This is a fascinating subject. I stumbled into it (without knowing of Chebyshev) while playing with a "lego walker" back in 2018. Even did a couple of blog posts [0,1] (in danish, and mostly for my own benefit) exploring the geometry.

Only recently did I learn of the Chebyshev linkage, which has a "lambda variant" [2] is basically what I was looking for in the walker (except it needs to be upside down, as in Chebyshevs own "walker" or "plantigrade" [3]).

[0]: https://hack42.dk/2018/04/lego-walker/ [1]: https://hack42.dk/2018/04/geogebra-og-gaamaskiner/ [2]: https://en.wikipedia.org/wiki/Chebyshev_lambda_linkage [3]: https://en.wikipedia.org/wiki/File:Tchebyshevs_plantigrade_m...

(Edit: formatting)