Chebyshev-like N=4 Polygon Wheel
90° span (not 180° span) Chebyshev linkage application.
Chebyshev N=2 Polygon Wheel ----- ①
This N=4 apparatus comes from above wheel. same analogy.
Can you have an inspiration from ① picture? (It depends on personal mathematical sense/ ability. (?))
cf. Chebyshev Linkage Wheel ---- ②
standard Chebyshev linkage angle is from 0° (too acute) to 180° angle --- this is inferior to.
From stability view, this property is bad.
But above implementation, angle is always moderate (not extremely value), so stable structure it is.
So, I think above algorism is superior to ② algorism.
■ More precise bar ratio
above I used, 4 (stride), 4 (height), 2√10 (=6.32, X-xbar), 4√2(=5.66, upper-bar), coordinator 2, 4
cf. 90° Chebyshev like straight line linkage Tuning
but more precise straight line ratio is
4 (stride), 3.66 (height), 6.5 (X-bar), 6.76 (upper-bar),
and, coordinator 2, 4.53 [coordinator is other value is OK]