Mimicking the motion of a Coconut Crab using 1-degree of freedom planar mechanisms

Team Members: Cecilia Corral, Haoran Xie, Pradeep Radhakrishnan and Sadhan Sathyaseelan

Introduction

Our goal is to mimic the motion of a coconut crab using one-degree of freedom planar mechanisms. An example of a coconut crab is shown in the video below. 

As you may notice in the video, there are two pairs of legs on either side of the crab body in addition to a pair of claws on the front and a pair of small legs on the rear side. The two pairs on either side are the main source of motion. The front claws and the rear legs serve as support apart from the obvious predatory function of the front claws. Though the crab can be categorized into a multi-degree of freedom system, we felt that it is possible to divide the motion into two categories - planar and lateral movements - by repeated analysis of the video (see above). Therefore, we are investigating through this project, the ability of 1-dof planar mechanism to mimic the planar motion of each leg in the coconut crab. If this attempt is successful, our goal of proving that simple mechanisms can predict complex motions will be achieved.

Tasks

In order to achieve our goal, we had decided to divide our work into several tasks and those are listed below. 

Mapping the Trajectory

The trajectory of each link was mapped