bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematic Analysis and Stiffness Characteristics of a Hybrid 2-DOF 7-Bar Linkage
Authors: Luo Zhenjun , Dai Jian S.
Published: April 2009

Parallel mechanisms have drawn interest due to many advantages such as large payload ratio, high structural stiffness, low inertias and high dynamic capacities. But there are also drawbacks such as limited workspace and more singularities. Therefore many research efforts have been given to hybrid mechanisms, especially to hybrid serial-parallel mechanisms. This paper presents a new hybrid 2-DoF 7-bar linkage and several related linkages. Such mechanisms allow much larger range of movement than parallel mechanisms, yet have larger stiffness than serial mechanisms, and are desirable for robot fingers and limbs. Kinematic properties of the hybrid 2-DoF 7-bar planar linkage are analyzed. Comparative analyses between it and several 2-DoF linkages are given based on conditioning mapping, stiffness mapping, global conditioning index and global stiffness index. The results demonstrate the applicability of such linkages.
Experimental Results of a 3-DOF Parallel Manipulator as an Earthquake Motion Simulator
Authors: Ottaviano Erika , Ceccarelli Marco , Castelli Gianni
Published: April 2009

Parallel manipulators are increasingly used in new applications by exploiting their better characteristics with respect to those of serial manipulators, such as higher stiffness, velocity and acceleration, payload. In this paper, experimental results are presented of a novel application of a 3-DOF CaPaMan (Cassino Parallel Manipulator) prototype to simulate point seismograms and 3D earthquake motion. The rigid body acceleration (linear acceleration, angular velocity and acceleration) has been experimentally analyzed to simulate real 3D earthquakes by using the parallel manipulator. Furthermore, first experimental results are reported to analyze earthquake effects on scaled civil structures.
Dynamic Modeling of the Traveling Chain Transmission
Authors: Bucknor Norman K.
Published: April 2009

The Traveling Chain Transmission (TCT) is a novel two-speed chain drive developed at the General Motors R&D Center [1]. In order to predict potential performance and develop design requirements, a multi-body dynamic model of the Traveling Chain Transmission (TCT) was developed and validated using dynamometer test data from the first TCT prototype hardware. A vehicle drivetrain model incorporating the TCT as part of a multi-speed transmission was also developed in order to study the potential performance of the TCT in a vehicle environment. The simulated transmission is a nominal 4-speed automatic transmission converted to a 5-speed transmission by replacing the fixed speed-ratio drop chain by the dual speed-ratio TCT. An upshift from 4th to 5th gear is simulated and the resulting torque and speed transients are predicted.
Dynamic Balancing of Four-Bar Linkages: A Convex Optimization Framework for Efficiently Obtaining Globally Optimal Counterweights
Authors: Demeulenaere Bram , Swevers Jan , De Schutter Joris
Published: April 2009

This paper focusses on reducing the dynamic reactions (shaking force, shaking moment and driving torque) of plane, crank-rocker four-bars through counterweight addition. Determining the mass parameters of the counterweights constitutes an optimization problem, which is classically considered to be nonlinear and hence difficult to solve. A first contribution of this paper is the proof that this optimization problem can be reformulated as a convex program, that is, a nonlinear optimization problem that still has a unique (and hence guaranteed global) optimum, which can be found with great efficiency. Because of the unique features of this formulation, it becomes possible to investigate (and by the guarantee of obtaining a global optimum, in fact prove) the ultimate limits of dynamic balancing, in a reasonable amount of time. When applied to a particular example, this results in design charts, which clearly illustrate (i) the tradeoff between minimizing the different dynamic reactions, and (ii) the fact that adding counterweights is effective, but at the cost of a significant amount of added mass. These design charts constitute a second contribution of the present work.
Acceleration and Dexterity Performance Indices for 6-DOF and Lower-Mobility Parallel Mechanism
Authors: Guo X. J. , Chang F. Q. , Zhu S. J.
Published: April 2009

On the basis of first-order and second-order kinematic influence coefficient matrices, dynamics characteristics indices for robot manipulator are presented in the paper. Different from indices before, these indices include not only the first-order kinematics influence coefficient matrix G, but also the second-order kinematic influence coefficient matrix H. Then with the global index, these indices can be used to guide the dynamics design.
A New Family of 4-DOF Parallel Mechanisms (1T-3R and 2T-2R) With Two Platforms and Its Application to a Footpad Device
Authors: Yoon Jungwon , Ryu Jeha
Published: April 2009

