Foot placement indicator for balance of planar bipeds with point feet

When humanoid robots are going to be used in society, they should be capable to maintain the balance. Knowing where to step appears to be crucially important to remain balanced. In this paper we contribute an algorithm for planar bipeds with point feet and an arbitrary number of non-massless links that can compute the foot step location such that bipedal balance is maintained. We call this algorithm the foot placement indicator (FPI). It is based on the foot placement estimator (FPE) and uses conservation of energy throughout the step taking into account the instantaneous impact dynamics at foot strike. A simulation case study on a five-link planar biped shows the effectiveness off the FPI.