Lateral Undulation of the Bendable Body of a Gecko-Inspired Robot for Energy-Efficient Inclined Surface Climbing

Abstract

Sprawling posture animals with their bendable spine, such as salamanders, and geckos, can perform agile and versatile locomotion including walking, swimming, and climbing. Therefore, several roboticists have used them as templates for robot designs to investigate and generate efficient locomotion. Typically, walking and/or swimming abilities are realized by salamander-inspired robots with a bendable body, whereas climbing ability is achieved on gecko-inspired robots with an oversimplified fixed body. In this study, we propose optimal bendable body design with three degrees of freedom (DOFs). Its implementation on a sprawling posture robot is inspired by geckos for climbing enhancement. The robot leg and body movements are coordinated and driven by central pattern generator (CPG)based neural control. As a consequence, the robot can climb using a combination of trot gait and lateral undulation of the bendable body with a C-shaped standing wave. Through the real robot experiments on a 3D force measuring platform, we demonstrate that, due to the dynamics of the bendable body movement, the robot can gain higher medio-lateral (Fx) ground reaction forces (GRFs) at its front legs as well as anterior-posterior (Fy) GRFs at its hind legs to increase the bending angular momentum (LAM ). This results in 52% and 54% reduced energy consumptions during climbing on steeper inclined solid and soft surfaces, respectively, compared to climbing with a fixed body. To this end, the study provides a basis for developing sprawling posture robots with a bendable body and neural control for energy-efficient inclined surface climbing with a possible extension towards agile and versatile locomotion, such as sprawling posture animals.

The Roles and Comparison of Rigid and Soft Tails in Gecko-Inspired Climbing Robots: A Mini-Review

“…The body motion and gait pattern also influence the tail design. A robot with a bendable body (Haomachai et al (2021)) may need a soft or lateral undulating tail to compensate for the body swing. A robot with a lizard-like gait pattern (raising two legs at the same time) (Shao et al (2022)) can benefit from a tail that provides a substantial preload or functions as additional support for stable slope climbing.…”

“…et al (2021)), have been extensively studied. Hence, geckoinspired climbing robots (Menon et al (2004); Unver et al (2006); Kim et al (2008); Jusufi et al (2008Jusufi et al ( , 2010Jusufi et al ( , 2011; Estrada et al (2014); Haomachai et al (2021); Shao et al (2022)) and dry adhesive materials (Murphy et al (2009); Bartlett et al (2012); Glick et al (2018); Suthisomboon et al (2021)) have rapidly been developed. They can adapt to different substrate surfaces (Kim et al (2008)) and even carry 100x their own weight (e.g., 9g climber (Hawkes et al (2015))).…”

SCALER: A Tough Versatile Quadruped Free-Climber Robot

“…Inchworm gait that extends and bends body sequentially is mimicked to allow a small soft robot to climb up on a pole [8]. The gecko in-plane bending movement is replicated in Slalom [14], which has reduced energy consumption in climbing by half compared to the rigid body on 30 • slope, equivalent to 0.5 Earth's gravity (0.5 G).…”

“…Grippers for climbing can be categorized by if there is explicit grasping, such as with fingers or not. Magnetic [18] or suction-based [19] end effectors, dry adhesive toes such as a gecko gripper [7], and EPDM Rubber [14] are other viable options for climbing robots. LEMUR 2B [2] has demonstrated a bouldering wall climbing by hocking a high-friction rubber wrapped end-effectors.…”

Design of a Variable Stiffness Gecko-Inspired Foot and Adhesion Performance Test on Flexible Surface

“…In 2000, AUTUMN et al [ 16 ] revealed the adhesion characteristics and mechanism of the gecko’s feet. In the past 20 years, the research on dry adhesion climbing robots has made great progress.…”