This paper proposes a new family of four degrees-of-freedom (dof) parallel mechanisms with two platforms and its application to a footpad device that can simulate the spatial motions of the human foot. The new mechanism consists of front and rear platforms, and three limbs. Two limbs with 6-dof serial joints (P-S-P-P) are attached to each platform and are perpendicular to the base plate, while the middle limb (Pe-Re-R or Pe-Pe-R) is attached to the revolute joint that connects the front and rear platforms. The middle limb is driven by the 2-dof driving mechanism that is equivalent active serial prismatic and revolute joints (Pe-Re), or prismatic and prismatic joints (Pe-Re) with two base-fixed prismatic actuators. Therefore, two new 4-dof parallel mechanisms with two platforms can generate pitch motion of each platform, and roll and heave motions (1T-3R) or pitch motion of each platform and two translational motions (2T-2R) at both platforms. Kinematic analyses of the 1T-3R mechanism were performed, including inverse and forward kinematics, and velocity analysis. Based on the 1T-3R mechanism, a footpad device was designed to generate foot trajectories for natural walking. Finally, simulations of the foot trajectories in the normal gait cycle were performed using the proposed footpad device.
Design, Analysis, Simulation and Experimental Results for a Rollerblading Robot
Authors: Chitta Sachin , Heger Frederik W. , Kumar Vijay
Published: April 2009

We present the design and gait generation for an experimental ROLLERBLADER. The ROLLERBLADER is a robot with a central platform mounted on omnidirectional casters and two 3 degree of freedom legs. A set of passive rollerblading wheels is attached to the end of each leg. The wheels give rise to nonholonomic constraints acting on the robot. The legs can be picked up and placed back on the ground allowing a combination of skating and walking gaits. We present two types of gaits for the robot. In the first gait, the legs are picked up and placed back on the ground. In the second gait, the wheels stay on the ground at all times. Experimental gait results for a prototype robot are also presented.
Prediction of System Natural Frequencies Using an Explicit Finite Element Code With Application to Belt-Drives
Authors: Wasfy Tamer , Leamy Michael , Meckstroth Rick J.
Published: April 2009

A time-accurate explicit finite element code is used to predict the natural frequencies of a typical class of flexible multibody systems — automotive accessory belt-drives. The system considered consists of a belt, two pulleys, and a tensioner. Two techniques are used to find the system natural frequencies: (a) applying a sharp impulse to the system and extracting the system natural frequencies from the resulting displacement/strain time-histories via an FFT; and (b) applying a harmonic force to the system and sweeping through a frequency range, while at the same time, monitoring for large system response. In the present paper a comparison between these two techniques is presented for a typical accessory drive. Also, recommendations are offered on how to best use each technique to efficiently extract the system’s natural frequencies.
Grasping and Control Issues in Adaptive End Effectors
Authors: Dubey Venketesh N. , Crowder Richard M.
Published: April 2009

Research into robotic grasping and manipulation has led to the development of a large number of tendon based end effectors. Many are, however, developed as a research tool, which are limited in application to the laboratory environment. The main reason being that the designs requiring a large number of actuators to be controlled. Due to the space and safety requirements, very few have been developed and commissioned for industrial applications. This paper presents design of a rigid link finger operated by a minimum number of actuators, which may be suitable for a number of adaptive end effectors. The adaptive nature built into the end effector (due to limited number of actuators) presents considerable problems in grasping and control. The paper discusses the issues associated with such designs. The research can be applicable to any adaptive end effectors that are controlled by limited number of actuators and evaluates their suitability in industrial environment.
On the Properties and the Determination of the Wrench-Closure Workspace of Planar Parallel Cable-Driven Mechanisms
Authors: Gouttefarde Marc , Gosselin Cle´ment M.
Published: April 2009

This paper presents a detailed analysis of the constant-orientation wrench-closure workspace of planar three-degree-of-freedom parallel mechanisms driven by four cables. The constant-orientation wrench-closure workspace is defined as the subset of the plane wherein, for a given orientation of the moving platform, any planar wrench applied on the moving platform can be balanced by the cable-driven mechanism. Based on mathematical observations, this workspace is proved to be the union of two disconnected sets that may or may not exist. Moreover, if the constant-orientation wrench-closure workspace (WCW) exists, its boundary is shown to be composed of portions of conic sections. Then, an algorithm that determines the constant-orientation wrench-closure workspace by means of a graphical representation of its boundary is introduced. Several examples are also included.
Dynamic Model and Performances of 2-DOF Mechanisms
Authors: Di Gregorio Raffaele
Published: April 2009

Tools that make it possible to measure the performances of manipulators are essential in many technical applications, for instance, when the optimal path to accomplish a task has to be chosen, or when different manipulator architectures have to be compared. This paper proposes new indices that fully describe the passive dynamic performances of manipulators with two degrees of freedom (dof). The proposed indices make it possible to compare the passive dynamic performances of different manipulator architectures, which can perform the same tasks, and can be used to build diagrams which highlight the effects of variations in the manipulator geometry on the manipulator dynamics. These features make them easy to be used in a design context. Finally, one application of the proposed indices will be presented and discussed.
On the Design of a 3-PRRR Spatial Parallel Compliant Mechanism
Authors: Wang Yang , Gosselin Cle´ment M.
Published: April 2009

