Soft robot model captures expansion and contraction with 7D deformation
PC7 Model: Dynamics of Expanding and Contracting Soft Robots using Piece-wise Constant 7D Deformation Based on Similarity Transformation Group
Robotics
Summary
Soft robots can change their length and shape by expanding or contracting like muscles. The authors created a new mathematical model that can describe these changes more completely than before by adding a dimension for scaling. This model builds on earlier approaches but includes expansion and shrinking explicitly using a 7D vector. They tested the model in simulations to show it works for soft, thin structures and artificial muscles. Their work helps better predict how soft robots move and deform dynamically.
What this means in practice
- •For soft roboticists: Model dynamic expansion and contraction in soft actuators for design and control improvements.
- •For robotics simulation engineers: Simulate soft robot behaviors with accurate deformation and scaling using the PC7 model in virtual environments.
Authors
Yamato Kudo, Taiki Ishigaki, Ko Ayusawa, Ko Yamamoto
Abstract
This paper proposes a novel soft robot model named piece-wise constant 7D deformation (PC7) model that can represent expanding and contracting deformation of, for example, artificial muscle actuator. In the proposed model, we newly define the 7D deformation vector based on SIM(3) - 3D similarity transformation group - whereas a 6D deformation vector was defined for Cosserat rod based on SE(3) - the special Euclid group - in the piece-wise constant strain (PCS) model proposed in the previous study. The additional dimension of the 7D deformation vector represents expanding and contracting deformation, which comes from the scaling parameter in SIM(3). Common mathematical properties between SE(3) and SIM(3) allow us to directly extend the kinematics and dynamics of the PCS model to those of the PC7 model. In particular, we derive the dynamical equation of the PC7 model based on Euler-Poincare equation in a mathematically precise manner. We validate the proposed model through dynamical simulations assuming a thin cylinder structure or McKibben-type artificial muscle actuator.