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Currently, pest control work using speed sprayers results in increasing numbers of safety accidents such as worker pesticide poisoning and rollover of vehicles during work. To address this, there is growing interest in autonomous driving technology for speed sprayers. To commercialize and rapidly expand the use of self-driving speed sprayers, an economically efficient self-driving speed sprayer using a minimum number of sensors is essential. This study developed an orchard passage map using location data acquired from positioning sensors to generate autonomous driving paths, without installing additional sensors. The method for creating the orchard passage map presented in this study was to create paths using location data obtained by manually driving the speed sprayer and merging them. In addition, to apply the orchard passage map when operating autonomously, a method is introduced for generating an autonomous driving path for the work start point movement path, work path, and return point movement path. [ABSTRACT FROM AUTHOR]

Path-planning research has been the key to mobile-robot-navigation technology. However, traditional path-planning algorithms have some shortcomings. To solve these problems, this paper proposes a fusion algorithm that combines the kinematical constrained A* algorithm with the Dynamic Window Approach (DWA) algorithm. The kinematical constrained A* algorithm can plan the global path, and then the DWA algorithm can plan the local path under the global path's guidance. Firstly, combined with robot kinematics, we improve the node-expansion method and heuristic-function model of the A* algorithm, which improves the search efficiency, reduces the number of path bends and lowers the computational cost so that the path generated by the A* algorithm better meets the needs of robot motion. Secondly, we optimize the trajectory-evaluation function of the DWA algorithm so that the local paths planned by the DWA algorithm are smoother and more coherent, which is easier for robot-motion execution. Finally, we extract the key nodes from the global path planned by the A* algorithm to guide the DWA algorithm for local path planning and dynamic-obstacle avoidance and to make the local path closer to the global path. Through simulation and practical experiments, the effectiveness of the fusion algorithm proposed in this paper is verified. [ABSTRACT FROM AUTHOR]

Abstract The paper considers dimensional synthesis of a path generator four-bar linkage by applying the modified Differential Evolution (DE) algorithm. During the search of the space, the DE algorithm may skip the right solution and lead to premature convergence. If the step is reduced, the search space is reduced as well, so that convergence becomes slower. Search efficiency may be achieved by including Lévy Flight in the DE algorithm. Namely, when the DE algorithm identifies the space of best solution, then a Levý Flight step is used for local search in that region, which significantly increases the exploitation capability and allows obtaining a very efficient solution of the optimization problem. The algorithm was tested with three examples of dimensional synthesis of a path generator four-bar linkage. The proposed algorithm can be very efficiently applied to solving very complex optimization problems. [ABSTRACT FROM AUTHOR]

In design matters, mechanisms with deformable elements are a step behind those with rigid bars, particularly if dimensional synthesis is considered a fundamental part of mechanism design. For the purposes of this work, a hybrid rigid–flexible four-bar mechanism has been chosen, the input bar being a continuum tendon of constant curvature. The coupler curves are noticeably more complex but offer more possibilities than the classical rigid four-bar counterpart. One of the objectives of this work is to completely characterize the coupler curves of this hybrid rigid–flexible mechanism, determining the number and type of circuits as well as constituent branches. Another important aim is to apply optimization techniques to the dimensional synthesis of path generation. Considerable progress in finding the best design solutions can be obtained if all the acquired knowledge about the coupler curves of this hybrid mechanism is integrated into the optimization algorithm. [ABSTRACT FROM AUTHOR]

The exact and approximate path synthesis problems require different synthesis methods, and mastering multiple design methods increases the engineers' burden. A unified drawing method can solve the synthesis problem of four and five positions in the existed studies. In this article, a novel unified synthesis method is proposed for the exact and approximate timing-path synthesis. The approximate timing-path synthesis problem is recombining into many groups of the exact timing-path synthesis. The exact timing-path synthesis formulas are derived based on the classical dyad method, while the simplified synthesis formulas are obtained by the linear elimination method with a specific order of elimination. A distance error formula is proposed to find the optimal group from all groups of solutions, where each group of solutions is the possible solution of the pre-recombination synthesis problem. Exact timing-path synthesis usually obtains several groups (12 or 2 groups, theoretically may be 0) of solutions with different kinematic properties, then the error formula is used to find the group of solutions that has the smallest rounding error. Finally, three cases test the proposed method and prove the effectiveness of the method in solving the timing-path synthesis problem by comparing the errors with the literature results. [ABSTRACT FROM AUTHOR]

Research on autonomous driving technology is actively underway to solve the facing problems in the agricultural field. Combine harvesters used in East Asian countries, including Korea, are tracked-type vehicles. The steering control system of the tracked vehicle has different characteristics from the wheeled vehicle used in the agricultural tractor. In this paper, a dual GPS antenna-based autonomous driving system and path tracking algorithm were developed for a robot combine harvester. An α-turn-type work path generation algorithm and a path tracking algorithm were developed. The developed system and algorithm were verified through experiments using actual combine harvesters. The experiment consisted of an experiment with harvesting work and an experiment without harvesting work. In the experiment without harvesting work, an error of 0.052 m occurred during working driving and 0.207 m during turning driving. In the experiment where the harvesting work was carried out, an error of 0.038 m occurred during work driving and 0.195 m during turning driving. As a result of comparing the non-work area and driving time to the results of manual driving, the self-driving experiment with harvesting work showed an efficiency of 76.7%. [ABSTRACT FROM AUTHOR]

