Kinematic Modeling and Control of Variable Curvature Soft Continuum Robots

The compliant structure and influence of external forces usually result in complex deformation of soft continuum robots, which makes the accurate modeling and control of the robot challenging. In this article, we present a new variable curvature kinematic modeling approach for soft continuum robots by taking the external forces into consideration, achieving both accurate motion simulation and feedforward control of the robot. To this end, the variable curvature configuration is first parameterized based on the absolute nodal coordinate formulation. Then, a kinematic model is developed to describe the mappings between the defined configuration space and the actuation space with payloads. With this model, we achieve accurate and fast motion simulation for the soft continuum robot with different payloads and input pressures within 1 ms, which is verified by a set of experiments. Finally, an inverse-model-based feedforward controller is developed for a two-section soft continuum robot. The experimental results of tracking complex trajectories verify the effectiveness of our model and control strategies. The average position error of the end effector is 2.89% of the robot length. This article can also be served as a tool to design and analyze soft continuum robots with a desired workspace.