Control of a Flexible Continuum Manipulator for Laser Beam Steering

Continuum manipulators with structural compliance can be utilized to steer a laser beam in constrained environments. However, the flexibility and nonlinear characteristics of continuum manipulators bring difficulty in precision manipulation. This study proposes a model-free control approach with visual feedback to control a tendon-driven flexible manipulator that can be integrated into an endoscope to steer a laser beam accurately. To overcome the noise from the visual feedback and disturbances from environment during operation, a local Jacobian matrix that maps the actuation space to the image space is approximated online by using the sensing data stored in limited memory, where the influence of outliers can be filtered. Then, a second-order sliding mode controller is developed to achieve robust control of the flexible manipulator in laser beam steering. Simulations and experiments are performed to demonstrate the effectiveness of the proposed control methods in different configurations.