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Shape Changing Mechanisms Solve Design Problems

19 September, 2014 (22:45) | design innovation | By: Chris McCarthy

A design problem that engineers frequently encounter is a curve that changes shape. For instance, take a spoiler on a high performance car. To get optimal performance, the downward force should be increased as the car takes a turn. An ideal way to achieve this is to allow the spoiler to change shape. This is no simple design task because an engineer wants the spoiler to remain a spoiler and do its job at every intermediary stage as it changes shape. To use another example, you don’t ever want a wing to stop being a wing. But you might want to enable a wing to change its shape during flight.

Professor Andrew Murray, Associate Professor Dave Myszka, and Dave Perkins (all of University of Dayton) and the students at University of Dayton’s Design of Innovative Machines Lab (DIMLab) are working on new technology to tackle these problems. Their work focuses on the theory and design of “morphing or adaptive structures” that can essentially change shape and still perform their function “through a wider range of operating conditions.” Design applications of this research include wings, extrusion dies, deformable mirrors for adaptive optics systems, morphing architectural structures, active aperture antennas, and (to come back down to Earth for a moment), pasta makers.

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Shape-Changing Wing with Internal Structure

Die design is an interesting manufacturing application of this research. A die is used in a manufacturing process where melted plastic or other such material, like pasta dough, is forced through a die in order to “form a long part of uniform cross-section” like tubes, pipes, molding — and fusilli. Professor Murray and his colleagues and students have applied their research to designing a die that can change shape as material is fed through it, enabling manufacturers to create new innovative products at low cost compared to other currently available technology like molding.

For more information on this research, visit DIMLab.  See video demonstrations of this technology here.  For reference material, see Persinger, J., Shmeideler, J., Murray, A., 2009, “Synthesis of Planar Rigid-Body Mechanisms Approximating Shape Changes Defined by Closed Curves.”

3D Printed Demining Training Aids

11 September, 2014 (18:32) | design innovation | By: Chris McCarthy

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Training people to diffuse landmines and other live ordnance left behind in conflict areas has always been a difficult thing. Successfully training Explosive Ordnance Disposal (EOD) Technicians requires hands-on education that gives the technician a true understanding of how a triggering mechanism inside live ordnance actually functions. For this reason, this kind of education requires effective training aids. The traditional training aids–either replicas or inert ordnance–are fragile, difficult to make, too intricate to be understood fully, hard to obtain in the case of inert ordnance, and impossible to ship internationally. Allen Tan from Golden West Humanitarian Foundation in collaboration with Asst. Professor Gim Song Soh and his students at Singapore University of Technology and Design have come up with an innovative solution to the problems this type of education presents.

They have created training aids that are engineered for a better understanding of how ordnance trigger mechanisms work. The plastic training aids display exact replicas of trigger mechanisms in cross-section, which gives the future ordnance disposal technician a better view of the kinds of mechanisms they will find in a real mine field. The AOTM devices are also resilient enough for classroom teaching.

aotm
How are these devices delivered to the various regions around the world where they are needed? They’re not. They’re 3-D printed. This innovation not only defeats the impossibility of shipping this kind of item all over the world, it also centralizes the construction of the devices in the region where they will be used. Countries benefit from this development of “sustainable indigenous assets capable of dealing with these issues as they are discovered” rather than putting the training in the hands of a third party (quote from Advanced Ordnance Training Materials by Allen Tan). It is a more sustainable way to run this kind of program.

Better training materials and affordable ways of providing them will lead directly to more effective—and safer–ordnance disposal programs around the world. The work that Professor Soh and his students at Singapore University of Technology and Design are doing with advanced ordnance teaching materials combines design innovation, active learning practice, and a forward-thinking embrace of 3D printing.

For more information please visit eodtrainingaids.com, Professor Gim Song Soh’s homepage, and an article written by Allen Tan.

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This animation prepared by Prof. Soh and his students illustrates the components of the SOTS-M2A1 trigger mechanism.

Wearable Robotics Put Spring in Your Step

4 September, 2014 (21:45) | design innovation | By: Chris McCarthy

Wearable electronics or “wearables” are seen as the next great wave of technology and commerce. Much of the popular talk about these kinds of products revolves around things like fitness trackers, augmented reality devices, and other machines you can wear that interact with, track, or add on to your experience with the world around you. Thomas Sugar, a professor at Arizona State University Polytechnic Campus and a wearable robotics expert works on a different kind of wearable.

