Natural Oscillations of Underactuated Cable-Driven Parallel Robots

Underactuated Cable-Driven Parallel Robots (CDPR) employ a number of cables smaller than the degrees freedom (DoFs) end-effector (EE) that they control. As consequence, EE is underconstrained and preserves some freedoms even when all actuators are locked, which may lead to undesirable oscillations. This paper proposes methodology for computation natural oscillation frequencies, whose knowledge has proven be convenient control purposes. procedure, based on linearization system internal dynamics about equilibrium configurations, can applied generic robot suspended by any comprised between 2 5. The kinematics, dynamics, stability stiffness free motion investigated in detail. validity proposed method demonstrated experiments 6-DoF prototypes actuated 2, 3, 4 cables. Additionally, order highlight interest robotic context, this modelling strategy trajectory planning 4-cable CDPR means frequency-based (multi-mode input shaping), latter experimentally compared with traditional non-frequency-based planners.