With the premiere of BattleBots Season 2 on the horizon (Thursday, June 23rd at 8PM EST on ABC), we would like to reveal our application design for denkbot!
INTRODUCTION
As many of you may know, our application for BattleBots Season 2 was declined.
The engineering handbook gives us one option after a design has been rejected: Go back to the drawing board.
To be more specific, and to avoid cliches, we will layout the basics of the design process:
- Define the Problem (bound the problem with requirements)
- Gather Information (research existing technologies)
- Brainstorm Ideas (start with ideas, not solutions; be open minded and collaborative)
- Develop Solutions (use CAD; prototype, embrace and learn from failure)
- Collect Feedback (put your solution to the test; trial by fire; be receptive of criticism)
- Improve the Design (continuous improvement)
Below is an info-graphic from the Chicago Architecture Foundation that sums up the design process very well.
We have received feedback, now it is time for us to improve our design!
To begin, we will do a full reveal of our BattleBots Season 2 Application!
THE REVEAL
Say hello to denkbot!
Figure 1 – denkbot overhead view
This low-profile destroyer features a powerful lifting arm and wields a devastating spinning drum. The primary weapon is the high RPM toothed spinning drum on the back of the robot. The secondary weapon is the lifting recessed in the low-profile chassis which compliments the spinning drum, as opponents travailing over the skirted frame can be redirected into the spinning drum via the lifting arm.
Figure 2 – denkbot interior view
Tightly packed motors, controllers, and batteries provide security for denkbot’s electronics in the interior of the chassis superstructure. Recessed wheels within the frame provide protection and ensure mobility throughout the match.
Figure 3 – denkbot motion animation
Bill of Materials
CHASSIS_MECHANICAL (Subtotal: $453.42)
Like every good robot, it all starts with the chassis. Hand crafted from the finest 6061 aluminum, this chassis is the rock upon which we build our denkbot.
| Item | Price | QTY | Item/Link | Name | Details |
| Drive Assembly | $226.71 | 2 | n/a | EXTRUDED ALUMINUM BARE SQUARE 6061 T6511 | Eight Ft. (96″ Length) – |
- CHASSIS_ELECTRICAL (Subtotal: $1,337.46)
Every robot needs a heart. Like the dashing Gene Wilder, we breathe life into our creation with the electrical potential of batteries! Specifically Lithium Polymer (LiPO) batteries via a Bussman Power Distribution Block (P.D.B.) and Hella Master Power Switches.
| Item | Price | QTY | Item# | Name | Details |
| Master Switch | $23.99 | 2 | Part# 0-SWHELLA1 | Hella Master Power Switch | Surge current: up to 1000 amps |
| P.D.B. | $289.00 | 1 | Mfr. Model # 16541-1 | Bussman P.D.B. | P.D. Block, 380A, 1P, 21P Secndary, 600V |
| Fuse | $50 | 6 | TPL-350 | Bussman DC P.D. Fuse | TPL-CO Rated 170VDC and below, 350A |
| Battery | $87.56 | 8 | ZC.4500.10S.3 | ZIPPY Compact LiPO Pack | 4500mAh; Voltage: 10S1P / 10 Cell / 37V |
- MOTION_MECHANICAL (Subtotal: $811.00)
To propel this destructive superstructure, we require the finest wheels, bearings, and gears available to modern humans. We choose the AmpFlow Gearmotor for its proven combat record in the battle-box and its compact package.
| Item | Price | QTY | Item/Link | Name | Details |
| Wheels | $25.00 | 4 | 4W | 4 Inch Wheel | Part of AmpFlow Gearmotor |
| Speed Reducer | $170.00 | 4 | 0SR | Speed Reducer | Part of AmpFlow Gearmotor |
| Wheel Bearing | $7.75 | 4 | 4XFJ2 | Needle Brg | Drawn Cup, Bore 0.750 In |
- MOTION_ELECTRICAL (Subtotal: $1,155.00)
When it comes to motion in combat robotics, one brand stands above the rest (maybe somebody should sponsor us for this high praise *wink-wink-nudge-nudge*). The AmpFlow A28-400 is the motor Daedalus would have choosen for his creations if he had had access to commutated direct current motors… or electricity for that matter.
| Item | Price | QTY | Item# | Name | Details |
| Drive Motor | $330 | 2 | A28-400 | A28-400 | Peak 4.3 Horse Power |
| Motor Controller | $495 | 1 | AmpFlow160 | Dual Motor Speed Controllers | 6 to 42 Volts; 160 Amps per channel |
- DRUM_MECHANICAL (Subtotal: $465.01)
The primary payload of this calamity rig is the drum spinner. Born from the hardiest dwarven forges, our drum is constructed of 316 Cold Finish Stainless Steel.
