The French national project COBOT aims to generate a cooperation between a human and a humanoid robot in order to lift and carry a table. To fluidly performsuch interaction,a model of gaitis neededto mimic human trajectories.Thus, we investigate which trajectories are spontaneously chosen by humans during locomotionwith a given initial and final positions. Thetrajectories ofthe Body Center Of Mass (BCOM)were then generatedthanks to two models: one based on parametric curves called clothoids and the other using Optimal Control (OC). These models have been chosen because previous researchesalready showntheir closeness to human locomotion. Indeed,it has been demonstrated that clothoid arcs givegood approximations of human trajectoriesduring gait (Arechavaletaet al., 2008). These trajectoriesare also well fitted by an OC model established by Mombauret al.(2010).In order tocomparethe trajectories generated with these models to human trajectories, an original experimental setup wasmade in the context of this study. This work is meant to be implemented in the walking pattern generator of a humanoid TALOS to improve its interaction with a human beingbyplanning its real-time behaviour during gait.