Kinematic Modeling of a Spatial Soft Robot by an Improved Analytical Method Based on Serial Robots

In this paper, kinematic modeling of a soft pneumatic robot, including a combination of 3 soft actuators, with the capability of spatial positioning is presented. The proposed kinematic model in this research, unlike former methods, corresponds the physics of robot and the main idea is modeling its configuration and movement by serial rigid robots which generate the same configuration and movement. The given kinematic model consists of forward and inverse problems and uses accurate geometrical solutions. In addition, velocity Jacobian of soft robot has been determined by two different approaches based on rigid serial robot principles. Furthermore, the robot work space and its configurations have been determined by considering the kinematic constraints. Modeling accuracy has been evaluated by finite element simulation and also experiments. Simulation results show the maximum error of 1.6% for the inverse kinematic model and the maximum error of forward kinematic model has been 13% in experiments due to manufacturing errors and gravity effects. These results demonstrate that the proposed model has proper accuracy for motion modeling and its control in future works.