Combat Robotics - Antweight

Turns out Saskatoon has a big combat robotics community, so of course I had to join! I looked at a lot of antweight (<1lb) robot designs on the web, watched some videos, spoke with some of the veteran builders, and started designing my own.

Putting all my ideas on paper.

Some goals that I had for my design were:

• Simple to manufacture. Some people go all-out and spend hours machining or get their frames waterjet cut. However, I wanted something that's easy to build - especially since I anticipate needing to make replacement parts often.
• Easily assembled. There can be little time between matches to fix your bot. I wanted to make sure mine is easy to pull apart, fix or swap whatever parts need replacement, and put it back together again.
• Can drive upside down. Other bots have wedges and lifter to flip your bot. I wanted to make sure that if my bot was flipped, I wouldn't be paralyzed. So my design had to be thin enough such that the wheels were able to touch the ground while upside down.
• Wedge, but with space for an upgrade. The recommendation for first time builders is to make a wedge. They are easier to build, easier to drive, and are less of a hassle (and hazard) overall. You also get to spend all 454 grams on reinforcing your bot, so it can be as strong as possible. I knew I would get bored of the wedge eventually, so I wanted to design-in a future vertical spinner.

After taking all of the above points into consideration, I came up with a number of different drawings. I settled on the following design (seen in the photo below). 

The chosen design.

I decided to use 0.8mm titanium for the base, back, and side plates and 1mm titanium for the wedge. A lot of other robots in the league have spinning blades or drums, as well as wedges. I thought it would be important to reinforce my bot from all sides. The top, however, isn't as critical, so I used garolite. I intend to use polycarbonate for the wheel protectors, but I may do some experimenting with other materials & designs.

I heard from a lot of builders that it's really important to hammer out your design before you start buying parts and cutting. I used Solidworks to model the bot in 3D. 

CAD mockup of my bot.

Because I'm a visual thinker (and CAD isn't quite as good as real life) I decided to make a cardboard mockup of my design. By doing so, I gained a better perspective on the space I'm working with and realised that I wanted more space inside the bot for a future upgrade - a vertical spinning blade, mounted at the top of the wedge. 

Cardboard mock-up.

Next it was time to build, so I ordered all the parts. FingerTech Robotics, the main supplier (internationally, in fact) for antweight robot parts is local to Saskatoon. So I was able to pick up all my parts that same day! Here are some wheels, motors, nutstrips, a battery charger, and a lot more.

Parts arrived!

This is all of the titanium cut into its shapes. Thankfully Kurtis from FingerTech had a shear cutter and I didn't have to struggle with a zip disk. 

First cuts of the titanium!

The next step was to drill mounting holes for all of the nutstrips and motor hubs. Turns out, drilling titanium isn't the easiest task. The drill press I was using had a wandering bit, which made the process even more challenging. After a few nights of struggling I had pieces that, with a struggle, were able to fit together. The result can be seen below.

Final look of the bot.

Hooking up the electronics is a very easy task as it's all plug and play components. The diagram below shows how everything is connected (courtesy of FingerTech Robotics).

At this point, my bot was almost complete! All I needed was driving practice and some weights at the front of the bot to balance the weight a bit. Unfortunately, due to some other commitments and the lack of time, I never got my bot to 100%. The weights were never attached to the front of my bot, and every acceleration had my wedge up in the area. Nonetheless, my battles where exhilarating, and now I'm more excited than ever to finish my bot.

At the competition, the rookies got to raid a parts bin - so I grabbed two motors, two motor controllers, and two motor hubs. That's almost enough for a whole new bot! So, inspired by Albert, another builder, I will try to bring another bot to the next competition. Nothing fancy, maybe just a 3D printed chassis for trial!