Mike Grauer's Final Project Report for Bio Inspired Robots Fall 2006

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Contents

Introduction

My robot is modeled on a polar bear, although the lurching and maladroit gait of my creation does little justice to the grace with which that largest of surviving Ursine comports itself. I opted for a four legged creature as it would be simpler to balance than a two legged one, and would require fewer parts than a six legged one. My overall design is fairly simple, with a single drive train and motor that powers all four legs and the offsets of the leg attachments to the body providing the body with stability.

My simulation model was created using the MSC Adams View software, essentially I created an abstracted virtual model of Adams geometric primitives based loosely on the proportions of the Lego pieces in the physical model. My virtual model evolved over time to finally approximate my physical model reasonably well. The rotational speed of the hip gears on the virtual model are closely matched to what I empirically measured on my walking physical model, and the gait of my virtual model is quite similar to the physical one, both in terms of the side to side lurching and the rising and falling of the front and rear body segments. I feel that the virtual model I have created is close enough to the physical model that I can perform parametric tests on the virtual model and feel confident that the findings would apply to the physical model--this idea of simulation and testing the virtual in place of the physical being one of the core ideas in this course. To this end I have actually used my virtual model to find what rotational speed on the hip gears would cause the robot's legs to become unsynchronized, resulting in the robot's loss of leg synchronization and stability, and eventually an overall bodily collapse. This kind of testing can stand in the place of having to try out different motors on the physical robot in order to find the fastest speed sustainable by the robot.

Here is a video of my physical robot walking, the book behind it is for a frame of reference.

Media:MJG-walker.AVI

Here is a video of my simulated virtual robot walking, note the similarity in gait to the physical robot.

Media:Goodwalker.avi

Robot Design and Rationale

Physical Assembly

Virtual Model and Physics Based Simulation

Useful Links and Resources

include lego robot book inclue lego robot pdf from handyboard include the adams tutorials