Modeling and Control of a Cable-Driven Robot for Inspection of Wide-Area Horizontal Workspaces

Cable Driven Parallel Manipulators (CDPMs) utilize flexible wire to actuate an end-effector, allowing rapid accelerations across large workspaces. CDPMs are predominantly modeled with rigid cables, greatly simplifying the analysis. This model is satisfactory for small, fixed masses traveling short distances. However, as cable length increases, the flexibility of the cables, including the variation in stiffness and damping as length changes, cannot be ignored. In addition, the end-effector, which may be modeled as a pendulum, will rotate and contribute to the motion. This paper presents the modeling and control of a large-scale, cable-driven parallel manipulator, with application to inspection of large workspaces. The multi-degree-of-freedom model developed takes into account flexibility of cables and the oscillatory dynamics of the end effector. The dominant dynamics are identified and used to design a control system to limit vibration.