• 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 QTI line sensors, stainless steel scoop, heavy steel ballast, screws, wrenches, and stand-offs for mounting your control board!
• The Cobra now includes two on-board motor controllers, three QTI analog/digital line sensors, and a bright blue LED power indicator.
• Special introductory price - may go up at any time!
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)
||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, QTI line sensors (two front, one rear), and a bright blue LED power indicator.
||Four 50:1 Gold Spark Gearmotors are epoxied and soldered in place.
||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.
||Four FingerTech Mini-Sumo Wheels. Shore A20 polyurethane - the highest traction mini-sumo wheels available.
||Includes three QRD1114 line sensors (2 front, 1 rear) wired into QTI configuration for digital or analog operation. Three headers connect to your control board. A circuit diagram is printed on the pcb.
||0.020" stainless steel angled scoop (can be legally sharpened to 0.010")
||An underweight mini-sumo is at a disadvantage! This steel ballast keeps the center of gravity low.
||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 fro
Two hex wrenches included for tightening screws and setscrews.
||Full-color assembly steps, wiring diagram, header pinouts, and sensor/motor controller instructions. Cobra_instructions_R2.pdf
||The chassis has a spot to accomodate a 44x24x29mm (1.75x0.93x1.15") battery. Our Rhino 11.1V 360mAh or Nanotech 11.1V 180mAh fit perfectly and will run the robot for dozens of matches. Min/Max Voltage: 6V-16V.
||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.
||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 checkout comments. (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
PIN 13 to Left motor PWM pin
PIN 12 to Right motor PWM pin
PIN 6 to Left motor DIR pin
PIN 5 to Right motor DIR pin
PIN 10 to Left line sensor power (W)
PIN 9 to Left line sensor input (R)
PIN 7 to Right line sensor power (W)
PIN 8 to Right line sensor input (R)
(Both line sensor B lines tie to Vss)
PIN 4 to Left IR LED output
PIN 11 to Left IR sensor input
PIN 15 to Right IR LED output
PIN 14 to Right IR sensor
PIN 1 to Piezo speaker (other side to VSS)
PIN 0 to StartLED (other side to 470R to VSS)
PIN 2 to added RightLED (optional - for displaying which sensor sees opponent)
Cobra GND to SumoBot Board VSS
Cobra VIN to SumoBot Board servo power (the middle pin from either of the two servo connector headers) - this allows you to turn the switch to position 1 and program/test without powering the motors. Position 2 adds power to the motors.
Battery wired to SumoBot board. Battery connector on Cobra unused.
Sample Code: SumoBot - Cobra V2 Basic Competition Program 1.0.bs2