Mechanisms, Transmissions and Applications

The paper studies the infinitesimal Burmester lines of the moving body at any instant, according to the invariance of the constraint ruled surface of the binary link C-C. A line-trajectory is expressed by the invariants of axodes of a rigid body in spatial motion. The Euler-Savary analogue of a line-trajectory in spatial movement is described in the Frenet frame of axodes. Both the stationary line congruence of constant axis curvature and the Ball line are revealed. The degenerated cases of the infinitesimal Burmester lines, the characteristic lines

L

HC

and

L

RC

, are discussed according to the H-C curvature and R-C curvature. An numerical example of a spatial linkage RCCC is given to show some of above results.

In this paper an educational and research software named GIM is presented. This software has been developed with the aim of approaching the difficulties students usually encounter when facing up to kinematic analysis of mechanisms. A deep understanding of the kinematic analysis is necessary to go a step further into design and synthesis of mechanisms. In order to support and complement the theoretical lectures, GIM software is used during the practical exercises, serving as an educational complementary tool reinforcing the knowledge acquired by the students.

The paper deals with a novel kinematic chain, which uses a geared linkage with linear actuation. The structure is used to actuate the mobile platform of a parallel planar manipulator (3-R

R

R). The main characteristics of the geared linkage with linear actuation are the large rotation angle with proper transmission angle and the approximately linear transmission function in a large range. These properties of the geared linkages with linear actuation as kinematic chain allow the avoiding of the first type singularities and an easier control of the mobile platform movement.

The paper presents an asymmetric three-degree-of-freedom parallel mechanism purposely conceived as a robotic device for tool positioning applications. The kinematic structure of the mechanism contains one central passive limb that constrains the end-effector motion to two translations and one rotation. This work deals with important issues related to the parallel mechanism, such as the position kinematics analysis and the singular configurations prediction.

This study is about the accuracy analysis of two degrees of freedom planar parallel manipulators consisting of five links (one of which is fixed) that are connected to each other with five revolute (R) or prismatic (P) joints. Among these manipulators, topologically RRRRR, PRRRP, RPRPR planar parallel manipulators are selected. Accuracy analysis is a common method to evaluate the performance of parallel manipulators. In this study, accuracy analysis of these planar parallel manipulators is presented by using local conditioning index and maximum positional error methods. For each of the manipulators, mathematical expressions for the local conditioning index and maximum positional errors are derived. These expressions are implemented using Matlab© environment and examples are presented to show the accuracy distributions over the workspace. The consistency between local conditioning index and maximum positional error is discussed.

A fundamental problem in four-bar linkage synthesis is to determine linkage parameters from a given coupler-curve equation, which is essentially an inverse problem to the linkage analysis. For many decades, this synthesis problem has been considered as overdetermined, which yields only approximate solutions. This paper presents a new result, which shows that a determined system of coupler-curve coefficient equations can be formulated, which leads to exact solutions of the linkage parameters. A method of linkage parameter determination from known coupler-curve equation is further developed, demonstrated with examples.

This paper introduces a rolling contact element and its usage in a planar manipulator. Starting from the state of the art in this field of motion technology, the kinematic structure of the manipulator is introduced. Three different cases for moving an object in a planar workspace are used for the derivation of the kinematics. Superposing these cases leads to the general kinematic equations where finally the input angles can be calculated.

Parametric commercial CAD environments can be used as interactive geometry software (IGS). Therefore they are the best tool for the implementation of graphical synthesis methods. This paper gives an introduction of using graphical synthesis methods solving two pose spatial guidance tasks with the B

ennett

linkage. The synthesis is presented for a hinge application.

To avoid close proximity between building envelope and a nearby power line, geometric methods to compute normal distances from spatial point, plane and line to a parabola, approximating the catenary, are developed using projection onto ideal planes. Then line geometry is applied for the first time to reveal a unified approach.

The study deals with motion generation with closed-loop mechanisms with several end-effectors. As a case study a single degree-of-freedom planar Watt II type six-bar mechanism with two end-effectors is worked on. Dyad formulation with complex numbers is made use of for the mathematical model. It is found that the motion synthesis is possible for at most three poses of the two end-effectors. The formulations are illustrated with numerical examples.

