Abstract
Passive-dynamic walkers are mechanical devices that walk down a slope without being propelled by motors or controllers. In this paper we present the design of two different knee mechanisms intended for use with such walkers. At first we developed a knee mechanism that uses permanent magnets to lock the knee in the extended position and conducted walking experiments with a planar passive-dynamic walker, which was built beforehand. The walker moved down an incline and we counted the steps that it made. After performing several hundred trials we developed our second knee mechanism featuring an active release from the extended position and performed the same experiments with the same walker outfitted with the new mechanism. We compared the results achieved with the two different knee mechanisms. The active mechanism made an increased number of successful walks down the slope from which we concluded that it is more reliable and easier to use and set up than the one with permanent magnets.