Design of one-degree-of-freedom (1-DOF) mechanisms is of paramount interest. This work deals with the generation of exact regular polygonal paths by using two particular 1-DOF mechanisms. The design of two-bar and three-bar mechanisms including non-circular gears is presented and evaluated. Differences in the kinematics of both mechanisms are discussed. The three-bar mechanism allows derivable velocity and acceleration curves during the whole trajectory, including the polygon vertices, a feature that cannot be achieved with the simpler two-bar mechanism. Hence, the three-bar mechanism makes it possible to generate perfect vertices using non-circular gears. To the best of the authors' knowledge, this mechanism is the first 1-DOF mechanism with articulated links and a non-circular gear transmission that can generate exact regular polygonal paths. The proposed mechanisms can also be applied to generate two straight lines with a given angle, which is another novel contribution of this work. A prototype of the three-bar mechanism has been developed for experimental validation. • A 1-DOF mechanism that can generate exact regular polygonal paths is presented. • Solutions with two- and three-bar mechanisms are analyzed. • The mechanism can also generate two exact straight lines with a given angle. • Non-circular gears are used to generate the required non-linear transmission. [ABSTRACT FROM AUTHOR]

Wire and arc additive remanufacturing (WAAR) technology has become a new solution for hot forging dies repair and remanufacturing. In this study, a path generation method is proposed for WAAR of hot forging dies. At first, a WAAR process of the hot forging die is presented, and considering the characteristics of large welding heat input and complex 3D digital model, the hybrid path planning strategy is confirmed as an appropriate strategy for WAAR. The developed hybrid path generation method for WAAR consists of three main steps: determine the direction of the scan line; divide and fill the internal area; and connect the sub-paths. The relatively optimal scanning direction is determined by calculating the length and inclination angle of each line segment in the contour lines, which reduces the possibility of sharp angles. The internal region is divided according to the position of the selected extreme points, and the path space is adjusted to avoid the occurrence of the unfilled phenomenon. At the stage of sub-path connection, some criteria are proposed to reduce the number of sub-paths. At last, the effectiveness and robustness of the proposed method are validated through the planar deposition experiment and the WAAR process of four damaged hot forging dies. [ABSTRACT FROM AUTHOR]

Automatic guidance systems and autonomous vehicles require tested methods of path generation to ensure successful maneuvers (such as automatic trajectory correction and headland turn management). In this study, an evolution of Zakin’s kinematic modeling, as applied in the automobile industry, is proposed for an agricultural poly-articulated vehicle (representing a tractor or other type of towing vehicle with one or more towed implements attached with an articulated hitch). Geometry, vehicle ground speed, and angular steering velocity are considered in the generation of maneuvering paths. Based on the specifics of real field conditions (slope, plant residue, resistance due to soil compaction, etc.), the initial model was improved by introducing correction coefficients. An experimental setup is proposed using a tractor with two towed implements and a testing method involving point-to-point path comparison. The modeling method has potential for integrating more complex procedures (such as path generation, geolocation, and following) into the design of a maneuvering management system for agricultural machines, which can contribute to the efficiency of field operations. [ABSTRACT FROM AUTHOR]

This article proposes an alternative constraint handling technique for the four-bar linkage path generation problem. The constraint handling technique that is traditionally applied uses an exterior penalty function, and has been found to be inefficient, particularly when dealing with constraints on the input angles. The new technique deals with both input crank rotation and Grashof's criterion. Four classical path generation problems are used to test the performance of the proposed technique. A new adaptive teaching–learning-based optimization (TLBO) scheme is used to solve several optimization problems. This technique is referred to here as teaching–learning-based optimization with a diversity archive (ATLBO-DA), and was specifically developed for this design problem. The results show that this new design concept gives better results than those of previous work, and that ATLBO-DA is superior to the original version and other metaheuristic algorithms. [ABSTRACT FROM AUTHOR]

A novel approach for optimizing reliable cable layouts in offshore wind farms is presented. While optimization models traditionally are designed to suggest acyclic cable routes, those developed in this work recognize that cyclic layouts reduce the consequences of cable failures. The models under study take into account that cables cannot cross each other, which, particularly in instances with restrictive cable capacity, can make it attractive to let cables follow a joint trajectory, and visit turbines without connecting to them. A two-layered optimization process is developed. The outer layer is associated with an integer programming problem, which is subject to simultaneous generation of rows and columns representing cable paths. In the inner layer, a problem identifying feasible low cost paths is solved, guided by optimal dual variable values in the continuous relaxation of the former problem. Results from experimental applications to existing wind farms show good promise of the method. [ABSTRACT FROM AUTHOR]

