FingerTech 'Cobra' Mini-Sumo Chassis

Price: 166.67 CAD
List Price: 213.57 CAD
123.36 USD 119.00 EUR
In Stock: 0

• Designed to be a competitive entry into the masters class of mini-sumo, this chassis has the ability to beat those big-wheeled servo bots every single time.

• Includes 4WD Gold Spark motors, four high-traction mini-sumo wheels, two on-board motor controllers, three QRE1113 line sensors, stainless steel scoop, heavy steel ballast, screws, wrenches, and stand-offs for mounting your control board!

  • Description
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• Designed to be a competitive entry into the masters class of mini-sumo, this chassis has the ability to beat those big-wheeled servo bots every single time.
• Includes 4WD Gold Spark motors, four high-traction mini-sumo wheels, two on-board motor controllers, three QRE1113 line sensors, stainless steel scoop, heavy steel ballast, screws, wrenches, and stand-offs for mounting your control board!

New Cobra R5!
• The Cobra R5 has a slide on-on-off power switch so you can turn power on to the whole robot or just the control board (for testing sensors and code), with power LEDs for each.
• Buttons for testing the on-board motor driver circuitry without need for a control board.
• QRE1113GR lines sensors that can be read with an analog input - no need to charge a capacitor and deal with timing!
• Indicator LEDs on each Line Sensor so you can see what the sensor sees!

 • Previous version Cobra R4 introduced two on-board motor controllers, three QTI analog/digital line sensors, and a bright blue LED power indicator.

The Cobra conforms to the mini-sumo ruleset of RoboGames, the world's largest robot competition. Most events uses these rules, but always check with your event organizer to make sure.
Width: 9.9cm (3.90")
Length: 9.75cm (3.84")
Height (ground to top of standoff): 3.77cm (1.48")
Weight: 333grams (11.75oz) - Maximum allowed in competition is 500g (17.63oz)

Kit Includes:
PCB Chassis:The Cobra baseplate is a circuit board that has mounting holes for the scoop, ballast and standoffs.  The newest revision includes on-board motor controllers, QRE1113GR digital/analog line sensors (two front, one rear) with green LED indicators, and bright red and blue LED power indicators.
Motors:Four 50:1 Gold Spark Gearmotors are epoxied and soldered in place.
Motor Control:The Cobra has two on-board motor drivers (left and right). To operate them, you will need to connect their DIR (direction) and PWM (speed) pins to a microcontroller. For DIR, 5V is forward direction and 0V is reverse. The PWM pins require a 5V pulse-width-modulated waveform for smooth operation.
Wheels:Four FingerTech Mini-Sumo Wheels.  Shore A20 polyurethane - the highest traction mini-sumo wheels available.
Line Sensors:Includes three QRE1113GR line sensors (2 front, 1 rear) wired for digital or analog operation. Three headers connect to your control board.
Scoop:0.020" stainless steel angled scoop (can be legally sharpened to 0.010" per RoboGames rules)
Steel Ballast:An underweight mini-sumo is at a disadvantage!  This steel ballast keeps the center of gravity low.
Screws:Four 6-32x0.375" screws for mounting the scoop, ballast and stand-offs.  Four for securing circuit board to standoffs.  Four washers for spacing ballast from pcb. Two hex wrenches included for tightening screws and setscrews.
Instructions:Full-color assembly steps, wiring diagram, header pinouts, and sensor/motor controller instructions. Cobra_instructions_R5.pdf (Cobra_instructions_R4.pdf)

Battery:The chassis has a spot to accomodate a 44x24x29mm (1.75x0.93x1.15") battery.  Our Galaxy 7.4V 300mAh or Galaxy 11.1V 180mAh fit perfectly and will run the robot for several matches.  Min/Max Voltage: 6V-16V.
Electronics:In the chassis kit, the brains are up to you.  We carry the user-friendly Arduino Uno's, but boards from the SumoVore, Mark III, or SumoBot will all work.  Use the PCB Mount Kit to fit boards with different hole patterns.
Sensors:Opponent detection can be anything you desire.  Infrared emitters/sensors are most common, but ultrasonic sensors are an option too.

Orders normally ship within 1-2 days. Other Gold Spark motor ratios can be used for an additional $10 fee - please add a note in the Additional Comments section of checkout for which ratio you would like. (35:1 is the most commonly used after the default 50:1, but make sure your sensors can react fast enough to the increased speed!)
 You can use a variety of boards to control your Cobra chassis. We have begun writing sample code for different systems. Coming up are Arduino, Parallax, Mark III, and Sumovore.

Parallax SumoBot Board (Cobra R4)

SumoBot Board P13 to Cobra Left motor PWM pin
SumoBot Board P12 to Cobra Right motor PWM pin
SumoBot Board P6 to Cobra Left motor DIR pin
SumoBot Board P5 to Cobra Right motor DIR pin

(Line sensors)
SumoBot Board P10 to Cobra Left line sensor power (W)
SumoBot Board P9 to Cobra Left line sensor input (R)
SumoBot Board P7 to Cobra Right line sensor power (W)
SumoBot Board P8 to Cobra Right line sensor input (R)
(Both Cobra line sensor B lines tie to SumoBot Board Vss)
(SumoBot Board only uses the two front line sensors by default.)