Because wear, clearance and backlash can be reduced or eliminated, one of the important advantages of compliant mechanisms is their potential to increase the mechanism precision dramatically. In this paper, a spatial compliant mechanism based on the 3-PRRR parallel mechanism driven by linear motors is presented. The design methodology is described and the kinematic and static models are developed. Using the “transmission ratio”, an effective and simple compensation method is designed. The performances of this mechanism are studied with the help of the structure simulation module in Pro-Mechanica. Using an open-loop control with compensation, measurements over a 20×20×20 mm3 workspace show that the position accuracy is smaller than 1 μm, i.e., 0.05% of the full range of motion and that the orientation error is less than 1 μradian.
A Compliant Instrument for Arthroscopic Joint Fusion
Authors: Tuijthof Gabrie¨lle J. M. , Herder Just L. , van Dijk C. Niek , Pistecky Peter V.
Published: April 2009

Due to its complex shape and its tightness, it is difficult to prepare the subtalar joint for fusion by means of a minimally invasive approach and conventional straight instruments. The preparation implies the establishment of bleeding contact surfaces. It is desirable to preserve the joint’s shape to keep congruent and smooth contact surfaces for optimal fusion. A compliant instrument was designed to facilitate the preparation by starting the design process from a clinically driven approach. The concept consists of a drill/mill unit at the tip that is steered through the joint by means of a passive automatic control. Since the joint will be fused, the cartilage and the subchondral bone layers should intentionally be damaged. This allows the use of the subtalar joint surfaces themselves as a guiding tunnel to preserve the joint’s shape. Thereto, a guidance frame was placed at the tip. The instrument is equipped with a special shaft that is compliant in one direction (perpendicular to the joint surfaces), and stiff in the two other directions to resist and transmit machining forces. The dimensioning of the instrument was performed by taking into account the specific shape of the subtalar joint. A prototype of the instrument was manufactured. The prototype is powered by a commonly used shaver system. The compliant instrument was tested in cadaver material, and gives promising results. In practice, the difference of the stiffness in y- and z-direction is at least a factor 100.
Finding Geometric Invariants From Time-Based Invariants for Spherical and Spatial Motions
Authors: Roth Bernard
Published: April 2009

This paper shows how the instantaneous invariants for time-independent motions can be obtained from time-dependent motions. Relationships are derived between those parameters that define a time-dependent motion and the parameters that define its geometrically equivalent time-independent motion. The time-independent formulations have the advantage of being simpler than the time dependent ones, and thereby lead to more elegant and parsimonious descriptions of motions properties. The paper starts with a review of the choice of canonical coordinate systems and instantaneous invariants for time-based spherical and spatial motions. It then shows how to convert these descriptions to time-independent motions with the same geometric trajectories. New equations are given that allow the computation of the geometric invariants from time-based invariants. The paper concludes with a detailed example of the third-order motion analysis of the trajectories of an open, spatial R-R chain.
Planar and Spatial Gravity Balancing With Normal Springs
Authors: te Riele Freek L. S. , Hekman Edsko E. G. , Herder Just L.
Published: April 2009

Very often, spring-to-gravity-balancing mechanisms are conceived with ideal (zero-free-length l0=0) springs. However, the use of ideal springs in the conception phase tends to lead to more complex mechanisms because the ideal spring functionality has to be approximated with normal springs. To facilitate construction of (gravity) balancers, employing normal springs (l0≠0) directly mounted between the link attachment points of the mechanism in the conception phase therefore seems beneficiary. This paper discusses spring mechanisms that enable perfect balancing of gravity acting on an inverted pendulum while employing normal springs between the spring-attachment points: The design synthesis of such mechanisms will be explained and balancing conditions will be derived, using a potential energy consideration.
The Design of a Novel Prismatic Drive for a Three-DOF Parallel-Kinematics Machine
Authors: Renotte J. , Chablat D. , Angeles J.
Published: April 2009

The design of a novel prismatic drive is reported in this paper. This transmission is based on Slide-O-Cam, a cam mechanism with multiple rollers mounted on a common translating follower. The design of Slide-O-Cam was reported elsewhere. This drive thus provides pure-rolling motion, thereby reducing the friction of rack-and-pinions and linear drives. Such properties can be used to design new transmissions for parallel-kinematics machines. In this paper, this transmission is optimized to replace ball-screws in Orthoglide, a three-DOF parallel robot optimized for machining applications.
A New Mobile Robot With a Passive Mechanism and a Stereo Vision System for Hazardous Terrain Exploration
Authors: Yoon Sukjune , Woo Chun-Kyu , Choi Hyun Do , Park Sung-Kee , Kang Sung-Chul , Kim Soo Hyun , Kwak Yoon Keun
Published: April 2009

