Adaptive and Singularity-Free Inverse Dynamics Models for Control of Parallel Manipulators With Actuation Redundancy
Adaptive and Singularity-Free Inverse Dynamics Models for Control of Parallel Manipulators With Actuation Redundancy
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DOI：
10.1115/detc2011-47943
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
A. Müller;T. Hufnagel
中科院分区：
文献类型：
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作者：
A. Müller;T. Hufnagel
冗余驱动是并联机床消除输入奇异、扩大可用工作空间的一种方法。从运动学的观点来看，致动器坐标的数量m超过冗余致动PKM（RA-PKM）的DOF δ。动力学模型是基于模型的控制的基础，通常用δ独立执行器坐标表示。这意味着，该模型表现出相同的奇异性作为非冗余PKM，即使RA-PKM是不奇异的。因此，RA-PKM模型的容许运动范围仅限于非冗余PKM。在本文中，另一种制定的动力学模型中的全套m致动器坐标。它导致一个冗余系统的m运动方程，是有效的，在整个范围内的运动。这个配方产生了一个逆动力学配方定制的实时实施。与独立坐标系中的标准公式相反，所提出的逆动力学公式不涉及控制矩阵的零空间中的控制力，即，它不允许产生内部预应力。这不是问题，因为后者通常不被利用。所提出的方法相比，最近提出的自适应坐标切换方法。实验结果表明，如果逆动力学解决方案被引入到基于模型的计算扭矩控制方案的平面2DOF RA-PKM.Copyright © 2011 by ASME
Redundant actuation of parallel kinematics machines (PKM) is a way to eliminate input-singularities and so to enlarge the usable workspace. From a kinematic point of view the number m of actuator coordinates exceeds the DOF δ of a redundantly actuated PKM (RA-PKM). The dynamics model, being the basis for model-based control, is usually expressed in terms of δ independent actuator coordinates. This implies that the model exhibits the same singularities as the non-redundant PKM, even though the RA-PKM is not singular. Consequently the admissible range of motion of the RA-PKM model is limited to that of the non-redundant PKM. In this paper an alternative formulation of the dynamics model in terms of the full set of m actuator coordinates is presented. It leads to a redundant system of m motion equations that is valid in the entire range of motion. This formulation gives rise to an inverse dynamics formulation tailored for real-time implementation. In contrast to the standard formulation in independent coordinates, the proposed inverse dynamics formulation does not involve control forces in the null space of the control matrix, i.e. it does not allow for the generation of internal prestresses, however. This is not problematic as the latter is usually not exploited. The proposed method is compared to the recently proposed adaptive coordinate switching method. Experimental results are reported if the inverse dynamics solution is introduced in model-based computed torque control scheme of a planar 2DOF RA-PKM.Copyright © 2011 by ASME