Active knee-release mechanism for passive-dynamic walking machines and walking cycle research

Passive-dynamic walkers are mechanical devices that walk down a slope without motors or controllers. In this paper we present our research in two distinctive parts. First, a design improvement on the classical four-legged passive-dynamic walking machine and second, an investigation on the timing of different stages in the human walking cycle and comparison of the results with the results obtained from our walker. We built a four-legged passive-dynamic walking machine with its inner and outer legs connected rigidly two by two, making it equivalent to a biped machine from a dynamics point of view. It features a new mechanism for an active release of the locked extended knee instead of using the more common knee-locking via suction cups mechanism. We conducted a series of experiments with this modified walker in which we counted the steps it made while walking down an incline. We compared the results with a previous design of the knee-locking mechanism that used permanent magnets. The improved model made an increased number of successful walks down the slope from which we concluded that the new active release mechanism is more reliable and easy to use and set up. For the walking cycle investigation, we put visual markers on a person walking casually down the same slope that we used for the walker experiments. We took a video of that person and measured the times between different events in one walking cycle. We calculated the average time intervals and made a comparison between the test subject and our walker within one cycle. We feel the timings derived from this investigation can be used to make the gait of our walker more human-like.