Groundhog knee deep in mine muck.2D mine map produced by Groundhog.3D mine map snapshot produced by Groundhog.Ferret1 deployed into the Mellon Institute void.Second generation Ferret with higher power laser range finder.Ferret2 scan of a limestone mine after a domeout, Kansas City, Kansas.Borehole deployable, inflatable mobile robot concept.
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Origins
The RadioShack robot in all its glory.RadioShack Robot

Once the class knew the conditions at the breach, the serach for a suitable chassis began. Due to the severe time constraints, building the chassis from the ground up was not feasible.

We began looking around the Robotics Institute for past or present projects that we could canabalize to get the parts we needed. The unfortunate victim of this search was the RadioShack robot. This robot was designed as a mock-up of a lunar rover. Since RadioShack was funding the research effort, the robot had a very large RadioShack symbol, hence the name.

The original chassis prior to modifications.ATV Chassis

Underneath the shiny exterior of the RadioShack robot was a solid chassis created when two front-ends for Honda All Terrain Vehicles (ATVs) where welded together. Since all four wheels were "front" wheels, they could all be both powered and steered.

The original chassis with wheels and a few more parts.Chassis with Wheels

After the chassis had been stripped, we inventoried the missing pieces that would be needed to restore the frame to something resembling an ATV. Primary among these components were the hubs and wheels, which are still on Groundhog at the moment, and the components to the second steering column. Shocks for all four wheels were also purchased.

Besides just being able to move, Groundhog needed to be able to map. The initial concept for generating a map was to use a scanning laser range finder produced by a CMU spin-off company, Quantapoint. The Quantapoint scanner uses time-off-flight measurements of a laser pulse to determine the range of nearby objects. By sweeping the laser +/- 45 degrees in the vertical direction and a full 360 degrees in the horiztontal direction, a complete scan of the surrounding area is generated. The only problem with this approach is that the version of scanner we were initially planning on using was very large and would not fit well with the current configuration of the chassis. This inevitablly led to an event refered to as "Chassis-in-a-Day".

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