This article focuses on the relation between workspace path geometry and the timing along the path, obtained via simple timing generators yielding constant end-link speed motion, natural motion, and two types of globally optimized joint velocity motions. The generators are designed within the Singularity-Consistent framework developed originally to tackle motion control in the vicinity of kinematic singularities. A comparative study highlights how performance expressed in terms of various kinematic and dynamic criteria of local (peak joint velocity and torque) and global (joint velocity/torque uniformity and total mechanical power) nature is influenced by the curvature of the path image in configuration space and by the vicinity of singular configurations. Results from simulations with a simple planar 2R limb and a spatial 3R positioning limb following linear and circular paths are presented.
This paper investigates the problem of attitude control for a rigid spacecraft. The main contribution of this paper is the design of an Euler-angle-based attitude controller. The design of the controller is based on the Singularity-Consistent notation. Therefore, the controller can handle the Euler angle singularity problem. Also, the controller guarantees an almost global exponential stability as long as the Euler angles can be defined. Numerical simulations are provided to illustrate the performance and show the effectiveness of the proposed controller for reduced-attitude maneuvers and large angle maneuvers.
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