Kinematic Geometry of Wheeled Vehicle Systems

1996 ◽  
Author(s):  
S. V. Sreenivasan ◽  
P. Nanua
Keyword(s):  
Geometric Approach ◽  
Companion Paper ◽  
Kinematic Chains ◽  
Uneven Terrain ◽  
Geometric Conditions ◽  
Kinematic Study ◽  
Vehicle Systems ◽  
Motion Characteristics ◽  
The One ◽  
Wheeled Vehicles

Abstract This paper addresses instantaneous motion characteristics of wheeled vehicles systems on even and uneven terrain. A thorough kinematic geometric approach which utilizes screw system theory is used to investigate vehicle-terrain combinations as spatial mechanisms that possess multiple closed kinematic chains. It is shown that if the vehicle-terrain combination satisfies certain geometric conditions, for instance when the vehicle operates on even terrain, the system becomes singular or non-Kutzbachian — it possesses finite range mobility that is different from the one obtained using Kutzbach criterion. An application of this geometric approach to the study of rate kinematics of various classes of wheeled vehicles is also included. This approach provides an integrated framework to study the kinematic effects of varying the vehicle and/or terrain geometric parameters from their nominal values. In addition, design enhancements of existing vehicles are suggested using this approach. This kinematic study is closely related to the force distribution characteristics of wheeled vehicles which is the subject of the companion paper [SN96].

Kinematic Geometry of Wheeled Vehicle Systems

1999 ◽  
Vol 121 (1) ◽  
pp. 50-56 ◽  
Author(s):  
S. V. Sreenivasan ◽  
P. Nanua
Keyword(s):  
Spherical Surface ◽  
Geometric Approach ◽  
First Order ◽  
Uneven Terrain ◽  
Geometric Conditions ◽  
Wheeled Vehicle ◽  
Kinematic Analyses ◽  
Motion Characteristics ◽  
The One ◽  
Wheeled Vehicles

This paper utilizes a kinematic-geometric approach to study the first-order motion characteristics of wheeled vehicles on even and uneven terrain. The results obtained from first-order studies are compared to those obtained from second order kinematic analyses, and special situations where the first-order analysis is inadequate are discussed. This approach is particularly suited for studying actively actuated vehicles since their designs typically do not include intentional passive compliances. It is shown that if a vehicle-terrain combination satisfies certain geometric conditions, for instance when a wheeled vehicle operates on even terrain or on a spherical surface, the system possesses a singularity—it possesses finite range mobility that is higher than the one obtained using Kutzbach criterion. On general uneven terrain, the same vehicles require undesirable ‘kinematic slipping’ at the wheel-terrain contacts to attain the mobility that it possesses on these special surfaces. The kinematic effects of varying the vehicle and/or terrain geometric parameters from their nominal values are discussed. The design enhancements that are required in existing off-road vehicles to avoid kinematic slipping are presented for a class of vehicles that include two-wheel axles in their designs.

Force Distribution Characteristics of Actively Reconfigurable Wheeled Vehicle Systems

1996 ◽  
Author(s):  
S. V. Sreenivasan ◽  
P. Nanua
Keyword(s):  
Geometric Approach ◽  
Companion Paper ◽  
Internal Force ◽  
Force Distribution ◽  
Partial Control ◽  
Uneven Terrain ◽  
Redundantly Actuated ◽  
Singular Configuration ◽  
Actuation Scheme ◽  
Wheeled Vehicles

Abstract This paper addresses the force distribution issues associated with redundantly actuated wheeled vehicles that are suited for operation on uneven terrain. Basic results relating to the partitioning of motion and force variables in these mechanisms are developed. The redundant actuation scheme allows for the control of force distribution in the system, in addition to motion control. The unique kinematic characteristics of wheeled systems, that makes these vehicles ‘singular’ on even terrain, and ‘near-singular’ on uneven terrain; and the presence of ‘kinematic slipping’ when these vehicles move on uneven terrain make their force distribution mathematics distinct from other systems considered in the literature. In a singular configuration, it is shown here that these active wheeled vehicles possess only a partial control over their internal force distribution. A procedure to partition the ‘force space’ into controllable and uncontrollable spaces is provided based on a geometric approach. Closed-form force space results are included for an actively articulated multi-module system (a generalization of a passive, articulated mobile robot that has been studied extensively in literature). The force distribution in actively reconfigurable wheeled vehicles is closely related to their rate kinematics. Rate kinematics of these vehicles has been studied in a companion paper [SN96].

