Shape Sensing of Continuum Robots using Direct Laser Writing
2026-06-17 • Robotics
Robotics
AI summaryⓘ
The authors explore a new way to measure the shape of flexible continuum robots, which are used for delicate surgeries. They use a laser to create special strain sensors directly on the robot's flexible joints, all in one step. These sensors accurately detect how much the robot joint bends, with small errors around 1.76 degrees. The team also shows that these sensors can help control the robot smoothly, keeping movements very precise with errors under 3 degrees.
continuum robotsstrain sensorsdirect laser writing (DLW)graphenerobotic jointclosed-loop controlshape sensingminimally invasive surgerypolymer carbonization
Authors
Amber K. Rothe, Nidhi Malhotra, Jaydev P. Desai
Abstract
Continuum robots offer a promising approach for minimally invasive and natural-orifice surgical procedures due to their inherent compliance and dexterity. However, this flexibility also makes estimating the current shape of the robot challenging. Several approaches have been used to reconstruct the shape of these robots, including imaging, optical sensing, magnetic sensing, and resistive sensing. Strain sensors fabricated using direct laser writing (DLW) could provide an alternative sensing method. This technique involves using a laser to induce carbonization of certain polymers to create graphene patterns, such as strain sensors. In this paper, we demonstrate how a flexible continuum joint and a DLW sensor can be machined as one monolithic structure using the same laser and the same setup. The fabricated sensors are characterized using linear and nonlinear models, which are used to predict the joint angle with error as low as 1.76 degrees. Furthermore, we demonstrate how a DLW sensor can be used to implement closed-loop control in a robotic joint, achieving tracking error under 3 degrees.