Stiffness modulation exploiting configuration redundancy in mobile cable robots

In this paper, we investigate the modulation of task space stiffness of mobile cable robots with elastic cables. The elasticity is introduced via springs connected in series with non-extensible cables. The benefit of such series elastic cables include tension control without using force sensors and tension redistribution. However, elasticity also reduces positioning accuracy and makes the system more prone to disturbances. Therefore, careful stiffness modulation is needed for better performance. We exploit the configuration redundancy in mobile cable robots to optimize certain desired task space stiffness criterion. Both simulation and experimental results are presented for validation.