Partial Contact Force Controllability in Active Wheeled Vehicles

1998 ◽  
Vol 123 (2) ◽  
pp. 169-175 ◽  
Author(s):  
B. J. Choi ◽  
S. V. Sreenivasan
Keyword(s):  
Contact Force ◽  
Geometric Approach ◽  
Contact Forces ◽  
Force Distribution ◽  
Distribution Problem ◽  
Passive Components ◽  
Uneven Terrain ◽  
Partial Contact ◽  
Force Components ◽  
Wheeled Vehicles

This paper presents a geometric approach for solving the force distribution problem in active wheeled vehicles (AWVs) moving on uneven surfaces. Here an active vehicle is defined as a system that includes independent actuators for all its internal joints. In general, AWVs do not possess omni-directional mobility, and they possess fewer actuators than the number of wheel-ground contact force components. This article presents an approach for separating the contact force vectors into active and passive components such that there exists an invertible square matrix that maps the active contact forces to the actuator efforts. An appropriate force allocation algorithm can then be developed for these systems. The concepts introduced in this article are demonstrated via an example of AWVs on uneven terrain. An example of force distribution in active legged vehicles (ALVs) that possess the same number of actuators as contact forces is also provided for comparison.

Analytic Form Solution of the Direct Position Analysis of a Wide Family of Three-Legged Parallel Manipulators

2005 ◽  
Vol 128 (1) ◽  
pp. 264-271 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Analytic Form ◽  
Parallel Manipulators ◽  
Analytical Form ◽  
Form Solution ◽  
Kinematic Chains ◽  
Position Analysis ◽  
In Series ◽  
The One ◽  
Generic Structures ◽  
Wide Family

A wide family of parallel manipulators (PMs) is the one that groups all PMs with three legs where the legs become kinematic chains constituted of a passive spherical pair (S) in series with either a passive prismatic pair (P) or a passive revolute pair (R) when the actuators are locked. The topologies of the structures generated by these manipulators, when the actuators are locked, are ten. Two out of these topologies are the SR-2PS topology (one SR leg and two PS legs) and the SP-2RS topology (one SP leg and two RS legs). This paper presents two algorithms. The first one determines all the assembly modes of the SR-2PS structures. The second one determines all the assembly modes of the SP-2RS structures. The presented algorithms can be applied without changes to solve, in analytical form, the direct position analysis (DPA) of all the parallel manipulators that generate a SR-2PS structure or a SP-2RS structure when the actuators are locked. In particular, the closure equations of two generic structures, one of type SR-2PS and the other of type SP-2RS, are written. The eliminants of the two systems of equations are determined and the solution procedures are presented. Finally, the proposed procedures are applied to real cases. This work demonstrates that (i) the DPA solutions of any PM that becomes a SR-2PS structure are at most eight, and (ii) the DPA solutions of any PM that becomes a SP-2RS structure are at most sixteen.