| Item | Price | QTY | Item/Link | Name | Details |
| Drum Core | $395.25 | 1 | n/a | COLD FINISH STAINLESS ROUND 316/316L | Three Ft. (36″) Length |
| Drum Teeth | $34.88 | 2 | n/a | COLD FINISH STAINLESS SQUARE 316/316L ANNEALED | Five Ft. (60″) Length |
- DRUM_ELECTRICAL (Subtotal: $825.00)
Seriously though, have you seen the specs on these AmpFlow A28-400 motors? They are like the Swiss Army Knife of high performance brushed DC motors… I bet McGyver could stop an entire army if he had a few of these things sitting around. (Please make all sponsorship checks payable to denkbots)
| Item | Price | QTY | Item# | Name | Details |
| Drive Motor | $330 | 1 | A28-400 | A28-400 | Peak 4.3 Horse Power |
| Motor Controller | $495 | 1 | AmpFlow160 | Dual Motor Speed Controllers | 6 to 42 Volts; 160 Amps per channel |
- LIFTER_MECHANICAL (Subtotal: $226.71)
The co-pilot on this wreck master is the lifter. Simple, yet effective, this lifting arm is built from all natural, free range, 6061 aluminum.
| Item | Price | QTY | Item/Link | Name | Details |
| Lifter Material | $226.71 | 1 | n/a | EXTRUDED ALUMINUM BARE SQUARE 6061 T6511 | Eight Ft. (96″ Length) – |
- LIFTER_ELECTRICAL (Subtotal: $374.95)
IT’S ROBOT LIFTING TIME! We use a Leeson gearmotor to do our lifting. The right-angle shaft allows us to fit the motor in our low-profile design, so we can make sure we are underneath everyone… all of the time.
| Item | Price | QTY | Item# | Name | Details |
| Leeson Gearmotor | $374.95 | 1 | T9FB234768 | Leeson Gearmotor-Right-Angle Shaft | 58RPM; 1/4HP; TENV;12VDC |
- TxRx (Subtotal: $99.00)
The cherry on top is the communication system. Using the tried and true Planetary Rover Transmitter and Receiver (TxRx), we can be sure that our denkbot hears our call!
| Item | Price | QTY | Item# | Name | Details |
| TxRx | $99.00 | 1 | 0-PRRCS | Planetary Rover Radio Control System | 6-Channel 2.4GHz |
denkbot Grand Total: $5,747.55
SUMMARY
After this overview of denkbot’s initial design, several areas for improvement can be identified. We will be exploring these improvements next week, along with the reveal of our redesign for denkbot! If you have any suggestions for our redesign, part selection, or just general observations please leave them in the comments below, we would love to hear from you!
If you have enjoyed the articles we have written so far and would like to follow along with our Season 3 redesign/build and future content please like on Facebook; follow on Twitter, Instagram, Flickr, and Google+; subscribe on YouTube; and fumble on Tumblr!
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The cost breakdown forgets armor, fasteners, pulleys/belts, drum shaft, or spares of anything, and seemingly only accounts for half the motors in the CAD images. 6061 isn’t impact resistant enough for a structural material on a combat robot. 7075 is much tougher with the same density, but most BattleBots use hardened steel or 6Al-4V titanium. Your frame and especially your lifter would deform when hit by other spinners. Impact force is proportional to the hardness of the materials in the collision, but your stainless steel teeth would be very soft – again, deforming on impact. S-7 tool steel hardened to exactly HR54C is what most builders use. Stronger and harder than stainless so it delivers more of the drum’s stored energy and does so without blunting. You have a 17.3 hp drivetrain but only 1/2 hp lifter. Each of your lifter motors is only rated for 158 in-lbs of torque, which gives a combined rating of 316 in-lbs. Lifting force is torque divided by the length of the lifting arm. If your lifting arm was even 24 inches long, it would only be rated to lift 13.2 lbs without damaging either the motors or the gearboxes. This falls way short of the 250 lbs required to lift a BattleBot. You’ve allocated a single 160A ESC channel per drive motor, but your drive motors stall at almost 600A. Most builders use a pair of 250A ESCs for each drive motor. Also, you’ll never see an experienced builder using a fuse in a combat robot. Fuses are meant to save money by protecting other electrical components by being the first thing to blow. Combat robots are not meant to save money. They’re meant to sacrifice electrical and mechanical components if necessary in order to squeeze every ounce of performance out of their parts and materials. Your fuse should be the parts themselves. Better to lose a match because your motor burned through its windings or your batteries started on fire than because a fuse blew. Especially in BattleBots, where you need to win every fight or be eliminated. No company is going to sponsor a team based on a reference on a website. You need to contact them in person with a solid business proposal. Show them what they’re getting in return for the parts they’re giving you. More importantly, show them (and the BattleBots selection committee) that you have the experience necessary to build a competent robot. You should begin by competing in lighter weight classes at smaller events. It’ll save you a lot of money while you’re still learning how to build a proper combat robot. Read this: http://riobotz.com/en/tutorial/ and join here: https://www.facebook.com/groups/RobotCombat/ and start asking a lot of questions.
Thank you so much for the feedback! We are just beginning our design for Season 3 and we will definitely be utilizing these resources moving forward!