Reconfigurable Cable-Driven Parallel Robots

缆索驱动并联机器人由一个末端执行器组成，末端执行器由若干缆索悬挂。每根电缆都缠绕在一个伺服驱动的线轴上，线轴固定在一个固定的框架上。末端执行器的位移通过同时在其各自的线轴上缠绕和退绕线缆来控制。我们对CDPR的兴趣来自于它们比传统的刚性连杆机器人具有的五个优点：（i）它们覆盖了大的工作空间;（ii）它们便宜;（iii）它们可以产生高速度和加速度-超音速已经被报道过了！(iv)它们是便携式的;（5）它们是可重新配置的。在我们看来，最后一个优势，CDPR快速重新配置的能力，在以前的研究中相对被忽视了。从许多实际应用的角度来看，这一点至关重要，因为机器人可以根据不同的工件或环境调整其几何形状和工作空间，这是大多数经典机器人无法做到的。因此，所提出的研究的目的是提高和证明电缆驱动的并联机器人的能力，重新配置。我们已经确定了工程师在为新任务重新配置CDPR时面临的三个重要挑战：为给定任务找到最佳机器人几何形状;改变末端执行器或其致动工具（例如，夹具、焊炬）;以及在重新配置后识别准确的CDPR几何形状。拟议的研究计划将解决这些挑战，在一系列的五个项目编号从4.1到4.5。** 在项目4.1中，我们将开发一种新的方法来跟踪CDPR的三维投影。该工作空间将考虑电缆中的张力限制、它们将产生的合力和力矩的范围以及电缆和末端执行器之间可能的碰撞。在项目4.2中，我们将开发一种新的自动合成CDPR的方法。这一方法将考虑到项目4.1中包括的所有物理限制，这是目前可用的方法所不可能做到的。为了证明其有效性，合成方法将被用来设计两个CDPR：一个用于大型表面的检查（项目4.5），另一个，在虚拟环境中提供触觉反馈的物理康复。** 在项目4.3和4.4中，我们将通过将其致动器从末端执行器移动到地面来提高CDPR工具的可重复性，从而允许将相同的电机和控制器用于不同的工具。这将降低工具的单位成本，从而允许制造更多不同的工具。运动和力将通过与已经形成CDPR的那些平行的附加线缆从固定致动器传递到移动末端执行器。在项目4.3中，我们将通过使用两个电机在差模中控制具有单自由度的工具。在项目4.4中，我们将扩展这一概念，从基座驱动三自由度机械臂，从而改进机器人技术中众所周知的宏-微机械手的想法。** 在项目4.5中，我们将应用以前开发的分析和综合方法来设计用于大表面自动无损检测（NDT）的CDPR。探针将安装在CDPR末端执行器上，并用于扫描各种几何形状的物体的实体模型，例如，飞机机翼或水库。该项目将使用项目4.1和4.2的结果，并将需要开发新的校准技术，以便在重新配置后可以精确识别CDPR的几何形状。除了为五名学生提供最先进的培训外，这项研究还将把CDPR的重新配置能力提高到可以应用于工业任务的功能水平。

Cable-driven parallel robots (CDPRs) consist of an end effector, which is suspended by a number of cables. Each cable is wound onto*a servo-actuated spool, which is rigidly attached to a fixed frame. The end effector displacements are controlled by simultaneously winding and unwinding the cables on their respective spools. Our interest in CDPRs stems from five advantages they hold over classical rigid-link robots: (i) They cover a large workspace; (ii) They are inexpensive; (iii) They can generate high speeds and accelerations---Supersonic speeds have been reported!; (iv) They are portable; (v) They are reconfigurable. In our opinion, this last advantage, the ability of CDPRs to quickly reconfigure, has been relatively neglected in previous research. From the perspective of many practical applications, this point is crucial, as the robot can then adapt its geometry and workspace to different workpieces or environments, which most classical robots cannot do.**The objective of the proposed research is thus to improve and demonstrate the ability of cable-driven parallel robots to reconfigure. We have identified three important challenges facing the engineer when reconfiguring a CDPR for a new task: finding the best robot geometry for a given task; changing the end effector or its actuated tool (e.g., gripper, welding torch); and identifying the exact CDPR geometry after it has reconfigured. The proposed research program will address these challenges in a series of five projects numbered from 4.1 to 4.5. **In project 4.1, we will develop a new method of tracing the three-dimensional workspaces of CDPRs. This workspace will take into account the tension limits in the cables, the range of resultant forces and moments they are to generate, and the possible collisions between cables and end effector. In project 4.2, we will develop a new method for the automatic synthesis of CDPRs. This method will take into account all the physical constraints included in project 4.1, which is not possible with currently available approaches. To demonstrate its effectiveness, the synthesis method will be used to design two CDPRs: one for the inspection of large surfaces (project 4.5), and the other, to provide haptic feedback in a virtual environment for physical rehabilitation. **In projects 4.3 and 4.4, we will improve the CDPR tool interchangeability by moving its actuators from the end effector to the ground, thus allowing to use the same motors and controllers for different tools. This will reduce the unit cost of a tool, thus allowing for more different tools to be made. The motion and forces will be transmitted from the fixed actuators to the moving end effector via additional cables parallel to those already forming the CDPR. In project 4.3, we will control a tool with a single degree of freedom by using two motors in differential mode. In project 4.4, we will extend this concept to drive a three-degree-of-freedom robotic arm from the base, thus improving on the idea of the macro-mini manipulator, which is well known in robotics. **In project 4.5, we will apply the analysis and synthesis methods previously developed to design a CDPR for the automatic non-destructive testing (NDT) of large surfaces. A probe will be mounted on the CDPR end effector, and used to scan mockups of objects of various geometries, e.g., an aircraft wing or a reservoir. This project will use the results of projects 4.1 and 4.2, and will require the development of new calibration techniques, so that the CDPR geometry can be precisely identified after it has reconfigured.**Besides providing state-of-the-art training to five students, this research will take the reconfiguration capabilities of CDPRs to a functional level that can be applied to industrial tasks.