Bulldog Bots Combat Robot

Sep 11’ –May 13’

Introduction:

The BulldogBots combat robot is a collective effort by a team of engineering students lead by myself throughout the various stages of research, development, design and finally manufacturing. The original bot produced by the club was a flipper design. They had only a one-year design and build cycle which proved to be ineffective in actual combat. We decided to increase the timeline for the design and construction to allow for the refinement of design and also to allow time to accrue funding for the bot.


Specifications:

Looking at other combat bots in the past, it appeared that high kinetic energy bots did the best in combat. We picked a horizontal spinner design in effort to maximize the potential kinetic energy output while keeping the design within the weight constrains. Using two brushless motors to drive the weapon system we have a theoretical output of 13HP using the 120Amps peak Kelly Brushless, sensored motor controllers.

To power it I have a customdesign A123 LifePO4 battery pack that will be spot welded together. The battery cells have the capability of 10 second discharge of 120Amps and 70 amps continuous with proper cooling. We plan to have 72 cells in the bot total and run the weapon on 44V and drive system on 22V. This should give us a competitive advantage by having a large high output battery pack. We designed a customcontrol system for the bot that will allow for two-way communication between the bot and the driver using Arduino microcontroller and XBEE 2.4GHZ wireless chips. This will allow us to view the condition of internal systems like battery voltage and motor temperature during combat. A custom GUI computer interface will allow for the use of different USB controllers and configurations for future combat robots.


Build Process:

The frame, weapon, and other components went through many design alliterations in Solidworks until we came up with the design shown above. The initial design for the bot only took about a week but went through another year of refinement. FEA was done on the frame and changed the design of the weapon assembly to lower the overall weight while still being theoretically structurally sound for combat. The components were purchased after the design was made and the build process began in early 2013. We used the OMAX waterjet in UMD ME department to cut out the frame pieces and had a local welder assemble the frame. Custom 3D printed motor mounts hold in the 18V Dewalt motors for each of the drive wheels.