Analysis of the motion
of planar mechanisms

Kinematics, Dynamics, Optimization

Computer Program developed by
dr. A.J. Klein Breteler
(retired from TU Delft, Netherlands)

The program is able to calculate the motion of any multi-link mechanism type. Not only kinematic transfer functions and derivatives with respect to input, but also the velocity and acceleration of any moving point of any element, and many other kinematic properties. In dynamics mode the (internal) forces, deformations and natural frequencies can be determined. In optimization mode the kinematic link dimensions can be calculated to fulfill a desired motion, specified with transfer functions, in the best possible manner. The theory is described in the lecture notes of the former course wb3303 'Mechanisms', taught at TU Delft until 2005. The (English) text can be downloaded as  PDF-file 

Input-command file

Before RUNMEC can be started an input-command file must be created. It must be a pure ASCII file, to be edited for instance with Notepad. The input command file describes, by means of some tables, the topology (structure) of the mechanism, its initial position, the requested output and the motion of the input link.
Output of the program consists of a logfile, animation on screen and user defined output like graphs and tabular functions. To give an impression an
example of such an input-command file can be viewed.
An extensive description of how to make an input-command file is presented in the manual, which can be downloaded as pdf-file, see below.


After start-up of the program the name of the input-command file must be entered (suggested extension: .mec). Suppose the name of this file is problemx.mec, then the name of the logfile will be suggested as problemx.out. In case of syntax errors in the input-command file or in case of calculation errors, like an immovable mechanism, a message will be written to the message area on screen and to the logfile.
The kinematic scheme will be the first result presented on screen. It is just an input-echo meant for graphical verification of the element description in the tables. The button "Adjust" is the only possible user action now; pressing it invokes the set-up of the equations and matrix inversion. In case of an illegal mechanism model this step will fail. When the adjustment to the initial position has been successful, the button "Run" can be activated. Now the calculation of transfer functions etc. starts.
During the calculation of the motion the mechanism will be drawn in all positions. When the last position has been reached, the graphs are ready to be viewed on the screen.
Using the right mouse button in the drawing area all graphical screen images can be zoomed, printed, copied to clipboard, saved (as windows metafile, file extension .emf) etc. 
New in Runmec version 5.0:  animation of the mechanism applying shapes (predefined parametric drawings of the links, see picture above, right).

Download of RUNMEC

The software runs under Windows XP and later. For educational and non-commercial use the software is free without any limitation. See for details the conditions for use 

Click the first button below for a download of the program. The file must be unzipped in a directory of your choice. The file Runmec54.exe is the actual program. In addition a number of examples of input-command files (sub-directories demo1...demo10) is available. They concern the examples described in the user manual RN_usman54.pdf. 
It is recommended to keep your own input-command files in separated sub-directories. 
Some utility programs are available for use with the products of Runmec:
    - PictFOB to view the results of a picture project file according the PION specification (Function OBjects or FOB's can  be created by Runmec),
    - FOBtools to create/edit a periodic function consisting of a chain of standard functions (as can be used by Runmec)
    - MTFview to view a graphics metafile according the GMS specification (as can be created by Runmec).

Click here for a download of Runmec 54, the manual and the examples (1.7MB)

Click here for a download of the utility programs (PictFOB, FOBtools and MTFview, 1.5 MB) 

NEW:  Runmec 5.4 has been configurated for a parallel development at the Windows10 platform. To distinguish the name Runmec54_XE will be used. This parallel product has indentical functionality, but does not run under Windows XP. Except for Windows10, this parallel version should also run under Windows 7 and 8, but this has not yet been tested. Is there anybody who likes to test the parallel version? Results will gratefully be received at the e-mail address below.

Click here for a download of Runmec54_XE - for Windows10 -(4,5MB)

Release history:

February 26, 2003: new release 3.4 issued, improving checks in input file and error messages
August 18, 2004 : Updated lecture notes available
October 6, 2004: new release 4.0
November 19, 2004: release 4.1 (update, improvements concerning pictures on the screen)
February 1, 2007: release 4.2 – 4.4, in which variable names and a formula editor can be used in the input command file. Further many improvements have been made in this new version
December 2007: release 4.5, new features concern friction forces and reading external forces from file.
February 2009: release 4.6, improvements on the optimization part (extensive checks in input file, bug fixed in first order motion conditions).
November 2012: release 4.7, use of units, improvement of pictures (fonts, line width, grids), saving of picture project.
March 2016: release 5.0, new feature: animation with shapes, new element type HB2.
January 2017: release 5.1, same functionality, some bugs removed, safer handling of some exceptions
February 2017: release 5.2, new animation features: interactiv display of evolutes, hodographs, polhodes, Bresse Circles
January 2018: release 5.3, input file more user friendly: definition of elements and co-ordinates by a name, free line sequence within tables
February 2019: release 5.4,  reaction forces at the frame added (new in 5.4);  bug when using the Beam element removed; shapes of the elements Beam and Unit updated

Last update: January 25, 2019

Remarks about Runmec can be addressed to:

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