This manuscript present my research activities on real-time vision-based behaviors for complex robots such as humanoids. The underlying main scientific question structuring this work is the following: "What are the decisional processes which make possible for a humanoid robot to generate motion in real-time based upon visual information ?" In soccer humans can decide to kick a ball while running and when all the other players are constantly moving. When recast as an optimization problem for a humanoid robot, finding a solution for such behavior is generally computationally hard. For instance, the problem of visual search consider in this work is NP-complete. The first part of this work is concerned about real-time motion generation. Starting from the general constraints that a humanoid robot has to fulfill to generate a feasible motion, some core problems are presented. From this several contributions allowing a humanoid robot to react to change in the environment are presented. They revolve around walking pattern generation, whole body motion for obstacle avoidance, and real-time foot-step planning in constrained environment. The second part of this work is concerned about real-time acquisition of knowledge on the environment through computer vision. Two main behaviors are considered: visual-search and visual object model construction. They are considered as a whole taking into account the model of the sensor, the motion cost, the mechanical constraints of the robot, the geometry of the environment as well as the limitation of the vision processes. In addition contributions on coupling Self Localization and Map Building with walking, real-time foot-steps generation based on visual servoing are presented. Finally the core technologies developed in the previous contexts were used in different applications: Human-Robot interaction, tele-operation, human behavior analysis. Based upon the feedback of several integrated demonstrators on the humanoid robot HRP-2, the last part of this thesis tries to draw some directions where innovative ideas may break some current technical locks in humanoid robotics.
