bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Dynamic Equations of Motion and Actuation Scheme for the Tetrahedron Based Variable Geometry Truss Manipulator
Authors: Sarma Radha , Kramer Steven N. , Ramamurti V. 
Published: March 2021

Abstract
The Variable Geometry Truss Manipulator (VGTM) is a truss structure composed of tetrahedron elements stacked upon each other. Although this manipulator is geometrically different from a serial link manipulator, it is kinematically equivalent to the serial link manipulator whereby the difference in construction lies in its 120° twist angles instead of the more common 0° or 90°. A study of the dynamic behavior of a manipulator is important for simulation of the motion of the manipulator, designing suitable control equations and for evaluating the kinematic design and structure of the manipulator. In this paper the dynamic equations of motion have been derived for the VGTM. The different components of the torques have been computed using the Lagrange-Euler equations with the intention of studying the contributions of each term. In addition, two actuation schemes for the VGTM have been studied: actuation at each joint axis and actuation at the apex of each triangular element. The motor requirements for each scheme have been obtained and compared. A case study has been performed for a typical trajectory this manipulator.
Geometrical Properties of Modelled Robot Elasticity: Part II — Center of Elasticity
Authors: Lipkin Harvey , Patterson Timothy 
Published: March 2021

Abstract
The elastic characteristics of many robot systems can be modeled by a 6 × 6 stiffness or compliance matrix. Several new and important results are presented via screw theory: i) A generalized center-of-elasticity is proposed based on Ball’s (1900) principal screws and its properties are investigated, ii) If a compliant axis exists, it is shown to pass through the center. iii) The perpendicular vectors from the center to the wrench-compliant axes are coplanar and sum to zero. A similar result holds for the twist-compliant axes, iv) Linear and rotational properties are characterized by dual ellipsoids in three-dimensional space. These elements simplify the understanding of complex elastic properties.
Path Generation for Two Cooperative Puma Robots
Authors: Chen Jau-Liang , Duffy Joseph 
Published: March 2021

Abstract
This paper describes the development of generating collision-free paths for a pair of cooperative PUMA robots as their end effectors grasp a workpiece in an obstacle-strewn environment. After the initial and goal positions of the wrist center are specified, a collision-free path for this pair of manipulators to move the workpiece safely to the final destination is generated. The algorithm is demonstrated via computer graphics animation on a Silicon Graphics IRIS 4D/70GT workstation.
Analysis and Synthesis of Frictionless Planar Grasping in an Image Space
Authors: Dai J. S. , Kerr D. R. 
Published: March 2021

Abstract
Theories are presented which describe the grasping of an arbitrary planar object using frictionless point contacts. The theories are based on screw algebra and line geometry, and allow the mapping of the contacts onto an image space, with the study of the necessary relationships between the contacts and the determination of whether these contacts can form a successful grasp. An identical mapping is also used for the relevant surface properties of the shape of the object to be grasped, so that synthesis of grasps can be achieved. Examples of the application of these theories are given.
Determination of the Singularity Loci of Spherical Three-Degree-of-Freedom Parallel Manipularors
Authors: Gosselin Clément M. , Sefrioui Jaouad 
Published: March 2021

Abstract
In this paper, an algorithm for the determination of the singularity loci of spherical three-degree-of-freedom parallel manipulators with prismatic atuators is presented. These singularity loci, which are obtained as curves or surfaces in the Cartesian space, are of great interest in the context of kinematic design. Indeed, it has been shown elsewhere that parallel manipulators lead to a special type of singularity which is located inside the Cartesian workspace and for which the end-effector becomes uncontrollable. It is therfore important to be able to identify the configurations associated with theses singularities.
The algorithm presented is based on analytical expressions of the determinant of a Jacobian matrix, a quantity that is known to vanish in the singular configurations. A general spherical three-degree-of-freedom parallel manipulator with prismatic actuators is first studied. Then, several particular designs are investigated. For each case, an analytical expression of the singularity locus is derived. A graphical representation in the Cartesian space is then obtained.
A New Approach to Type Synthesis of Spatial Robotic Mechanisms
Authors: Malik Akhtar N. , Kerr D. R. 
Published: March 2021

