Mathematisches Modell

The theorem of Roberts on three-bar motion

Kurzbeschreibung: The model illustrates the theorem of Roberts, which says that to any given link quadrilateral with a certain three-bar curve two further quadrilaterals can be found which have the same three-bar curve. In his below mentioned paper A. Cayley gives the following construction, how to find a given link quadrilateral OABM with the coupled triangle ABC the two other link quadrilaterals, that have all the same three-bar curve.
In the given figure the parallelograms OACD and BMFC are drawn. Over the sides DC and CF two trinagles are constructed, which are similar to the triangle ABC, such that for their angles holds: angle CDE = angle FCG = angle BAC, and angle DCE = angle CFG = angle ABC. By drawing the parallelogram ECGN one gets the third fixed point N. These three link quadrilaterals that force the point C on the same three-bar curve are marked by different colours in the model.

Urheber*in: Stoll / Rechtewahrnehmung: Institut für Geometrie der Technischen Universität Dresden

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Location
Technische Universität Dresden, Institut für Geometrie
Collection
Mathematische Modelle, Technische Universität Dresden
Other number(s)
97612-000 (Objektnummer)
907/204 (Katalognummer)
Measurements
40 x 49 x 6 (in cm)
1750 (in g)
Material/Technique
Metal lacquered

Classification
Kinematics (Fachgebiet)

Event
Herstellung
(who)
Stoll (Hersteller)
Event
Sammeltätigkeit
(when)
23.09.1959

Last update
25.03.2025, 11:48 AM CET

Data provider

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Object type

  • Mathematisches Modell

Time of origin

  • 23.09.1959

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