Delta Force Mini Sumo Robot

September 2001

Delta Force Delta Force


Delta Force is the second robot I designed to compete in autonomous mini sumo contests. I originally intended to build a simple wedge bot target drone to aid in developing defense strategies for my other sumo bot ROBOR. It worked much better than I thought. It beats ROBOR in every match except ones contrived to put Delta Force at a severe disadvantage.

Delta force took about three weeks to build. I reused most of the programming code from ROBOR. If you want to see schematics and source code click here to download a zip file. The schematics are large gif images suitable for printing.


Feb. 15 2003: Delta Force wins AHRC 2003 Robot Rally Mini Sumo contest for the second time and remains undefeated. This year I replaced the 2 AAA batteries with a 9 volt battery. This increased the motor voltage from 12 to 18. Delta force is almost 50% faster than it was last year and had no trouble defeating it's opponents.

Feb. 9 2002: Delta Force wins AHRC 2002 Robot Rally Mini Sumo contest and remains undefeated. Click here for pictures. Delta Force has some additional features not present when this page was originally published. I added 2 AAA batteries to increase the power supply to 12 volts and added a drop-down false white line on the rear to help prevent rear end attacks. There is also a rubber brake pad on the bottom rear to prevent being pushed backward when the front end is lifted.

Data Sheet
Size 9.9cm(W) x 9.9cm(L) x 6.8cm(H)
Weight 498 grams
CPU PIC16F877-20/SP with 16 MHZ Crystal
8K ROM 368 Byte RAM
Motors Two Lego 350 RPM 9 volt gear motors
Motor driver
Speed Control Software generated Pulse Rate Modulaton with Back-EMF feedback. Pulse width is constant.
Tires Two 30.4 mm diameter Lego tires
Wheels Custom made steel
Drive system Direct drive from Lego motor shaft
Speed 36 cm/sec
Pushing force 450 grams (wheels spinning)
Power Two Alkaline 9 volt batterys
Motor Current 60mA crusing, 400 mA pushing
Sensors Two reflective IR sensors for edge detection
Custom two channel active IR to locate opponents
Telemetry Connector for external transmitter
Linx TXM-418-RM (9600 baud 418 MHZ)

Delta Force bottom view

Bottom view.

Rear disassembled view

Rear view.

Active IR sensor board visible.


Side disassembled view

Side view, disassembled.


Active IR sensor board

Closeup of the active IR sensor board.

Small black device in center is an IR pin photo diode.  Two pairs of high power IR LEDs are on the left and right sides. They are pulsed at 1/2 amp, 500 times per second.


Controller board

Controller board.



Custom steel wheel, Lego tire, stock Lego wheel

Using steel for the wheel material added 48 grams above the weight using stock lego wheels.


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