The Effect of Sprawl Angle and Wall Inclination on a Bipedal, Dynamic Climbing Platform

Abstract

Animals have shown the ability to climb vertical surfaces with high speed and stability. Utilizing the underlying dynamics of these animals, robotic platforms have been developed that climb vertical surfaces with similar speed. It is hypothesized that the pre-incidence angle of the legs, commonly referred to as sprawl angle, for these robotic platforms can significantly affect vertical velocities, efficiency, and stability as well as passively controlling body oscillations. To date, little empirical work has been conducted on the effect of sprawl angle and wall inclination on the performance of dynamic climbing platforms. This paper presents initial research utilizing a biologically inspired dynamical climbing platform to understand the effect of sprawl angle and wall inclination on dynamic climbing. Simulations have shown that a sprawl angle of 30 • maximizes vertical velocity overall, while experimental results show that a sprawl angle of approximately 10 • maximizes vertical velocity, while in both increasing sprawl angle increases lateral velocities over all wall inclinations.

Towards maneuverability in plane with a dynamic climbing platform

“…An existing 2D dynamic simulation developed in Working Model 2D and initially presented in [3] was utilized to perform an initial study on the effect of the proposed control methods on the dynamic climbing platform and parametrize the scope of experimental trials for the physical platform.…”

“…The vertical climbing behavior of a number of animal species have been successfully captured by the planar Full-Goldman template [1]. While this bipedal, dynamic climbing template has motivated the design of high-speed robotic platforms that approach vertical speeds of their biological progenitors [2] [3], it has focused on linear locomotion on vertical surfaces. Animals not only excel at climbing at high speeds, but also at performing high-speed maneuvers in the vertical plane.…”

“…The simplified bipedal design of the Full-Goldman template led to the development of the Dynoclimber platform [2] and the miniature bipedal dynamic climber [3] [13]. Both platforms implement legs via linear sliders actuated by crank-slider mechanisms and show characteristic high speed dynamic climbing.…”

“…The platform utilizes a passivecompliant wrist mechanism and dactyl claws for attachment on carpeted climbing surfaces. Utilizing dynamically scaled design criteria from the Full-Goldman template, the platform has shown biologically similar dynamic climbing at vertical velocities of 37.0 ± 3.4cms −1 [3]. Utilizing higher stride frequencies than biologically scaled values, the platform has recently demonstrated speeds of up to 56.0cms −1 .…”

“…Previous analysis has shown that the pre-incidence angle of the legs, or sprawl angle, has a pronounced effect on velocity profiles and locomotion properties [14] [3]. Consequently the effect of sprawl angle on maneuverability is considered in relation to the proposed maneuvering methods described below.…”