The paper discusses the dimension synthesis procedure of the crank-slider mechanism, matching a given input angle and a desired output stroke, for the best possible transfer quality (highest minimum value of the transmission angle), according to the German guideline VDI-2126 (1989). A modified approach is proposed in which the transmission angle just needs to be acceptable. This leads to a much simpler synthesis procedure that covers the most relevant design criteria, like the minimum transmission angle, space occupation and occurrence of dead points. The link dimensions can be obtained from a diagram or can be calculated using simple formulas.

The paper demonstrates the use of a diagram for synthesis of the crank-slider mechanism, matching a given input angle and a desired output stroke, for the best possible transfer quality (transmission angle). The diagram is part of a new proposal of the German guideline VDI-2126 (1989). Examples concerning non-symmetric solutions—applicable to larger input angles—are presented that show the procedure to achieve sufficient transfer quality and to choose or avoid dead points. The transfer functions of the solutions of a typical example are drawn to discuss the various design options.

Design guidelines, such as the VDI guidelines, help the designer in the synthesis of gears and mechanisms for standard recurring tasks. The guidelines provide graphical and computational methods, leading the designer systematically to solve the task. In addition to the actual synthesis process, they often contain diagrams and formulas to support identification of a “good” mechanism. This paper shows how the synthesis method derived from such guidelines can be integrated into modern 3D parametric CAD systems. In addition, design criteria can be used in the search for “good” mechanisms which are specifically tailored to the particular application and thus cannot be covered in general guidelines. In order to take into account such criteria in the individual optimization, the editor should work dynamically, interactively and associatively. Simultaneously with the modification of the mechanism via the graphical input device of his of her CAD system, the editor has to identify and manage the new mechanism dimensions, space requirement and the quality of its criteria. The paper clearly shows also that by using design guidelines in conjunction with parametric CAD systems, synergies are realized. The design engineer is offered a good guide to the solution of the task in his or her usual working environment. The use of features and parameters in CAD systems is explained and solutions are shown to design the mechanism according to requirements. Typical applications are shown using the 3D CAD systems CATIA V5 and Pro/Engineer Wildfire 5.0.

Drive simulators using serial robots, such as the KUKA robot “Robocoaster”, are becoming attractive for situations in which the workspace of traditional Stewart platforms is not suited to accommodate large target rotations, allowing for a wider range of possibilities. Nevertheless—even when using serial robots—the exact target motion can often not be exactly reproduced. In these cases, motion cueing algorithms (MCA) are used to produce a motion which feels as realistic as possible while remaining in the robot acceleration workspace. This paper analyzes the numerical properties of all currently existing MCA (classical, adaptive, optimal, and model predictive control) and selects the most suitable MCA using objective criteria. It also introduces a new procedure for tuning the optimal MCA such that it behaves as good as and even better than much more involved techniques based on the model predictive control (MPC). The new algorithm, termed ZyRo-K, shows best properties for reproducing the desired linear specific force while reducing the rotational false cues. While the work shown in this paper is restricted to numerical evaluation using state-of-the-art “goodness” metrics, the application and test of the algorithms for human passengers on a Robocoaster is currently being prepared and will be published in the near future.

The influence of vehicle torsional stiffness on the lateral load transfer has been largely studied and are present on many publications. This work aims to go further on this evaluation, not only demonstrating how the lateral load transfer varies when the vehicle is subjected to a lateral acceleration but also evaluating, based on a robust engineering method (Taguchi), in which situation the vehicle response to external factors is significantly influenced by structural stiffness.

This research addresses to children locomotion system for designing special orthosis and prosthesis mechanical systems. The research aim is to obtain the motion laws developed by a child locomotion system and with these, the knee joint connection forces will be obtained through an analytical method for walking activity. These parameters are useful for an orthotic system design of a 7 years old child. The research is based on an experimental analysis developed with ultra high-speed video equipment on 20 children and a dynamic analysis by using Newton-Euler method completed with Lagrange multipliers. The obtained dynamic parameters are used as input data for a new knee orthosis design. Virtual simulations are performed by using MSC Adams which validates a new knee orthosis prototype.