This paper addresses the design and performance analysis for a preview control laser range finder (LRF) based terrain-following system for fixed-wing unmanned aerial vehicles. The complexity and performance of such systems depend predominantly on the chosen concept and the layout of its hardware components, mainly its sensors. The related estimation and control algorithms designed for the terrain-following task have to further address system uncertainties and disturbances. In this paper, a laser range sensor based terrain-following system is proposed. The various error factors are discussed and the error propagation through the system is analyzed. The resulting error model is first verified using a numerical simulation, Subsequently, it is utilized to quantify the system tracking error, outline the preferred values for various system parameters in order to achieve higher terrain-following performance, and finally suggest the optimal pointing angle for the LRF. The suggested analysis approach and results grant an effective analytical method for designing such terrain-following system and evaluating its performance. [ABSTRACT FROM AUTHOR]

• The bidirectional rotations of the rotary axes are avoided as much as possible to decrease the inspection error. • Multi-axis simultaneous ability of the on-machine probe is used to reduce the inspection path length. • The accessible space is established not only on the inspection locations but also the locations between them. On-machine inspection becomes a trend for obtaining the real shape of the workpiece in adaptive machining. Troubled by the overlapping structure of the impeller, and the positioning error from the rotary axes of the machine tool, it is a challenge to generate an on-machine inspection path to balance efficiency and accuracy. Reducing inspection path helps to reduce the occupied time of the machine tool. Thus, to let the stylus needn't leave the impeller's channel during the inspection, the accessible space of whole inspection path is addressed in path generation. In order to improve accuracy, the inspection error affected by the positioning errors of the rotary worktable is discussed. Furthermore, the error differences of the unidirectional and bidirectional rotations of the rotary axes are considered in path generation. By the stylus orientation optimization, the bidirectional rotations of rotary axes are prevented as much as possible. At last, the effectiveness of improving inspection efficiency and accuracy is verified by the impeller on-machine inspection. The inspection time can be reduced to less than 40% of traditional inspection, and the inspection error can be decreased 0.008 mm at least. [ABSTRACT FROM AUTHOR]

Quasi-tangential laser processing, also called laser turning, is increasingly applied for various applications. Specifically, its ability to generate complex geometries with small feature sizes at high precision and surface quality in hard, brittle, and electrically non-conductive materials is a key benefit. Due to the geometric flexibility, the process is well suited for prototyping in hard-to-machine materials such as ceramics, carbides, and super-abrasives. However, the lack of advanced software solutions for this novel process hitherto limited the exploitation of the potential. Here, we discuss a unique computer-aided manufacturing approach for synchronous 7-axes laser manufacturing with quasi-tangential strategies. This gives the peerless possibility to process arbitrary geometries, which cannot be manufactured with conventional techniques. A detailed description of the path calculation with derivation and procedures is given. The generated machine code is tested on a laser manufacturing setup consisting of five mechanical and two optical axes. Following, a processed cylindrical ceramic specimen with a continuously varying profile along a helical path is presented. The profile is constituted by a rectangular over half-spherical to a triangular groove with defined pitch on the helix. This demonstrator provides the validation of the presented CAM solution. Measurements of the produced specimen show high adherence with the target geometry and an average deviation below 10 μm. [ABSTRACT FROM AUTHOR]

In manufacturing industries, offline programming (OLP) platforms provide an independent methodology for robot integration using 3D model simulation away from the actual robot cell and production process, reducing integration time and costs. However, traditional OLP platforms still require prior knowledge of the workpiece position in a predefined environment, which requires complex human operations and specific-purpose designs, highly reducing the autonomy of the systems. The presented approach proposes to overcome these problems by defining a novel automated offline programming system (AOLP), which integrates a flexible and intuitive OLP platform with a state-of-the-art autonomous object pose estimation method, to achieve an environment and model independent platform for automatic robotic manufacturing. The autonomous recognition capabilities of the three-dimensional vision system provide the relative position of the workpiece model in the OLP platform, with robustness against clutter, illumination, and object material. After that, the user-friendly OLP platform allows an efficient and automatic path generation, simulation, robot code generation, and robot execution. The proposed system precision and robustness are analyzed and validated in a real-world environment on four different sets of experiment. Finally, the proposed system's features are discussed and compared with other available solutions for practical industrial manufacturing, showing the advantages of the proposed approach. Overall, despite sensor resolution limitations, the proposed system shows a remarkable precision and promising direction towards highly efficient and productive manufacturing solutions. [ABSTRACT FROM AUTHOR]

Highlights • Four cases of synthesis of four-bar mechanisms were considered. • A novel algorithm, hybrid Lagrange interpolation differential evolution algorithm (HLIDE), was proposed. • HLIDE significantly outperforms other compared algorithms in all cases. • HLIDE significantly improves the accuracy of four-bar mechanisms of the cited literature in four cases. Abstract A hybrid Lagrange interpolation differential evolution algorithm (HLIDE) is proposed in this study for path synthesis of four-bar mechanisms. HLIDE combines two algorithms of differential evolution (DE) with Lagrange interpolation local search (LILS). LILS performs a local search in the neighborhood of the best individual to enhance the local exploitation capability of DE. In addition, an adaptive local search strategy is presented to further improve the efficiency of LILS. This technique can adaptively apply LILS based on the performance of LILS and DE in previous generations. To evaluate the efficiency and accuracy of HLIDE, five cases of path synthesis involving four-bar mechanisms were tested. Moreover, three well-known evolutionary algorithms, i.e., particle swarm optimization, teaching-learning-based optimization, and differential evolution, were implemented and compared in the five cases. Previous solutions for the same path generation problems by different evolutionary algorithms are summarized and compared in this study. Experimental results showed that HLIDE has significantly better performance in solving the synthesis problems of mechanisms when compared to other algorithms. [ABSTRACT FROM AUTHOR]

