Abstract Industrial arm-type robots have multiple degrees-of-freedom (DoFs), but the use of the roll-pitch-roll wrist configuration yields singularities inside the reachable workspace. Excessive joint velocities will occur and result in a poor path tracking response when encountering the wrist singularities. Arm-type robots currently do not have enough dexterity to move the end-effector path away from the wrist singularities. Robots with redundant DoFs can be used to provide additional dexterity required to avoid the singularities and reduce the excessive joint velocities. An end-effector wrist module is proposed to provide two redundant DoFs when interfaced with an existing 6-DoF robot. The new 8-DoF robot has a compact roll-pitch-yaw wrist that has no singularities inside the reachable workspace. Hence excessive joint velocities can be avoided. The highly redundant robot can also be used to avoid collisions in various directions. Three path tracking examples with experiments are provided to show the advantages of the proposed design when compared with existing redundant or non-redundant robots. We expect that this module can serve as a cost-effective solution in applications where singularity-free motion or collision-free motion is required

中文翻译：

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一种用于手臂型机器人运动学冗余操作的末端执行器腕部模块

摘要 工业手臂型机器人具有多个自由度 (DoF)，但使用滚-俯仰-滚手腕配置会在可到达的工作空间内产生奇点。当遇到手腕奇点时，会发生过大的关节速度并导致路径跟踪响应不佳。手臂型机器人目前没有足够的灵巧性来将末端执行器路径从手腕奇点移开。具有冗余自由度的机器人可用于提供避免奇异点和降低过度关节速度所需的额外灵活性。当与现有的 6-DoF 机器人接口时，建议使用末端执行器腕部模块提供两个冗余的自由度。新的 8-DoF 机器人有一个紧凑的横滚俯仰偏航手腕，在可到达的工作空间内没有奇点。因此可以避免过大的关节速度。高度冗余的机器人还可用于避免各个方向的碰撞。提供了三个带有实验的路径跟踪示例，以显示与现有冗余或非冗余机器人相比，所提出设计的优势。我们希望该模块可以在需要无奇点运动或无碰撞运动的应用中作为一种经济高效的解决方案