RC Tank Combat
State-of-the-Art Review for Track Motors and Controllers
Joe Sommer, April 2005
Most operational tanks that have engaged in battles use EV Warrior motors with about 9:1 reduction ratio operating at 12 VDC. Only one operational tank uses 24 VDC. Most tanks weigh 80 to 100 pounds.
Most drive motors pull about 10 to 20 A current each and produce top speed from about 3 to 5 mph. Motors should each provide about 400 in.lbf torque on nominal 4 inch DIA drive sprockets for full-skid turns.
Almost all tanks use forward/off/reverse control with mixing for single joystick operation of two tracks. Only two operational tanks use proportional speed control.
During the 2005 battle season, we will probably see several more tanks upgrade to 24 VDC. Due to the scarcity of EV Warriors, we will see more use of 24 VDC (and perhaps even 36 VDC) scooter motors.
This combination of 12 to 24 VDC and 20 A requires motors controllers that are larger than standard electronic speed controllers (ESC) used in RC monster trucks and 1/16 Tamiya tanks. Our voltage/current requirements are closer to middleweight BattleBots.
Due to cost considerations, most tanks currently use home-made controllers. A few have tried
commercial controllers designed for BattleBots or small industrial vehicles.
An excellent how-to article is available at http://www.rctankcombat.com/articles/speed-control/
The following brief overview of motor control techniques is presented to help new tankers. It is not intended as a critique or sales pitch for any single method. It is by no means complete.
I have tested most of these methods, so I feel comfortable discussing them. Internet links and comments are provided below the table.
The bottom line is that there is no best solution for everyone. You must select
whether you absolutely need proportional speed control and are ready to pay the price,
or if the lower cost and simplicity of forward/off/reverse control is better for your tank.
RoboteQ AX3500 - $395
Wow! Provides proportional control for two tracks with mixing.
Vantec RDFR23 - $325 (bigger versions also available)
Provides proportional control for two tracks with mixing. Vantecs are widely used in BattleBots.
Robot Power OSMC - $209 assembled, $169 kit (need two)
Provides proportional speed control for one track. You will need two OSMCs and a mixer ($90).
(I have not tested this one.)
IFI Victor 883 - $150 plus $15 driver (need two)
Provides proportional speed control for one track. You will need two Victors and a mixer. Almost 20,000 sold.
Diverse Electronics MC7 - $85 (need two)
Provides proportional speed control for one track. You will need two MC7s and one RCIC2_SC mixer $45.
Anvilus Relay SSR Controller - $100
Provides either forward/off/reverse or proportional speed control for two tracks with mixing. You will need two SSRs ($25 each) for proportional speed control.
Anvilus Mini Relay Controller - $25 plus relays
Provides forward/off/reverse control for two tracks with mixing or without mixing. You must provide relays (about $10).
Tri-Pact Speed Control - $22 plus two servos
This is by far, the simplest and most cost-effective method to control two tracks with mixing. Used in more tanks than any other method.
Direct servo control of switches or drill triggers - $?
Simple and cheap
Used in one or two tanks. Difficult to do right-left track mixing for single joystick control.