Abstract Lighting strike protection is not intrinsically provided on modern composite built aircraft due to the lower electrical conductivity of composite materials. A highly conductive copper foil is manually applied onto the fuselage in multiple overlapping tapes. Known automation processes are not adequate for wide tapes particularly in the case of large double-curved surfaces. One key technology for enabling an automated process is tape trajectory generation with a focus on automation constraints. We are introducing a new tape application mechanism for a single wide tape. Our algorithm generates geometry induced layup trajectories, taking into account geometric conditions. We experimentally demonstrate a wrinkle-free automated application. Based on the first algorithm, a second algorithm addresses the challenging issue of an optimised surface coverage with multiple tapes for a fuselage section. A tape application fitness criterion is defined and implemented. We point out that a computer-based algorithm is advantageous for determining the proper arrangement of multiple tapes. It is thus now possible to create a multiple tape design that can be applied with an automation process. In addition, the optimisation leads to a reduction of consumed and wasted tape material in the fuselage production process. [ABSTRACT FROM AUTHOR]

This paper deals with the development of a Computer-Aided Robotic Machining Process Planning package based on SolidWorks. The main aim of the package is to generate an efficient, collision-free, nominal tool path needed for edge finishing and inspection by utilizing a 6-DoF robotic arm. The overall nominal tool path involves analyzing the geometry of the workpiece, determining and designing an efficient collision-free tool path and finally generating the tool path data for the robot and verifying it. This package significantly simplifies the complexity of planning an efficient path for performing edge finishing and inspection. ABB IRB2000 robot is chosen for executing the generated tool path. Ultimately, such path is to be utilized as the nominal tool path by any control strategy present in the literature for a complete automatic edge finishing process. [ABSTRACT FROM AUTHOR]

Dimensional synthesis is a type of inverse problem in linkage kinematics where the objective is to calculate the linkage dimensions required to achieve prescribed linkage output motion. It includes three distinct subcategories: motion generation, path generation and function generation. The authors’ first work surveyed developments in quantitative four-bar motion generation. This work concludes the presentation of developments in four-bar dimensional synthesis by surveying the developments made in quantitative four-bar path and function generation since 1970. While early path and function generation methods (like motion generation methods) were primarily qualitative, ongoing advancements in computing hardware and software continue to make quantitative motion generation more practical. [ABSTRACT FROM AUTHOR]

In nature, there are thousands of flapping insects and flying bird's species. Each one has spectacular flight stability, dynamic and operates in high diversity of flight speed and mission. Each one has superior effectiveness and high efficiency. This paper relates with design and model of an efficient hummingbird mechanism during hovering flight. The proposed mechanism represents new and different concept for point of Nano aerial vehicle's (NAV's) mechanism design. In this study, flapping wing tip path for hummingbird was generated from morphological experiment data's. Slider crank mechanism was designed to be an effective mechanism and same motion with path of hummingbird and analyzed on Simulink with driving crank flapping frequency as 25 Hz. During hovering, forces occurring on designed mechanism were calculated. The system modeled on MATLAB using of Sim-mechanics Toolboxes. [ABSTRACT FROM AUTHOR]

This paper presents a real-time dynamic path planning method for autonomous driving that avoids both static and moving obstacles. The proposed path planning method determines not only an optimal path, but also the appropriate acceleration and speed for a vehicle. In this method, we first construct a center line from a set of predefined waypoints, which are usually obtained from a lane-level map. A series of path candidates are generated by the arc length and offset to the center line in the s - ρ coordinate system. Then, all of these candidates are converted into Cartesian coordinates. The optimal path is selected considering the total cost of static safety, comfortability, and dynamic safety; meanwhile, the appropriate acceleration and speed for the optimal path are also identified. Various types of roads, including single-lane roads and multi-lane roads with static and moving obstacles, are designed to test the proposed method. The simulation results demonstrate the effectiveness of the proposed method, and indicate its wide practical application to autonomous driving. [ABSTRACT FROM AUTHOR]

We address the accurate single arm robotic garment folding. The folding capability is influenced mostly by the folding path which is performed by the robotic arm. This paper presents a newmethod for the folding path generation based on the static equilibrium of forces. The existing approach based on a similar principle confirmed to be accurate for one-dimensional strips only. We generalize the method to two-dimensional shapes by modeling the garment as an elastic shell. The path generated by our method prevents the garment from slipping while folding on a low friction surface. We demonstrate the accuracy of this approach by comparing our paths (a) with the existing method when one-dimensional strips of different materials were modeled, and (b) experimentally with real robotic folding. [ABSTRACT FROM AUTHOR]