The purpose of this project is to develop a mobile robot for hazardous terrain exploration. The exploration of hazardous terrain requires the development of a passive mechanism adaptable to such terrain and a sensing system for obstacle avoidance, as well as a remote control. We designed a new mobile robot, the Ronahz 6-wheel robot, which uses a passive mechanism that can adapt to hazardous terrains and building stairways without any active control. The suggested passive linkage mechanism consists of a simple four-bar linkage mechanism. In addition, we install a stereo vision system for obstacle avoidance, as well as a remote control. Wide dynamic range CCD cameras are used for outdoor navigation. A stereo vision system commonly requires high computational power. Therefore, we use a new high-speed stereo correspondence algorithm, triangulation, and iterative closest point (ICP) registration to reduce computation time. Disparity maps computed by a newly proposed, high-speed method are sent to the operator by a wireless LAN equipment. At the remote control site, a three-dimensional digital map around a mobile robot is built by ICP registration and reconstruction process, and this three-dimensional map is displayed for the operator. This process allows the operator to sense the environment around the robot and to give commands to the mobile robot when the robot is in a remote site.
Connecting Quantitive Data and Qualitative States for Robotic Systems
Authors: Liu Honghai , Coghill George M.
Published: April 2009

This study presents an approach, the unit circle (UC), to bridge numerical data from each variable of robotic systems and its corresponding qualitative state so that current qualitative methods (e.g. fuzzy models) can apply to general robotic systems. A manipulator is described as a collection of constraints holding among time-varying, interval-valued parameters. The UC representation is presented, and the continuous motion of the end-effector is evaluated by the change of directions of qualitative angle and qualitative length. Analytical formulas of qualitative velocity and qualitative acceleration are derived. The characteristic mapping is introduced for fault detection and diagnosis in terms of the UC. In the end simulation results demonstrate the feasibility of the UC approach for fault diagnosis. The UC representation of robots concerns a global assessment of the systems behaviour, and it might be used for the purpose of monitoring, diagnosis, and explanation of physical systems. This is the first step to fault diagnosis and remediation for robots (e.g. Beagle 2) using qualitative methods.
On Calculating the Degrees of Freedom or Mobility of Overconstrained Linkages
Authors: Rico Jose´ Mari´a , Ravani Bahram
Published: April 2009

This paper reformulates and extends the new, group theoretic, mobility criterion recently developed by the authors, Rico and Ravani [1]. In contrast to the Kutzbach-Gru¨bler criterion, the new mobility criterion, and the approach presented apply to a large class of overconstrained linkages. The criterion is reformulated, in terms of the well known Jacobian matrices, for exceptional linkages; it is extended to linkages with partitioned mobility as well as trivial linkages. In addition, an extension of the criterion is presented that would allow the computation of degrees-of-freedom of several cases of paradoxical linkages. The case of classical paradoxical linkages such as the Bennett and Goldberg linkages still remains unsolved but some insight into the application of the new mobility criterion for these linkages is also presented.
Design and Analysis of a Hybrid Parallel Platform That Incorporates Tensegrity
Authors: Marshall Matthew , Crane Carl D.
Published: April 2009

A new hybrid parallel platform device that is based on tensegrity is introduced in this paper. A tensegrity structure is one that is comprised of members that are either in tension (ties) or compression (struts). The device studied in this paper replaces the ‘upper’ and ‘lower’ set of ties of a 3-strut tensesgrity system with rigid bodies. Further, the three struts are replaced by three leg connectors whose lengths can be changed via prismatic actuators. The three remaining ties are replaced by the series combination of a spring and a non-compliant tie where the length of the non-compliant tie can be controlled. An analysis is presented that shows how the connector leg lengths and non-compliant tie lengths can be determined so as to position and orient the upper platform at a desired pose and at a desired total potential energy level. It is the control of the potential energy in the system that makes this new hybrid parallel-platform unique.
An Underactuated Prosthesis Finger Mechanism With Rolling Joints
Authors: Jobin Jean-Philippe , Buddenberg Harold S. , Herder Just L.
Published: April 2009

This paper presents a novel conceptional design of a prosthetic finger and its optimization. The finger consists of two phalanges, interconnected by rolling contact joints. A novel conceptual design of the rolling joints is presented that combines the advantages of two previously reported versions, i.e. minor dimensional errors do not result in complete loss of preload and associated backlash, while they guarantee precise positioning as long as the joint load is below the preload. The two phalanges are driven by a single tendon. Consequently, this concept is adaptive, yet underactuated (less degrees of actuation than degrees of freedom). A multibody model of the finger was made, based on a general dynamic model. This paper focusses on the static model that was derived from the general model in order to optimize the dimensional design for uniform force distribution, regardless of size and shape of the object. For the optimization, a genetic algorithm was used. A dimensional design was found that features a standard deviation of the ratio of pinch force to operating force of only 1.2 percent over a range of motion of 60 degrees for each joint.
Variable Configuration Tracked Mobile Robot for Demining Operations
Authors: Kim Sang-Do , Lee Cheong-Hee , Yoon Suk-June , Jeong Hae-Kwan , Kang Sung-Chul , Kim Mun-Sang , Kwak Yoon Keun
Published: April 2009

