Kinematic modelling and closed-loop control of a novel soft continuum robot

In recent years, soft continuum robots (SCRs) have gained a lot of attention due to their excellent adaptability and reliability, and various new soft materials have been proposed to give more possibilities for the design of SCRs. However, characteristics such as large deformations and geometric nonlinearities of soft materials make the modeling and control of SCRs challenging. In this paper, a novel soft continuum robot (NSCR) consisting of four origami structure units is proposed. The origami structure units are designed using the Kresling origami pattern, and the units are endowed with capacities for contraction/extension and bending through three stable state characteristics of the Kresling origami. Based on the constant curvature assumption, the kinematic model of NSCR is established using the D-H method. A closed-loop model-free control system is proposed by using the vision system to acquire the real-time position data of the NSCR. Meanwhile, a multi-strategy improved horned lizard optimization algorithm (MHLOA) is designed to optimally select the parameters of the control system, which dramatically improves the control performance of the system. The optimization ability and improvement effect on the control system of the MHLOA algorithm are verified by test functions, simulations and experiments. The relevant experiment results show that the proposed kinematic model can finely describe the motion of the NSCR. The closed-loop model-free control system can also control the NSCR to reach the target position or trajectory under acceptable errors, and make the NSCR has excellent performance in terms of repeatability accuracy.