There exist three main resolution approaches to address the three types of synthesis problems explained above: graphical, analytical, and optimization-based methods. This work also proposes a new method to represent paths: normalized shape-descriptor vector(s) (NSDV(s)), which are similar to turning functions but simpler to define. Despite not being widely used in mechanism synthesis yet, they are promising strategies according to the results found by the referred authors. Another valid option considered for this purpose is the use of Fourier descriptors . For instance, Nadal et al. propose to use turning functions , which are popular for pattern recognition ,, , to compare paths. For this reason, there exist alternatives to describe paths regardless of their size and position. However, these variations might not prevent the engineer from accepting the studied configuration after transforming its variables adequately. This strategy is straightforward yet limited: It cannot appreciate similarity when the path produced by the considered mechanism is either translated, rotated or scaled with respect to the reference. In this context, it is common to use the Euclidean distance between the points of both curves to define the cost function ,, , which is known as an absolute error-based metric. This work deals with path synthesis, which requires minimizing the difference between the desired path and the one described by the coupler point of the linkage. Walking machines and machining tools are some fields in which this kind of problem arises. These angles can be either part of the requirements, leading to a prescribed-timing problem, or can be freely chosen by the designer. Concerning path synthesis techniques, they focus on the motion described by a specific point of a linkage, referred to as the coupler point, for a given set of input angles. For instance, this strategy is valuable for loading machines and airplane high-lifts . In motion synthesis, the goal is to control the movement of the coupler link, also known as the floating link or connecting rod, including its position and orientation. Automobile steering systems and solar trackers are application examples of this approach. Depending on the requirements, this second approach can be further classified into function, motion, and path synthesis, which are explained below.įunction synthesis techniques focus on defining a relation between the crank input angles and the angular displacement of the rocker, which usually acts as the output link of the mechanism.
On the contrary, synthesis deals with initially determining their geometrical parameters to perform the desired motion. In both cases, the analyzed mechanisms must have been previously designed. Analysis may focus on (i) kinematics, that is, the movement that mechanisms describe without attending forces, and (ii) dynamics, i.e., when considering forces and inertial parameters. There exist two different approaches for studying them: analysis and synthesis. According to the results achieved, it arises as a valuable tool in terms of accuracy, convenience, and availability.įor years, four-bar mechanisms, also known as linkages, have been widely used in industrial and everyday applications.
#Long path tool open source software#
The software package has been used for addressing six well-known problems from the literature. This method, referred to as normalized shape-descriptor vector(s) (NSDV(s)) and presented in this paper, allows us to handle paths without being affected by translation, rotation, and scale changes. It also includes a new method for expressing and comparing paths, and hence, to define the optimization criterion. This tool offers four different optimizers from the literature, one of them specially designed for mechanism synthesis. This paper presents SALAR Mechanism Synthesizer, a new open-source software package that aims to be an easy-to-use yet powerful tool for addressing this kind of problem. It consists in calculating the length of the bars defining a mechanism so that a particular point of its structure follows the desired trajectory. In this area, path synthesis is a common problem.
Four-bar mechanisms are widespread in industrial and quotidian applications, but their design requires deep knowledge and experience in Mechanisms and Machine Theory.
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