Abstract
This paper presents a new approach for carrying out the type synthesis of spatial parallel platform-type mechanisms, used as robot manipulators. It takes into account the total mobility of the system and the partial mobility of its sub-mechanisms. The paper also provides the necessary and sufficient conditions for the mechanisms to function with specified end-effector freedoms, which are described in two theorems. The total number of possible mechanisms with given mobility and structure are tabulated. The work is based on a modified Grübler mobility criterion and also on the consideration of kinematic restraints.
Path Planning for an Articulated Transporter/Manipulator System
Authors: Chiang Shih-chien , Crane Carl D. , Duffy Joseph 
Published: March 2021

Abstract
This work addresses the three dimensional path planning for an Articulated Transporter/Manipulator System (ATMS) in a given working environment. A vertical motion capability provides the ATMS a new ability which can be used to advantage in the generation of collision free paths. It also complicates the path planning process, however, by not being constrained to a 2D environment. A hierarchical structure of path planning is developed to decompose the three-dimensional path planning problem into several two-dimensional sub-problems.
Real Time Trajectory Modification Using a Closed Form Solution
Authors: Hummels Michael R. , Cipra Raymond J. 
Published: March 2021

Abstract
An on-line trajectory modification and path planning strategy is developed which will allow a robot to respond in an efficient manner to real time sensory input. The approach developed here eliminates the need for solving many equations by developing a closed form algorithm. It uses two fourth order curves for the transition phases with a constant velocity section in between. Although this is done by providing additional constraints to the curve, it makes the problem of determining the trajectory much easier to solve, while providing continuous higher derivatives. It also provides a safe and efficient way of modifying trajectories based on the robots joint rate limits, joint acceleration limits, jerk limits, and desired time interval between trajectory modifications for a 4-1-4 trajectory. This method involves the solution of one second order equation and is directed toward real time applications.
Optimal Trajectory Resolution for the Coordination of Two Robots in Contact Operations
Authors: Tabarah E. , Benhabib B. , Fenton R. G. , Hexner G. 
Published: March 2021

Abstract
A new method is presented for the optimal coordination of a two-robot system performing contact operations. One of the robots carries a tool and performs the specific contact operation on a workpiece which is grasped and maneuvered by the second robot. The two robots move simultaneously relative to each other so that the tool maintains contact with the workpiece while moving along its prescribed trajectory at a constant speed. This prescribed trajectory, which is specified with respect to the workpiece frame, is thus resolved into a pair of conjugate trajectories, one for each robot, and specified in the world coordinate frame. This resolution process does not yield a unique solution, i.e. there exist an infinity of conjugate-trajectory pairs corresponding to a given tool trajectory. This paper presents a technique for resolving the original tool trajectory, where the robots’ conjugate trajectories are parameterized using polynomial functions. A method is then developed for selecting the optimal pair of conjugate trajectories on the basis of minimizing a given choice of cost function. This optimization is further enhanced by coupling it to a procedure for selecting the optimal layout of the robots within the workcell, resulting in the best possible solutions. Numerical simulation results support the validity of the proposed technique.
An Application of Planar Two Parameter Motion Curvature Theory to the Trajectory Generation Problem of a Two-Link Manipulator
Authors: Stanišić M. M. , Lodi K. , Pennock G. R. 
Published: March 2021

Abstract
This paper illustrates a new application of planar curvature theory to the geometric problem of trajectory generation by a two-link manipulator. The theory yields the instantaneous speed ratio, and the rate of change of the speed ratio, which correspond to the geometry of a desired point trajectory. Separate from the purely geometric speed ratio problem (i.e. the coordination problem) is the time based problem of controlling the joint rates in order to move with the specified path variables.
On The Kinematic Design of Manipulators for Limited Access Workspaces (LAWS)
Authors: Shooter Steven B. , Reinholtz Charles F. , Dhande Sanjay G. 
Published: March 2021

