Fig. 4

Six degree-of-freedom manipulator used in the experiments. Situations of Experiment I. a Configuration A (\({\varvec{p}}_d=[0.26, -0.01, 0.52]^T\mathrm {m}\), \({\tilde{{\varvec{\alpha}}}}_d = [-0.152, 0.507, -0.07]^T\)). b Configuration B (\({\varvec{p}}_d=[0.31, 0.02, 0.45]^T\mathrm {m}\), \(\tilde{{\varvec{\alpha }}}_d=[0.455, 0.377, 0.309]^T\)). c Configuration C (\({\varvec{p}}_d=[0.23,-0.06,0.54]^T\mathrm {m}\), \(\tilde{{\varvec{\alpha }}}_d=[-0.653,0.334,-0.405]^T\))