Explicit Dynamic equations are needed for simulation and control in the field of Mechatronics. Several classical methods are available to get Dynamic equations. Regarding those methods that aim exclusively at the equations relating applied torques and motion generated, i.e. avoiding any calculus of joint wrenches, Analytical mechanics offers several approaches. For serial mechanisms, Lagrange equations are very convenient and systematic. However, finding such mathematical expressions can be cumbersome when facing closed-loop mechanisms even with the help of Lagrange multipliers. Moreover, this is quite complex if spatial rotations are considered, and hence, generalized coordinates are very much coupled in the expressions of Lagrange functions to be differentiated. Boltzmann-Hamel equations come to help in this regard. In this paper, authors show the finding of the dynamic equations of the

$$3\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{P} RS$$

lower-mobility parallel manipulator using the Boltzmann-Hamel equations and exploring the effect of coupled freedoms in the rotation of the end-effector.

Gear adaptive variator is the toothed transmission with the variable transfer ratio which is adapting to the variable loading. Unsuccessful attempts of creation of a gear variator were undertaken repeatedly. The main problem is—maintenance of constant engagement of cogwheels of a variator. The decision of this problem can be based on use of a kinematic chain with two degrees of freedom. Earlier it was proved that this kinematic chain with closed contour possesses the effect of force adaptation. The gear variator can be performed in the form of the closed differential mechanism. The external variable technological loading changes the transfer ratio itself without any control system. The gear variator opens essentially new concept of creation of adaptive engineering for machines with variable technological resistance (for example, adaptive gearbox of car). The theory of a gear variator is based on discovery «Effect of force adaptation in mechanics» which is published in leading editions of world press. In the paper the bases of the theory of a gear adaptive variator are presented.

The paper presents a novel approach for conceptual structural design of a complex machine part. The approach consists of the following four steps: (i) building a geometric-physical model, (ii) extracting a conceptual model, (iii) meeting the strength and stiffness requirements, and (iv) considering structural manufacturability and aesthetics. Due to the design constraints of a complex machine part in both geometrical and physical requirements, a geometric model is built as a simple geometric shape including all connection surfaces. And a physical model is a finite element model with loads and connection constraints incorporated. The conceptual model is a truss structure in accordance with the material distribution and load paths under different load cases. During designing conceptual structure, its skeleton is accomplished according to the optimal material distribution. The dimensions of the structural skeleton are determined based on the required structural strength and stiffness. Finally, by taking into account the manufacturability and aesthetic appearance, a conceptual structure with the required dimensions is accepted as the actual structure of the machine part. Using a gearbox design as an illustrative example, we demonstrated that the proposed approach is efficient and reliable. The new conceptual structure, produced using this approach for a gearbox, is superior to the empirical and analogical approaches because of lack of proven and reliable design methodology in the literature.

In this paper, a torsional-translational coupled nonlinear dynamic model for planetary gear train with three planet gears is developed to investigate its vibration characteristic. In this lumped-parameter model, gears and carrier all have three degrees of freedom: two translations and one rotation. The equations of motion of the dynamic model are built in consideration of gear elastic deformation and time-varying mesh stiffness. Gear elastic compatibility equations are developed to describe the relationship between displacements, elastic deformations and transmission errors. Thus, dynamic equations of the planetary gear train consist of equations of motion and gear elastic compatibility equations can be found and the effects of support stiffness and flexible planet pin on vibration characteristic have been addressed. The results show floating central gear and flexible planet pin can avoid critical operating conditions, which provides a theoretical guideline for the design of planetary gear train.

Analysis of planetary gear coupled with additional friction gear is analyzed in the present paper. The parts of the system are a compound planetary gear and a friction or hydro-kinetic gear. The kinematical and dynamical analyzes are described. Some variants of the system are considered. The standard methods e.g. Willis formulas and graphical-analytical methods were utilized.

In this paper, we present the mechanical design of a tripod leg mechanism for a Cassino biped locomotor. Kinematic properties are investigated to select the proper stroke of the linear actuators and the radius difference between the moving and base plates. Workspace optimization of the adopted 3-UPU manipulator is computed by considering the Global Condition Index and universal joints constraints. Step design of the foot plate is presented and analyzed to improve the performance by changing the initial length and reassembling of the three limbs in the leg mechanism.

A novel pipeline robot that can realize both inchworm gait and a new concept of

Self

-

crossing motion

(SCM) gait is proposed. The robot is composed of two identical spatial foldable platforms and three identical RPR (revolute-prismatic-revolute) kinematic chains. The foldable platform that is essentially an improved plane-symmetric Bricard linkage with special twist angle can achieve a continuous turning inside out. By taking advantage of the locomotion cooperation among two platforms and three kinematic chains, the robot possesses large deformation capabilities (adapt to different pipe size), different locomotion modes (SCM, inchworm), and foldable and expandable capabilities (fold into flat or prism shape). Two different SCM strategies are described respectively. As displayed in dynamic simulation with integrated locomotion gaits, the SCM movement performs a larger step length and fast speed than general inchworm locomotion.

