Various Gaiting Encounters and Counterbalance for a Humanoid Robot Based on Five-Mass with Angular Momentum Model

Robotics field have been a glowing research topics. Many conventional mobile robots are designed as wheeled type that are limited to the simple work and environment. But, as the mechanism and computer science are improved, humanoid robots are capable of handling more complicated works and co-work with human. To make sure the robot works well in that environment, walking stability plays an important role for this issue. The zero moment point (ZMP) theory has been proposed for determining whether robots fall down or not, i.e. stable or not. If the ZMP is outside of the footprint polygon, the bipedal robots might fall down or unstable. Linear inverted pendulum model (LIPM), regarded as the one-mass model, simplifies whole masses as a mass point. In order to reduce modeling errors LIPM has been implemented, and the three-mass model and multiple-mass inverted pendulum model (MMIPM) are developed. In addition to these researches, to reduce the error caused by the rational momentum and limited linear momentum, improved model with a flywheel showing embodiment of the centroid moment of inertia replaces single LIPM. To improve the accuracy of model and coherence to our mechanism, we further propose the five-mass with angular momentum model that combines the three-mass model and law of conservation of angular momentum. The proposed model not only considers the effect of rotational momentum, but also takes arm movements into account. In other words, as we design the leg motion, the balance of the moment of momentum through two arm motion is estimated in a meantime. Therefore, the research tends to simplify the high degrees-of-freedom actuator system to a simple model based on the ZMP theory mentioned in this thesis. To examine the performance of the proposed model, we further design different levels of motions. In this thesis, we have different motions, such as kicking, straight path walking, sudden changes of stride length, arbitrary curved path walking, and patterns with different waist height, etc. In summary, an effective walking pattern generator based on the five-mass with angular momentum model is proposed. The proposed model consists of two parts: the five-mass model simplified from a high degrees-of-freedom actuator system, and the balance of the rotational momentum while was not taken into consideration in previous researches. We utilize upper limbs, including arms and the trunk, to counterbalance the rotational momentum caused by lower limbs. The balanced motion is effective to reduce the modeling errors, and improves the ZMP tracking performance.