽  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Kinematic Chains ◽  
Structural Differences ◽  
The Individual ◽  
Independent Loops

Kinematic chains differ due to the structural differences between them. The location of links, joints and loops differ in each kinematic chain to make it unique. Two similar kinematic chains will produce similar motion properties and hence are avoided. The performance of these kinematic chains also depends on the individual topology, i.e. the placement of its entities. In the present work an attempt has been made to compare a family of kinematic chains based on its structural properties. The method is based on identifying the chains structural property by using its JOINT LOOP connectivity table. Nomenclature J - Number of joints, F - Degree of freedom of the chain, N - Number of links, L - Number of basic loops (independent loops plus one peripheral loop).

Combined Graph Layout Algorithms for Automated Sketching of Kinematic Chains

2012 ◽  
Author(s):  
Martín A. Pucheta ◽  
Nicolás E. Ulrich ◽  
Alberto Cardona
Keyword(s):  
Computational Cost ◽  
Kinematic Chain ◽  
Initial Position ◽  
Graph Representation ◽  
Combinatorial Algorithms ◽  
Graph Layout ◽  
Kinematic Chains ◽  
Aesthetic Characteristics ◽  
Edge Crossings ◽  
Independent Loops

The graph layout problem arises frequently in the conceptual stage of mechanism design, specially in the enumeration process where a large number of topological solutions must be analyzed. Two main objectives of graph layout are the avoidance or minimization of edge crossings and the aesthetics. Edge crossings cannot be always avoided by force-directed algorithms since they reach a minimum of the energy in dependence with the initial position of the vertices, often randomly generated. Combinatorial algorithms based on the properties of the graph representation of the kinematic chain can be used to find an adequate initial position of the vertices with minimal edge crossings. To select an initial layout, the minimal independent loops of the graph can be drawn as circles followed by arcs, in all forms. The computational cost of this algorithm grows as factorial with the number of independent loops. This paper presents a combination of two algorithms: a combinatorial algorithm followed by a force-directed algorithm based on spring repulsion and electrical attraction, including a new concept of vertex-to-edge repulsion to improve aesthetics and minimize crossings. Atlases of graphs of complex kinematic chains are used to validate the results. The layouts obtained have good quality in terms of minimization of edge crossings and maximization of aesthetic characteristics.

Decentralized Adaptive Control of a Directly Driven Hydraulic Manipulator: Part 1: Theory

1995 ◽  
Vol 209 (3) ◽  
pp. 191-196 ◽  
Author(s):  
K A Edge ◽  
F Gomes de Almeida
Keyword(s):  
Adaptive Control ◽  
Variable Structure ◽  
System Stability ◽  
Design Parameters ◽  
Variable Structure Systems ◽  
Model Following ◽  
Reference Type ◽  
Control Objective ◽  
Manipulator Design ◽  
Following Error

A new approach to adaptive control of manipulators is presented in this paper. The proposed controller for each individual axis is of the model reference type, designed through the use of variable structure systems theory. A novel feature of the controller is the introduction of a series-parallel model of the model-following error. The use of this model ensures system stability even if the manipulator design parameters or payload bounds are exceeded. Chattering of the system, associated with variable structure systems, is eliminated by arranging for the control objective to be physically achievable.

A Novel Method for Constructing Multi-Mode Deployable Polyhedron Mechanisms Using Symmetric Spatial RRR Compositional Units

2018 ◽  
Author(s):  
Jieyu Wang ◽  
Xianwen Kong
Keyword(s):  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Single Loop ◽  
Kinematic Chains ◽  
The Third ◽  
Motion Modes ◽  
3D Printed ◽  
Novel Method ◽  
Multi Mode ◽  
Motion Mode

A novel construction method is proposed to construct multimode deployable polyhedron mechanisms (DPMs) using symmetric spatial RRR compositional units, a serial kinematic chain in which the axes of the first and the third revolute (R) joints are perpendicular to the axis of the second R joint. Single-loop deployable linkages are first constructed using RRR units and are further assembled into polyhedron mechanisms by connecting single-loop kinematic chains using RRR units. The proposed mechanisms are over-constrained and can be deployed through two approaches. The prism mechanism constructed using two Bricard linkages and six RRR limbs has one degree-of-freedom (DOF). When removing three of the RRR limbs, the mechanism obtains one additional 1-DOF motion mode. The DPMs based on 8R and 10R linkages also have multiple modes, and several mechanisms are variable-DOF mechanisms. The DPMs can switch among different motion modes through transition positions. Prototypes are 3D-printed to verify the feasibility of the mechanisms.

Sign in / Sign up

Export Citation Format

Share Document