Influence of the number of humanoid vertebral column pitch joints in flexion movements

This paper deals with 2D simulations of a humanoid robot equipped with back bone pitch joints to study the advantages of having such a mechanism for daily human-like movements. The movements under investigation here involve knee flexion for sitting down on a chair or picking up objects on the floor. The model used for the humanoid robot is based on a kid-sized human body. The trunk is decomposed into a thorax and a lumbar part. As the lumbar region is the most mobile part in the human vertebral column, vertebrae are only placed in the robots lumbar part. Simulations are carried out in the sagittal plane to investigate the influence of the number of vertebra pitch joint on the movements. Results show that a number of two pitch joints is a good tradeoff in matter of work at hip and thorax inclination.