Electronic speed controller
From Combat Robot
An Electronic speed controller (ESC) acts like a switch that very rapidly turns current to the motor on and off -- more 'on' time in relation to 'off' time results in greater total power to the motor and more speed. This switching action wastes less power than a simple resistance potentiometer, and the ESC is smaller and weighs less as well. R/C servos have a low-power ESC as part of their structure.
ESCs are rated by the amperage they can supply without thermal failure. This is typically expressed as continuous amps for a given time period, such as: 30 amps for 5 minutes, 20 amps continuous, 55 amps peak. Many 'hobby' ESCs for R/C cars have misleading specifications based entirely on the peak rating of the individual electronic components that has no basis in the real world.
Note that overvolting a motor causes a proportional increase in amperage. Failure to account for this can result in a blown ESC. See the article on Stall current for guidance in determining ESC capacity.
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For Drive
ESCs suitable for combat robotics drivetrains have the ability to reverse the motor direction. Some builders prefer controllers that use regenerative braking when the signal is centered for more control. Many hobby ESCs have an undesirable "reverse delay" function that pauses response before allowing reverse operation and slows robot response time. A robot utilizing the translational drift drive would require an ESC capable of very rapid switching, but might not require a reverse function.
For Weapons
Specialized 'forward only' ESCs like the Victor 833 SC are suitable for some types of weapon control. While electronic speed control may cost more than a mechanical contactor of equal current rating, ESCs allow for proportional control (slow/fast) that lets you "ramp up" the power to avoid a large current drain and voltage drop when starting up a spinning weapon.
For Brushless Motors
Brushless motors require specialized circuitry to replace the function of the commutoator and brushes in conventional motors. This circuitry is included in speed controllers for brushless motors. Because of this extra circuitry, ESCs for brushless motors cannot be used for brushed motors, and vice-versa.
External Links
- 4QD PRO 120 for large 'bots.
- Barello antweight ESCs.
- IFI Victor ESCs - hobbyweights and up.
- Sozbot ESCs for antweights.
- Vantec for large 'bots.