This paper proposes a new variant of teaching-learning based optimization (TLBO) for optimal path synthesis of a four-bar linkage. The new TLBO algorithm is called self-adaptive population size teaching-learning based optimization (SAP-TLBO) which is altered from the original version by integrating a self-adaptive strategy for population sizing. A new concept of path generation is designed for problems without prescribed timing, which is proposed to avoid the timing constraint. In the first stage, two traditional path generation test problems are used to test the proposed technique and the new optimizer. Then, the new optimizer is used to solve five mechanical design problems. The results show that the new design concept for path synthesis gives significantly better results than the classical exterior penalty function technique, whereas the computational time is increased. SAP-TLBO is significantly superior to its original version and other meta-heuristics. [ABSTRACT FROM AUTHOR]

This paper investigates and conceptualises industry endogenous sources of innovation in a context of path dependency. With an embedded case study of the mature multi-technology lighting industry, it considers two cases of technology generation (fluorescent lamps and light-emitting diodes) that have occurred under the dominance of established incandescent technology. The results demonstrate the existence of common driving forces (variety of performance criteria and variety of lighting applications) behind the development of the existing path and the generation of two new paths. Such common driving forces indicate the existence of a reactive sequence or a logical causal relationship between the existing and the new paths, which serve as an enabling mechanism in endogenous path generation. [ABSTRACT FROM AUTHOR]

This paper presents a new objective function for the optimization of path-generator four-bar linkages. A four-bar linkage includes four revolute joints, two of which are connected to the coupler link. These two joints, which are known as the moving joints of the linkage, have a remarkable characteristic: both trace circular curves. Using this fact, a new methodology is presented. In this methodology, a dyad is considered which exactly traces the desired path. On the plane attached to the moving link of the dyad, an unlimited number of points can be defined. Among these points, the point which traces a circular curve is very important since this point together with the moving joint of the dyad can be considered as the two moving joints of a four-bar linkage. In order to evaluate the path generated by each point and find the point that traces a near-circular curve, the Circular Proximity Function (CPF) is implemented. Using CPF, a new objective function is introduced that has the lowest number of optimization variables. The optimization process is carried out by the method of differential evolution (DE). Three example problems were solved which resulted in the synthesis of crank-rocker four-bar linkages. Three example problems are solved in this paper demonstrating the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

The On-machine measurement (OMM), which measures a workpiece during or after the machining process in the machining center, has the advantage of measuring the workpiece directly within the work space without moving it. However, the path generation procedure used to determine the measuring sequence and variables for the complex features of a target workpiece has the limitation of requiring time-consuming tasks to generate the measuring points and mostly relies on the proficiency of the on-site engineer. In this study, we propose a touch-probe path generation method using similarity analysis between the feature vectors of three-dimensional (3-D) shapes for the OMM. For the similarity analysis between a new 3-D model and existing 3-D models, we extracted the feature vectors from models that can describe the characteristics of a geometric shape model; then, we applied those feature vectors to a geometric histogram that displays a probability distribution obtained by the similarity analysis algorithm. In addition, we developed a computer-aided inspection planning system that corrects non-applied measuring points that are caused by minute geometry differences between the two models and generates the final touch-probe path. [ABSTRACT FROM AUTHOR]

Path generating adjustable mechanisms with continuous adjustment have been studied in literature, wherein the synthesis has been commonly based on the position kinematics of the mechanism. Many real life applications would, however, demand that the coupler point traces the path at specified velocity and acceleration, thus necessitating development of inverse velocity and acceleration analyses. Further, the inverse dynamic analysis needs to be carried out from the viewpoint of mechanical design and motion control of the mechanism. In this paper, inverse kinematic and dynamic analysis of a path generating four-bar mechanism with continuous one-parameter adjustment is presented. The kinematic analysis is presented for both, the non-singular and singular configurations of the mechanism. Newton's equations of motion are solved by introducing a set of generalized unknowns, resulting in explicit formulae for all the unknowns. The dynamic analysis approach is general and is applicable to any multi-degree-of-freedom single-loop planar mechanism with revolute joints. Results are presented for illustrative examples and future extension of the presented work is discussed. [ABSTRACT FROM AUTHOR]

This paper presents a path generation method for automated vehicle based on Bezier curve. Derivation of smooth path is one of important subjects for vehicle navigation system. Bezier curve is a smooth parametric curve, but adequate assignment of its control points that determine the shape of Bezier curve is not a simple problem. In the proposed method, first n th-order base Bezier curve in N -dimension is derived with the end point constraints (location and velocity). As a next step, path modification is done by using constrained optimization with designated via-points. The presented method is tested by several calculation experiments in case of 2-dimensional and 3-dimensional path. The results are shown and discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper is devoted to an autonomous approach to a moving ship for unmanned vehicles. The problem is introduced and formulated first. Cooperation between the vehicle and the ship is needed, such that the moving ship to be approached is set to move at a constant speed along a straight line or a circle. Hence, an approaching algorithm based on 3-D path generation is proposed. The 3-D vehicle trajectory produced by the path generation realizes smooth transition from the initial pose to the final pose with geometric constraints. The final poses the unmanned vehicle and the ship's reach simultaneously are analyzed and obtained based on 3-D path generation. The related parameters for autonomous navigation of an unmanned vehicle are discussed according to the straight line or the circle that the ship sails along. The approaching algorithm is sequentially summarized. The simulations are conducted, and the results show the effectiveness and real-time performance of the proposed method. [ABSTRACT FROM PUBLISHER]

