Full Sized Folding Bicycle

Folding Bicycle

Folding Bicycle

Michael Sutherland and his team at Zennen Engineering designed this full-size folding bicycle that has a dramatically different folding action from current designs.

Montague Bikes provides a popular line folding full sized bicycles, which fold sideways around the seat tube.

Zennen Engineering has a new concept that they are kind enough to say was inspired by our UCI Folding Structure. This new design rotates the rear wheel support around the bottom bracket, and folds the front forks against the down tube and seat tube to form a compact package. It is a unique movement.


Jon Stokes, in our Robotics and Automation Lab, helped by adding the four-bar function generator to combine the two folding actions. It is a great concept, and it will be interesting to see if it achieves commercial success.

Four-bar Extrusion Die

Fourbar Extrusion

Fourbar Extrusion

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.


Walking Machines

Leg Mechanisms

Leg Mechanisms


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:

UCI Folding Structure

Another version of a six-bar folding linkage

Another version of a six-bar folding linkage

This is a little more compact version of the six-bar folding linkage that Kaustubh Sonawale found using MechGen 3.0.

A six-bar linkage designed to fold a structure

A six-bar linkage designed to fold a structure

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.

Port Closure Eight-Bar

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.

Long Travel Six-Bar Suspension

Long travel suspensions

Long travel suspensions

Mark Plecnik has applied his research on the design of six-bar linkage function generators to the challenge of a long travel independent suspension for an off-road vehicle. UCI race car engineering students built a 1/5 scale model of his latest design and compared its performance to his calculated design. For more detail see his video:


A Six-bar Linkage for Wing Flapping

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.

Rectilinear Motion using and Eight-Bar Linkage


Kaustubh Sonawale and Yang Liu worked together on this design study for a micro-mechanical motion amplifier. It is an interconnected set of three eight-bar linkages.

This is a design concept for a rectilinear eight-bar suspension. It does not manage body roll but it does provide compact large travel.


This animation was prepared by Yang Liu for a linkage designed by Kaustubh Sonawale. The eight-bar linkage guides the platform in the approximation to rectilinear motion.

Mechanical Calculation of the Ballistic Function


This Stephenson III six-bar linkage sets the elevation of a ballistic trajectory to reach a specified distance downrange given an initial velocity of 500 m/s. This function is described in Computing Linkages by A. Svoboda (pg 285). Mark Plecnik obtained this linkage after evaluating almost 100,000 different designs.