Spatial kinematic modeling of a long and thin continuum robotic cable

Abstract

In this paper, we present a new forward kinematic model for a novel class of long and thin continuum robots for operation in spatial workspace. Such robots are well suited for navigation through unstructured environments with superior reach using their flexible and thin profile, especially for inspection applications. This cable-like continuum robot design [1] has a concentric backbone arrangement but is spring-loaded and tendon-actuated, has improved compliance with a light and compact motor-encoder actuation mechanism. To account for the spring-loading, a compression factor is introduced on top of the established constant curvature continuum kinematics. The resulting continuum or shape variables are then estimated as a function of the measurable encoder variables. The effectiveness of the model is validated by performing experiments with the robot prototype.

Smart Material-Actuated Flexible Tendon-Based Snake Robot

“…A detailed analysis of tendon-based actuator activity was presented in this work [13]. A new kinematic model was introduced for the spring loading and concentric nature of the new robotic cable design [14]. The new modified kinematic formulation for 2D and 3D operations is the other significant contribution made in relation to the modelling of long and thin continuum cable-like robots.…”

Vine-Inspired Continuum Tendril Robots and Circumnutations

“…A representative long, thin continuum robot tendril, used to demonstrate the plant-inspired strategies in this paper, is shown in Figure 1. Based on a spring-loaded concentric tube design [29], the tendril has three serially-connected, independently-controllable sections. Each section can be bent in two dimensions, via three remotely-actuated tendons, comprised of Dyneema fishing line, running along the backbone and terminated at the end of the section.…”

“…Each of the motors rests on a load cell, allowing for measurement of approximate tension feedback. The combination of encoder feedback and tension sensing allows for a more accurate estimation of tendon length than previous designs, to determine robot shape [29]. The thin profile and high compliance of tendril robots makes operating them an interesting challenge.…”

Efficient Spatial Dynamics for Continuum Arms

“…Because of their tentacle-like dexterity and inherent compliance, continuum robots are well suited for tasks in cluttered, delicate, or unstructured environments. Inspired by muscular structures such as tongues [1], elephant trunks [2,3] and octopus arms [4,5], continuum arms can elongate, contract, and bend at any point [6,7]. In addition to compliance and dexterity, potential advantages over traditional rigid-link robots include reduced manipulator weight, better fault tolerance [8], and human FIGURE 1: (a) Serial multisection continuum arm handling an object, (b) continuum sections as gentle fingers of a grasping manipulator (from [10]), (b) continuum sections as compliant limbs of a quadruped robot (from [11]) friendly interaction [9].…”