This work deals with a new smooth path generation method for a mobile robot having a tricycle configuration. The method uses elementary and bi-elementary paths in order to create four kind of basic curves or paths. The proposed algorithm takes into account the real robot dimensions and can be applied for any initial and final orientation of the robot. The method generates a smooth path which is warranted to be very near of the original planning. [ABSTRACT FROM AUTHOR]

This paper presents a new method for the path generation of spherical four-bar crank-slider mechanism. Based on the established mathematical model of the spherical four-bar crank-slider mechanism, the expression of the coupler curve is determined. Then, depending on Fourier series theory, the immanent connection between coupler curve and its corresponding harmonic characteristic parameters is discovered. Meanwhile, by the analysis of the basic dimensional type and the coupler curve, different step size for each parameter of the basic dimensional type is chosen. Thus, by putting the harmonic characteristic components and associated basic dimensional type of spherical four-bar crank-slider mechanism together, a variable step size numerical atlas database of the spherical four-bar crank-slider mechanism is created. Furthermore, by using fuzzy identification method, the best suitable basic dimensional type of spherical four-bar crank-slider mechanism for prescribed coupler curve is obtained. Finally, an example is given to illustrate the synthesis process and the application of this method. [ABSTRACT FROM AUTHOR]

Traditional metaheuristics are easy to fall into local optimum when solving complex dimensional synthesis problems. To solve this problem, a repellency evolutionary algorithm (REA) is proposed in this paper. The REA includes two repulsive mutation behaviors. The first one is that two parent individuals are considered as repulsive sources, and the offspring individual is repelled by parent. The other one is that one parent individual is considered as the source of repellency and repels the other parent individual, then the offspring learn their behaviors. These two mutation behaviors have the following common characteristics. First, the population no longer learns from the current global optimum to avoid population falling into the local optimum region. Second, the offspring search in any direction except the location of the parent. To demonstrate the efficiency of REA, CEC2014 and five case studies of dimensional synthesis were conducted. Seven novel metaheuristics were implemented to compare with REA. Moreover, their solutions were compared with that obtained by other algorithms from previous literature. The experimental results validated the practicability and performance advantage of REA in solving benchmarks and dimensional synthesis problems. [ABSTRACT FROM AUTHOR]

This work addresses the inverse problems of expanded motion and path generation for the spatial (revolute–revolute–spherical–spherical, RRSS) linkage and the 4R spherical linkage with order and branch elimination. Two constrained non-linear equation systems are presented in this work for RRSS and 4R spherical motion and path generation with order and branching constraints. Both equation systems include the spatial four-link displacement model (by Suh and Radcliffe) as an objective function along with order and branching inequality constraints. As examples, both a branch defect-free and order defect-free RRSS linkage 4R spherical linkage are synthesized to approximate expanded groups of precision positions. [ABSTRACT FROM AUTHOR]

Abstract: The problem of path generation for the spherical 4R mechanism is solved using the Differential Evolution (DE) algorithm. Formulas for the spherical geodesics are employed in order to obtain the parametric equation for the generated trajectory. Direct optimization of the objective function gives the solution to the path generation task without prescribed timing. Therefore, there is no need to separate this task into two stages to perform the optimization. Moreover, the order defect problem can be solved without difficulty by means of manipulations of the individuals in the DE algorithm. Two examples of optimum synthesis showing the simplicity and effectiveness of this approach are included. [Copyright &y& Elsevier]

Abstract: This paper presents a computer-aided linkage design system for tracing prescribed open or closed planar curves. The mechanism design is considered a mixture of science and art. The former is about utilizing computers to rigorously size a mechanism in meeting a set of design requirements and the latter is about taking advantage of designers’ experience to narrow down the design domain and speed up the design process. The ultimate goal of the presented design system is to incorporate both science and art into the linkage design process by (1) developing an automatic design framework that is based on library searching and optimization techniques and (2) developing an interactive design framework that is based on advanced human–computer interfaces. To enable the design automation framework, we first pre-built a library of open and closed planar curves generated by commonly used planar linkages. We then turned the classical linkage path generation problem into a library searching problem together with a local optimization problem. To enable the interactive design framework, we developed a set of design interfaces that facilitate designers to intervene and steer the design process. This hybrid design system was developed based on our existing VRMDS (Virtual Reality Mechanism Design Studio) framework. To demonstrate its functionalities, we provided four representative design cases of 4-bar and crank-slider linkages. The result shows that the system returned a desired solution in seconds. We also demonstrate the extensibility of the system by implementing designs of planar 4-bar and crank-slider linkages. [Copyright &y& Elsevier]