This paper introduces a link-type tracked mobile robot developed for demining operations. The robot consists of three parts: a front frame, a rear frame, and a body. The front frame is connected to the rear frame by a rotational passive adaptation mechanism, which is a driving mechanism of the robot. This passive adaptation mechanism enables the proposed robot good adaptability to uneven terrain including stairs. The link structure gives rise to a small, simple, and energy efficient vehicle. In addition, the new demining system adaptable to the proposed tracked mobile robot is discussed on how to clear small anti-personnel mines with a non-explosive method. Both the motion of the demining rake and the design parameters of the demining unit are analyzed. Finally, a presentation follows on how the new demining system can unearth small anti-personnel mines with a non-explosive method.
Minimizing Performance Variation for the Compliant Floating-Opposing-Arm Clutch
Authors: Weight Ryan G. , Howell Larry L. , Magleby Spencer P.
Published: April 2009

This work has established a model for the behavior of the Floating-Opposing-Arm FOA centrifugal clutch and used it to determine the most sensitive design variables, to minimize performance variations, and to predict the behavior of stacked layers. By manufacturing the compliant clutch in multiple layers, not only is it feasible to produce these clutches in high volumes, but the variations in engagement and torque performance decreased, therefore allowing the clutch to perform more consistently. In addition, the FOA design accounts for performance sensitivity to variations in both design parameters and manufacturing processes and minimizes such variations. FOA clutch testing showed that the compliant clutch is comparable to the benchmark clutch in both engagement speed and torque capacity.
Compliant Force Modelling for Impact Analysis
Authors: Zhang Yuning , Sharf Inna
Published: April 2009

Contact dynamics modeling remains an intensive area of research with new applications emerging in robotics, biomechanics and multibody dynamics areas. Many formulations for contact dynamics problem have been proposed. The two most prominent categories include the discrete approach, which employs the impulse-momentum relations, and the continuous approach, which requires integration of dynamics equations through the contact phase. A number of methods in the latter category are based on an explicit compliant model for the contact force. One such model was developed by Hunt and Crossley three decades ago who introduced a nonlinear damping term of the form λxnx˙ into the contact force model. In addition to proposing the general form of this damping component of the contact force, Hunt and Crossley derived a simple expression for relating the damping coefficient λ to the coefficient of restitution e. This model gained considerable popularity due to its simplicity and realistic physics. It also spurred new research in the area, specifically on how to evaluate the damping coefficient λ. Subsequently, several authors put forward different approximations for λ, however, without clearly revealing the range of validity of their simplifying assumptions or the accuracy limitations of the resulting contact force models. The authors of this paper analyze the various approaches employed to derive the damping coefficient. We also evaluate and compare performance of the corresponding models by using a meaningful measure for their accuracy. A new derivation is proposed to calculate more precisely the damping coefficient for the nonlinear complaint contact model. Numerical results comparing all models are presented for a sphere dropping on a stationary surface.
A Novel Six Degree-of-Freedom Parallel Manipulator With Three Legs
Authors: Vakil Mohammad , Pendar Hodjat , Zohoor Hassan
Published: April 2009

In this paper, a novel six degrees-of-freedom (6-DOF) parallel manipulator actuated by three base-mounted partial spherical actuators is proposed. The parallel manipulator consists of a base, a moving platform and three connecting legs. Each leg has spherical (S), prismatic (P) and universal (U) joints (SPU) in serial manner. The spherical joints are partially actuated due to the fact that the actuators of each leg are used only to specify its leg’s direction. The inverse and forward pose kinematics as well as the singularity points of the aforementioned mechanism is described in the article. In the inverse pose kinematics, active joint variables could be calculated with no need for the evaluation of passive joint variables. It will be shown that the inverse pose kinematics has sixty-four (64) solutions (64 different configurations exists for the inverse pose problem). In the forward pose kinematics, instead of twelve nonlinear equations derived by equaling the transformation matrices of each leg through Denavit-Hartenberg notation, only three nonlinear equations with less nonlinearity could be solved via numerical method, and therefore the numerical method converges more rapidly to the answer. Finally two different sets of singularity points with different natures are obtained.
Design and Feasibility Testing of a Novel Device for Automatic Distraction Osteogenesis of the Mandible
Authors: Crane Nathan B. , Gray J. Michael , Mendelowitz Sarah E. , Wheeler Jason W. , Slocum Alexander H.
Published: April 2009

Mandibular distraction osteogenesis is a medical procedure for lengthening the mandible bone by stimulating natural bone-healing mechanisms via a mechanical device that exerts a force on the mandible in one or more directions. Many mandibular distraction devices must be placed externally and most rely on the patient to manually actuate the device each day. This project focuses on the design of an automatically actuated, single degree-of-freedom, implantable distraction device that would be minimally visible after installation. Such a device could reduce errors from patient compliance and would be an important first step toward increasing the capability of future devices. A simple motor and leadscrew system was used with a custom designed impact transmission and controller. A test was conducted on a prototype to determine the feasibility of the design and measure the overall system efficiency. The device was able to move the required 70 N load at a rate of about 1 mm per minute. Compared to an equivalent device utilizing a planetary gearhead to amplify the torque, the impact coupling is significantly less efficient. However, the necessary increase in battery size has only a small impact on the total device length. For a system with the same motor and force output, the impact coupling system is shorter than the gearhead-based system due to a 50% reduction in transmission length.
Design and Configuration of Machine Vision Robotic Cells in a Manufacturing System
Authors: Lu Roberto F.
Published: April 2009