(The two opponent sensors are wired by plugging components into the SumoBot Board as described in the next four lines)
SumoBot Board P4 to Left IR LED output
SumoBot Board P11 to Left IR sensor input
SumoBot Board P15 to Right IR LED output
SumoBot Board P14 to Right IR sensor

(The piezo speaker and LEDs are wired by plugging components into the SumoBot Board, as described in the next three lines)
SumoBot Board P1 to Piezo speaker (other side to VSS)
SumoBot Board P0 to StartLED (other side to 470R to VSS)
SumoBot Board P2 to added RightLED (optional - for displaying which sensor sees opponent)

SumoBot Board VSS to Cobra GND
In Cobra R5: SumoBot Board servo power to Cobra BATT (Servo power is the middle pin from either of the two servo connector headers)
[In Cobra R4: SumoBot Board servo power to Cobra Vin. (Servo power is the middle pin from either of the two servo connector headers) Battery wired to SumoBot Board. Battery connector on Cobra R4 is unused. This allows you to turn the SumoBot Board switch to position 1 and program/test without powering the motors. Position 2 adds power to the motors.]

 Sample Code: SumoBot - Cobra V2 Basic Competition Program 1.0.bs2

Arduino Uno
While we work on full instructions, here is a quick code sample to get your motors driving!

Arduino PIN 3 to Cobra Right PWM
Arduino PIN 4 to Cobra Right DIR
Arduino PIN 5 to Cobra Left PWM
Arduino PIN 6 to Cobra Left DIR
Arduino Gnd to Cobra GND
Arduino Vin to Cobra BATT
Battery plugged into Cobra rear 2-pin connector.

 Sample Code:
// Arduino Motor Control - sweeps both motors back and forth
int sweep = 255;
int dir = 1;
//Pin hookups:
int PWMR = 3; // use analogWrite(PWMR,val) to control the Right motor speed
int DIRR = 4; // use DigitalWrite(DIRR,val) to control the Right motor direction
int PWML = 5; // use analogWrite(PWML,val) to control the Left motor speed
int DIRL = 6; // use DigitalWrite(DIRL,val) to control the Left motor direction

void setup() {
pinMode(PWMR, OUTPUT); // sets the pin as output
pinMode(PWML, OUTPUT); // sets the pin as output
pinMode(DIRR, OUTPUT); // sets the pin as output
pinMode(DIRL, OUTPUT); // sets the pin as output

void loop() {
for(sweep = 255; sweep >= 30; sweep -= 20) {
digitalWrite(DIRR, dir); // R motor direction forward
digitalWrite(DIRL, dir); // L motor direction forward
analogWrite(PWMR, sweep); // R motor speed
analogWrite(PWML, sweep); // L motor speed
if(dir==0) dir=1; else dir=0; // change motor direction

Here is a quick video showing the top speed using 50:1 Spark motors at 11.1V.
9 Product Reviews - Average rating 4.9 / 5 (Show All)
Excellent Platform - Super Support
- 28th April 2016
We ordered one of the Cobra chassis for our high school robotics program. It arrived in perfect shape, but we had issues with the left motors. Kurtis from FingerTech was excellent at helping diagnose the issue, then actually fixing the board for us. When the board failed again, FingerTech was again excellent at supporting us. I don't know if the issue was a problem with the onboard motor driver or the students plugging things in wrong. Either way, FingerTech was great to deal with.
First Robot Build
- 20th October 2015
This is a great product and they give great support. I was making a simply mistake wiring my Mini-Sumo Chassis for a combat robot with their Tiny ESC and Tiny Mixer but within a couple hours of me emailing asking them about it I had a friendly and fully informative response of how to fix it. I will definitely be ordering more items from them for future combat robot builds. The shipping speed is excellent with me living in the United States and them being based out of Canada. Most of my packages where received within a week of ordering.
Cobra - mini sumo robot
- 25th February 2015
The FingerTech Cobra is one of the best sumo robot chassis we have tested. Being a robot competitor itself, FingerTech knows what is needed for such a robot.
- 25th February 2015
A great kit. Goes together in literally like 2 minutes. Super high quality. I preordered the version with built in motor drivers and it was definitely worth the wait. Now my kids want one.
- 15th July 2014
It arrived completely perfect, and I'm very impressed by this chassis. The on-board circuitry helps a lot, and the motors are really powerful. Cannot wait to test it in a competition!
- 21st March 2014
I tested every motor with an H Bridge and very closed delays and they respond extremely nice. Everything came in order except for one thing,one motor wasn't well pasted and came hanging in the bag, but after a quick fix everything was in order. [FT: we now ship differently!]
Very nice product :D I'm using this for a competition, just looking for some nice sharp sensors, good servos and already making my hand made aluminum body. 4.6/5
Very good design, but not very well protected in the package
- 30th April 2012
That's a very good design. I like the ballast, wheels and motors. But the chassis didn't come well packaged because a motor was unstuck when it arrived at my home. [We have listened and now pack the Cobra's differently. Thanks! -FingerTech]
Superb Machine!
- 06th March 2012
The description doesn't do it justice. The ballast is BELOW the garolite chassis for a mighty low center of gravity. The force required to push it side-ways on my desk while parked easily exceeded 1 kgf, so the tyres are pure magic at gripping smooth surfaces. When it hits my older sumo-bot the Cobra simply plows it out of the way like it wasn't even there! Impressive!
Great starter and competition kit
- 24th February 2012
I have been very impressed with this kit and can't wait to get it into a competition. See images and project details at
FingerTech Mini-Sumo Wheels (pair)

• Want to be at the top of the minisumo class but your robot's wheels keep slipping?  Look no further!
• Top-quality competition wheels made from high-traction polyurethane and injection-molded hubs.

FingerTech 'Cobra' PCB Mount Kit
• Using the Cobra chassis with an existing circuit board?  You'll need a good way to mount that PCB!
• This PCB Mounting Kit makes easy work of boards with different hole layouts.
Kingduino Uno R3
Kingduino Uno R3 - 26.13 CAD

• Give your robot a brain!  The Kingduino Uno is an excellent control board for the Cobra Mini-Sumo Kit.
• Interfaces easily with a myriad of sensors.
• Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It's intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.

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