Singularity-oriented design and analysis of parallel robots

并联机器人由通过多个铰接腿连接到基座的移动的平台组成。由于其无可争议的更高速度，精度和刚度的优势，并联机器人正在迅速成为任何需要约束运动的应用的标准。已经有一百多种商业产品基于并联机器人（例如，运动模拟器、工业机器人和机床）。然而，并联机器人具有某些不可忽视的缺点。这些机器人通常有一个小的工作空间，是由不希望的奇异分割。在工业中用于消除奇点的传统方法基本上是将已经很小的工作空间限制为仅一个无奇点段。显然，这种方法加剧了并联机器人工作空间小的问题。建议的研究计划的第一个目标是消除或减少奇点在早期设计阶段。将探讨的三种可能的方法之一是合成并联机器人，永远不会有奇点的关节限制，执行器行程，或腿的长度。另一种可能的方法是使用冗余致动器来完全（而不仅仅是部分）消除给定工作模式（逆运动学问题的给定解）的奇异性。第三种方法是设计非冗余并联机器人，其具有减小尺寸的奇点（例如，曲线而不是曲面）。建议的研究计划的第二个目标是研究尖齿并联机器人。这些机器人可以切换装配模式（一个解决方案的直接运动学），而不通过一个奇点。显然，在不知道其交叉点的情况下使用尖点机器人是危险的。如果一个尖形机器人进入一个无奇异性的装配模式改变路径，平台将以一种完全意想不到的方式移动。

Parallel robots consist of a mobile platform connected to a base through a plurality of articulated legs. Due to their undisputable advantages of higher speed, precision, and rigidity, parallel robots are quickly becoming the standard for any application where constrained motion is required. Already, more than a hundred commercially available products are based on parallel robots (e.g., motion simulators, industrial robots, and machine tools). However, parallel robots have certain disadvantages that are not negligible. These robots usually have a small workspace that is segmented by undesirable singularities. The conventional approach used in industry to eliminate singularities is basically limiting the already small workspace to only one of the singularity-free segments. Obviously, this approach exacerbates the problem of small workspace in parallel robots. The first objective of the proposed research program is to eliminate or reduce singularities at the early design stage. One of the three possible approaches that will be explored is to synthesize parallel robots that can never have singularities whatever the joint limits, actuator strokes, or leg lengths. Another possible approach is to use redundant actuators to completely (not only partially) eliminate singularities for a given working mode (a given solution of the inverse kinematic problem). A third approach is to design non-redundant parallel robots that have singularities of reduced dimension (e.g., curves instead of surfaces). The second objective of the proposed research program is to study cuspidal parallel robots. These robots can switch an assembly mode (a solution of the direct kinematics) without passing through a singularity. It is clearly dangerous to use a cuspidal robot without knowledge of its crosspoints. If a cuspidal robot enters a singularity-free assembly-mode changing path, the platform will move in an entirely unexpected way.