Large scale applications of behaviorally realistic transport models pose several challenges to transport modelers on both the demand and the supply sides. On the supply side, path-based solutions to the user assignment equilibrium problem help modelers in enhancing the route choice behavior modeling, but require them to generate choice sets by selecting a path generation technique and its parameters according to personal judgments. This paper proposes a methodology and an experimental setting to provide general indications about objective judgments for an effective route choice set generation. Initially, path generation techniques are implemented within a synthetic network to generate possible subjective choice sets considered by travelers. Next, ‘true model estimates’ and ‘postulated predicted routes’ are assumed from the simulation of a route choice model. Then, objective choice sets are applied for model estimation and results are compared to the ‘true model estimates’. Last, predictions from the simulation of models estimated with objective choice sets are compared to the ‘postulated predicted routes’. A meta-analytical approach allows synthesizing the effect of judgments for the implementation of path generation techniques, since a large number of models generate a large amount of results that are otherwise difficult to summarize and to process. Meta-analysis estimates suggest that transport modelers should implement stochastic path generation techniques with average variance of its distribution parameters and correction for unequal sampling probabilities of the alternative routes in order to obtain satisfactory results in terms of coverage of ‘postulated chosen routes’, reproduction of ‘true model estimates’ and prediction of ‘postulated predicted routes’. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a new error function that can be used for optimum synthesis of path generating mechanisms. The proposed error function is formulated in a way that makes it suitable for use in applications when the primary requirement is that the synthesized path should match closely with the prescribed path. The proposed error function is used in the optimum synthesis of four-bar mechanisms. The method of differential evolution is used to carry out the optimization. Results for three path synthesis problems are presented. Results obtained by using the proposed error function are compared with those obtained by using the commonly used cumulative squares of Euclidean distance error function, on the basis of the values of transverse and longitudinal errors between the prescribed and synthesized paths. The usefulness of the proposed error function is established on the basis of the comparative results. [Copyright &y& Elsevier]

This paper describes the development of an infrastructure-based path-tracking control system. The control system consists of an infrastructure sensor module, a vehicle controller and actuator modules. A reference path is defined from a start point to a destination and a modified reference path is generated to obtain a safe vehicle trajectory for collision avoidance in the case where obstacles and other vehicles exist. Receiving information about vehicle position, heading angle and obstacles surrounding the vehicle from an infrastructure sensor module, the vehicle controller calculates control inputs such as steering wheel angle, throttle angle and brake torque to track the modified reference path which guarantees minimum clearance to obstacles. The vehicle controller comprises three parts: a path-generation algorithm, a path-following controller and a speed controller. The path-generation algorithm generates the modified reference path using the model predictive control method. The path-following controller calculates steering angle in order to track the modified reference path. From the speed controller, throttle and brake control inputs are generated to follow the reference velocity. The path-tracking control system was implemented using a test vehicle and an infrastructure sensor module. [ABSTRACT FROM AUTHOR]

The calculation of mechanism parameters required to achieve or approximate a set of prescribed rigid-body path points is determined by the use of Four-bar path generation. This work will discuss the use of path generation while considering the position tolerance resulting from joint running clearance. Not only will this work discuss the use of path generation of four-bar mechanism in its familiar form, it will include position tolerance as a result of joint running clearance. The standards of American National Standard Institute (ANSI) will be applied in this study. This paper will implement the joint tolerances into the conventional planar four-bar path generation model displacement matrix as a design constraint. This synthesis will produce a planar four-bar mechanism with moving pivots and length tolerance limits from which any mechanism can be created to travel throughout the prescribed path for a coupler point with its specified tolerance. An example to demonstrate the synthesis of a four-bar mechanism with joint tolerances is included. [ABSTRACT FROM AUTHOR]

Abstract: In a companion paper published elsewhere [4], we proposed a design approach based on the general redundancy concept to improving the dynamic performance of a mechanism, especially shaking moment and driving torque attenuation. The approach was based on the redundancy function of the servomotor, so the approach is called redundancy servomotor (RSM). In this paper, we apply the RSM to the path generator problem in mechanism design. We will demonstrate how path generator design and dynamic performance improvement can be performed in an integrated manner with the RSM approach. The proposed RSM design procedure can be applied to any type of path generators (four-bar linkage, five-bar linkage, etc.). The contribution of this paper is the proposed RSM design procedure and technique with which to result in a path generator with a better dynamic performance. The other contribution is the proposed approach to the design of the servomotor''s trajectory or plan, which is useful to the joint-level path planning problem in robotics. [Copyright &y& Elsevier]

A wide range of rapid prototyping (RP) methods are available commercially. Even though the hardware and production materials of these RP methods differ, their production techniques are built on the same idea: layer-by-layer material additive manufacturing. Whatever the material is used, it is deposited, vulcanized, or melted by following a pre-determined path, and each layer is stowed on the previous one to create the 3D model which is designed by using a computer-aided design program. The path which is followed while creating the model is very crucial. In this paper, a novel idea for path generation for RP processes is introduced. This new method is based on computer numerical controlled milling operation. Although the RP process and the milling process are completely opposite of each other since one of them is an additive and the other one is a subtractive method, the paths which are followed for these operations are very similar and based on the same idea: The progress goes on layer by layer. In this novel method, cutter location source files are used to create paths for RP processes. Examples of the prototypes produced by using this new method are also presented in the paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a systematic solution framework for the kinetostatic synthesis of compliant four-bar mechanisms. The goal of the kinetostatic synthesis is to find feasible compliant mechanism solutions for a given set of kinematic and force/energy specifications. Similar to the synthesis of rigid body linkages, we first classify kinetostatic synthesis problems into three major categories: function, motion and path generations. The kinetostatic synthesis equations are derived by combining the kinematic synthesis and static equilibrium equations. We then propose a comprehensive framework based on polynomial solvers for obtaining solutions to these synthesis equations. When kinematic and static equations are decoupled, we solve first kinematic equations independently and then solve static equations for springs'' stiffness. While they are coupled, we transform them into a polynomial form and solve them simultaneously with polynomial solvers. For this case a parameter continuation is devised to avoid computing for the junk solutions. At last, three representative examples are provided to demonstrate the solution process and verify the solution framework. [Copyright &y& Elsevier]

