Inspired by the muscle structures of elephant trunk, octopus arm and tongue, the soft continuous arm developed based on bionics can extend, contract and bend along any point of its structure. Compared with the rigid and flexible manipulator, it has the features of high flexibility, complex environment adaptability and safe human-machine interactivity. In order to achieve its full operation function, the soft continuous arm must move faster and more accurately. Therefore, it is important to established the accurate and efficient dynamics model for the soft continuous arm. In this paper, a three-dimensional (3D) kinematic and dynamic model of the soft continuous arm based on the modal method is simulated and discussed.Firstly, the spatial kinematics model of the soft continuous arm is established based on the modal method, in which, the deformation of the soft continuous arm is assumed to be an arc without torsion, and the complex nonlinear function is approximated by a simple mathematical function. It is easily to derivate the accurate, non-singularity and unique modal transformation matrix. The modal method overcomes the limitations of the previous models (for example, using the curve parameters that assumes the curvature of the cross section is not zero, and the dynamic model does not include the pure linear motion). The modal method used&nbsp;in this paper can describe the spatial bending motion of the soft continuous arm. Also, the method&nbsp;overcomes effectively&nbsp;the singularity problem caused by using the curve parameters to simulate the pure linear motion.Secondly, the paper investigated the dynamics characteristics of the soft continuous arm. When the classical Lagrange method is used to derive the dynamic equation of the soft continuous arm, a large number of complex nonlinear integral calculations are inevitably involved, and the computational efficiency is low in the numerical simulation. The modal method used in this paper greatly simplifies the complex nonlinear integral calculation and improves the efficiency of numerical simulation. The simulation results of the pure elongation and bending of the soft continuous arm show that the modal method used in this paper can obtain the accurate dynamics responses of the soft continuous arm quickly.Finally, the motion equations derived from the modal method can be recursively computed effectively and the method can be extended to multi-segment soft continuous arms to obtain effective and accurate numerical results. It provides an effective basis for further research on the optimization design and real-time dynamic control of the soft continuous arm.

Kinematic and Dynamic Modelling and Simulation of Soft Continuous Arm Based on Modal Method

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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