A novel legged-vehicle called dual quadruped vehicle (DQV) is proposed. The DQV contains two identical single-driven quadruped mechanisms which are composed of single degree-of-freedom (DoF) planar mechanisms. Based on the functional requirements, the construction of leg mechanism is presented. The arrangement of overall vehicle is described, and the steering analysis is discussed. Finally, the dynamic simulation and experimental system are carried out to verify the validity of the theoretical analysis and the maneuverability of the prototype. By decreasing the DoFs, it is useful for the reduction of the cost and simplification of the control algorithm. What’s more, the reliability and practicality of the walking vehicle can also be enhanced.

In the present paper, an approach to generate a minimal set of serial manipulators that provide the required motion directions without redundant solutions is introduced. Besides the architectures, the Denavit-Hartenberg parameters that can be used as optimization parameters in a posterior geometrical synthesis are extracted. The motion directions are defined through a required motion vector which is modified in order to consider the orientation of the robot base. All suitable architectures are generated from a set of discrete Denavit-Hartenberg parameters. The method removes all isomorphisms from the set of suitable architectures significantly reducing the number of solutions, i.e. the computational effort. In order to illustrate the advantage of the proposed method, the number of solutions generated with and without detection of isomorphisms are given. Finally, an example of architectures with four degrees of freedom is given.

Optimal 2D flapping wing kinematics and wing shape are obtained based on well-established unsteady flow characteristics to maximize the mean lift. Flow characteristics, e.g., creation and evolution (strength and position) of the attached leading and trailing edge vortex, vortex shedding and subsequent wake capture, Kramer’s and transient effects, are modeled via the potential flow analyses performed on a finite set of cross flow planes. The stabilizing axial flow across the helical vortex is computed by considering the variation in span-wise vortex properties and centrifugal forces due to wing rotation. Post detachment, vortex decay is captured in the wake. The consequent variation in pressure around the wing chord is used to compute the mean lift per cycle.

Brain retractor is an instrument that delivers a steady retraction for retaining a working channel within the brain during brain surgery. Yet, current brain retractors still look forward to some augmentations, e.g., the adjustable retraction distance and spatula angle, the fine and coarse adjustments and the changeable spatulas. Though there are already existing designs that possess one to three functions mentioned above, but none of them integrates all the aforementioned four design variables together. In this paper, we propose a new mechanism concept that possesses all of the above functions. To achieve adjustable retraction distance, a threaded slider is meshed with a screw. Two pairs of bevel gears and a rod make up the mechanism for adjustable angle of retraction spatula. The fine and coarse adjustments for the retraction distance are achieved by using planetary gear trains. We also designed a spatula holder with multiple sizes of spatulas to accomplish changeable spatulas. The CAD models of the new design are presented.

One of the applications of haptic technology is in education and training. Handwriting for first year-elementary students has been included in the curriculum for some years in Turkey as the first and only writing skill to be taught. Providing these students with a haptic assistance device during the handwriting learning process is the global aim of this work. Among the other components of the design such as electronics, controls and communication, mechanism design is a critical component to be considered for optimization of the device at different levels. This paper aims to address a solution to meet the design criteria through ergonomic design for user along with optimized force exertion capabilities.

For extravehicular activities in space, as mounting and dismounting devices and maintenance, a teleoperated robotic arm is frequently used to spare the human operator from the dangers in orbital space. For precision handling operations such as clamping, inserting and screwing bolts, etc., visual feedback is not sufficient. In this paper, a lightweight 3DoF haptic exoskeleton is developed to control a robotic arm in a natural way by copying operator movements and assisting the operator in feeling the loads in the robotic hand.

To realize the soft work handling application for automated cloth sheet ironing machine, a multi-arm robot system which can operate a cloth sheet handling and spreading operations is developed. This robot system consists of two rectangular coordinates type robot arms and one rotational joint type robot arm. And this system has the detection system using infra-red detection sensors to detect the cloth sheet edge and the sheet existence. And to avoid the collision, the motion plane of these robots is parallel to the particular plane on the Cartesian frame. In this report, considering the motion of a cloth sheet handling by human hands and the co-operative motion for the multi-arm robot system, the quantification method of the cloth sheet handling spreading operations by the geometrical calculation are proposed. Especially, the quantification method of the carton box assembling operations is applied to this motion. And considering the conventional finding approach of the cloth sheet edge by human hands, the cloth sheet existence and overlapping detection method without image-processing is proposed. Also, based on the motion test results, it is clear that the robot system can pick up and spread the cloth sheet edges.

