Dexterity Comparison and Analysis of Multi-Contact-Aided Continuum Manipulators

Continuum robots are being increasingly used in minimally invasive surgery because of their high dexterity. Most studies have adopted the redundancy approach–increase the number of actuation Degrees of Freedom (DOFs)–to improve the performance of robots. However, a continuum robot with a large number of actuation DOFs will feature a complex structure and necessitate sophisticated motion control. This letter uses the multi-contact-aided (MCA) concept to increase the dexterity of continuum robots. Based on the structure and kinematic model of the MCA robot (MCAR), the dexterity of MCARs with different height profiles and DOFs is analyzed and compared. By means of contact blocks arrangement and increased DOFs, we achieve the dexterity enhancement of the MCAR compared to the constant curvature robot (CCR) under the same workspace. Then, we investigate the rationale of dexterity improvement of MCAR with different height profiles. The design optimization of MCRA with nondecreasing workspace is also conducted to achieve the maximal total dexterity over the workspace. Simulation results reveal that the total dexterity of the optimized MCAR is 3.82 times than that of the CCR, the maximum single-point dexterity of the optimized MCAR is 3.57 times than that of the CCR. Finally, experiments are conducted to validate the dexterity of the optimized MCAR, and a phantom study is performed to highlight the clinical superiority of the MCRA.