Parallel mechanisms have been employed as architectures of high-precision vibration isolation systems. However, their performances in all degrees of freedom (DOFs) are nonidentical. The conventional solution to this problem is isotropic mechanism design, which is laborious and can hardly be achieved. This article proposes a novel concept; namely, isotropic control, to solve this problem. Dynamic equations of parallel mechanisms with base excitation are established and analyzed. An isotropic control framework is then synthesized in modal space. We derive an explicit relationship between modal control force and actuation force in joint space, enabling implementation of the isotropic controller. The multi-DOF system is transformed into multiidentical single-DOF systems. Under the framework of isotropic control, parallel mechanisms obtain an identical frequency response for all modes. An identical corner frequency, active damping, and rate of low-frequency transmissibility are achieved for all modes using a combining proportional, integral, and double integral compensator as a subcontroller. A 6-U P S parallel mechanism is presented as an example to demonstrate effectiveness of the new approach.

中文翻译：

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隔振并联机构的动力学和各向同性控制

并行机制已被用作高精度振动隔离系统的体系结构。但是，它们在所有自由度（DOF）中的表现都不相同。解决该问题的常规方法是各向同性的机构设计，这是费力的并且难以实现。本文提出了一个新颖的概念。即各向同性控制，以解决这个问题。建立并分析了具有基本激励的并联机构的动力学方程。然后在模态空间中合成各向同性控制框架。我们推导出关节空间中模态控制力和致动力之间的明确关系，从而实现各向同性控制器的实现。多自由度系统已转换为多身份单自由度系统。在各向同性控制的框架下，并行机制为所有模式获得相同的频率响应。使用比例，积分和双积分组合补偿器作为子控制器，对于所有模式，都可获得相同的转角频率，有效阻尼和低频透射率。6U P 以并行机制为例，说明了新方法的有效性。