Direct Position Analysis in Analytical Form of Parallel Manipulators Generating Structures With Topology SR-2PS

2004 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Analytical Form ◽  
Solution Procedure ◽  
Generic Structure ◽  
Kinematic Chains ◽  
Position Analysis ◽  
In Series ◽  
The One ◽  
Wide Family

A wide family of parallel manipulators (PMs) is the one that groups all the PMs with three legs where the legs become kinematic chains constituted of a passive spherical pair (S) in series with either a passive prismatic pair (P) or a passive revolute pair (R) when the actuators are locked. The topologies of the structures generated by these manipulators, when the actuators are locked, are ten. One out of these topologies is the SR-2PS topology (one SR leg and two PS legs). This paper presents an algorithm that determines all the assembly modes of the structures with topology SR-2PS in analytical form. The presented algorithm can be applied without changes to solve, in analytical form, the direct position analysis of any parallel manipulator which generates a SR-2PS structure when the actuators are locked. In particular, the closure equations of a generic structure with topology SR-2PS are written. The eliminant of this system of equations is determined and the solution procedure is presented. Finally, the proposed procedure is applied to a real case. This work demonstrates that the solutions of the direct position analysis of any parallel manipulator which generates a SR-2PS structure when the actuators are locked are at most eight.

Hydrodynamic and Experimental Analysis on a Novel Hybrid Offshore Renewable Structure

2009 ◽  
Author(s):  
Kurt Delpeche
Keyword(s):  
Renewable Energy ◽  
Mooring Line ◽  
Floating Structure ◽  
Scaled Model ◽  
Novel Structure ◽  
Wave Heights ◽  
Mean Water Level ◽  
Motion Characteristics ◽  
The One ◽  
The Cost

Since the Kyoto Protocol in Japan in 1997, countries have been on a drive to reduce their carbon emissions but recently this drive has been given a new thrust. Security of energy supplies is now a high priority and one of the possible methods is by harnessing offshore renewable energy. It is proposed, that the use of a hybrid or a combination of two sources of renewable energy that utilizes a single floating structure can effectively reduce the cost of delivering renewable energy. Cost reduction is of key importance, however, it will not be the focus of this paper as it is a well proven concept. However, the motion characteristics of such a novel structure as the one that is presented here has never been fully examined and the literature is very limited on the subject. A scaled model of a conceptual structure was fabricated and subjected to regular waves for a range of wave heights and periods. The effect of wave-current interaction was noted and mooring line forces were measured. Conventional hydrodynamic analysis and rules used in ship structures and semi-submersible design were merged into one cohesive analysis and a comparison was made with the experimental results. There are two operational states that are mentioned, the ‘hybrid mode’ i.e. acting as a barge and a semisubmersible by virtue of the volume of the structure below the Mean Water Level (MWL). The second state is the ‘semisubmersible mode’, which has the pontoon and 75% column of the structure only below the MWL.

Implementation of Low Computational Cost Nonlinear Formulation for Multibody Railroad Vehicle Systems

2007 ◽  
Author(s):  
Graham G. Sanborn ◽  
Jason R. Heineman ◽  
Ahmed A. Shabana
Keyword(s):  
Degrees Of Freedom ◽  
Computational Cost ◽  
Companion Paper ◽  
Computer Interface ◽  
Model Parameters ◽  
Nonlinear Formulation ◽  
Vehicle Systems ◽  
Railroad Applications ◽  
Railroad Vehicle ◽  
Low Computational Cost

In a companion paper [1], a low computational cost nonlinear formulation was presented to for the analysis of the forces of long trains. The formulation allows systematically changing the number of degrees of freedom of each rail car and includes the force inputs that are typically found in railroad applications. In this paper, the implementation of this nonlinear formulation is described. A computer interface is also developed in order to allow the user to operate a virtual train model in real time and also change the model parameters and car connectivity conditions. Numerical results are presented in order to demonstrate the use of the formulation proposed and its computer implementation.