Abstract
Robotic manipulators for Limited Access WorkSpaces, or LAWS manipulators, must operate in unalterable, confined environments accessed through constrictive portals. The characteristics of these manipulators distinguish them from currently accepted classes of industrial robots and field robots and evoke a particular design strategy. Special consideration must be given to the ability of the LAWS manipulator to service a target workspace while constrained within the boundaries of a confined environment. Applications for robots that can operate in limited access workspaces exist in the nuclear, construction, mining, and medical industries, among others. This paper characterizes LAWS manipulators and develops a strategy for their kinematic design. This strategy is then applied to the design and analysis of a typical LAWS manipulator.
Determination of the Workspace of the 3-DOF Double-Octahedral Variable-Geometry-Truss Manipulator
Authors: Arun V. , Padmanabhan Babu , Kolady Krishnan , Reinholtz Charles F. 
Published: March 2021

Abstract
This paper presents methods to determine the workspace of the 3-DOF double-octahedral variable-geometry-truss manipulator (VGTM). These methods take advantage of some of the geometric properties inherent in octahedral VGT construction and define regions in space whose intersection results in the workspace of the manipulator. This approach of obtaining a ‘common volume’ can be extended to other parallel manipulators.
Push-Pull Pair of Single Action Mechanisms to Preload Strut and Node Joints in the Robotic Assembly of Structures in Space
Authors: Brewer W. V. 
Published: March 2021

Abstract
When strut and node components are used for truss construction or repair, an assembly problem occurs if a strut must fit between nodes whose separation distance is either more or less than the design specification. In such circumstances two actions would permit continued assembly:
1. Change strut length
2. Move the nodes.
Variable length struts fit between nodes and (or) move them. They are preloaded at the joint against a reference length in an attempt to maintain the desired dimension. As a by-product they either pull the nodes together or push them apart. Most cannot do both, and are therefore characterized as “single action”; those that can do both are “double action”.
Double action mechanisms are currently being used for robotic truss assembly because they solve the above stated crucial problem in both directions. Single action mechanisms tend to exhibit superior performance in all other categories. They benefit from the attributes that accompany their simplicity.
The titled concept combines the major advantage of double action with the simplicity of single action. This is demonstrated with an example.
Full-Wave Bi-Directional Rotation-Rectifier to Assist Robotic End-Effectors in the Automated Assembly of Large Truss Structures in Space
Authors: Brewer W. V. 
Published: March 2021

Abstract
In 1987 work was initiated on the Automated Structural Assembly Laboratory (ASAL) at NASA/LaRC to demonstrate the feasibility of robotic construction in orbit. To move itself as the structure grows, the robot is mounted on a carriage that traverses a beam which moves longitudinally, similar to a gantry crane. Gantry motions will be operated by the self-sufficient robot with its wrist roll motion. Interfaces for the robot at each gantry motor shaft are provided for that purpose. Wrist roll is limited by the large and growing number of wires that must communicate thru the wrist joint to connect the end-effector to power, sensory devices, and computation services. Rotation-Rectifiers applied to robot mobility simplify the end-effector to motor shaft interface, reduce the number of interface operations that must be performed, and convert oscillating robot wrist roll motions to continuous rotation in either direction.
Forward Kinematics of the General 6-6 Fully Parallel Mechanism: An Exhaustive Numerical Approach via a Mono-Dimensional-Search Algorithm
Authors: Innocenti C. , Parenti-Castelli V. 
Published: March 2021

