Model 04: straight line mechanism according Watt
Kinematic scheme:
Dimensions:
|
|
Measured at
model [m] |
optimized |
|
a |
0.27 |
0.2533 |
|
b |
0.27 |
0.2533 |
|
c |
0.13 |
0.1202 |
|
d |
0.492 |
(0.492) |
|
e |
0.12 |
(0.12) |
Explanation:
Point C, half way at the coupler bar, traces a 8-shaped
curve (lemniscate). This curve has two parts that approximate a straight line.
None of the links can make a full rotation. Main application: as a (passive)
kinematic guidance along a line, instead of a rail or slot. The advantage is
that only rotational joints are used and thus problems with dust, play, wear, frictional
forces etc. can be avoided.
Literature:
Remarks:
The optimization was performed with the computer
program Runmec. The optimized dimensions show a somewhat better approximation
to the straight line. The drawing is on scale using the measured model
dimensions.