Distribution of Cotton in Rectangular Pipeline for Horizontal Foreign Fiber Removed Device

2014 ◽  
Vol 951 ◽  
pp. 113-119
Author(s):  
Gai Li Gao ◽  
Guan Jun Wang ◽  
Peng Chuan Liu
Keyword(s):  
Cross Sections ◽  
Volume Fraction ◽  
Flow Direction ◽  
Simulation Method ◽  
Optimum Length ◽  
Two Phase ◽  
Maximum Volume Fraction ◽  
The Cross ◽  
Motion Characteristics ◽  
The One

A numerical simulation method using the model of the gas-cotton two-phase is used to analyze the distribution of the cotton in the rectangular pipeline for a horizontal foreign fiber removed device. According to the motion characteristics of the cotton, the optimum length of the rectangular pipeline is found and the distribution of the cotton in the pipeline is obtained. The simulation results show that the optimum length is for the cross-section pipeline. At the same time, in the range of the cotton mainly flows in the middle of the pipeline bottom and the maximum volume fraction of the cotton is 4.5%, at the both sides of the pipeline bottom the cotton is less and the average volume fraction of the cotton is 1%, and there is no the cotton in the middle and upper part of the pipeline; in the range of , the cotton increases rapidly in the middle and upper part of the pipeline and the volume fraction is about 2.7% at ; in the range of , the cotton flows steadily and the volume fractions of the cotton are the same in the middle and upper part of the pipeline, about 2.7% but 1.5% in the lower part of the one. In addition, for the level centers of the cross-sections perpendicular to the cotton flow direction, in the unsteady zone the volume fraction curves of the cotton are symmetrical like a saddle, and in the steady zone the cotton is evenly distributed and its volume fraction curves are horizontal lines.

Design Considerations for an Articulated Leg-Wheel Locomotion Subsystem

2004 ◽  
Author(s):  
Seung Kook Jun ◽  
Venkat N. Krovi
Keyword(s):  
Sagittal Plane ◽  
Degree Of Freedom ◽  
Kinematic Synthesis ◽  
Ground Clearance ◽  
Uneven Terrain ◽  
Design Considerations ◽  
Serial Chain ◽  
Vehicle Systems ◽  
Lower Pair ◽  
Adequate Ground

In this paper, we examine and evaluate candidate articulated leg-wheel subsystem designs for use in vehicle systems with enhanced uneven-terrain locomotion capabilities. The leg-wheel subsystem designs under consideration consist of disk wheels attached to the chassis through an articulated linkage containing multiple lower-pair joints. Our emphasis is on creating a design that permits the greatest motion flexibility between the chassis and wheel while maintaining the smallest degree-of-freedom (d.o.f.) within the articulated chain. In particular, we focus our attention on achieving two goals: (i) obtaining adequate ground clearance by designing the desired/feasible motions of the wheel axle, relative to the chassis, using methods from kinematic synthesis; and (ii) reducing overall actuation requirements by a judicious mix of structural equilibration design and spring assist. We examine this process in the context of two candidate designs — a coupled-serial-chain configuration and four-bar-configuration — for the articulated-leg-wheel subsystem. The performance of planar variants of these designs, operating in the sagittal plane, is evaluated and representative results are presented to highlight the process.

Direct kinematics of a manipulator with three mobilities

2021 ◽  
Vol 12 (7) ◽  
pp. 1875-1900
Author(s):  
Florian Ion Tiberiu Petrescu ◽  
Relly Victoria V. Petrescu
Keyword(s):  
Large Mass ◽  
Human Being ◽  
Paper Briefly ◽  
Kinematic Study ◽  
The One ◽  
Direct Kinematics

In the industrial halls it is often necessary to handle large objects, with a large and large table, which have to be transported not over long distances but moved from one place to another, raised, then lowered to various levels, left or right. Such repeated manipulations of heavy and dangerous objects can be done only with the help of a manipulator, which can be a crane, a specially designed trolley, a complicated robot or a simple manipulator as is the case for the one presented in the paper. The paper briefly presents the kinematic study of a manipulator with three mobilities, which can be used both in industrial halls and in garages, depending on its suitably chosen constructive size, which at smaller dimensions can be handled very easily. This manipulator can carry large loads, thus easing the work of the human being and preventing it from major dangers that can occur during the transport of large pieces and a large mass.

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