Abstract
A new numerical method for the solution of the direct position analysis of the six d.o.f. fully parallel mechanism with general geometry, often referred to as generalized Stewart platform mechanism, is presented. The main feature of the method, making it attractive with respect to the methods available in the literature, is the ability to find out all the real solutions of the direct position analysis. The effectiveness of the new algorithm relies upon the solution of only one equation in one unknown. That equation is strictly representative of the problem, i.e., it is free from extraneous roots and every solution of the direct position analysis entails the existence of a root for the equation. A case study is reported.
Workspace of Beetle Body As a Function of Foot Position
Authors: Foo C. K. , Fichter E. F. , Fichter B. L. 
Published: March 2021

Abstract
Body workspace with foot positions fixed was examined for 16 sets of foot positions at 3 body heights using a simulation model of a darkling beetle. Body orientation was held constant and all foot positions were symmetrical about the bilateral symmetry plane. Horizontal plane sections of body workspace were plotted.
Maximum body workspace areas were nearly always at the observed normal resting height of the beetle. Maximum body workspace areas occurred with feet in the relative positions they have when near the centers of their respective workspaces. Changing positions of front and hind feet had much more influence on shape and area of body workspace than changing positions of middle feet. Conclusions from this study raise important considerations for the design of walking machines.
Design and Motion Planning of Multi-Limb Robotic Systems: The Force-Workspace Approach
Authors: Madhani Akhil , Dubowsky Steven 
Published: March 2021

Abstract
A method, called the Force Workspace (FW) approach, is presented for the design and motion planning of mobile multi-limb robotic systems which must as part of their tasks apply large forces over large ranges of motion. These systems will be limited by actuator force/torque saturation limits, system-environment force and moment constraints such as friction, and kinematic joint limits. The FW can be used for the quantitative design of such systems and enables motions to be planned to perform tasks without violating the above constraints. Examples of FW based design and planning are given for a robotic climbing machine.
The Mechanical Design of a Parallel Actuated Joint for an Articulated Mobile Robot
Authors: Ridgeway Shannon , Crane Carl D. , Adsit Phillip , Harrell Roy 
Published: March 2021

Abstract
The suitability of the parallel planar actuator (PPA) to application in an articulated mobile robot is evaluated. Examination of several joint actuation schemes is presented along with the introduction of the PPA. The PPA has a high joint torque generating capacity and a distributed structure that leads to a light, stiff mechanism. A segment of an articulated mobile robot with the kinematic configuration of the PPA has been designed and fabricated. The design process is outlined and the major components are described. The mechanism is operational and meets major design criteria.
A Derivation of the Pole Curve Equations in the Projective Plane
Authors: Brady Michael H. , Peterson Steven W. 
Published: March 2021

Abstract
The traditional four-position method of mechanism synthesis focuses on the poles corresponding to four displacements. From these poles arise equations for the center-points and circle-points of possible four-bar linkages. However, if one of the poles is infinite (the associated displacement is a pure translation), the established derivations for the pole curve equation break down. This problem is rectified by expressing the pole curve equation in the projective plane, because all points, including points at infinity, have finite homogeneous coordinates. In Part I of this paper, this form of the pole curve equation is applied to opposite-pole quadrilaterals formed by four finite poles. This projective derivation is an analytic expression of Alt’s graphical construction of the pole curve. The pole curve is the intersection of a pair of projective pencils of circles (one pencil for each side of a pair of opposite sides in the opposite-pole quadrilateral) which are defined by the homogeneous coordinates of the poles. The resulting equation for the pole curve is a function of the locations of the poles and of the orientation of one opposite side of the opposite-pole quadrilateral relative to the other.
A Straight-Line Mechanism and its Application in Vehicles
Authors: Zhang S. J. , Sanger D. J. 
Published: March 2021

Abstract
This paper describes a mechanism which generates straight-line motion segments and which is especially appropriate for use as the basis for a walking wheel in various kinds of vehicles. The straight-line motion capability, with multiple legs in the wheel, is exploited to ensure that the height of the wheel centre above ground is maintained constant. Thus, the wheel can be used on hard surfaces as well as on soft surfaces, with a suitable foot attached to the leg to ensure that an appropriate level of ground pressure is maintained.
Synthesis of Single-Input and Multiple-Output Port Mechanisms With Springs for Specified Energy Absorption
Authors: Jenuwine John G. , Midha Ashok 
Published: March 2021

