On the Static Workspace of Large Dimension Cable-Suspended Robots With Non Negligible Cable Mass

Abstract

In most studies on parallel cable-driven robots, cables are supposed to be massless and inextensible. However, in the case of large dimension robots, cable mass and elasticity cannot be neglected anymore. Based on a well-known cable static model which takes these characteristics into account, the formulation of the inverse kinematics of n cable/n-DOF cable-driven robots is presented. The consequences of this modeling on the usual static workspace definition is then discussed. Notably, as the tension in a cable is not constant, the maximal tension along the cable has to be found. An example of a planar 3 cable/3-DOF robot is used to highlight that, in some particular poses, the mobile platform can be in static equilibrium while some cables are hanging below the platform. Finally, new limiting factors for the definition of the static workspace are introduced and applied to the same planar robot example which shows the significance of taking into account cable mass and elasticity.

Simplified static analysis of large-dimension parallel cable-driven robots

“…Finally, note that this extension is relevant if the validity criteria of Eq. (12) or Eq. (13) is verified and if the cables can be considered inextensible.…”

Motion control strategy and stability analysis for high-speed cable-driven camera robots with cable inertia effects

“…The effects of the cable sags on the dynamics must be taken into account for large-span cables. 31,32 Therefore, a cable catenary model is first established. The local coordinate system ðA i À x s i z s i Þ in the vertical plane is established as shown in Figure 3.…”

Computing Cross-Sections of the Workspace of Cable-Driven Parallel Robots with 6 Sagging Cables

“…Numerous works have addressed the problem of workspace calculation of CDPR [1,2,3,4,5,6,8,10,12,17,20,22] but most of them assume non deformable and non elastic cables. Discretisation-based method has been proposed for elastic cables [11] and for a simplified sagging cable model [18]. But this approach requires to assume that the inverse kinematics problem has a single solution, which is not true for a complete sagging cable model [14].…”