Climbee

A robot that climbs

A partial view of the robot Climbee

Introduction

Climbee is a project to design and fabricate a robot that can climb steep, smooth surfaces. Its name is a combination of “climb” and “bee”, which indicates its origin. Inspiration was drawn from honey bees in the Biomimetics Lab, Department of Mechanical Engineering, Tsinghua University.

A detailed document describing Climbee project can be found here.

Inspiration

Inspiration of this project comes from the observation of honey bees in our lab. Honey bees have relatively ponderous body equipped with small feet. Nevertheless, they are able to walk on vertical planes without much effort. On observation of honeybee’s footpad deformation during attching and detaching, we are able to offer a structural reason (instead of a material one) for honey bees’, probably along with many other insects’, extraordinary ability to climb.

High-speed-camera-captured honey bee's footpad microstructural deformation.

During the attaching process, bee’s footpad will expand, thus generating enough force to adhere to the wall. During detaching, on the other hand, the area of their footpad will shrink. Climbee utilizes a small piece of elastic iron as the base of its foodpad, so as to achieve the same effect.

Design

The design of Climbee aims at achieving maximum climbing ability with the simplest mechanical design. (However, only the latter was fully-achieved ;) ) I was greatly inspired by CLASH robot and the flying monkey.

The CLASH robot

Climbee uses one DC motor to actuate all six legs and let them sway in a similar motion to real insects’ legs. The basic principle is explained in the paper linked above. I used Solidworks to design the prototype of Climbee. The legs are designed to be structures of open boxes, such that the facets can rotate around the edges, hence the deformation of legs.

Using one motor to realize hexopedal gait

With this design, the robot is small enough to fit into a normal person’s palm. A small climbing robot proves flexible and widely applicable. Climbee weighs only 22 grams.

Climbee mainly consists of several modules:

  • upper body
  • lower body
  • legs
  • footpads
  • motor
  • linkage structure

During motion, the centroid of the upper body rotates about the centroid of the lower body, taking all legs to swing in the desired pattern.

Fabrication

The fabrication process using laser cutter

Climbee is designed to be fabricated easily. The base of the robot - upper and lower body, are 3D-printed. The legs are laser-cut fiberglass composites, with edges cut and a thin film of PET attached, so that it can be folded up in 3D space to form a box.

CAD model of a leg unfolded in 2D space An actual leg to be folded

Footpads of the robot were simply made of adherent materials, PU material, since material is not the focus of this project.

Award

This project won the third prize at Challenge Cup of Tsinghua University 2017.

The video below shows the first prototype of climbee’s prformance under different conditions.

Acknoledgements

The project was accomplished by Rui Wang, in 2017, under the supervision of Prof. Shaoze Yan. Most of the work is done at Skyworks workshop, where the robot was fabricated from scratch.

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