A novel approach to robotic climbing using continuum appendages in in-situ exploration

Abstract

This paper presents an analysis of the ability of continuum "hook" appendages to transform robot climbing.The key innovation is via exploitation of contact and impact dynamics when "grasping" the terrain. We introduce a new ellipsoid measure and use it to analyze and select the optimal shape and motion of tunable continuum hooks for given terrains and climbing scenarios. This new ellipsoid is a generalization of impact ellipsoids used previously for traditional rigid-link robots. We illustrate and support the analysis using results from laboratory experiments using a novel robot rover with continuum appendages developed by our research group.

Locomotion with continuum limbs

“…Since the contact points are constrained ground reaction forces do not appear in (12) [19]. Input joint torques are calculated by (14) utilizing walking trajectories generated in section III-C. Parameter values based on approximated measured values given in Table I were used in the simulations and as a first approximation only linear kinetic energies of continuum limbs were considered.…”

“…The input joint torques, τ are then computed in (14) by adding proportional velocity and positional feedback to the computed torques via inverse dynamics where K P and K D are position and velocity feedback error gains.…”

“…In the area of locomotion, the six legged robot presented in [13] was the first to use flexible legs. A study on continuum limbs for grasping in climbing situations appeared in [14] for a tripedal robot. Also, passive walking with fixed microrubber legs has been explored in [15].…”

Bioinspired locomotion and grasping in water: the soft eight-arm OCTOPUS robot

“…A very large number of manipulators could be mentioned as previous attempts. Recalling all of them is out of the scope of the present work, but if we take into consideration only continuum and bioinspired manipulators, only a few works remain: two robots inspired by the elephant trunk were presented at Clemson University, the elephant trunk based on prismatic joints actuated by cables (Walker, 2000) and the OCTARM which is based on a series of pneumatic actuators (Walker et al, 2005), both capable of reproducing elephant trunk behaviour and the latter recently used to climb structures (Walker et al, 2012); the FESTO Bionic Handling was developed on the same basic idea, exploiting pneumatic actuators arranged in parallel and serial manner; the OCRobotics Snake Arm is an example of octopus-inspired manipulator which again uses tendons to orient a series of parallel rigid endplates (Walker, 2013 andWebster andJones, 2010-an extensive and exhaustive overview regarding the design and control of continuum robots is reported). In this context, soft-material based robots represent a new trend: soft robots are devices which can actively interact with the environment and which can undergo "large" deformations relying on inherent or structural compliance 1 .…”

Soft-Legged Wheel-Based Robot with Terrestrial Locomotion Abilities

“…Rone and Ben-Tzvi (2014) proposed a continuum hybrid actuated tail structure (tendon and rod driving mechanisms) able to generate forces in the x-, y-and z-directions for improving stabilization in locomotion in presence of external disturbances. Another example of soft robot is presented in Walker et al (2012). Here, the authors proposed a soft, adaptable, and compliant continuum robot using hooks for its anchorage in low-gravity environments and McKibben air muscles for the continuum arm usable either as arm manipulator or legged locomotion mechanism.…”