Abstract
A means of synthesis of single-input and multiple-output port mechanisms for specified energy absorption is formulated for multiple precision points. The synthesis presented makes use of an extension of the loop closure method which includes expressions for energy absorption by linear spring elements. The configuration considered locates spring elements at two output ports of a multi-loop, planar mechanism. Economies realized for the symmetric mechanism are discussed for both one and two plane symmetry. Synthesis examples are included for both the general and symmetric mechanism. Special applications presented include synthesis of a constant force mechanism and synthesis of a mechanism suited to the energy absorption requirements of an automotive crashworthiness system.
Simulation of Mechanical Systems With Multiple Frictional Contacts
Authors: Wang Yin-Tien , Kumar Vijay 
Published: March 2021

Abstract
There are several applications in robotics and manufacturing in which nominally rigid objects are subject to multiple frictional contacts with other objects. In most previous work, rigid body models have been used to analyze such systems. There are two fundamental problems with such an approach. Firstly, the use of frictional laws, such as Coulomb’s law, introduce inconsistencies and ambiguities when used in conjunction with the principles of rigid body dynamics. Secondly, hypotheses traditionally used to model frictional impacts can lead to solutions which violate principles of energy conservation. In this paper these problems are explained with the help of examples. A new approach to the simulation of mechanical systems with multiple, frictional constraints is proposed which is free of such difficulties.
Multiple Flywheel Recuperation System
Authors: Marinov Philip , Pavlov Stefan 
Published: March 2021

Abstract
A multiple flywheel is studied for the purpose of storing and recuperating kinetic energy. The objective of the design of such systems is a maximum storage and recuperation of the stored energy. The dynamical models of the proposed and the conventional system are compared. Coefficients of storing and recuperating efficiency are introduced for demonstrating the advantages of the multiple flywheel system. An optimization is made regarding to maximum recuperating efficiency.
Systematic Synthesis and Applications of Novel Multi-Degree-of-Freedom Differential Systems
Authors: Kota Sridhar , Bidare Srinivas 
Published: March 2021

Abstract
A two-degree-of-freedom differential system has been known for a long time and is widely used in automotive drive systems. Although higher degree-of-freedom differential systems have been developed in the past based on the well-known standard differential, the number of degrees-of-freedom has been severely restricted to 2n. Using a standard differential mechanism and simple epicyclic gear trains as differential building blocks, we have developed novel whiffletree-like differential systems that can provide n-degrees of freedom, where n is any integer greater than two. Symbolic notation for representing these novel differentials is also presented. This paper presents a systematic method of deriving multi-degree-of-freedom differential systems, a three and four output differential systems and some of their practical applications.
Determination of the Shortest Crank in Four Position Synthesis: A Numerical Apporach
Authors: Song Shin-Min , Lu Fu-Hung , Chen Ning-Xin , Waldron Kenneth J. 
Published: March 2021

Abstract
The shortest crank of a four position synthesis can be determined by solving a statically determinate five-bar structure and a set of seven nonlinear equations have been proposed for this purpose. In this paper a numerical method which can directly solve the shortest crank is presented. It is found that a direct implementation of the original seven equations has two problems: many spurious solutions and poor numerical stability. And the spurious solutions are of the following two types: solutions with incorrect signs of angles and solutions with incorrect geometry. In order to solve the problems, a set of ten equations is developed and parameter perturbation method is applied. Furthermore, a set of eight equations is developed for better numerical stability. Both the ten and eight equations can eliminate the spurious solutions with incorrect geometry. Yet the spurious solutions with incorrect signs of angles can only be rectified after convergence. An automatic search algorithm is included to automatically search the shortest crank in the solution space. Many examples are given to illustrate this numerical approach.