Most fixed automations in traditional manufacturing systems are not equipped to manage product variations efficiently. This paper presents a design and configuration for a machine-vision-equipped robotic packing cell that is capable of managing a wide range of product sizes. Product size information is gathered at an earlier stage in the manufacturing process and then transferred electronically to the robot cell. Different controllers are needed to manage robot cell functions related to incoming product, machine vision, robot control, robot manipulator, and multiple layers of safety control information. Each controller, due to the nature of its function, has different advantages in processing different data types. In order to achieve the highest possible robot manipulator utilization rate, the assignment of information processing among controllers needs to be thoughtfully planned, especially for the critical mathematical routines. Coordination and calibration between charged-coupled device (CCD) cameras and robots in existing manufacturing facilities are configured with considerations for building vibrations, lighting conditions, and signal processing assignments among the available devices. System efficiency is improved when the vision signal, robot logical signal, and robot manipulator signal processing units are running cohesively in parallel. The capability of the machine-vision-assisted robot end effector automatic path adjustment, to pick up and pack different sizes of products dynamically, allows a higher level of flexibility and efficiency. This paper describes a feasible design and configuration for an integrated machine vision robotic cell in a manufacturing system.
Mobility of 4R1P-Type Five-Bars Using Characteristics Charts
Authors: Guo W. Z. , Zou H. J. , Han B. , Zhang Q.
Published: April 2009

The mobility is analyzed for the 4R1P-type planar closed-loop five-bar linkages using characteristics charts and four-bar Grashof criterion by introducing the virtual link. Based on dimensional relations of the three RR-type links, the five-bars are divided into three categories: Class I, Class II and Class III. Class I satisfies rmax < rmid + rmin, Class II satisfies rmax > rmid + rmin and Class III holds the equality. In the characteristics charts, Class I has a circular slide reachable range with two Grashof regions and two non-Grashof ones separated by three Grashof boundaries C1, C2 and C3, as well as one structure boundary B3; Class II has a ringed range with one Grashof region and two non-Grashof ones separated by the void boundary A1 instead of C1, two Grashof boundaries C2 and C3, as well as B3; and Class III has a circular range with three regions separated by C2, C3 and B3. From the four-bar Grashof criterion, the five-bars have two fully revolute joints at the Grashof regions while no such joints at the non-Grashof regions. Specially, the five-bars have Grashof change points at the Grashof boundaries and keep in line at A1 and B3. Each class includes further sub-classes. Several cases are illustrated for the applications.
ProtoFold: Part I — Nanokinematics for Analysis of Protein Molecules
Authors: Kazerounian Kazem , Latif Khalid , Rodriguez Kimberly , Alvarado Carlos
Published: April 2009

Proteins are evolution’s mechanisms of choice. Study of nano-mechanical systems must encompass an understanding of the geometry and conformation of protein molecules. Proteins are open or closed loop kinematic chains of miniature rigid bodies connected by revolute joints. The Kinematics community is in a unique position to extend the boundaries of knowledge in nano biomechanical systems. ProtoFold is a software package that implements novel and comprehensive methodologies for ab initio prediction of the final three-dimensional conformation of a protein, given only its linear structure. In this paper, we present the methods utilized in the kinematics notion and kinematics analysis of protein molecules. The kinematics portion of ProtoFold incorporates the Zero-Position Analysis Method and draws upon other recent advances in robot manipulation theories. We claim that the methodology presented is a computationally superior and more stable alternative to traditional molecular dynamics simulation techniques.
A Counter-Rotary Counterweight (CRCW) for Light-Weight Dynamic Balancing
Authors: Herder Just L. , Gosselin Clement M.
Published: April 2009

Shaking forces and moments are often undesired. Complete balancing of these effects usually is associated with considerable additional mass and inertia. This paper proposes a light-weight solution concept to the complete force and moment balancing of linkages based on the combination of a counterweight and a separate counter-rotation into a single element. This element will be called a counter-rotary counterweight (CRCW). It will be shown that for a 1dof rotatable link a reduction of added mass by about 40% and a reduction by about 20% of added inertia have been achieved, as compared to a standard solution, after optimization of both mechanisms for minimal inertia. Generalization of the proposed principle is also discussed.
ProtoFold: Part II — A Successive Kineto-Static Compliance Method for Protein Conformation Prediction
Authors: Kazerounian Kazem , Latif Khalid , Alvarado Carlos
Published: April 2009