Abstract: A new real-coded evolutionary algorithm is proposed for application to path synthesis of a four-bar linkage. This new evolutionary algorithm is obtained by combining differential evolution (DE) with the real-valued genetic algorithm (RGA). We term this the “GA–DE hybrid algorithm.” The only difference between the proposed algorithm and RGA is in the content of the crossover. The crossover operation in the RGA is replaced by differential vector perturbation, with the best individual or some excellent individuals as the base vectors. Thus, both the main perturbation of differential vectors and the minor perturbation of mutation are used as genetic operators in the GA–DE hybrid algorithm. The efficiency and accuracy of the proposed method are tested using four cases. Findings show that much more accurate solutions for three cases are obtained with this method than those obtained using other evolutionary methods as discussed in the literature. A moveable stick diagram of the synthesized mechanisms can be obtained using the 2D sketch feature of SolidWorks®. This can be used to check whether the synthesized mechanisms encounter circuit defects or are incapable of motion. [Copyright &y& Elsevier]

Abstract: An optimal synthesis method is developed for multi-phase continuous path generation of adjustable planar four-bar linkages. The non-adjustable driving dyad is first determined optimally using full rotation requirements. With coupler angles at all design points calculated, the driven dyad is found by another optimization based on the link length structural error. This method uses less design variables and results in compact error functions. A numerical example demonstrates its effectiveness. [Copyright &y& Elsevier]

A unified procedure for the synthesis of planar linkages that may take the form of rigid body, fully compliant or partially compliant mechanisms is presented. The procedure automates the selection of mechanism topology as characterized by the number and connectivity of the links as well as the nature of the connections between them, the mechanism shape as characterized by the shapes of the individual links, and the mechanism dimensions which include the locations of the joints and the cross-sectional dimensions of the links. The synthesis task is posed as a constrained optimization problem and is solved by a hybrid, elite-preserving genetic algorithm. Three examples of compact mechanisms that trace different non-smooth paths in response to a single, monotonic and bounded force input are used to illustrate the synthesis capability of the procedure. Prototypes of the designs are built and tested to verify their performance. It is observed that in all three examples, partially compliant mechanism designs offer better conformance with design intent than either rigid body or fully compliant mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: Four-bar mechanisms traditionally are made of rigid links and they are used for path, motion or function generation. Actively changing the length of the rocker in a crank rocker four-bar mechanism results in the tip of the rocker following a closed path. In this paper a crank rocker mechanism has been designed with a variable length rocker using an Ionic Polymer Metal Composite (IPMC). A pseudo rigid body model is used to represent the IPMC bending during path generation and a dynamic model is developed to relate the position of the rocker tip and the input voltage required to bend the IPMC. A simple control system has been designed that can apply a desired voltage to the IPMC using pulse width modulation, for obtaining a particular deformation. Experimental results of a path generated using the proposed mechanism is presented. This mechanism has wide application in micro robots for pick and place applications, actively controllable partially complaint mechanisms, adaptive structures, etc. [Copyright &y& Elsevier]

The specific contribution made by this work in the area of geared five-bar path generation is the formulation of a non-linear optimization problem that includes elastic deflection, static torque and buckling constraints. Using this model, geared five-bar path generators are also synthesized with respect to static torque, deflection constraints and buckling constraints for a given rigid-body load. [ABSTRACT FROM AUTHOR]

This paper aims at developing a novel spiral machining technique for four- or five-axis milling of blades. The main contributions are twofold. First, detailed algorithms are presented to model the blade surface with the idea that it can be separated into four patches, i.e., the pressure surface, the suction surface, the leading edge surface, and the trailing edge surface. The G1 continuity across the boundary of each patch is considered. Second, based on the four patches modeled, the key routine of a new spiral machining method is further addressed in detail. It is carried out by machining the pressure and suction surfaces actually whereas passing by the leading and trailing edges in air cut. Experimental results show that the proposed methods can improve the machining quality and avoid overcut near the leading and trailing edges. [ABSTRACT FROM AUTHOR]

Abstract: A desired continuous path can be generated precisely by an adjustable four-bar linkage. In this paper, a slider is used to adjust the pivot location of the driven side link. The linkage feasibility conditions and path generation flexibilities are analyzed. The synthesis model is established based on the optimal adjustment of the slider location. The global optimal solution is searched by genetic algorithm. The effectiveness of the synthesis approach proposed in the paper is verified by two demonstrated examples. [Copyright &y& Elsevier]