Along with his colleagues and students, he has developed a new generation of powered prosthetic devices that can be used for rehabilitation and as prosthetics for amputees. He works on spring-based robots that enhance human mobility based on lightweight energy storing springs that allow for a more responsive and therefore more functional human gait. His devices make position control calculations 1,000 times per second to make the prosthetics as human as possible.

springactive-odyssey
Sugar starts from a “human being first” research perspective since his devices must be wearable and efficient. In his devices, spring power and motor power combine to create a powered system that gives prosthetic ankles the “push off” and “toe pick up” they need in order to mimic the function of human ankles.

His idea of a robotic tendon is much more efficient than a direct drive system, which would require more electricity and larger, more powerful motors.   In fact, his innovation uses half the required energy of a direct drive system powered prosthetic ankle.

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In a different device attached to the ankle Sugar uses able-bodied movement to harvest energy from walking. His company SpringActive developed a boot attachment with the military in mind that turns walking into back up power for batteries with negligible metabolic cost.

The real world and commercial applications for this kind of research are far reaching.   For more on Thomas Sugar’s and his colleagues’ work, visit SpringActive.com and http://innovation.asu.edu/

Singular Designs is now on-line

4 August, 2014 (04:17) | Engineering Data | By: Prof. McCarthy

MechGen 3

MechGen 3

Please see our Singular Designs web-site. We look forward to providing our MechGen synthesis software to simplify your linkage design process in SolidWorks. Also see Mechanism Generator.

Workshop on 21st Century Kinematics

28 July, 2014 (09:04) | Robotics Information | By: Prof. McCarthy

21st Century Kinematics

21st Century Kinematics

The NSF Workshop on 21st Century Kinematics at the 2012 ASME IDETC Conference in Chicago, IL on August 11-12, 2012 consisted of a series of presentations and a book of supporting material prepared by the workshop contributors.

The book is now available at amazon.com: 21st Century Kinematics–The 2012 NSF Workshop.

And here are the seven primary presentations given at the workshop.

  1. Computer-Aided Invention of Mechanisms and Robots. J. Michael McCarthy, Professor, University of California, Irvine.
  2. Mechanism Synthesis for Modeling Human Movement. Vincenzo Parenti-Castelli, Professor, University of Bologna.
  3. Algebraic Geometry and Kinematic Synthesis. Manfred Husty, Professor, University of Innsbruck.
  4. Kinematic Synthesis of Compliant Mechanisms. Larry Howell, Professor, Brigham Young University.
  5. Kinematics and Numerical Algebraic Geometry. Charles Wampler, Technical Fellow, General Motors Research and Development.
  6. Kinematic Analysis of Cable Robotic Systems. Vijay Kumar, Professor, University of Pennsylvania.
  7. Protein Kinematics. Kazem Kazerounian, Professor, University of Connecticut.

Colleagues joined in with two additional presentations:

Many thanks to the contributors and the attendees for an outstanding workshop.

Update: The presentation links have been fixed.

Mechanism and Robotics Notes

27 July, 2014 (17:50) | Commentary | By: Prof. McCarthy

The server in our UCI Robotics and Automation Laboratory has been revived (thank you Kaustubh). This means the links to course notes and to Mathematica notebooks have been reestablished. Synthetica.eng.uci.edu now links to my web-page which needs work. A laboratory page that will replace this soon.

Eight-bar motion amplifier

3 June, 2014 (20:17) | Linkage Animations | By: Prof. McCarthy

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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.

Rectilinear eight-bar suspension

17 April, 2014 (03:17) | Linkage Animations | By: Prof. McCarthy

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

Rectilinear eight-bar linkage

9 April, 2014 (19:57) | Linkage Animations | By: Prof. McCarthy

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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.

Six-bar linkage with rectilinear moving link

20 January, 2014 (23:15) | Linkage Animations | By: Prof. McCarthy



This is an animation of a Watt I six-bar linkage with a translating link that does not rotate (select the video to begin the animation). This is obtained using GeoGebra to execute a construction described by E. A. Dijksman in his book Motion Geometry of Mechanisms.