MotionGen: An iOS and Android app for planar four-bar motion generation

MotionGen is an indigenously developed app for Apple iOS and Google Android platforms to help mechanism designers solve planar four-bar motion generation problem. The app is a computer implementation of authors' recent work in developing a unified framework for the synthesis and simulation of planar four-bar mechanisms for the motion generation problem. Simplicity, high-utility, and wide-spread adoption of planar four-bar linkages have made them one of the most studied topics in Kinematics leading to development of algorithms and theories that deal with path-, function-, and motion generation-problems. Yet to date, there have been no attempts to develop efficient computational algorithms amenable to real-time computation of both type and dimensions of planar four-bar mechanisms for a given motion. MotionGen solves this problem effectively by extracting the geometric constraints of a given motion to provide the best dyad-types as well as dimensions of a total of up to six four-bar linkages. The unified algorithm also admits additional practical constraints, such as imposition of fixed- and moving-pivot and -line locations along with mixed exact- and approximatesynthesis scenarios. In that regard, its synthesis capabilities set it apart from other softwares of its ilk. However, its simulation approach also departs from more traditional methods, which typically involves assembling four rigid bodies and then designating fixed and moving links. Instead, the MotionGen requires users to assemble only two of the geometric constraints of mechanical dyads for quick prototyping of planar four-bar linkages. The app is equipped with an intuitive graphical user interface that allows a fluid dialog with the user to facilitate rapid manipulation and visualization of linkages.