I am a Distinguished Professor in the Department of Mechanical and Aerospace Engineering at the University of California, Irvine. I manage the web-page http://mechanicaldesign101.com where I try to collect useful information about machine design (https://en.wikipedia.org/wiki/Linkage_(mechanical) ). I also monitor Wikipedia articles on machine theory under the username Prof_McCarthy. If you see anything that needs correction, please let me know. For several years now, I have had my students use Geogebra to design the leg mechanisms for walking machines. You can see this work on my YouTube channel https://youtube.com/mechanicaldesign101/