This paper presents an efficient and novel computational protein prediction methodology called Kineto-Static Compliance Method. Successive Kineto-Static Fold Compliance is a methodology for predicting a protein molecule’s motion under the effect of an inter-atomic force field without the need for molecular dynamic simulation. Instead, the chain complies under the Kineto-Static effect of the force field in such a manner that each rotatable joint changes by an amount proportional to the effective torque on that joint. This process successively iterates until all of the joint torques have converged to zero. This configuration is equivalent to a stable, globally optimized potential energy state of the system or, in other words, the final conformation of the protein. This methodology is implemented in a computer software package named ProtoFold. In this paper, we have used Protofold to predict the final conformation of a small peptide chain segment, an alpha helix, and the Triponin protein chains from a denatured configuration. The results show that torques in each joint are minimized to values very close to zero, which demonstrates the method’s effectiveness for protein conformation prediction.
Equivalent Spatial Parallel Mechanisms for the Modelling of the Ankle Passive Motion
Authors: Di Gregorio R. , Parenti-Castelli V. , O’Connor J. J. , Leardini A.
Published: April 2009

The human ankle anatomical complex comprises the ankle and subtalar joints. The ankle represents the tibiotalar joint, connecting the tibia above, the fibula laterally and the talus below. Modelling of human joint passive motion is of great clinical relevance both for ligament reconstruction and for prosthesis design. The use of (equivalent) planar and spatial mechanisms for the kinematic modelling of joint passive motion proved to be a promising approach as it has been successfully utilized for the knee joint recently. Clinical evidence and experimental measurements led to infer that the relative passive motion between the tibia and the talus is a complex but single repeatable path constrained by articular surfaces and ligaments. The relative motion has the feature of a one degree of freedom rigid body guidance motion. Based on these considerations this paper presents two different equivalent spatial parallel mechanisms for this modelling. The mechanism links are taken from bones, ligaments and tendon structures, while kinematic pairs are appropriately chosen according to the corresponding type of anatomical connections. Simulation results are compared with corresponding experiments ones confirming the potential of the proposed approach.
A Compliant Rolling Contact Joint and Its Application in a 3-DOF Planar Parallel Mechanism With Kinematic Analysis
Authors: Jeanneau Ame´lie , Herder Just , Laliberte´ Thierry , Gosselin Cle´ment
Published: April 2009

This paper first presents the concept and the fabrication of a new type of compliant rolling joint which combines the advantages of compliant mechanisms with those of rolling link mechanisms. In this joint, flexible bands create the necessary constraints to enforce a rolling movement between two links. Then, the rapid prototyping techniques used for the compliant rolling joint fabrication are described. The kinematics of one application of this joint in a 3-DOF planar parallel mechanism are then presented. A semigraphical method was used to find the solutions to the inverse kinematic problem. Finally, the workspace analysis and the velocity equations are presented.
Lowering Upender Design and Synthesis
Authors: Van de Ven James , Stackley Mark
Published: April 2009

A rigorous mechanism design approach was used to optimize a six-bar linkage fulfilling the task of lowering a 5-ton roll of paper from one elevation to another while changing its orientation by 90 degrees. This problem was motivated by a need in paper mills to improve upon the poor space and efficiency attributes of the current mechanism. The design approach used the problem statement to develop explicit design specifications. A formal type synthesis process was used to determine the optimal class of mechanism to meet the defined design specifications. This process yielded two classes of advantageous mechanisms, the Watt I and Stephenson III, which were further developed by dimensional synthesis. Using different approaches to the dimensional synthesis technique allowed three different mechanisms to be created that all moved the paper roll through the design positions. Distinguishing the best suited mechanism required a performance evaluation of static and dynamic states in addition to geometric evaluation. This work resulted in the optimization of a Stephenson III six-bar mechanism, generated by creating a path with prescribed timing base four-bar and an auxiliary motion control dyad, that met all of the design specifications.
Dynamic Modeling of Quadrupedal Running Gaits Using a Simple Template With Asymmetrical Body Mass Distribution
Authors: Zou Hong , Schmiedeler James P.
Published: April 2009

Most quadruped robots capable of running have employed bounding gaits at speeds far below those at which an animal of equal mass would gallop, which is a similar gait. This paper extends the spring-loaded inverted pendulum (SLIP) model to capture the key characteristics of trotting and galloping in biological systems. The objective is to establish a tool that will aid in determining the speed at which bounding or galloping is efficient for robotic systems. The SLIP model includes a linear damper in the legs to model all energy losses in a stride, and in the case of bounding, the body is taken to have an asymmetrical mass distribution. Results indicate that the model exhibits biological characteristics for both trotting and galloping, although duty factors are unrealistically low. Including leg mass in the models to account for additional energy loss does not offer improvement over the use of a linear damper alone.
A Method to Evaluate and Calculate the Mobility of a General Compliant Parallel Manipulator
Authors: Yu Jingjun , Bi Shusheng , Zong Guanghua
Published: April 2009

