Automating Tension Calibration for Tendon-Driven Continuum Robots: A Low-Cost Approach Towards Consistent Teleoperation

We present a low-cost method to automate tension calibration for tendon-driven continuum robots (TDCRs), particularly those lacking tension sensing. Our method utilizes Hall effect sensors to localize the robot's tip with respect to the one-dimensional trajectory it follows under individual tendon actuation. We propose two workflows for robots with and without a static model, making the method generalizable to other tendon-driven soft robots. We demonstrate our method's ability to repeatably tension the tendons through associated tendon displacements. The calibration approach's measured repeatability ($\pm 0.03 ~\text{mm}$) is also benchmarked against manual calibration on a TDCR prototype, and its accuracy in achieving target tensions is assessed $((0.06 \pm 0.20) \mathrm{N})$. We further investigate how tension calibration impacts open-loop tracking accuracy, confirming the effectiveness of our method to enhance motion consistency in open-loop control and teleoperation.