Omnidirectional Walking and Active Balance for Soccer Humanoid Robot

Soccer Humanoid robots must be able to fulfill their tasks in a highly dynamic soccer field, which requires highly responsive and dynamic locomotion. It is very difficult to keep humanoids balance during walking. The position of the Zero Moment Point (ZMP) is widely used for dynamic stability measurement in biped locomotion. In this paper, we present an omnidirectional walk engine, which mainly consist of a Foot planner, a ZMP and Center of Mass (CoM) generator and an Active balance loop. The Foot planner, based on desire walk speed vector, generates future feet step positions that are then inputs to the ZMP generator. The cart-table model and preview controller are used to generate the CoM reference trajectory from the predefined ZMP trajectory. An active balance method is presented which keeps the robot's trunk upright when faced with environmental disturbances. We have tested the biped locomotion control approach on a simulated NAO robot. Our results are encouraging given that the robot has been able to walk fast and stably in any direction with performances that compare well to the best RoboCup 2012 3D Simulation teams.