A compliant parallel manipulator (CPM), is a kind of compliant mechanism characterizes a complicate topological structure and multiple degrees of freedom. As one of the kinematic characteristics of a CPM, the mobility of a CPM become complicate compared to its rigid-counterpart. In order to describe such a complicate kinematic characteristic of a CPM, “primary mobility of a compliant parallel manipulator” concept is proposed. By means of the screw theory, a method of quantifying the primary mobility of the CPM is investigated under the ground that the compliance matrix of the manipulator should be calculated primarily. By using this method, the primary mobility of two typical compliant parallel manipulators, one is a planar 3-RRR CPM and the other a spatial 3-RRPR CPM, is addressed respectively. This proposed method is also instructive for analyzing the instantaneous mobility of a general degenerate-DOF parallel manipulator or a Parallel Kinematic Machine (PKM).
Prototype of a Redundant Parallel Robot Wrist
Authors: Hess-Coelho Tarcisio A.
Published: April 2009

This paper presents a prototype of a 4-dof robot wrist based on a redundant kinematic parallel structure. It shows the built prototype, and all subsystems are described in detail. The analysis of mechanism topology is performed, so its kinematic structure is characterized in terms of moving links, active and passive joints. By means of developed kinematic model, occurrence of singular configurations is predicted and workspace is evaluated. Finally, actuator driving torques are estimated for some motions of end-effector.
On the Design of Planar Reactionless Parallel Mechanisms
Authors: Fattah Abbas , Agrawal Sunil K.
Published: April 2009

A reactionless machine will not apply reaction forces and moments on the mounting base during motion. This article presents the theory for design of a reactionless planar parallel mechanism. The salient features of this design are: (i) it uses auxiliary parallelograms to locate the center of mass of each leg at the base, (ii) choice of geometric and inertial parameters to satisfy the recationless conditions, (iii) selection of trajectory to achieve a reactionless design. We illustrate the reactionless feature of such a mechanism through computer simulations.
An Algorithm for the Enumeration of Serial and/or Parallel Combinations of Kinematic Building Blocks
Authors: Yan Hong-Sen , Ou Feng-Ming , Tang Ming-Feng
Published: April 2009

An algorithm is presented, based on graph theory, for enumerating all feasible serial and/or parallel combined mechanisms from the given rotary or translational power source and specific kinematic building blocks. Through the labeled out-tree representations for the configurations of combined mechanisms, the enumeration procedure is developed by adapting the algorithm for the enumeration of trees. A rotary power source and four kinematic building blocks: a crank-rocker linkage, a rack-pinion, a double-slider mechanism, and a cam-follower mechanism, are chosen as the combination to illustrate the algorithm. And, two examples are provided to validate the algorithm.
Geometric Properties of Point-Line Trajectories
Authors: Ting Kwun-Lon , Zhang Yi
Published: April 2009

A point-line refers to the combination of a directed line with an endpoint along the line. To trace a point-line trajectory, one must control not only the trajectory of the endpoint but also the direction of the point-line. This paper examines point-line trajectories by regarding a point-line trajectory as the combination of the endpoint trajectory referred to as the directrix and the trajectory of a unit vector in the point-line direction referred to as the indicatrix. A point-line trajectory is therefore characterized by the characteristics of the directrix, indicatrix, and the relationship between them. The paper presents (1) the characteristic numbers to characterize a point-line trajectory, especially the relationship between the directrix and indicatrix; (2) concepts of velocity at the striction point, the shifting velocity along the striction curve, and the shifting speed along the point-line; (3) The visualization of a point-line motion up to the second order; (4) the coordination of the indicatrix and directrix. An example is given to demonstrate the orientation control of the point-line with respect to the point trajectory.
Mobility of Stephenson Six-Bar Chains: Part I — Circuit and Circuit Defect
Authors: Guo Xiao-Ning , Chu Jin-Kui
Published: April 2009

Circuit defect is a fundamental and difficult problem in the process of linkage synthesis. In this paper, a Stephenson six-bar chain can be regarded as combination of a four-bar chain and a dyad. Base on the distance of two common joints shared by the four-bar chain and the dyad, the principle is elucidated and the model is established for circuit identification of Stephenson six-bar chains. The criteria and procedures to automatically identify the circuit and circuit defect of Stephenson six-bar chains are developed. The results provide theoretical basis and technical method for computer aided dimensional scheme selection of Stephenson six-bar mechanisms synthesis. In addition, the model for circuit identification can be directly used to solve the motion order defect that is often encountered in Stephenson six-bar mechanisms synthesis.
Mechanical Efficiency Analysis of a Cardan Joint
Authors: Cavacece M. , Pennestri` E. , Valentini P. P. , Vita L.
Published: April 2009

This investigation concerns with the mechanical efficiency of Cardan joints. The model includes also the effects due to manufacturing and mounting errors and the influence of rotation speed on the efficiency. The joint has been modeled as an RCCC spatial linkage and the full dynamic analysis performed by means of dual vectors algebra.