As strange as it may seem, the world has now grown accustomed to the site of DIY robots duking it out in the field of battle. Beginning on Comedy Central in 2000 and resurrected for ABC in 2015, the show BattleBots has taken what was previously seen as a nerdy endeavor—the design of robots—and showcased it for what it truly is: ingenious awesomeness.
Now that drones and quadcopters have taken flight into the cultural zeitgeist, as well, it's about time that robots from both the ground and air start kicking some tin can keisters. For the latest season of the series, BattleBots has broadened its bot base to include flying robots.
With only six weeks to create a battle drone for the show, MBS Robotics relied on 3D printing to create its robotic warrior, AfterByte. The robotics team, which manufacturers bots and custom electronics in Edmonton, Canada, first used fused deposition modeling (FDM) to 3D print the body for its drone in ABS plastic.
While the team claimed that the extruded, plastic body could handle the weight of the drone's two aluminum arms, the design ultimately failed. The FDM body would split due to the Z-axis weaknesses between layers. MBS Robotics then turned to the Form 2 stereolithography (SLA) 3D printer from Formlabs, even going so far as to replace the aluminum arms with SLA parts.“As far as the FDM versus SLA differences go, our engineers did a few not-too-scientific ‘hammer’ tests to find the point of failure on the different materials,” explained Lucas Sloan, Team Captain and main bot driver for MBS Robotics.“ Formlabs' tough resin required surprising effort to damage critically, whereas the FDM print predictably failed between layers (delaminating as we call it) with little effort. This was the most obvious problem with FDM.”
He added, “Where it got interesting was that in order to increase the strength of a FDM print we had to print with more shell layers and increase surface area. This distributed the stress between layers, but also increased the surface area to the point that the drone was huge and the frame was creating a significant amount of resistance to the downward moving air.”
Altogether, the SLA-printed AfterByte was capable of handling all 10 lbs of mass. Sloan said, “By switching to the Form 2 we were able to cut our surface area by more than half and the total wing span (diagonally from blade tip to blade tip) from 52 in down to 34 in. By doing this, we not only found the Form 2 frame to be stronger, but also a better flying frame, despite a minor increase in weight.”Additionally, due to the detail and precision of SLA, the overall design was improved. The MBS team was able to 3D print complex parts with hidden interior channels through which wires could be weaved. Multiple parts were then welded together to assemble the larger structure, resulting in a design impossible with traditional manufacturing techniques.
While all over the prototypes for AfterByte were 3D printed with Formlabs' tough resin, MBS ultimately printed two complete drones, one in tough resin, for the final battle, and one in clear as a means of showcasing the drone's overall design, as the material made it possible to see the wires installed into the internal channels of the robot's frame.
MBS Robotics further leveraged the Form 2 to 3D print a landing pad from flexible resin. Attached to the 3D-printed pad were a Dyson vacuum motor, allowing AfterByte to attach itself to competing bots with a force of over 4 psi, and a Dewalt impact drill held in place by a 3D-printed mount made from Formlabs' tough resin. Combined, AfterByte had the ability to clamp onto another robot and lay into it with the drill with 120 ft lb of power.AfterByte made its TV debut on May 10th on ABC's season 2 teaser episode "BATTLEBOTS: The Gears Awaken.” Fast forward to minute 17 or so to see MBS compete on the ABC website or you can watch some footage of AfterByte performing safety tests in the clip below. Sloan said that AfterByte and MBS's ground bot, Basilisk, will receive updates and upgrades in the future, explaining, “Any robot builder will tell you that building their perfect bot is a never ending adventure.”
For those interested in building AfterByte at home or in the shop, MBS has released the free STL files for the AfterByte MINI on Pinshape. According to Sloan, “even with just $9.00 motors, the AfterByte MINI is a ninja."