In almost all industrial sectors handling processes are automated through the use of robotic systems. However, in the manufacture of fiber-reinforced structures with complex geometries, the handling of dry, pre-impregnated semi-finished textiles is still performed mainly manually resulting in long processing times, low reproducibility and high manufacturing costs. A previous AiF research project “AutoPreforms” aimed at the automation of the entire production process of components with uniaxial curvature. The scope of this AiF research project “AutoHD” is to fully automate the draping and handling process of complex, three-dimensional fiber composite structures with high degrees of deformation and multiaxial curvature (e.g. car wings). Based on a draping simulation wrinkles can already be recognized during the draping process and counteracted by the developed mechanical structure. This is achieved by the utilization of the bending stiffness of textile semi-finished products, a flexible end-effector and a built-in optical quality assurance process. In this paper the main aspects of preforming processes are described revealing the challenges of the project. With examples of currently existing systems, the objective and innovative contribution of the project are described. The paper serves as initial presentation of the project and its solution approaches.

This work deals with the singularity and workspace analyses of a three-degree-of-freedom mechanism for rear independent suspensions, capable to adjust simultaneously the camber, rear steering and roll angles. This mechanism is able to improve handling performance when compared to the vehicle with a passive suspension mechanism. The inverse kinematic model was developed for the velocity kinematic analysis. The Jacobian matrices are applied to investigate the mechanism singularity configuration. Finally, the reachable workspace is obtained using the discretization method. The obtained results have shown there is not singular configuration inside the specified workspace. The available workspace can attend the camber and rear steering angles stroke. Moreover, this workspace can be obtained by using standard joints and actuators.

This paper deals with the mathematical model creation of a controlled mechanical system (weaving machine). The controlled mechanical system is composed of a constrained mechanical system and its drive and regulation. Motion equations of a constrained mechanical system are formed on the basis of the Langrangian equations of a mixed type—LEMT through an expert system, such as MSC.ADAMS. Drives of weaving machine mechanisms are implemented by synchronous servomotors. For mathematical description of this type of electric motor, a D,Q coil model was used. For the description of a permanent magnet excited synchronous machine the idealized equations of synchronous machines were used. The goal of a simulation model creation, was to determine the characteristic parameters of electric motors in the dependence on the heald shaft number and working speed.

When investigating movements of working links of manufacturing and handling machine mechanisms, we often face a serious problem in complying with positional accuracy in relation to the production technology. The design of a working mechanism seeks to minimize inertial forces or to reduce the weights of mechanism links. Then, the consequence is a reduction of stiffness with significant deviations from the prescribed trajectory. Deviations are caused by natural oscillations of links of the kinematic chain of a working mechanism. The paper outlines the methodology of designing a displacement law for the periodic working movements of electronic cams. As an exemplary displacement law, it is used VDI_2143 Praktische Anwendung.

Novel linear microsteppers are designed for high-speed and high-resolution positioning actuators. In general, most microsteppers equipped with a multi-layered piezoelectric actuator for positioning have difficulty to improve their feed rate because of the small stroke of the actuator, despite their excellent positioning resolution. The microstepper in this study employs two electromagnets for clamping the rail, and one electromagnet for longitudinal actuation of the mechanism. Use of electromagnets with a larger stroke enables a high-speed feed rate and allows for the use of inexpensive low-voltage amplifiers. Moreover, the toggle mechanisms reduce the actuator’s displacement and enlarge the actuator’s force. Because the relation between the input and output displacements of the toggle mechanism is non-linear, the microstepper achieves both high-speed and high-resolution positioning as necessary. This paper deals with experimental mechanisms equipped with two types of actuators based on one or two gaps between the armature and the iron core of the electromagnet. First, the fundamental design of the microstepper with two toggle mechanisms actuated by an electromagnet is introduced. Next, an experiment using each of the two sets of microsteppers we manufactured is described. As a result, the microsteppers are capable of of 1 mm/s maximum speed and a positioning resolution better than 0.1 µm.