Abstract
The most important feature of this paper is to transform the complex motion of robot turning into a simple translational motion, thus simplifying the dynamic model. Compared with the method that generates a center of mass (COM) trajectory directly by the inverted pendulum model, this method is more precise. The non-inertial reference is introduced in the turning walk. This method can translate the turning walk into a straight-line walk when the inertial forces act on the robot. The dynamics of the robot model, called linear inverted pendulum (LIP), are changed and improved dynamics are derived to make them apply to the turning walk model. Then, we expend the new LIP model and control the zero moment point (ZMP) to guarantee the stability of the unstable parts of this model in order to generate a stable COM trajectory. We present simulation results for the improved LIP dynamics and verify the stability of the robot turning.
Highlights
The basic functionality required for humanoid robots is the ability to achieve various human movements
The input of the state space of the linear inverted pendulum (LIP) system can be expressed as xIRF = [ xcom com zmp system is the velocity of the zero moment point (ZMP):
For the humanoid robot walk, what we need is the trajectory in the world coordinate reference so we need to convert the trajectory in the Inertial Reference (IRF) into the trajectory under the world coordinate reference
Summary
The basic functionality required for humanoid robots is the ability to achieve various human movements. In the trajectory planning method, the ZMP is seen as a linear inverted pendulum (LIP) which is a simplified model. The robot is regarded as a point, and the entire mass is concentrated at the center of the mass Another trajectory planning method considers the humanoid robot as a seven-link model. Newer gait-planning methods [9,10,11,12,13] have been developed that do not rely on the ZMP and have produced marked improvements in humanoid robot walking. Most research has applied straight-line walking models directly to the turning walks [24] This method does not take into account the effect of the robot’s own rotation on the actual ZMP so in the lateral direction, the actual ZMP will be different form the planned ZMP.
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