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2017 ASME Mechanisms and Robotics Conference

July 28, 2017/by Prof. McCarthy

The program for the 2017 ASME Mechanisms and Robotics Conference is now on-line. You can access it at the link: ASME MR Conference

The papers from the UCI Robotics and Automation Lab are:

Design of Wearable Lower Leg Orthotic Based on Six-Bar Linkage by Shramana Ghosh;
The Design and Manufacture of a Gear-Coupled Serial Chain to Trace the Butterfly Curve by Yang Liu;
Design of a Spatial Six-Bar Flapping Wing Mechanism for Combined Control of Swing and Pitch by Peter Wang

2017 MR Conf Program

Design Research in China: Changzhou

March 12, 2017/by Prof. McCarthy

Our trip through China concluded at a conference and workshop at Changzhou University. This video highlights the Changzhou conference on innovation in Robotics and Intelligent Manufacturing, the beauty of the city of Changzhou, and a rainy night in Shanghai.

Our colleagues in China can see this video on YouKu at: Design Research in China: Changzhou

Changzhou YouKu

Design Research in China: Dalian

December 31, 2016/by Prof. McCarthy

Design Research Dalian

This is the third of five videos highlighting design research across China. This captures the beauty of Dalian, a city on the Yellow sea, and the excellent research in precision machine design by colleagues and their students at Dalian University of Technology.

Here is a link to this video on Youku for our colleagues in China:
http://v.youku.com/v_show/id_XMTg5MDg4MzI0NA==.html

Youku Dalian

Design Research in China: Xi’an

December 13, 2016/by Prof. McCarthy

Design Research Xian

This video of our visit to Xi’an captures the beauty of the city and its surroundings, as well as the personality of the excellent professors and students at Xidian University.

For our colleagues in China, here is a link to a Youku version of this video: http://v.youku.com/v_show/id_XMTg2MzQ5NDI4MA==.html

Youku Xian Video

Prototype of the Trifolium Mechanism

December 13, 2016/by Prof. McCarthy

Trifolium prototype

Yang Liu and Peter Yang designed and built this physical prototype of our Trifolium mechanism. It is fabricated from ABS using the Stratasys Fortus system in UCI’s Institute for Design and Manufacturing Innovation.

Our Chinese colleagues can view this video on Youku at the link: http://v.youku.com/v_show/id_XMTg2MzQ2MjE5Mg==.html

Youku Trifolium Prototype

Design Research in China: Tianjin

November 24, 2016/by Prof. McCarthy

Design Research Tianjin

Chris McCarthy filmed and edited this video of our visit to Tianjin, which showcases the design research in mechanisms and robotics at Tianjin University and captures the energy and beauty of the city and its people.

For our colleagues in China this video is available on youku.com: http://v.youku.com/v_show/id_XMTgzMTIyMTg1Ng==.html

Youku Design Tianjin

Manufacturing Prototype for the Butterfly Linkage

November 23, 2016/by Prof. McCarthy

Prototype Butterfly Linkage

This animation is taken from Yang Liu’s detailed design drawings for the manufacturing prototype of the Butterfly Linkage. The component parts are to be constructed by additive manufacturing.

This animation includes the music of Explosions in the Sky:

For our colleagues in China this animation is available through youku.com: http://v.youku.com/v_show/id_XMTgzMzA5ODQyOA==.html

Youku Prototype Butterfly

Design of Drawing Mechanisms

October 20, 2016/by Prof. McCarthy

Mechanical systems that draw trigonometric curves provide a versatile way to draw complex curves. Yang Liu designed this serial chain consisting of 14 links coupled by a belt drive to draw the Butterfly curve.

The Butterfly curve is an example of a trigonometric plane curve, and our study of Kempe’s design of linkages to draw algebraic curves has lead us to a way to design serial chains that draw these curves.

Here is how it is done.

Butterfly curve

Trigonometric curves. A trigonometric plane curve is a parametrized curve with coordinate functions, P = (x, y), that are finite Fourier series,

Trigonmetric equation

where a_k , b_k , c_k and d_k are real coefficients and theta ranges from 0 to $latex 2\pi$.

A large number of well-known curves have this form, such as Limacon of Pascal, the Cardioid, Trifolium, Hypocycloid and Lissajous figures.

A coupled serial chain. Without going into too much detail, it is possible to use the coefficients a_k , b_k, c_k and d_k to define the link dimensions,

Link dimensions

and the initial angles,

Initial angles

These parameters allow us to redefine the trigonometric equations of the curve as the coordinate equations of the links of a serial chain,

Serial chain equations

This equation identifies the curve as the end of a serial chain consisting of a sequence of links L₁, M₁, L₂, M₂ and so on, such that the L_k links rotate counter clockwise and the M_k links rotate clockwise both at the rate $latex k\theta$.

The initial angles define the configuration of the serial chain when $latex \theta=0$.

The Butterfly drawing mechanism. The trigonometric curve of the Butterfly linkage is defined by the coefficients in the following table,

Table of Butterfly coefficients

These coefficients are used to calculate the dimensions and initial configuration of the serial chain listed in the following table,

Table of Butterfly link dimensions

The result is a serial chain consisting of 14 links that are coordinated to move together as the base rotates. The end-point of the chain draws the Butterfly curve.

Butterfly drawing mechanism

2016 Mechanisms and Robotics Conference

August 13, 2016/by Prof. McCarthy

Symposia organized for the 2016 Mechanisms and Robotics Conference

The 2016 Mechanisms and Robotics conference is part of International Design Engineering Technical Conferences organized by ASME International in Charlotte, North Caroline, August 22-24.

Plenary speaker Bernard Roth is the Academic Director of Stanford University’s d.school and the author of the Achievement Habit.

For some reason, ASME has broken these links to the 2016 IDETC conference, but you can find out more about each of the symposia at the conference overview link: 2016 ASME Mechanism and Robotics Conference Overview. Then select the Expand all Symposia Link to see the sessions and a list of papers.

Motion Gen Linkage Design App

August 8, 2016/by Prof. McCarthy

MotionGen is a planar four-bar linkage simulation and synthesis app that helps users synthesize planar four-bar linkages by assembling two of the planar RR-, RP- and PR-dyad types, (R refers to a revolute or hinged joint and P refers to a prismatic or sliding joint).

The input task is a planar motion given as a set of discrete positions and orientations and the app computes type and dimensions of synthesized planar four-bar linkages, where their coupler interpolates through the given poses either exactly or approximately while minimizing an algebraic fitting error. The algorithm implemented in the app extracts the geometric constraints (circular, fixed-line or line-tangent-to-a-circle) implicit in a given motion and matches them with corresponding mechanical dyad types enumerated earlier. In the process, the dimensions of the dyads are also computed. By picking two dyads at a time, a planar four-bar linkage is formed. Due to the degree of polynomial system created in the solution, up to a total of six four-bar linkages can be computed for a given motion.

MotionGen display

MotionGen also lets users simulate planar four-bar linkages by assembling the constraints of planar dyads on a blank- or image-overlaid screen. This constraint-based simulation approach mirrors the synthesis approach and allows users to input simple geometric features (circles and lines) for assembly and animation. As an example of the Simulation capabilities of the app, Figure shows a walking robot driven by two sets of planar four-bar linkages where the foot approximately traces a trajectory of walking motion. The users can input two dyads on top of an imported image of a robot or machine to verify the motion and make interactive changes to the trajectories.

Anurag Purwar describes MotionGen and its applications in this video:

MotionGen is available as a free download at both Google Play- and Apple’s iTunes-Stores.