Lawrence Funke and Prof. James Schmiedeler of the University of Notre Dame Locomotion and Biomechanics Lab show that the movement of a morphing linkage through its target profiles can be improved by coordinating actuation of the sub-chains. This was presented at the Mechanisms and Robotics Conference which was part of the 2015 ASME Design Engineering Technical Conferences, August 2-5, in Boston, MA. The video below shows the improvement obtained by moving from 1 to 3 coordinated actuators.
Animations of linkage movement.
Prof. Andrew Murray and his team at the Design of Innovative Machines Laboratory have developed a dynamic extrusion die that changes shape while in operation. This provides a new capability for rapid manufacture of innovative geometry for metal and plastic bars, channels, hoses, and more. For more information see his laboratory website, University of Dayton DIMLab.
This video provides an extreme introduction to the DIM Lab at the University of Dayton.
An outcome of Mark Plecnik’s research on the kinematic synthesis of six-bar linkages is a variety of designs for the leg mechanisms of small walking machines.
We hope to build this walker over the summer. It has one drive motor on each side:
This is my favorite because it couples the legs on one side with a pantograph linkage. The leg joints are living hinges. and it seems this the entire leg system can be cut from a single sheet of plastic:
This is a design study for a walker with eight legs on one side, 16 total:
This is a little more compact version of the six-bar folding linkage that Kaustubh Sonawale found using MechGen 3.0.
This six-bar linkage was designed to deploy and stow a structure. It was developed by Kaustubh Sonawale to demonstrate the capabilities of MechGen 3.0.
This port closure tool curls back on itself to provide internal stitches to close a trocar port used for non-invasive surgery. This is the result of a collaboration between Kaustubh Sonawale and Jon Stokes.
Select this link, Four-bar linkages, for a Geogebra book that illustrates linkages ranging from a lever to a crank-rocker that open a door. This includes the construction of a four-bar linkage that coordinates the open and closed positions with specific input crank angles, called a four-bar function generator. The iPad application, MechGen FG, computes four-bar function generators for five coordinated values of the input and output cranks.
Please select this link to open the Geogebra Book containing constructions of a number of interesting linkages. This is an introduction to the useful movement available with articulated systems.
Mark Plecnik shows that six-bar function generators can be used to drive a serial chain and produce a realistic wing flapping gait. Using trajectories obtained through video analysis by researchers Bret W. Tobalske and Kenneth P. Dial, “Flight Kinematics of Black-billed Magpies and Pigeons Over A Wide Range of Speeds,” Mark constructed functions for the joints of the serial chain, designed the function generators, and animated the results. Select this link for more information on Mark Plecnik and his work.
Researchers at Disney Research Zurich provide yet an other design system with the goal of moving digital character design into physical form. This work by Vittorio Megaro (ETH Zurich) and Bernhard Thomaszewski (Disney Research Zürich) and their colleagues can be viewed as two-position synthesis of four-bar “joints” that connect bodies in a serial chain, which are then driven by a sequence of four-bar function generators. They 3D print the result to obtain a cartoon character that moves with the rotation of a crank. Select this link for more information.