RESUMO
In order to achieve a high speed of skating robot based on the leg structure - with passive wheels on even ground - the motion characteristics of human roller skating are studied in this paper. Utilizing a three dimensional motion capture system, the linear and turning gait are analyzed to express the motion characteristics of human roller skating. According to the observation and analysis, the normal linear gait can be divided into four phases and normal turning can be divided into three phases. The spin angle between the sagittal plane and the roller skate of the supporting leg is mainly generated by the external/internal rotation of the hip joint instead of the ankle, and the spin angular velocity of the body with one supporting leg is mainly generated by the roller angle of passive wheels. A new model we named the 'skating inverted pendulum' - based on the motion and angle features of the roller skating gait - is presented, which can be used to describe the characteristics of one supporting leg. The structure of roller skates and how they improve stability for roller skating, and the method of turning with a small radius are discussed.